--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1CollectedHeap.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,5371 @@
+/*
+ * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/metadataOnStackMark.hpp"
+#include "classfile/stringTable.hpp"
+#include "classfile/symbolTable.hpp"
+#include "code/codeCache.hpp"
+#include "code/icBuffer.hpp"
+#include "gc/g1/bufferingOopClosure.hpp"
+#include "gc/g1/concurrentG1Refine.hpp"
+#include "gc/g1/concurrentG1RefineThread.hpp"
+#include "gc/g1/concurrentMarkThread.inline.hpp"
+#include "gc/g1/g1Allocator.inline.hpp"
+#include "gc/g1/g1CollectedHeap.inline.hpp"
+#include "gc/g1/g1CollectionSet.hpp"
+#include "gc/g1/g1CollectorPolicy.hpp"
+#include "gc/g1/g1CollectorState.hpp"
+#include "gc/g1/g1EvacStats.inline.hpp"
+#include "gc/g1/g1FullGCScope.hpp"
+#include "gc/g1/g1GCPhaseTimes.hpp"
+#include "gc/g1/g1HeapSizingPolicy.hpp"
+#include "gc/g1/g1HeapTransition.hpp"
+#include "gc/g1/g1HeapVerifier.hpp"
+#include "gc/g1/g1HotCardCache.hpp"
+#include "gc/g1/g1OopClosures.inline.hpp"
+#include "gc/g1/g1ParScanThreadState.inline.hpp"
+#include "gc/g1/g1Policy.hpp"
+#include "gc/g1/g1RegionToSpaceMapper.hpp"
+#include "gc/g1/g1RemSet.inline.hpp"
+#include "gc/g1/g1RootClosures.hpp"
+#include "gc/g1/g1RootProcessor.hpp"
+#include "gc/g1/g1SerialFullCollector.hpp"
+#include "gc/g1/g1StringDedup.hpp"
+#include "gc/g1/g1YCTypes.hpp"
+#include "gc/g1/heapRegion.inline.hpp"
+#include "gc/g1/heapRegionRemSet.hpp"
+#include "gc/g1/heapRegionSet.inline.hpp"
+#include "gc/g1/suspendibleThreadSet.hpp"
+#include "gc/g1/vm_operations_g1.hpp"
+#include "gc/shared/gcHeapSummary.hpp"
+#include "gc/shared/gcId.hpp"
+#include "gc/shared/gcLocker.inline.hpp"
+#include "gc/shared/gcTimer.hpp"
+#include "gc/shared/gcTrace.hpp"
+#include "gc/shared/gcTraceTime.inline.hpp"
+#include "gc/shared/generationSpec.hpp"
+#include "gc/shared/isGCActiveMark.hpp"
+#include "gc/shared/preservedMarks.inline.hpp"
+#include "gc/shared/referenceProcessor.inline.hpp"
+#include "gc/shared/taskqueue.inline.hpp"
+#include "logging/log.hpp"
+#include "memory/allocation.hpp"
+#include "memory/iterator.hpp"
+#include "memory/resourceArea.hpp"
+#include "oops/oop.inline.hpp"
+#include "prims/resolvedMethodTable.hpp"
+#include "runtime/atomic.hpp"
+#include "runtime/init.hpp"
+#include "runtime/orderAccess.inline.hpp"
+#include "runtime/vmThread.hpp"
+#include "utilities/align.hpp"
+#include "utilities/globalDefinitions.hpp"
+#include "utilities/stack.inline.hpp"
+
+size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
+
+// INVARIANTS/NOTES
+//
+// All allocation activity covered by the G1CollectedHeap interface is
+// serialized by acquiring the HeapLock. This happens in mem_allocate
+// and allocate_new_tlab, which are the "entry" points to the
+// allocation code from the rest of the JVM. (Note that this does not
+// apply to TLAB allocation, which is not part of this interface: it
+// is done by clients of this interface.)
+
+class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
+ private:
+ size_t _num_dirtied;
+ G1CollectedHeap* _g1h;
+ G1SATBCardTableLoggingModRefBS* _g1_bs;
+
+ HeapRegion* region_for_card(jbyte* card_ptr) const {
+ return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
+ }
+
+ bool will_become_free(HeapRegion* hr) const {
+ // A region will be freed by free_collection_set if the region is in the
+ // collection set and has not had an evacuation failure.
+ return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
+ }
+
+ public:
+ RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
+ _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
+
+ bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
+ HeapRegion* hr = region_for_card(card_ptr);
+
+ // Should only dirty cards in regions that won't be freed.
+ if (!will_become_free(hr)) {
+ *card_ptr = CardTableModRefBS::dirty_card_val();
+ _num_dirtied++;
+ }
+
+ return true;
+ }
+
+ size_t num_dirtied() const { return _num_dirtied; }
+};
+
+
+void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
+ HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
+}
+
+void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
+ // The from card cache is not the memory that is actually committed. So we cannot
+ // take advantage of the zero_filled parameter.
+ reset_from_card_cache(start_idx, num_regions);
+}
+
+// Returns true if the reference points to an object that
+// can move in an incremental collection.
+bool G1CollectedHeap::is_scavengable(const void* p) {
+ HeapRegion* hr = heap_region_containing(p);
+ return !hr->is_pinned();
+}
+
+// Private methods.
+
+HeapRegion*
+G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
+ MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
+ while (!_secondary_free_list.is_empty() || free_regions_coming()) {
+ if (!_secondary_free_list.is_empty()) {
+ log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
+ "secondary_free_list has %u entries",
+ _secondary_free_list.length());
+ // It looks as if there are free regions available on the
+ // secondary_free_list. Let's move them to the free_list and try
+ // again to allocate from it.
+ append_secondary_free_list();
+
+ assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
+ "empty we should have moved at least one entry to the free_list");
+ HeapRegion* res = _hrm.allocate_free_region(is_old);
+ log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
+ "allocated " HR_FORMAT " from secondary_free_list",
+ HR_FORMAT_PARAMS(res));
+ return res;
+ }
+
+ // Wait here until we get notified either when (a) there are no
+ // more free regions coming or (b) some regions have been moved on
+ // the secondary_free_list.
+ SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
+ }
+
+ log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
+ "could not allocate from secondary_free_list");
+ return NULL;
+}
+
+HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
+ assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
+ "the only time we use this to allocate a humongous region is "
+ "when we are allocating a single humongous region");
+
+ HeapRegion* res;
+ if (G1StressConcRegionFreeing) {
+ if (!_secondary_free_list.is_empty()) {
+ log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
+ "forced to look at the secondary_free_list");
+ res = new_region_try_secondary_free_list(is_old);
+ if (res != NULL) {
+ return res;
+ }
+ }
+ }
+
+ res = _hrm.allocate_free_region(is_old);
+
+ if (res == NULL) {
+ log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
+ "res == NULL, trying the secondary_free_list");
+ res = new_region_try_secondary_free_list(is_old);
+ }
+ if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
+ // Currently, only attempts to allocate GC alloc regions set
+ // do_expand to true. So, we should only reach here during a
+ // safepoint. If this assumption changes we might have to
+ // reconsider the use of _expand_heap_after_alloc_failure.
+ assert(SafepointSynchronize::is_at_safepoint(), "invariant");
+
+ log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
+ word_size * HeapWordSize);
+
+ if (expand(word_size * HeapWordSize)) {
+ // Given that expand() succeeded in expanding the heap, and we
+ // always expand the heap by an amount aligned to the heap
+ // region size, the free list should in theory not be empty.
+ // In either case allocate_free_region() will check for NULL.
+ res = _hrm.allocate_free_region(is_old);
+ } else {
+ _expand_heap_after_alloc_failure = false;
+ }
+ }
+ return res;
+}
+
+HeapWord*
+G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
+ uint num_regions,
+ size_t word_size,
+ AllocationContext_t context) {
+ assert(first != G1_NO_HRM_INDEX, "pre-condition");
+ assert(is_humongous(word_size), "word_size should be humongous");
+ assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
+
+ // Index of last region in the series.
+ uint last = first + num_regions - 1;
+
+ // We need to initialize the region(s) we just discovered. This is
+ // a bit tricky given that it can happen concurrently with
+ // refinement threads refining cards on these regions and
+ // potentially wanting to refine the BOT as they are scanning
+ // those cards (this can happen shortly after a cleanup; see CR
+ // 6991377). So we have to set up the region(s) carefully and in
+ // a specific order.
+
+ // The word size sum of all the regions we will allocate.
+ size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
+ assert(word_size <= word_size_sum, "sanity");
+
+ // This will be the "starts humongous" region.
+ HeapRegion* first_hr = region_at(first);
+ // The header of the new object will be placed at the bottom of
+ // the first region.
+ HeapWord* new_obj = first_hr->bottom();
+ // This will be the new top of the new object.
+ HeapWord* obj_top = new_obj + word_size;
+
+ // First, we need to zero the header of the space that we will be
+ // allocating. When we update top further down, some refinement
+ // threads might try to scan the region. By zeroing the header we
+ // ensure that any thread that will try to scan the region will
+ // come across the zero klass word and bail out.
+ //
+ // NOTE: It would not have been correct to have used
+ // CollectedHeap::fill_with_object() and make the space look like
+ // an int array. The thread that is doing the allocation will
+ // later update the object header to a potentially different array
+ // type and, for a very short period of time, the klass and length
+ // fields will be inconsistent. This could cause a refinement
+ // thread to calculate the object size incorrectly.
+ Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
+
+ // Next, pad out the unused tail of the last region with filler
+ // objects, for improved usage accounting.
+ // How many words we use for filler objects.
+ size_t word_fill_size = word_size_sum - word_size;
+
+ // How many words memory we "waste" which cannot hold a filler object.
+ size_t words_not_fillable = 0;
+
+ if (word_fill_size >= min_fill_size()) {
+ fill_with_objects(obj_top, word_fill_size);
+ } else if (word_fill_size > 0) {
+ // We have space to fill, but we cannot fit an object there.
+ words_not_fillable = word_fill_size;
+ word_fill_size = 0;
+ }
+
+ // We will set up the first region as "starts humongous". This
+ // will also update the BOT covering all the regions to reflect
+ // that there is a single object that starts at the bottom of the
+ // first region.
+ first_hr->set_starts_humongous(obj_top, word_fill_size);
+ first_hr->set_allocation_context(context);
+ // Then, if there are any, we will set up the "continues
+ // humongous" regions.
+ HeapRegion* hr = NULL;
+ for (uint i = first + 1; i <= last; ++i) {
+ hr = region_at(i);
+ hr->set_continues_humongous(first_hr);
+ hr->set_allocation_context(context);
+ }
+
+ // Up to this point no concurrent thread would have been able to
+ // do any scanning on any region in this series. All the top
+ // fields still point to bottom, so the intersection between
+ // [bottom,top] and [card_start,card_end] will be empty. Before we
+ // update the top fields, we'll do a storestore to make sure that
+ // no thread sees the update to top before the zeroing of the
+ // object header and the BOT initialization.
+ OrderAccess::storestore();
+
+ // Now, we will update the top fields of the "continues humongous"
+ // regions except the last one.
+ for (uint i = first; i < last; ++i) {
+ hr = region_at(i);
+ hr->set_top(hr->end());
+ }
+
+ hr = region_at(last);
+ // If we cannot fit a filler object, we must set top to the end
+ // of the humongous object, otherwise we cannot iterate the heap
+ // and the BOT will not be complete.
+ hr->set_top(hr->end() - words_not_fillable);
+
+ assert(hr->bottom() < obj_top && obj_top <= hr->end(),
+ "obj_top should be in last region");
+
+ _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
+
+ assert(words_not_fillable == 0 ||
+ first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
+ "Miscalculation in humongous allocation");
+
+ increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
+
+ for (uint i = first; i <= last; ++i) {
+ hr = region_at(i);
+ _humongous_set.add(hr);
+ _hr_printer.alloc(hr);
+ }
+
+ return new_obj;
+}
+
+size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
+ assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
+ return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
+}
+
+// If could fit into free regions w/o expansion, try.
+// Otherwise, if can expand, do so.
+// Otherwise, if using ex regions might help, try with ex given back.
+HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
+ assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
+
+ _verifier->verify_region_sets_optional();
+
+ uint first = G1_NO_HRM_INDEX;
+ uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
+
+ if (obj_regions == 1) {
+ // Only one region to allocate, try to use a fast path by directly allocating
+ // from the free lists. Do not try to expand here, we will potentially do that
+ // later.
+ HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
+ if (hr != NULL) {
+ first = hr->hrm_index();
+ }
+ } else {
+ // We can't allocate humongous regions spanning more than one region while
+ // cleanupComplete() is running, since some of the regions we find to be
+ // empty might not yet be added to the free list. It is not straightforward
+ // to know in which list they are on so that we can remove them. We only
+ // need to do this if we need to allocate more than one region to satisfy the
+ // current humongous allocation request. If we are only allocating one region
+ // we use the one-region region allocation code (see above), that already
+ // potentially waits for regions from the secondary free list.
+ wait_while_free_regions_coming();
+ append_secondary_free_list_if_not_empty_with_lock();
+
+ // Policy: Try only empty regions (i.e. already committed first). Maybe we
+ // are lucky enough to find some.
+ first = _hrm.find_contiguous_only_empty(obj_regions);
+ if (first != G1_NO_HRM_INDEX) {
+ _hrm.allocate_free_regions_starting_at(first, obj_regions);
+ }
+ }
+
+ if (first == G1_NO_HRM_INDEX) {
+ // Policy: We could not find enough regions for the humongous object in the
+ // free list. Look through the heap to find a mix of free and uncommitted regions.
+ // If so, try expansion.
+ first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
+ if (first != G1_NO_HRM_INDEX) {
+ // We found something. Make sure these regions are committed, i.e. expand
+ // the heap. Alternatively we could do a defragmentation GC.
+ log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
+ word_size * HeapWordSize);
+
+ _hrm.expand_at(first, obj_regions, workers());
+ g1_policy()->record_new_heap_size(num_regions());
+
+#ifdef ASSERT
+ for (uint i = first; i < first + obj_regions; ++i) {
+ HeapRegion* hr = region_at(i);
+ assert(hr->is_free(), "sanity");
+ assert(hr->is_empty(), "sanity");
+ assert(is_on_master_free_list(hr), "sanity");
+ }
+#endif
+ _hrm.allocate_free_regions_starting_at(first, obj_regions);
+ } else {
+ // Policy: Potentially trigger a defragmentation GC.
+ }
+ }
+
+ HeapWord* result = NULL;
+ if (first != G1_NO_HRM_INDEX) {
+ result = humongous_obj_allocate_initialize_regions(first, obj_regions,
+ word_size, context);
+ assert(result != NULL, "it should always return a valid result");
+
+ // A successful humongous object allocation changes the used space
+ // information of the old generation so we need to recalculate the
+ // sizes and update the jstat counters here.
+ g1mm()->update_sizes();
+ }
+
+ _verifier->verify_region_sets_optional();
+
+ return result;
+}
+
+HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
+ assert_heap_not_locked_and_not_at_safepoint();
+ assert(!is_humongous(word_size), "we do not allow humongous TLABs");
+
+ uint dummy_gc_count_before;
+ uint dummy_gclocker_retry_count = 0;
+ return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
+}
+
+HeapWord*
+G1CollectedHeap::mem_allocate(size_t word_size,
+ bool* gc_overhead_limit_was_exceeded) {
+ assert_heap_not_locked_and_not_at_safepoint();
+
+ // Loop until the allocation is satisfied, or unsatisfied after GC.
+ for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
+ uint gc_count_before;
+
+ HeapWord* result = NULL;
+ if (!is_humongous(word_size)) {
+ result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
+ } else {
+ result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
+ }
+ if (result != NULL) {
+ return result;
+ }
+
+ // Create the garbage collection operation...
+ VM_G1CollectForAllocation op(gc_count_before, word_size);
+ op.set_allocation_context(AllocationContext::current());
+
+ // ...and get the VM thread to execute it.
+ VMThread::execute(&op);
+
+ if (op.prologue_succeeded() && op.pause_succeeded()) {
+ // If the operation was successful we'll return the result even
+ // if it is NULL. If the allocation attempt failed immediately
+ // after a Full GC, it's unlikely we'll be able to allocate now.
+ HeapWord* result = op.result();
+ if (result != NULL && !is_humongous(word_size)) {
+ // Allocations that take place on VM operations do not do any
+ // card dirtying and we have to do it here. We only have to do
+ // this for non-humongous allocations, though.
+ dirty_young_block(result, word_size);
+ }
+ return result;
+ } else {
+ if (gclocker_retry_count > GCLockerRetryAllocationCount) {
+ return NULL;
+ }
+ assert(op.result() == NULL,
+ "the result should be NULL if the VM op did not succeed");
+ }
+
+ // Give a warning if we seem to be looping forever.
+ if ((QueuedAllocationWarningCount > 0) &&
+ (try_count % QueuedAllocationWarningCount == 0)) {
+ log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
+ }
+ }
+
+ ShouldNotReachHere();
+ return NULL;
+}
+
+HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
+ AllocationContext_t context,
+ uint* gc_count_before_ret,
+ uint* gclocker_retry_count_ret) {
+ // Make sure you read the note in attempt_allocation_humongous().
+
+ assert_heap_not_locked_and_not_at_safepoint();
+ assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
+ "be called for humongous allocation requests");
+
+ // We should only get here after the first-level allocation attempt
+ // (attempt_allocation()) failed to allocate.
+
+ // We will loop until a) we manage to successfully perform the
+ // allocation or b) we successfully schedule a collection which
+ // fails to perform the allocation. b) is the only case when we'll
+ // return NULL.
+ HeapWord* result = NULL;
+ for (int try_count = 1; /* we'll return */; try_count += 1) {
+ bool should_try_gc;
+ uint gc_count_before;
+
+ {
+ MutexLockerEx x(Heap_lock);
+ result = _allocator->attempt_allocation_locked(word_size, context);
+ if (result != NULL) {
+ return result;
+ }
+
+ if (GCLocker::is_active_and_needs_gc()) {
+ if (g1_policy()->can_expand_young_list()) {
+ // No need for an ergo verbose message here,
+ // can_expand_young_list() does this when it returns true.
+ result = _allocator->attempt_allocation_force(word_size, context);
+ if (result != NULL) {
+ return result;
+ }
+ }
+ should_try_gc = false;
+ } else {
+ // The GCLocker may not be active but the GCLocker initiated
+ // GC may not yet have been performed (GCLocker::needs_gc()
+ // returns true). In this case we do not try this GC and
+ // wait until the GCLocker initiated GC is performed, and
+ // then retry the allocation.
+ if (GCLocker::needs_gc()) {
+ should_try_gc = false;
+ } else {
+ // Read the GC count while still holding the Heap_lock.
+ gc_count_before = total_collections();
+ should_try_gc = true;
+ }
+ }
+ }
+
+ if (should_try_gc) {
+ bool succeeded;
+ result = do_collection_pause(word_size, gc_count_before, &succeeded,
+ GCCause::_g1_inc_collection_pause);
+ if (result != NULL) {
+ assert(succeeded, "only way to get back a non-NULL result");
+ return result;
+ }
+
+ if (succeeded) {
+ // If we get here we successfully scheduled a collection which
+ // failed to allocate. No point in trying to allocate
+ // further. We'll just return NULL.
+ MutexLockerEx x(Heap_lock);
+ *gc_count_before_ret = total_collections();
+ return NULL;
+ }
+ } else {
+ if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
+ MutexLockerEx x(Heap_lock);
+ *gc_count_before_ret = total_collections();
+ return NULL;
+ }
+ // The GCLocker is either active or the GCLocker initiated
+ // GC has not yet been performed. Stall until it is and
+ // then retry the allocation.
+ GCLocker::stall_until_clear();
+ (*gclocker_retry_count_ret) += 1;
+ }
+
+ // We can reach here if we were unsuccessful in scheduling a
+ // collection (because another thread beat us to it) or if we were
+ // stalled due to the GC locker. In either can we should retry the
+ // allocation attempt in case another thread successfully
+ // performed a collection and reclaimed enough space. We do the
+ // first attempt (without holding the Heap_lock) here and the
+ // follow-on attempt will be at the start of the next loop
+ // iteration (after taking the Heap_lock).
+ result = _allocator->attempt_allocation(word_size, context);
+ if (result != NULL) {
+ return result;
+ }
+
+ // Give a warning if we seem to be looping forever.
+ if ((QueuedAllocationWarningCount > 0) &&
+ (try_count % QueuedAllocationWarningCount == 0)) {
+ log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
+ "retries %d times", try_count);
+ }
+ }
+
+ ShouldNotReachHere();
+ return NULL;
+}
+
+void G1CollectedHeap::begin_archive_alloc_range(bool open) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+ if (_archive_allocator == NULL) {
+ _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
+ }
+}
+
+bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
+ // Allocations in archive regions cannot be of a size that would be considered
+ // humongous even for a minimum-sized region, because G1 region sizes/boundaries
+ // may be different at archive-restore time.
+ return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
+}
+
+HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+ assert(_archive_allocator != NULL, "_archive_allocator not initialized");
+ if (is_archive_alloc_too_large(word_size)) {
+ return NULL;
+ }
+ return _archive_allocator->archive_mem_allocate(word_size);
+}
+
+void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
+ size_t end_alignment_in_bytes) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+ assert(_archive_allocator != NULL, "_archive_allocator not initialized");
+
+ // Call complete_archive to do the real work, filling in the MemRegion
+ // array with the archive regions.
+ _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
+ delete _archive_allocator;
+ _archive_allocator = NULL;
+}
+
+bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
+ assert(ranges != NULL, "MemRegion array NULL");
+ assert(count != 0, "No MemRegions provided");
+ MemRegion reserved = _hrm.reserved();
+ for (size_t i = 0; i < count; i++) {
+ if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
+ return false;
+ }
+ }
+ return true;
+}
+
+bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
+ size_t count,
+ bool open) {
+ assert(!is_init_completed(), "Expect to be called at JVM init time");
+ assert(ranges != NULL, "MemRegion array NULL");
+ assert(count != 0, "No MemRegions provided");
+ MutexLockerEx x(Heap_lock);
+
+ MemRegion reserved = _hrm.reserved();
+ HeapWord* prev_last_addr = NULL;
+ HeapRegion* prev_last_region = NULL;
+
+ // Temporarily disable pretouching of heap pages. This interface is used
+ // when mmap'ing archived heap data in, so pre-touching is wasted.
+ FlagSetting fs(AlwaysPreTouch, false);
+
+ // Enable archive object checking used by G1MarkSweep. We have to let it know
+ // about each archive range, so that objects in those ranges aren't marked.
+ G1ArchiveAllocator::enable_archive_object_check();
+
+ // For each specified MemRegion range, allocate the corresponding G1
+ // regions and mark them as archive regions. We expect the ranges
+ // in ascending starting address order, without overlap.
+ for (size_t i = 0; i < count; i++) {
+ MemRegion curr_range = ranges[i];
+ HeapWord* start_address = curr_range.start();
+ size_t word_size = curr_range.word_size();
+ HeapWord* last_address = curr_range.last();
+ size_t commits = 0;
+
+ guarantee(reserved.contains(start_address) && reserved.contains(last_address),
+ "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
+ p2i(start_address), p2i(last_address));
+ guarantee(start_address > prev_last_addr,
+ "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
+ p2i(start_address), p2i(prev_last_addr));
+ prev_last_addr = last_address;
+
+ // Check for ranges that start in the same G1 region in which the previous
+ // range ended, and adjust the start address so we don't try to allocate
+ // the same region again. If the current range is entirely within that
+ // region, skip it, just adjusting the recorded top.
+ HeapRegion* start_region = _hrm.addr_to_region(start_address);
+ if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
+ start_address = start_region->end();
+ if (start_address > last_address) {
+ increase_used(word_size * HeapWordSize);
+ start_region->set_top(last_address + 1);
+ continue;
+ }
+ start_region->set_top(start_address);
+ curr_range = MemRegion(start_address, last_address + 1);
+ start_region = _hrm.addr_to_region(start_address);
+ }
+
+ // Perform the actual region allocation, exiting if it fails.
+ // Then note how much new space we have allocated.
+ if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
+ return false;
+ }
+ increase_used(word_size * HeapWordSize);
+ if (commits != 0) {
+ log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
+ HeapRegion::GrainWords * HeapWordSize * commits);
+
+ }
+
+ // Mark each G1 region touched by the range as archive, add it to
+ // the old set, and set the allocation context and top.
+ HeapRegion* curr_region = _hrm.addr_to_region(start_address);
+ HeapRegion* last_region = _hrm.addr_to_region(last_address);
+ prev_last_region = last_region;
+
+ while (curr_region != NULL) {
+ assert(curr_region->is_empty() && !curr_region->is_pinned(),
+ "Region already in use (index %u)", curr_region->hrm_index());
+ curr_region->set_allocation_context(AllocationContext::system());
+ if (open) {
+ curr_region->set_open_archive();
+ } else {
+ curr_region->set_closed_archive();
+ }
+ _hr_printer.alloc(curr_region);
+ _old_set.add(curr_region);
+ HeapWord* top;
+ HeapRegion* next_region;
+ if (curr_region != last_region) {
+ top = curr_region->end();
+ next_region = _hrm.next_region_in_heap(curr_region);
+ } else {
+ top = last_address + 1;
+ next_region = NULL;
+ }
+ curr_region->set_top(top);
+ curr_region->set_first_dead(top);
+ curr_region->set_end_of_live(top);
+ curr_region = next_region;
+ }
+
+ // Notify mark-sweep of the archive
+ G1ArchiveAllocator::set_range_archive(curr_range, open);
+ }
+ return true;
+}
+
+void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
+ assert(!is_init_completed(), "Expect to be called at JVM init time");
+ assert(ranges != NULL, "MemRegion array NULL");
+ assert(count != 0, "No MemRegions provided");
+ MemRegion reserved = _hrm.reserved();
+ HeapWord *prev_last_addr = NULL;
+ HeapRegion* prev_last_region = NULL;
+
+ // For each MemRegion, create filler objects, if needed, in the G1 regions
+ // that contain the address range. The address range actually within the
+ // MemRegion will not be modified. That is assumed to have been initialized
+ // elsewhere, probably via an mmap of archived heap data.
+ MutexLockerEx x(Heap_lock);
+ for (size_t i = 0; i < count; i++) {
+ HeapWord* start_address = ranges[i].start();
+ HeapWord* last_address = ranges[i].last();
+
+ assert(reserved.contains(start_address) && reserved.contains(last_address),
+ "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
+ p2i(start_address), p2i(last_address));
+ assert(start_address > prev_last_addr,
+ "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
+ p2i(start_address), p2i(prev_last_addr));
+
+ HeapRegion* start_region = _hrm.addr_to_region(start_address);
+ HeapRegion* last_region = _hrm.addr_to_region(last_address);
+ HeapWord* bottom_address = start_region->bottom();
+
+ // Check for a range beginning in the same region in which the
+ // previous one ended.
+ if (start_region == prev_last_region) {
+ bottom_address = prev_last_addr + 1;
+ }
+
+ // Verify that the regions were all marked as archive regions by
+ // alloc_archive_regions.
+ HeapRegion* curr_region = start_region;
+ while (curr_region != NULL) {
+ guarantee(curr_region->is_archive(),
+ "Expected archive region at index %u", curr_region->hrm_index());
+ if (curr_region != last_region) {
+ curr_region = _hrm.next_region_in_heap(curr_region);
+ } else {
+ curr_region = NULL;
+ }
+ }
+
+ prev_last_addr = last_address;
+ prev_last_region = last_region;
+
+ // Fill the memory below the allocated range with dummy object(s),
+ // if the region bottom does not match the range start, or if the previous
+ // range ended within the same G1 region, and there is a gap.
+ if (start_address != bottom_address) {
+ size_t fill_size = pointer_delta(start_address, bottom_address);
+ G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
+ increase_used(fill_size * HeapWordSize);
+ }
+ }
+}
+
+inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
+ uint* gc_count_before_ret,
+ uint* gclocker_retry_count_ret) {
+ assert_heap_not_locked_and_not_at_safepoint();
+ assert(!is_humongous(word_size), "attempt_allocation() should not "
+ "be called for humongous allocation requests");
+
+ AllocationContext_t context = AllocationContext::current();
+ HeapWord* result = _allocator->attempt_allocation(word_size, context);
+
+ if (result == NULL) {
+ result = attempt_allocation_slow(word_size,
+ context,
+ gc_count_before_ret,
+ gclocker_retry_count_ret);
+ }
+ assert_heap_not_locked();
+ if (result != NULL) {
+ dirty_young_block(result, word_size);
+ }
+ return result;
+}
+
+void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
+ assert(!is_init_completed(), "Expect to be called at JVM init time");
+ assert(ranges != NULL, "MemRegion array NULL");
+ assert(count != 0, "No MemRegions provided");
+ MemRegion reserved = _hrm.reserved();
+ HeapWord* prev_last_addr = NULL;
+ HeapRegion* prev_last_region = NULL;
+ size_t size_used = 0;
+ size_t uncommitted_regions = 0;
+
+ // For each Memregion, free the G1 regions that constitute it, and
+ // notify mark-sweep that the range is no longer to be considered 'archive.'
+ MutexLockerEx x(Heap_lock);
+ for (size_t i = 0; i < count; i++) {
+ HeapWord* start_address = ranges[i].start();
+ HeapWord* last_address = ranges[i].last();
+
+ assert(reserved.contains(start_address) && reserved.contains(last_address),
+ "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
+ p2i(start_address), p2i(last_address));
+ assert(start_address > prev_last_addr,
+ "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
+ p2i(start_address), p2i(prev_last_addr));
+ size_used += ranges[i].byte_size();
+ prev_last_addr = last_address;
+
+ HeapRegion* start_region = _hrm.addr_to_region(start_address);
+ HeapRegion* last_region = _hrm.addr_to_region(last_address);
+
+ // Check for ranges that start in the same G1 region in which the previous
+ // range ended, and adjust the start address so we don't try to free
+ // the same region again. If the current range is entirely within that
+ // region, skip it.
+ if (start_region == prev_last_region) {
+ start_address = start_region->end();
+ if (start_address > last_address) {
+ continue;
+ }
+ start_region = _hrm.addr_to_region(start_address);
+ }
+ prev_last_region = last_region;
+
+ // After verifying that each region was marked as an archive region by
+ // alloc_archive_regions, set it free and empty and uncommit it.
+ HeapRegion* curr_region = start_region;
+ while (curr_region != NULL) {
+ guarantee(curr_region->is_archive(),
+ "Expected archive region at index %u", curr_region->hrm_index());
+ uint curr_index = curr_region->hrm_index();
+ _old_set.remove(curr_region);
+ curr_region->set_free();
+ curr_region->set_top(curr_region->bottom());
+ if (curr_region != last_region) {
+ curr_region = _hrm.next_region_in_heap(curr_region);
+ } else {
+ curr_region = NULL;
+ }
+ _hrm.shrink_at(curr_index, 1);
+ uncommitted_regions++;
+ }
+
+ // Notify mark-sweep that this is no longer an archive range.
+ G1ArchiveAllocator::set_range_archive(ranges[i], false);
+ }
+
+ if (uncommitted_regions != 0) {
+ log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
+ HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
+ }
+ decrease_used(size_used);
+}
+
+HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
+ uint* gc_count_before_ret,
+ uint* gclocker_retry_count_ret) {
+ // The structure of this method has a lot of similarities to
+ // attempt_allocation_slow(). The reason these two were not merged
+ // into a single one is that such a method would require several "if
+ // allocation is not humongous do this, otherwise do that"
+ // conditional paths which would obscure its flow. In fact, an early
+ // version of this code did use a unified method which was harder to
+ // follow and, as a result, it had subtle bugs that were hard to
+ // track down. So keeping these two methods separate allows each to
+ // be more readable. It will be good to keep these two in sync as
+ // much as possible.
+
+ assert_heap_not_locked_and_not_at_safepoint();
+ assert(is_humongous(word_size), "attempt_allocation_humongous() "
+ "should only be called for humongous allocations");
+
+ // Humongous objects can exhaust the heap quickly, so we should check if we
+ // need to start a marking cycle at each humongous object allocation. We do
+ // the check before we do the actual allocation. The reason for doing it
+ // before the allocation is that we avoid having to keep track of the newly
+ // allocated memory while we do a GC.
+ if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
+ word_size)) {
+ collect(GCCause::_g1_humongous_allocation);
+ }
+
+ // We will loop until a) we manage to successfully perform the
+ // allocation or b) we successfully schedule a collection which
+ // fails to perform the allocation. b) is the only case when we'll
+ // return NULL.
+ HeapWord* result = NULL;
+ for (int try_count = 1; /* we'll return */; try_count += 1) {
+ bool should_try_gc;
+ uint gc_count_before;
+
+ {
+ MutexLockerEx x(Heap_lock);
+
+ // Given that humongous objects are not allocated in young
+ // regions, we'll first try to do the allocation without doing a
+ // collection hoping that there's enough space in the heap.
+ result = humongous_obj_allocate(word_size, AllocationContext::current());
+ if (result != NULL) {
+ size_t size_in_regions = humongous_obj_size_in_regions(word_size);
+ g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
+ return result;
+ }
+
+ if (GCLocker::is_active_and_needs_gc()) {
+ should_try_gc = false;
+ } else {
+ // The GCLocker may not be active but the GCLocker initiated
+ // GC may not yet have been performed (GCLocker::needs_gc()
+ // returns true). In this case we do not try this GC and
+ // wait until the GCLocker initiated GC is performed, and
+ // then retry the allocation.
+ if (GCLocker::needs_gc()) {
+ should_try_gc = false;
+ } else {
+ // Read the GC count while still holding the Heap_lock.
+ gc_count_before = total_collections();
+ should_try_gc = true;
+ }
+ }
+ }
+
+ if (should_try_gc) {
+ // If we failed to allocate the humongous object, we should try to
+ // do a collection pause (if we're allowed) in case it reclaims
+ // enough space for the allocation to succeed after the pause.
+
+ bool succeeded;
+ result = do_collection_pause(word_size, gc_count_before, &succeeded,
+ GCCause::_g1_humongous_allocation);
+ if (result != NULL) {
+ assert(succeeded, "only way to get back a non-NULL result");
+ return result;
+ }
+
+ if (succeeded) {
+ // If we get here we successfully scheduled a collection which
+ // failed to allocate. No point in trying to allocate
+ // further. We'll just return NULL.
+ MutexLockerEx x(Heap_lock);
+ *gc_count_before_ret = total_collections();
+ return NULL;
+ }
+ } else {
+ if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
+ MutexLockerEx x(Heap_lock);
+ *gc_count_before_ret = total_collections();
+ return NULL;
+ }
+ // The GCLocker is either active or the GCLocker initiated
+ // GC has not yet been performed. Stall until it is and
+ // then retry the allocation.
+ GCLocker::stall_until_clear();
+ (*gclocker_retry_count_ret) += 1;
+ }
+
+ // We can reach here if we were unsuccessful in scheduling a
+ // collection (because another thread beat us to it) or if we were
+ // stalled due to the GC locker. In either can we should retry the
+ // allocation attempt in case another thread successfully
+ // performed a collection and reclaimed enough space. Give a
+ // warning if we seem to be looping forever.
+
+ if ((QueuedAllocationWarningCount > 0) &&
+ (try_count % QueuedAllocationWarningCount == 0)) {
+ log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
+ "retries %d times", try_count);
+ }
+ }
+
+ ShouldNotReachHere();
+ return NULL;
+}
+
+HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
+ AllocationContext_t context,
+ bool expect_null_mutator_alloc_region) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+ assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
+ "the current alloc region was unexpectedly found to be non-NULL");
+
+ if (!is_humongous(word_size)) {
+ return _allocator->attempt_allocation_locked(word_size, context);
+ } else {
+ HeapWord* result = humongous_obj_allocate(word_size, context);
+ if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
+ collector_state()->set_initiate_conc_mark_if_possible(true);
+ }
+ return result;
+ }
+
+ ShouldNotReachHere();
+}
+
+class PostCompactionPrinterClosure: public HeapRegionClosure {
+private:
+ G1HRPrinter* _hr_printer;
+public:
+ bool doHeapRegion(HeapRegion* hr) {
+ assert(!hr->is_young(), "not expecting to find young regions");
+ _hr_printer->post_compaction(hr);
+ return false;
+ }
+
+ PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
+ : _hr_printer(hr_printer) { }
+};
+
+void G1CollectedHeap::print_hrm_post_compaction() {
+ if (_hr_printer.is_active()) {
+ PostCompactionPrinterClosure cl(hr_printer());
+ heap_region_iterate(&cl);
+ }
+
+}
+
+void G1CollectedHeap::abort_concurrent_cycle() {
+ // Note: When we have a more flexible GC logging framework that
+ // allows us to add optional attributes to a GC log record we
+ // could consider timing and reporting how long we wait in the
+ // following two methods.
+ wait_while_free_regions_coming();
+ // If we start the compaction before the CM threads finish
+ // scanning the root regions we might trip them over as we'll
+ // be moving objects / updating references. So let's wait until
+ // they are done. By telling them to abort, they should complete
+ // early.
+ _cm->root_regions()->abort();
+ _cm->root_regions()->wait_until_scan_finished();
+ append_secondary_free_list_if_not_empty_with_lock();
+
+ // Disable discovery and empty the discovered lists
+ // for the CM ref processor.
+ ref_processor_cm()->disable_discovery();
+ ref_processor_cm()->abandon_partial_discovery();
+ ref_processor_cm()->verify_no_references_recorded();
+
+ // Abandon current iterations of concurrent marking and concurrent
+ // refinement, if any are in progress.
+ concurrent_mark()->abort();
+}
+
+void G1CollectedHeap::prepare_heap_for_full_collection() {
+ // Make sure we'll choose a new allocation region afterwards.
+ _allocator->release_mutator_alloc_region();
+ _allocator->abandon_gc_alloc_regions();
+ g1_rem_set()->cleanupHRRS();
+
+ // We may have added regions to the current incremental collection
+ // set between the last GC or pause and now. We need to clear the
+ // incremental collection set and then start rebuilding it afresh
+ // after this full GC.
+ abandon_collection_set(collection_set());
+
+ tear_down_region_sets(false /* free_list_only */);
+ collector_state()->set_gcs_are_young(true);
+}
+
+void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
+ assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
+ assert(used() == recalculate_used(), "Should be equal");
+ _verifier->verify_region_sets_optional();
+ _verifier->verify_before_gc();
+ _verifier->check_bitmaps("Full GC Start");
+}
+
+void G1CollectedHeap::prepare_heap_for_mutators() {
+ // Delete metaspaces for unloaded class loaders and clean up loader_data graph
+ ClassLoaderDataGraph::purge();
+ MetaspaceAux::verify_metrics();
+
+ // Prepare heap for normal collections.
+ assert(num_free_regions() == 0, "we should not have added any free regions");
+ rebuild_region_sets(false /* free_list_only */);
+ abort_refinement();
+ resize_if_necessary_after_full_collection();
+
+ // Rebuild the strong code root lists for each region
+ rebuild_strong_code_roots();
+
+ // Start a new incremental collection set for the next pause
+ start_new_collection_set();
+
+ _allocator->init_mutator_alloc_region();
+
+ // Post collection state updates.
+ MetaspaceGC::compute_new_size();
+}
+
+void G1CollectedHeap::abort_refinement() {
+ if (_hot_card_cache->use_cache()) {
+ _hot_card_cache->reset_card_counts();
+ _hot_card_cache->reset_hot_cache();
+ }
+
+ // Discard all remembered set updates.
+ JavaThread::dirty_card_queue_set().abandon_logs();
+ assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
+}
+
+void G1CollectedHeap::verify_after_full_collection() {
+ check_gc_time_stamps();
+ _hrm.verify_optional();
+ _verifier->verify_region_sets_optional();
+ _verifier->verify_after_gc();
+ // Clear the previous marking bitmap, if needed for bitmap verification.
+ // Note we cannot do this when we clear the next marking bitmap in
+ // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
+ // objects marked during a full GC against the previous bitmap.
+ // But we need to clear it before calling check_bitmaps below since
+ // the full GC has compacted objects and updated TAMS but not updated
+ // the prev bitmap.
+ if (G1VerifyBitmaps) {
+ GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
+ _cm->clear_prev_bitmap(workers());
+ }
+ _verifier->check_bitmaps("Full GC End");
+
+ // At this point there should be no regions in the
+ // entire heap tagged as young.
+ assert(check_young_list_empty(), "young list should be empty at this point");
+
+ // Note: since we've just done a full GC, concurrent
+ // marking is no longer active. Therefore we need not
+ // re-enable reference discovery for the CM ref processor.
+ // That will be done at the start of the next marking cycle.
+ // We also know that the STW processor should no longer
+ // discover any new references.
+ assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
+ assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
+ ref_processor_stw()->verify_no_references_recorded();
+ ref_processor_cm()->verify_no_references_recorded();
+}
+
+void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
+ print_hrm_post_compaction();
+ heap_transition->print();
+ print_heap_after_gc();
+ print_heap_regions();
+#ifdef TRACESPINNING
+ ParallelTaskTerminator::print_termination_counts();
+#endif
+}
+
+void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
+ GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
+ g1_policy()->record_full_collection_start();
+
+ print_heap_before_gc();
+ print_heap_regions();
+
+ abort_concurrent_cycle();
+ verify_before_full_collection(scope->is_explicit_gc());
+
+ gc_prologue(true);
+ prepare_heap_for_full_collection();
+
+ G1SerialFullCollector serial(scope, ref_processor_stw());
+ serial.prepare_collection();
+ serial.collect();
+ serial.complete_collection();
+
+ prepare_heap_for_mutators();
+
+ g1_policy()->record_full_collection_end();
+ gc_epilogue(true);
+
+ // Post collection verification.
+ verify_after_full_collection();
+
+ // Post collection logging.
+ // We should do this after we potentially resize the heap so
+ // that all the COMMIT / UNCOMMIT events are generated before
+ // the compaction events.
+ print_heap_after_full_collection(scope->heap_transition());
+}
+
+bool G1CollectedHeap::do_full_collection(bool explicit_gc,
+ bool clear_all_soft_refs) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+
+ if (GCLocker::check_active_before_gc()) {
+ // Full GC was not completed.
+ return false;
+ }
+
+ const bool do_clear_all_soft_refs = clear_all_soft_refs ||
+ collector_policy()->should_clear_all_soft_refs();
+
+ G1FullGCScope scope(explicit_gc, do_clear_all_soft_refs);
+ do_full_collection_inner(&scope);
+
+ // Full collection was successfully completed.
+ return true;
+}
+
+void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
+ // Currently, there is no facility in the do_full_collection(bool) API to notify
+ // the caller that the collection did not succeed (e.g., because it was locked
+ // out by the GC locker). So, right now, we'll ignore the return value.
+ bool dummy = do_full_collection(true, /* explicit_gc */
+ clear_all_soft_refs);
+}
+
+void G1CollectedHeap::resize_if_necessary_after_full_collection() {
+ // Include bytes that will be pre-allocated to support collections, as "used".
+ const size_t used_after_gc = used();
+ const size_t capacity_after_gc = capacity();
+ const size_t free_after_gc = capacity_after_gc - used_after_gc;
+
+ // This is enforced in arguments.cpp.
+ assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
+ "otherwise the code below doesn't make sense");
+
+ // We don't have floating point command-line arguments
+ const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
+ const double maximum_used_percentage = 1.0 - minimum_free_percentage;
+ const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
+ const double minimum_used_percentage = 1.0 - maximum_free_percentage;
+
+ const size_t min_heap_size = collector_policy()->min_heap_byte_size();
+ const size_t max_heap_size = collector_policy()->max_heap_byte_size();
+
+ // We have to be careful here as these two calculations can overflow
+ // 32-bit size_t's.
+ double used_after_gc_d = (double) used_after_gc;
+ double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
+ double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
+
+ // Let's make sure that they are both under the max heap size, which
+ // by default will make them fit into a size_t.
+ double desired_capacity_upper_bound = (double) max_heap_size;
+ minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
+ desired_capacity_upper_bound);
+ maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
+ desired_capacity_upper_bound);
+
+ // We can now safely turn them into size_t's.
+ size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
+ size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
+
+ // This assert only makes sense here, before we adjust them
+ // with respect to the min and max heap size.
+ assert(minimum_desired_capacity <= maximum_desired_capacity,
+ "minimum_desired_capacity = " SIZE_FORMAT ", "
+ "maximum_desired_capacity = " SIZE_FORMAT,
+ minimum_desired_capacity, maximum_desired_capacity);
+
+ // Should not be greater than the heap max size. No need to adjust
+ // it with respect to the heap min size as it's a lower bound (i.e.,
+ // we'll try to make the capacity larger than it, not smaller).
+ minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
+ // Should not be less than the heap min size. No need to adjust it
+ // with respect to the heap max size as it's an upper bound (i.e.,
+ // we'll try to make the capacity smaller than it, not greater).
+ maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
+
+ if (capacity_after_gc < minimum_desired_capacity) {
+ // Don't expand unless it's significant
+ size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
+
+ log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
+ "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
+ capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
+
+ expand(expand_bytes, _workers);
+
+ // No expansion, now see if we want to shrink
+ } else if (capacity_after_gc > maximum_desired_capacity) {
+ // Capacity too large, compute shrinking size
+ size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
+
+ log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
+ "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
+ capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
+
+ shrink(shrink_bytes);
+ }
+}
+
+HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
+ AllocationContext_t context,
+ bool do_gc,
+ bool clear_all_soft_refs,
+ bool expect_null_mutator_alloc_region,
+ bool* gc_succeeded) {
+ *gc_succeeded = true;
+ // Let's attempt the allocation first.
+ HeapWord* result =
+ attempt_allocation_at_safepoint(word_size,
+ context,
+ expect_null_mutator_alloc_region);
+ if (result != NULL) {
+ assert(*gc_succeeded, "sanity");
+ return result;
+ }
+
+ // In a G1 heap, we're supposed to keep allocation from failing by
+ // incremental pauses. Therefore, at least for now, we'll favor
+ // expansion over collection. (This might change in the future if we can
+ // do something smarter than full collection to satisfy a failed alloc.)
+ result = expand_and_allocate(word_size, context);
+ if (result != NULL) {
+ assert(*gc_succeeded, "sanity");
+ return result;
+ }
+
+ if (do_gc) {
+ // Expansion didn't work, we'll try to do a Full GC.
+ *gc_succeeded = do_full_collection(false, /* explicit_gc */
+ clear_all_soft_refs);
+ }
+
+ return NULL;
+}
+
+HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
+ AllocationContext_t context,
+ bool* succeeded) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+
+ // Attempts to allocate followed by Full GC.
+ HeapWord* result =
+ satisfy_failed_allocation_helper(word_size,
+ context,
+ true, /* do_gc */
+ false, /* clear_all_soft_refs */
+ false, /* expect_null_mutator_alloc_region */
+ succeeded);
+
+ if (result != NULL || !*succeeded) {
+ return result;
+ }
+
+ // Attempts to allocate followed by Full GC that will collect all soft references.
+ result = satisfy_failed_allocation_helper(word_size,
+ context,
+ true, /* do_gc */
+ true, /* clear_all_soft_refs */
+ true, /* expect_null_mutator_alloc_region */
+ succeeded);
+
+ if (result != NULL || !*succeeded) {
+ return result;
+ }
+
+ // Attempts to allocate, no GC
+ result = satisfy_failed_allocation_helper(word_size,
+ context,
+ false, /* do_gc */
+ false, /* clear_all_soft_refs */
+ true, /* expect_null_mutator_alloc_region */
+ succeeded);
+
+ if (result != NULL) {
+ assert(*succeeded, "sanity");
+ return result;
+ }
+
+ assert(!collector_policy()->should_clear_all_soft_refs(),
+ "Flag should have been handled and cleared prior to this point");
+
+ // What else? We might try synchronous finalization later. If the total
+ // space available is large enough for the allocation, then a more
+ // complete compaction phase than we've tried so far might be
+ // appropriate.
+ assert(*succeeded, "sanity");
+ return NULL;
+}
+
+// Attempting to expand the heap sufficiently
+// to support an allocation of the given "word_size". If
+// successful, perform the allocation and return the address of the
+// allocated block, or else "NULL".
+
+HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+
+ _verifier->verify_region_sets_optional();
+
+ size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
+ log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
+ word_size * HeapWordSize);
+
+
+ if (expand(expand_bytes, _workers)) {
+ _hrm.verify_optional();
+ _verifier->verify_region_sets_optional();
+ return attempt_allocation_at_safepoint(word_size,
+ context,
+ false /* expect_null_mutator_alloc_region */);
+ }
+ return NULL;
+}
+
+bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
+ size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
+ aligned_expand_bytes = align_up(aligned_expand_bytes,
+ HeapRegion::GrainBytes);
+
+ log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
+ expand_bytes, aligned_expand_bytes);
+
+ if (is_maximal_no_gc()) {
+ log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
+ return false;
+ }
+
+ double expand_heap_start_time_sec = os::elapsedTime();
+ uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
+ assert(regions_to_expand > 0, "Must expand by at least one region");
+
+ uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
+ if (expand_time_ms != NULL) {
+ *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
+ }
+
+ if (expanded_by > 0) {
+ size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
+ assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
+ g1_policy()->record_new_heap_size(num_regions());
+ } else {
+ log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
+
+ // The expansion of the virtual storage space was unsuccessful.
+ // Let's see if it was because we ran out of swap.
+ if (G1ExitOnExpansionFailure &&
+ _hrm.available() >= regions_to_expand) {
+ // We had head room...
+ vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
+ }
+ }
+ return regions_to_expand > 0;
+}
+
+void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
+ size_t aligned_shrink_bytes =
+ ReservedSpace::page_align_size_down(shrink_bytes);
+ aligned_shrink_bytes = align_down(aligned_shrink_bytes,
+ HeapRegion::GrainBytes);
+ uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
+
+ uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
+ size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
+
+
+ log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
+ shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
+ if (num_regions_removed > 0) {
+ g1_policy()->record_new_heap_size(num_regions());
+ } else {
+ log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
+ }
+}
+
+void G1CollectedHeap::shrink(size_t shrink_bytes) {
+ _verifier->verify_region_sets_optional();
+
+ // We should only reach here at the end of a Full GC which means we
+ // should not not be holding to any GC alloc regions. The method
+ // below will make sure of that and do any remaining clean up.
+ _allocator->abandon_gc_alloc_regions();
+
+ // Instead of tearing down / rebuilding the free lists here, we
+ // could instead use the remove_all_pending() method on free_list to
+ // remove only the ones that we need to remove.
+ tear_down_region_sets(true /* free_list_only */);
+ shrink_helper(shrink_bytes);
+ rebuild_region_sets(true /* free_list_only */);
+
+ _hrm.verify_optional();
+ _verifier->verify_region_sets_optional();
+}
+
+// Public methods.
+
+G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
+ CollectedHeap(),
+ _collector_policy(collector_policy),
+ _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
+ _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
+ _g1_policy(create_g1_policy(_gc_timer_stw)),
+ _collection_set(this, _g1_policy),
+ _dirty_card_queue_set(false),
+ _is_alive_closure_cm(this),
+ _is_alive_closure_stw(this),
+ _ref_processor_cm(NULL),
+ _ref_processor_stw(NULL),
+ _bot(NULL),
+ _hot_card_cache(NULL),
+ _g1_rem_set(NULL),
+ _cg1r(NULL),
+ _g1mm(NULL),
+ _preserved_marks_set(true /* in_c_heap */),
+ _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
+ _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
+ _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
+ _humongous_reclaim_candidates(),
+ _has_humongous_reclaim_candidates(false),
+ _archive_allocator(NULL),
+ _free_regions_coming(false),
+ _gc_time_stamp(0),
+ _summary_bytes_used(0),
+ _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
+ _old_evac_stats("Old", OldPLABSize, PLABWeight),
+ _expand_heap_after_alloc_failure(true),
+ _old_marking_cycles_started(0),
+ _old_marking_cycles_completed(0),
+ _in_cset_fast_test() {
+
+ _workers = new WorkGang("GC Thread", ParallelGCThreads,
+ /* are_GC_task_threads */true,
+ /* are_ConcurrentGC_threads */false);
+ _workers->initialize_workers();
+ _verifier = new G1HeapVerifier(this);
+
+ _allocator = G1Allocator::create_allocator(this);
+
+ _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
+
+ _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
+
+ // Override the default _filler_array_max_size so that no humongous filler
+ // objects are created.
+ _filler_array_max_size = _humongous_object_threshold_in_words;
+
+ uint n_queues = ParallelGCThreads;
+ _task_queues = new RefToScanQueueSet(n_queues);
+
+ _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
+
+ for (uint i = 0; i < n_queues; i++) {
+ RefToScanQueue* q = new RefToScanQueue();
+ q->initialize();
+ _task_queues->register_queue(i, q);
+ ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
+ }
+
+ // Initialize the G1EvacuationFailureALot counters and flags.
+ NOT_PRODUCT(reset_evacuation_should_fail();)
+
+ guarantee(_task_queues != NULL, "task_queues allocation failure.");
+}
+
+G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
+ size_t size,
+ size_t translation_factor) {
+ size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
+ // Allocate a new reserved space, preferring to use large pages.
+ ReservedSpace rs(size, preferred_page_size);
+ G1RegionToSpaceMapper* result =
+ G1RegionToSpaceMapper::create_mapper(rs,
+ size,
+ rs.alignment(),
+ HeapRegion::GrainBytes,
+ translation_factor,
+ mtGC);
+
+ os::trace_page_sizes_for_requested_size(description,
+ size,
+ preferred_page_size,
+ rs.alignment(),
+ rs.base(),
+ rs.size());
+
+ return result;
+}
+
+jint G1CollectedHeap::initialize_concurrent_refinement() {
+ jint ecode = JNI_OK;
+ _cg1r = ConcurrentG1Refine::create(&ecode);
+ return ecode;
+}
+
+jint G1CollectedHeap::initialize() {
+ CollectedHeap::pre_initialize();
+ os::enable_vtime();
+
+ // Necessary to satisfy locking discipline assertions.
+
+ MutexLocker x(Heap_lock);
+
+ // While there are no constraints in the GC code that HeapWordSize
+ // be any particular value, there are multiple other areas in the
+ // system which believe this to be true (e.g. oop->object_size in some
+ // cases incorrectly returns the size in wordSize units rather than
+ // HeapWordSize).
+ guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
+
+ size_t init_byte_size = collector_policy()->initial_heap_byte_size();
+ size_t max_byte_size = collector_policy()->max_heap_byte_size();
+ size_t heap_alignment = collector_policy()->heap_alignment();
+
+ // Ensure that the sizes are properly aligned.
+ Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
+ Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
+ Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
+
+ // Reserve the maximum.
+
+ // When compressed oops are enabled, the preferred heap base
+ // is calculated by subtracting the requested size from the
+ // 32Gb boundary and using the result as the base address for
+ // heap reservation. If the requested size is not aligned to
+ // HeapRegion::GrainBytes (i.e. the alignment that is passed
+ // into the ReservedHeapSpace constructor) then the actual
+ // base of the reserved heap may end up differing from the
+ // address that was requested (i.e. the preferred heap base).
+ // If this happens then we could end up using a non-optimal
+ // compressed oops mode.
+
+ ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
+ heap_alignment);
+
+ initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
+
+ // Create the barrier set for the entire reserved region.
+ G1SATBCardTableLoggingModRefBS* bs
+ = new G1SATBCardTableLoggingModRefBS(reserved_region());
+ bs->initialize();
+ assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
+ set_barrier_set(bs);
+
+ // Create the hot card cache.
+ _hot_card_cache = new G1HotCardCache(this);
+
+ // Carve out the G1 part of the heap.
+ ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
+ size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
+ G1RegionToSpaceMapper* heap_storage =
+ G1RegionToSpaceMapper::create_mapper(g1_rs,
+ g1_rs.size(),
+ page_size,
+ HeapRegion::GrainBytes,
+ 1,
+ mtJavaHeap);
+ os::trace_page_sizes("Heap",
+ collector_policy()->min_heap_byte_size(),
+ max_byte_size,
+ page_size,
+ heap_rs.base(),
+ heap_rs.size());
+ heap_storage->set_mapping_changed_listener(&_listener);
+
+ // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
+ G1RegionToSpaceMapper* bot_storage =
+ create_aux_memory_mapper("Block Offset Table",
+ G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
+ G1BlockOffsetTable::heap_map_factor());
+
+ G1RegionToSpaceMapper* cardtable_storage =
+ create_aux_memory_mapper("Card Table",
+ G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
+ G1SATBCardTableLoggingModRefBS::heap_map_factor());
+
+ G1RegionToSpaceMapper* card_counts_storage =
+ create_aux_memory_mapper("Card Counts Table",
+ G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
+ G1CardCounts::heap_map_factor());
+
+ size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
+ G1RegionToSpaceMapper* prev_bitmap_storage =
+ create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
+ G1RegionToSpaceMapper* next_bitmap_storage =
+ create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
+
+ _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
+ g1_barrier_set()->initialize(cardtable_storage);
+ // Do later initialization work for concurrent refinement.
+ _hot_card_cache->initialize(card_counts_storage);
+
+ // 6843694 - ensure that the maximum region index can fit
+ // in the remembered set structures.
+ const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
+ guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
+
+ // Also create a G1 rem set.
+ _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
+ _g1_rem_set->initialize(max_capacity(), max_regions());
+
+ size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
+ guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
+ guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
+ "too many cards per region");
+
+ FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
+
+ _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
+
+ {
+ HeapWord* start = _hrm.reserved().start();
+ HeapWord* end = _hrm.reserved().end();
+ size_t granularity = HeapRegion::GrainBytes;
+
+ _in_cset_fast_test.initialize(start, end, granularity);
+ _humongous_reclaim_candidates.initialize(start, end, granularity);
+ }
+
+ // Create the G1ConcurrentMark data structure and thread.
+ // (Must do this late, so that "max_regions" is defined.)
+ _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
+ if (_cm == NULL || !_cm->completed_initialization()) {
+ vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
+ return JNI_ENOMEM;
+ }
+ _cmThread = _cm->cmThread();
+
+ // Now expand into the initial heap size.
+ if (!expand(init_byte_size, _workers)) {
+ vm_shutdown_during_initialization("Failed to allocate initial heap.");
+ return JNI_ENOMEM;
+ }
+
+ // Perform any initialization actions delegated to the policy.
+ g1_policy()->init(this, &_collection_set);
+
+ JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
+ SATB_Q_FL_lock,
+ G1SATBProcessCompletedThreshold,
+ Shared_SATB_Q_lock);
+
+ jint ecode = initialize_concurrent_refinement();
+ if (ecode != JNI_OK) {
+ return ecode;
+ }
+
+ JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
+ DirtyCardQ_FL_lock,
+ (int)concurrent_g1_refine()->yellow_zone(),
+ (int)concurrent_g1_refine()->red_zone(),
+ Shared_DirtyCardQ_lock,
+ NULL, // fl_owner
+ true); // init_free_ids
+
+ dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
+ DirtyCardQ_FL_lock,
+ -1, // never trigger processing
+ -1, // no limit on length
+ Shared_DirtyCardQ_lock,
+ &JavaThread::dirty_card_queue_set());
+
+ // Here we allocate the dummy HeapRegion that is required by the
+ // G1AllocRegion class.
+ HeapRegion* dummy_region = _hrm.get_dummy_region();
+
+ // We'll re-use the same region whether the alloc region will
+ // require BOT updates or not and, if it doesn't, then a non-young
+ // region will complain that it cannot support allocations without
+ // BOT updates. So we'll tag the dummy region as eden to avoid that.
+ dummy_region->set_eden();
+ // Make sure it's full.
+ dummy_region->set_top(dummy_region->end());
+ G1AllocRegion::setup(this, dummy_region);
+
+ _allocator->init_mutator_alloc_region();
+
+ // Do create of the monitoring and management support so that
+ // values in the heap have been properly initialized.
+ _g1mm = new G1MonitoringSupport(this);
+
+ G1StringDedup::initialize();
+
+ _preserved_marks_set.init(ParallelGCThreads);
+
+ _collection_set.initialize(max_regions());
+
+ return JNI_OK;
+}
+
+void G1CollectedHeap::stop() {
+ // Stop all concurrent threads. We do this to make sure these threads
+ // do not continue to execute and access resources (e.g. logging)
+ // that are destroyed during shutdown.
+ _cg1r->stop();
+ _cmThread->stop();
+ if (G1StringDedup::is_enabled()) {
+ G1StringDedup::stop();
+ }
+}
+
+size_t G1CollectedHeap::conservative_max_heap_alignment() {
+ return HeapRegion::max_region_size();
+}
+
+void G1CollectedHeap::post_initialize() {
+ ref_processing_init();
+}
+
+void G1CollectedHeap::ref_processing_init() {
+ // Reference processing in G1 currently works as follows:
+ //
+ // * There are two reference processor instances. One is
+ // used to record and process discovered references
+ // during concurrent marking; the other is used to
+ // record and process references during STW pauses
+ // (both full and incremental).
+ // * Both ref processors need to 'span' the entire heap as
+ // the regions in the collection set may be dotted around.
+ //
+ // * For the concurrent marking ref processor:
+ // * Reference discovery is enabled at initial marking.
+ // * Reference discovery is disabled and the discovered
+ // references processed etc during remarking.
+ // * Reference discovery is MT (see below).
+ // * Reference discovery requires a barrier (see below).
+ // * Reference processing may or may not be MT
+ // (depending on the value of ParallelRefProcEnabled
+ // and ParallelGCThreads).
+ // * A full GC disables reference discovery by the CM
+ // ref processor and abandons any entries on it's
+ // discovered lists.
+ //
+ // * For the STW processor:
+ // * Non MT discovery is enabled at the start of a full GC.
+ // * Processing and enqueueing during a full GC is non-MT.
+ // * During a full GC, references are processed after marking.
+ //
+ // * Discovery (may or may not be MT) is enabled at the start
+ // of an incremental evacuation pause.
+ // * References are processed near the end of a STW evacuation pause.
+ // * For both types of GC:
+ // * Discovery is atomic - i.e. not concurrent.
+ // * Reference discovery will not need a barrier.
+
+ MemRegion mr = reserved_region();
+
+ bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
+
+ // Concurrent Mark ref processor
+ _ref_processor_cm =
+ new ReferenceProcessor(mr, // span
+ mt_processing,
+ // mt processing
+ ParallelGCThreads,
+ // degree of mt processing
+ (ParallelGCThreads > 1) || (ConcGCThreads > 1),
+ // mt discovery
+ MAX2(ParallelGCThreads, ConcGCThreads),
+ // degree of mt discovery
+ false,
+ // Reference discovery is not atomic
+ &_is_alive_closure_cm);
+ // is alive closure
+ // (for efficiency/performance)
+
+ // STW ref processor
+ _ref_processor_stw =
+ new ReferenceProcessor(mr, // span
+ mt_processing,
+ // mt processing
+ ParallelGCThreads,
+ // degree of mt processing
+ (ParallelGCThreads > 1),
+ // mt discovery
+ ParallelGCThreads,
+ // degree of mt discovery
+ true,
+ // Reference discovery is atomic
+ &_is_alive_closure_stw);
+ // is alive closure
+ // (for efficiency/performance)
+}
+
+CollectorPolicy* G1CollectedHeap::collector_policy() const {
+ return _collector_policy;
+}
+
+size_t G1CollectedHeap::capacity() const {
+ return _hrm.length() * HeapRegion::GrainBytes;
+}
+
+void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
+ hr->reset_gc_time_stamp();
+}
+
+#ifndef PRODUCT
+
+class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
+private:
+ unsigned _gc_time_stamp;
+ bool _failures;
+
+public:
+ CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
+ _gc_time_stamp(gc_time_stamp), _failures(false) { }
+
+ virtual bool doHeapRegion(HeapRegion* hr) {
+ unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
+ if (_gc_time_stamp != region_gc_time_stamp) {
+ log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
+ region_gc_time_stamp, _gc_time_stamp);
+ _failures = true;
+ }
+ return false;
+ }
+
+ bool failures() { return _failures; }
+};
+
+void G1CollectedHeap::check_gc_time_stamps() {
+ CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
+ heap_region_iterate(&cl);
+ guarantee(!cl.failures(), "all GC time stamps should have been reset");
+}
+#endif // PRODUCT
+
+void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
+ _hot_card_cache->drain(cl, worker_i);
+}
+
+void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
+ DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
+ size_t n_completed_buffers = 0;
+ while (dcqs.apply_closure_during_gc(cl, worker_i)) {
+ n_completed_buffers++;
+ }
+ g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
+ dcqs.clear_n_completed_buffers();
+ assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
+}
+
+// Computes the sum of the storage used by the various regions.
+size_t G1CollectedHeap::used() const {
+ size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
+ if (_archive_allocator != NULL) {
+ result += _archive_allocator->used();
+ }
+ return result;
+}
+
+size_t G1CollectedHeap::used_unlocked() const {
+ return _summary_bytes_used;
+}
+
+class SumUsedClosure: public HeapRegionClosure {
+ size_t _used;
+public:
+ SumUsedClosure() : _used(0) {}
+ bool doHeapRegion(HeapRegion* r) {
+ _used += r->used();
+ return false;
+ }
+ size_t result() { return _used; }
+};
+
+size_t G1CollectedHeap::recalculate_used() const {
+ double recalculate_used_start = os::elapsedTime();
+
+ SumUsedClosure blk;
+ heap_region_iterate(&blk);
+
+ g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
+ return blk.result();
+}
+
+bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
+ switch (cause) {
+ case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
+ case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
+ case GCCause::_update_allocation_context_stats_inc: return true;
+ case GCCause::_wb_conc_mark: return true;
+ default : return false;
+ }
+}
+
+bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
+ switch (cause) {
+ case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
+ case GCCause::_g1_humongous_allocation: return true;
+ default: return is_user_requested_concurrent_full_gc(cause);
+ }
+}
+
+#ifndef PRODUCT
+void G1CollectedHeap::allocate_dummy_regions() {
+ // Let's fill up most of the region
+ size_t word_size = HeapRegion::GrainWords - 1024;
+ // And as a result the region we'll allocate will be humongous.
+ guarantee(is_humongous(word_size), "sanity");
+
+ // _filler_array_max_size is set to humongous object threshold
+ // but temporarily change it to use CollectedHeap::fill_with_object().
+ SizeTFlagSetting fs(_filler_array_max_size, word_size);
+
+ for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
+ // Let's use the existing mechanism for the allocation
+ HeapWord* dummy_obj = humongous_obj_allocate(word_size,
+ AllocationContext::system());
+ if (dummy_obj != NULL) {
+ MemRegion mr(dummy_obj, word_size);
+ CollectedHeap::fill_with_object(mr);
+ } else {
+ // If we can't allocate once, we probably cannot allocate
+ // again. Let's get out of the loop.
+ break;
+ }
+ }
+}
+#endif // !PRODUCT
+
+void G1CollectedHeap::increment_old_marking_cycles_started() {
+ assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
+ _old_marking_cycles_started == _old_marking_cycles_completed + 1,
+ "Wrong marking cycle count (started: %d, completed: %d)",
+ _old_marking_cycles_started, _old_marking_cycles_completed);
+
+ _old_marking_cycles_started++;
+}
+
+void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
+ MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
+
+ // We assume that if concurrent == true, then the caller is a
+ // concurrent thread that was joined the Suspendible Thread
+ // Set. If there's ever a cheap way to check this, we should add an
+ // assert here.
+
+ // Given that this method is called at the end of a Full GC or of a
+ // concurrent cycle, and those can be nested (i.e., a Full GC can
+ // interrupt a concurrent cycle), the number of full collections
+ // completed should be either one (in the case where there was no
+ // nesting) or two (when a Full GC interrupted a concurrent cycle)
+ // behind the number of full collections started.
+
+ // This is the case for the inner caller, i.e. a Full GC.
+ assert(concurrent ||
+ (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
+ (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
+ "for inner caller (Full GC): _old_marking_cycles_started = %u "
+ "is inconsistent with _old_marking_cycles_completed = %u",
+ _old_marking_cycles_started, _old_marking_cycles_completed);
+
+ // This is the case for the outer caller, i.e. the concurrent cycle.
+ assert(!concurrent ||
+ (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
+ "for outer caller (concurrent cycle): "
+ "_old_marking_cycles_started = %u "
+ "is inconsistent with _old_marking_cycles_completed = %u",
+ _old_marking_cycles_started, _old_marking_cycles_completed);
+
+ _old_marking_cycles_completed += 1;
+
+ // We need to clear the "in_progress" flag in the CM thread before
+ // we wake up any waiters (especially when ExplicitInvokesConcurrent
+ // is set) so that if a waiter requests another System.gc() it doesn't
+ // incorrectly see that a marking cycle is still in progress.
+ if (concurrent) {
+ _cmThread->set_idle();
+ }
+
+ // This notify_all() will ensure that a thread that called
+ // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
+ // and it's waiting for a full GC to finish will be woken up. It is
+ // waiting in VM_G1IncCollectionPause::doit_epilogue().
+ FullGCCount_lock->notify_all();
+}
+
+void G1CollectedHeap::collect(GCCause::Cause cause) {
+ assert_heap_not_locked();
+
+ uint gc_count_before;
+ uint old_marking_count_before;
+ uint full_gc_count_before;
+ bool retry_gc;
+
+ do {
+ retry_gc = false;
+
+ {
+ MutexLocker ml(Heap_lock);
+
+ // Read the GC count while holding the Heap_lock
+ gc_count_before = total_collections();
+ full_gc_count_before = total_full_collections();
+ old_marking_count_before = _old_marking_cycles_started;
+ }
+
+ if (should_do_concurrent_full_gc(cause)) {
+ // Schedule an initial-mark evacuation pause that will start a
+ // concurrent cycle. We're setting word_size to 0 which means that
+ // we are not requesting a post-GC allocation.
+ VM_G1IncCollectionPause op(gc_count_before,
+ 0, /* word_size */
+ true, /* should_initiate_conc_mark */
+ g1_policy()->max_pause_time_ms(),
+ cause);
+ op.set_allocation_context(AllocationContext::current());
+
+ VMThread::execute(&op);
+ if (!op.pause_succeeded()) {
+ if (old_marking_count_before == _old_marking_cycles_started) {
+ retry_gc = op.should_retry_gc();
+ } else {
+ // A Full GC happened while we were trying to schedule the
+ // initial-mark GC. No point in starting a new cycle given
+ // that the whole heap was collected anyway.
+ }
+
+ if (retry_gc) {
+ if (GCLocker::is_active_and_needs_gc()) {
+ GCLocker::stall_until_clear();
+ }
+ }
+ }
+ } else {
+ if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
+ DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
+
+ // Schedule a standard evacuation pause. We're setting word_size
+ // to 0 which means that we are not requesting a post-GC allocation.
+ VM_G1IncCollectionPause op(gc_count_before,
+ 0, /* word_size */
+ false, /* should_initiate_conc_mark */
+ g1_policy()->max_pause_time_ms(),
+ cause);
+ VMThread::execute(&op);
+ } else {
+ // Schedule a Full GC.
+ VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
+ VMThread::execute(&op);
+ }
+ }
+ } while (retry_gc);
+}
+
+bool G1CollectedHeap::is_in(const void* p) const {
+ if (_hrm.reserved().contains(p)) {
+ // Given that we know that p is in the reserved space,
+ // heap_region_containing() should successfully
+ // return the containing region.
+ HeapRegion* hr = heap_region_containing(p);
+ return hr->is_in(p);
+ } else {
+ return false;
+ }
+}
+
+#ifdef ASSERT
+bool G1CollectedHeap::is_in_exact(const void* p) const {
+ bool contains = reserved_region().contains(p);
+ bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
+ if (contains && available) {
+ return true;
+ } else {
+ return false;
+ }
+}
+#endif
+
+// Iteration functions.
+
+// Iterates an ObjectClosure over all objects within a HeapRegion.
+
+class IterateObjectClosureRegionClosure: public HeapRegionClosure {
+ ObjectClosure* _cl;
+public:
+ IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
+ bool doHeapRegion(HeapRegion* r) {
+ if (!r->is_continues_humongous()) {
+ r->object_iterate(_cl);
+ }
+ return false;
+ }
+};
+
+void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
+ IterateObjectClosureRegionClosure blk(cl);
+ heap_region_iterate(&blk);
+}
+
+void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
+ _hrm.iterate(cl);
+}
+
+void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
+ uint worker_id,
+ HeapRegionClaimer *hrclaimer) const {
+ _hrm.par_iterate(cl, worker_id, hrclaimer);
+}
+
+void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
+ _collection_set.iterate(cl);
+}
+
+void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
+ _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
+}
+
+HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
+ HeapRegion* result = _hrm.next_region_in_heap(from);
+ while (result != NULL && result->is_pinned()) {
+ result = _hrm.next_region_in_heap(result);
+ }
+ return result;
+}
+
+HeapWord* G1CollectedHeap::block_start(const void* addr) const {
+ HeapRegion* hr = heap_region_containing(addr);
+ return hr->block_start(addr);
+}
+
+size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
+ HeapRegion* hr = heap_region_containing(addr);
+ return hr->block_size(addr);
+}
+
+bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
+ HeapRegion* hr = heap_region_containing(addr);
+ return hr->block_is_obj(addr);
+}
+
+bool G1CollectedHeap::supports_tlab_allocation() const {
+ return true;
+}
+
+size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
+ return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
+}
+
+size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
+ return _eden.length() * HeapRegion::GrainBytes;
+}
+
+// For G1 TLABs should not contain humongous objects, so the maximum TLAB size
+// must be equal to the humongous object limit.
+size_t G1CollectedHeap::max_tlab_size() const {
+ return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
+}
+
+size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
+ AllocationContext_t context = AllocationContext::current();
+ return _allocator->unsafe_max_tlab_alloc(context);
+}
+
+size_t G1CollectedHeap::max_capacity() const {
+ return _hrm.reserved().byte_size();
+}
+
+jlong G1CollectedHeap::millis_since_last_gc() {
+ // See the notes in GenCollectedHeap::millis_since_last_gc()
+ // for more information about the implementation.
+ jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
+ _g1_policy->collection_pause_end_millis();
+ if (ret_val < 0) {
+ log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
+ ". returning zero instead.", ret_val);
+ return 0;
+ }
+ return ret_val;
+}
+
+void G1CollectedHeap::prepare_for_verify() {
+ _verifier->prepare_for_verify();
+}
+
+void G1CollectedHeap::verify(VerifyOption vo) {
+ _verifier->verify(vo);
+}
+
+bool G1CollectedHeap::supports_concurrent_phase_control() const {
+ return true;
+}
+
+const char* const* G1CollectedHeap::concurrent_phases() const {
+ return _cmThread->concurrent_phases();
+}
+
+bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
+ return _cmThread->request_concurrent_phase(phase);
+}
+
+class PrintRegionClosure: public HeapRegionClosure {
+ outputStream* _st;
+public:
+ PrintRegionClosure(outputStream* st) : _st(st) {}
+ bool doHeapRegion(HeapRegion* r) {
+ r->print_on(_st);
+ return false;
+ }
+};
+
+bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
+ const HeapRegion* hr,
+ const VerifyOption vo) const {
+ switch (vo) {
+ case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
+ case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
+ case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
+ default: ShouldNotReachHere();
+ }
+ return false; // keep some compilers happy
+}
+
+bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
+ const VerifyOption vo) const {
+ switch (vo) {
+ case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
+ case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
+ case VerifyOption_G1UseMarkWord: {
+ HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
+ return !obj->is_gc_marked() && !hr->is_archive();
+ }
+ default: ShouldNotReachHere();
+ }
+ return false; // keep some compilers happy
+}
+
+void G1CollectedHeap::print_heap_regions() const {
+ LogTarget(Trace, gc, heap, region) lt;
+ if (lt.is_enabled()) {
+ LogStream ls(lt);
+ print_regions_on(&ls);
+ }
+}
+
+void G1CollectedHeap::print_on(outputStream* st) const {
+ st->print(" %-20s", "garbage-first heap");
+ st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
+ capacity()/K, used_unlocked()/K);
+ st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
+ p2i(_hrm.reserved().start()),
+ p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
+ p2i(_hrm.reserved().end()));
+ st->cr();
+ st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
+ uint young_regions = young_regions_count();
+ st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
+ (size_t) young_regions * HeapRegion::GrainBytes / K);
+ uint survivor_regions = survivor_regions_count();
+ st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
+ (size_t) survivor_regions * HeapRegion::GrainBytes / K);
+ st->cr();
+ MetaspaceAux::print_on(st);
+}
+
+void G1CollectedHeap::print_regions_on(outputStream* st) const {
+ st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
+ "HS=humongous(starts), HC=humongous(continues), "
+ "CS=collection set, F=free, A=archive, TS=gc time stamp, "
+ "AC=allocation context, "
+ "TAMS=top-at-mark-start (previous, next)");
+ PrintRegionClosure blk(st);
+ heap_region_iterate(&blk);
+}
+
+void G1CollectedHeap::print_extended_on(outputStream* st) const {
+ print_on(st);
+
+ // Print the per-region information.
+ print_regions_on(st);
+}
+
+void G1CollectedHeap::print_on_error(outputStream* st) const {
+ this->CollectedHeap::print_on_error(st);
+
+ if (_cm != NULL) {
+ st->cr();
+ _cm->print_on_error(st);
+ }
+}
+
+void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
+ workers()->print_worker_threads_on(st);
+ _cmThread->print_on(st);
+ st->cr();
+ _cm->print_worker_threads_on(st);
+ _cg1r->print_worker_threads_on(st); // also prints the sample thread
+ if (G1StringDedup::is_enabled()) {
+ G1StringDedup::print_worker_threads_on(st);
+ }
+}
+
+void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
+ workers()->threads_do(tc);
+ tc->do_thread(_cmThread);
+ _cm->threads_do(tc);
+ _cg1r->threads_do(tc); // also iterates over the sample thread
+ if (G1StringDedup::is_enabled()) {
+ G1StringDedup::threads_do(tc);
+ }
+}
+
+void G1CollectedHeap::print_tracing_info() const {
+ g1_rem_set()->print_summary_info();
+ concurrent_mark()->print_summary_info();
+}
+
+#ifndef PRODUCT
+// Helpful for debugging RSet issues.
+
+class PrintRSetsClosure : public HeapRegionClosure {
+private:
+ const char* _msg;
+ size_t _occupied_sum;
+
+public:
+ bool doHeapRegion(HeapRegion* r) {
+ HeapRegionRemSet* hrrs = r->rem_set();
+ size_t occupied = hrrs->occupied();
+ _occupied_sum += occupied;
+
+ tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
+ if (occupied == 0) {
+ tty->print_cr(" RSet is empty");
+ } else {
+ hrrs->print();
+ }
+ tty->print_cr("----------");
+ return false;
+ }
+
+ PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
+ tty->cr();
+ tty->print_cr("========================================");
+ tty->print_cr("%s", msg);
+ tty->cr();
+ }
+
+ ~PrintRSetsClosure() {
+ tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
+ tty->print_cr("========================================");
+ tty->cr();
+ }
+};
+
+void G1CollectedHeap::print_cset_rsets() {
+ PrintRSetsClosure cl("Printing CSet RSets");
+ collection_set_iterate(&cl);
+}
+
+void G1CollectedHeap::print_all_rsets() {
+ PrintRSetsClosure cl("Printing All RSets");;
+ heap_region_iterate(&cl);
+}
+#endif // PRODUCT
+
+G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
+
+ size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
+ size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
+ size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
+
+ size_t eden_capacity_bytes =
+ (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
+
+ VirtualSpaceSummary heap_summary = create_heap_space_summary();
+ return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
+ eden_capacity_bytes, survivor_used_bytes, num_regions());
+}
+
+G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
+ return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
+ stats->unused(), stats->used(), stats->region_end_waste(),
+ stats->regions_filled(), stats->direct_allocated(),
+ stats->failure_used(), stats->failure_waste());
+}
+
+void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
+ const G1HeapSummary& heap_summary = create_g1_heap_summary();
+ gc_tracer->report_gc_heap_summary(when, heap_summary);
+
+ const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
+ gc_tracer->report_metaspace_summary(when, metaspace_summary);
+}
+
+G1CollectedHeap* G1CollectedHeap::heap() {
+ CollectedHeap* heap = Universe::heap();
+ assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
+ assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
+ return (G1CollectedHeap*)heap;
+}
+
+void G1CollectedHeap::gc_prologue(bool full) {
+ // always_do_update_barrier = false;
+ assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
+
+ // This summary needs to be printed before incrementing total collections.
+ g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
+
+ // Update common counters.
+ increment_total_collections(full /* full gc */);
+ if (full) {
+ increment_old_marking_cycles_started();
+ reset_gc_time_stamp();
+ } else {
+ increment_gc_time_stamp();
+ }
+
+ // Fill TLAB's and such
+ double start = os::elapsedTime();
+ accumulate_statistics_all_tlabs();
+ ensure_parsability(true);
+ g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
+}
+
+void G1CollectedHeap::gc_epilogue(bool full) {
+ // Update common counters.
+ if (full) {
+ // Update the number of full collections that have been completed.
+ increment_old_marking_cycles_completed(false /* concurrent */);
+ }
+
+ // We are at the end of the GC. Total collections has already been increased.
+ g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
+
+ // FIXME: what is this about?
+ // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
+ // is set.
+#if defined(COMPILER2) || INCLUDE_JVMCI
+ assert(DerivedPointerTable::is_empty(), "derived pointer present");
+#endif
+ // always_do_update_barrier = true;
+
+ double start = os::elapsedTime();
+ resize_all_tlabs();
+ g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
+
+ allocation_context_stats().update(full);
+
+ MemoryService::track_memory_usage();
+ // We have just completed a GC. Update the soft reference
+ // policy with the new heap occupancy
+ Universe::update_heap_info_at_gc();
+}
+
+HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
+ uint gc_count_before,
+ bool* succeeded,
+ GCCause::Cause gc_cause) {
+ assert_heap_not_locked_and_not_at_safepoint();
+ VM_G1IncCollectionPause op(gc_count_before,
+ word_size,
+ false, /* should_initiate_conc_mark */
+ g1_policy()->max_pause_time_ms(),
+ gc_cause);
+
+ op.set_allocation_context(AllocationContext::current());
+ VMThread::execute(&op);
+
+ HeapWord* result = op.result();
+ bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
+ assert(result == NULL || ret_succeeded,
+ "the result should be NULL if the VM did not succeed");
+ *succeeded = ret_succeeded;
+
+ assert_heap_not_locked();
+ return result;
+}
+
+void
+G1CollectedHeap::doConcurrentMark() {
+ MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
+ if (!_cmThread->in_progress()) {
+ _cmThread->set_started();
+ CGC_lock->notify();
+ }
+}
+
+size_t G1CollectedHeap::pending_card_num() {
+ size_t extra_cards = 0;
+ JavaThread *curr = Threads::first();
+ while (curr != NULL) {
+ DirtyCardQueue& dcq = curr->dirty_card_queue();
+ extra_cards += dcq.size();
+ curr = curr->next();
+ }
+ DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
+ size_t buffer_size = dcqs.buffer_size();
+ size_t buffer_num = dcqs.completed_buffers_num();
+
+ return buffer_size * buffer_num + extra_cards;
+}
+
+class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
+ private:
+ size_t _total_humongous;
+ size_t _candidate_humongous;
+
+ DirtyCardQueue _dcq;
+
+ // We don't nominate objects with many remembered set entries, on
+ // the assumption that such objects are likely still live.
+ bool is_remset_small(HeapRegion* region) const {
+ HeapRegionRemSet* const rset = region->rem_set();
+ return G1EagerReclaimHumongousObjectsWithStaleRefs
+ ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
+ : rset->is_empty();
+ }
+
+ bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
+ assert(region->is_starts_humongous(), "Must start a humongous object");
+
+ oop obj = oop(region->bottom());
+
+ // Dead objects cannot be eager reclaim candidates. Due to class
+ // unloading it is unsafe to query their classes so we return early.
+ if (heap->is_obj_dead(obj, region)) {
+ return false;
+ }
+
+ // Candidate selection must satisfy the following constraints
+ // while concurrent marking is in progress:
+ //
+ // * In order to maintain SATB invariants, an object must not be
+ // reclaimed if it was allocated before the start of marking and
+ // has not had its references scanned. Such an object must have
+ // its references (including type metadata) scanned to ensure no
+ // live objects are missed by the marking process. Objects
+ // allocated after the start of concurrent marking don't need to
+ // be scanned.
+ //
+ // * An object must not be reclaimed if it is on the concurrent
+ // mark stack. Objects allocated after the start of concurrent
+ // marking are never pushed on the mark stack.
+ //
+ // Nominating only objects allocated after the start of concurrent
+ // marking is sufficient to meet both constraints. This may miss
+ // some objects that satisfy the constraints, but the marking data
+ // structures don't support efficiently performing the needed
+ // additional tests or scrubbing of the mark stack.
+ //
+ // However, we presently only nominate is_typeArray() objects.
+ // A humongous object containing references induces remembered
+ // set entries on other regions. In order to reclaim such an
+ // object, those remembered sets would need to be cleaned up.
+ //
+ // We also treat is_typeArray() objects specially, allowing them
+ // to be reclaimed even if allocated before the start of
+ // concurrent mark. For this we rely on mark stack insertion to
+ // exclude is_typeArray() objects, preventing reclaiming an object
+ // that is in the mark stack. We also rely on the metadata for
+ // such objects to be built-in and so ensured to be kept live.
+ // Frequent allocation and drop of large binary blobs is an
+ // important use case for eager reclaim, and this special handling
+ // may reduce needed headroom.
+
+ return obj->is_typeArray() && is_remset_small(region);
+ }
+
+ public:
+ RegisterHumongousWithInCSetFastTestClosure()
+ : _total_humongous(0),
+ _candidate_humongous(0),
+ _dcq(&JavaThread::dirty_card_queue_set()) {
+ }
+
+ virtual bool doHeapRegion(HeapRegion* r) {
+ if (!r->is_starts_humongous()) {
+ return false;
+ }
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ bool is_candidate = humongous_region_is_candidate(g1h, r);
+ uint rindex = r->hrm_index();
+ g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
+ if (is_candidate) {
+ _candidate_humongous++;
+ g1h->register_humongous_region_with_cset(rindex);
+ // Is_candidate already filters out humongous object with large remembered sets.
+ // If we have a humongous object with a few remembered sets, we simply flush these
+ // remembered set entries into the DCQS. That will result in automatic
+ // re-evaluation of their remembered set entries during the following evacuation
+ // phase.
+ if (!r->rem_set()->is_empty()) {
+ guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
+ "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
+ G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
+ HeapRegionRemSetIterator hrrs(r->rem_set());
+ size_t card_index;
+ while (hrrs.has_next(card_index)) {
+ jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
+ // The remembered set might contain references to already freed
+ // regions. Filter out such entries to avoid failing card table
+ // verification.
+ if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
+ if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
+ *card_ptr = CardTableModRefBS::dirty_card_val();
+ _dcq.enqueue(card_ptr);
+ }
+ }
+ }
+ assert(hrrs.n_yielded() == r->rem_set()->occupied(),
+ "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
+ hrrs.n_yielded(), r->rem_set()->occupied());
+ r->rem_set()->clear_locked();
+ }
+ assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
+ }
+ _total_humongous++;
+
+ return false;
+ }
+
+ size_t total_humongous() const { return _total_humongous; }
+ size_t candidate_humongous() const { return _candidate_humongous; }
+
+ void flush_rem_set_entries() { _dcq.flush(); }
+};
+
+void G1CollectedHeap::register_humongous_regions_with_cset() {
+ if (!G1EagerReclaimHumongousObjects) {
+ g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
+ return;
+ }
+ double time = os::elapsed_counter();
+
+ // Collect reclaim candidate information and register candidates with cset.
+ RegisterHumongousWithInCSetFastTestClosure cl;
+ heap_region_iterate(&cl);
+
+ time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
+ g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
+ cl.total_humongous(),
+ cl.candidate_humongous());
+ _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
+
+ // Finally flush all remembered set entries to re-check into the global DCQS.
+ cl.flush_rem_set_entries();
+}
+
+class VerifyRegionRemSetClosure : public HeapRegionClosure {
+ public:
+ bool doHeapRegion(HeapRegion* hr) {
+ if (!hr->is_archive() && !hr->is_continues_humongous()) {
+ hr->verify_rem_set();
+ }
+ return false;
+ }
+};
+
+uint G1CollectedHeap::num_task_queues() const {
+ return _task_queues->size();
+}
+
+#if TASKQUEUE_STATS
+void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
+ st->print_raw_cr("GC Task Stats");
+ st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
+ st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
+}
+
+void G1CollectedHeap::print_taskqueue_stats() const {
+ if (!log_is_enabled(Trace, gc, task, stats)) {
+ return;
+ }
+ Log(gc, task, stats) log;
+ ResourceMark rm;
+ LogStream ls(log.trace());
+ outputStream* st = &ls;
+
+ print_taskqueue_stats_hdr(st);
+
+ TaskQueueStats totals;
+ const uint n = num_task_queues();
+ for (uint i = 0; i < n; ++i) {
+ st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
+ totals += task_queue(i)->stats;
+ }
+ st->print_raw("tot "); totals.print(st); st->cr();
+
+ DEBUG_ONLY(totals.verify());
+}
+
+void G1CollectedHeap::reset_taskqueue_stats() {
+ const uint n = num_task_queues();
+ for (uint i = 0; i < n; ++i) {
+ task_queue(i)->stats.reset();
+ }
+}
+#endif // TASKQUEUE_STATS
+
+void G1CollectedHeap::wait_for_root_region_scanning() {
+ double scan_wait_start = os::elapsedTime();
+ // We have to wait until the CM threads finish scanning the
+ // root regions as it's the only way to ensure that all the
+ // objects on them have been correctly scanned before we start
+ // moving them during the GC.
+ bool waited = _cm->root_regions()->wait_until_scan_finished();
+ double wait_time_ms = 0.0;
+ if (waited) {
+ double scan_wait_end = os::elapsedTime();
+ wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
+ }
+ g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
+}
+
+class G1PrintCollectionSetClosure : public HeapRegionClosure {
+private:
+ G1HRPrinter* _hr_printer;
+public:
+ G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
+
+ virtual bool doHeapRegion(HeapRegion* r) {
+ _hr_printer->cset(r);
+ return false;
+ }
+};
+
+void G1CollectedHeap::start_new_collection_set() {
+ collection_set()->start_incremental_building();
+
+ clear_cset_fast_test();
+
+ guarantee(_eden.length() == 0, "eden should have been cleared");
+ g1_policy()->transfer_survivors_to_cset(survivor());
+}
+
+bool
+G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+ guarantee(!is_gc_active(), "collection is not reentrant");
+
+ if (GCLocker::check_active_before_gc()) {
+ return false;
+ }
+
+ _gc_timer_stw->register_gc_start();
+
+ GCIdMark gc_id_mark;
+ _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
+
+ SvcGCMarker sgcm(SvcGCMarker::MINOR);
+ ResourceMark rm;
+
+ g1_policy()->note_gc_start();
+
+ wait_for_root_region_scanning();
+
+ print_heap_before_gc();
+ print_heap_regions();
+ trace_heap_before_gc(_gc_tracer_stw);
+
+ _verifier->verify_region_sets_optional();
+ _verifier->verify_dirty_young_regions();
+
+ // We should not be doing initial mark unless the conc mark thread is running
+ if (!_cmThread->should_terminate()) {
+ // This call will decide whether this pause is an initial-mark
+ // pause. If it is, during_initial_mark_pause() will return true
+ // for the duration of this pause.
+ g1_policy()->decide_on_conc_mark_initiation();
+ }
+
+ // We do not allow initial-mark to be piggy-backed on a mixed GC.
+ assert(!collector_state()->during_initial_mark_pause() ||
+ collector_state()->gcs_are_young(), "sanity");
+
+ // We also do not allow mixed GCs during marking.
+ assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
+
+ // Record whether this pause is an initial mark. When the current
+ // thread has completed its logging output and it's safe to signal
+ // the CM thread, the flag's value in the policy has been reset.
+ bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
+
+ // Inner scope for scope based logging, timers, and stats collection
+ {
+ EvacuationInfo evacuation_info;
+
+ if (collector_state()->during_initial_mark_pause()) {
+ // We are about to start a marking cycle, so we increment the
+ // full collection counter.
+ increment_old_marking_cycles_started();
+ _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
+ }
+
+ _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
+
+ GCTraceCPUTime tcpu;
+
+ FormatBuffer<> gc_string("Pause ");
+ if (collector_state()->during_initial_mark_pause()) {
+ gc_string.append("Initial Mark");
+ } else if (collector_state()->gcs_are_young()) {
+ gc_string.append("Young");
+ } else {
+ gc_string.append("Mixed");
+ }
+ GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
+
+ uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
+ workers()->active_workers(),
+ Threads::number_of_non_daemon_threads());
+ workers()->update_active_workers(active_workers);
+ log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
+
+ TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
+ TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
+
+ // If the secondary_free_list is not empty, append it to the
+ // free_list. No need to wait for the cleanup operation to finish;
+ // the region allocation code will check the secondary_free_list
+ // and wait if necessary. If the G1StressConcRegionFreeing flag is
+ // set, skip this step so that the region allocation code has to
+ // get entries from the secondary_free_list.
+ if (!G1StressConcRegionFreeing) {
+ append_secondary_free_list_if_not_empty_with_lock();
+ }
+
+ G1HeapTransition heap_transition(this);
+ size_t heap_used_bytes_before_gc = used();
+
+ // Don't dynamically change the number of GC threads this early. A value of
+ // 0 is used to indicate serial work. When parallel work is done,
+ // it will be set.
+
+ { // Call to jvmpi::post_class_unload_events must occur outside of active GC
+ IsGCActiveMark x;
+
+ gc_prologue(false);
+
+ if (VerifyRememberedSets) {
+ log_info(gc, verify)("[Verifying RemSets before GC]");
+ VerifyRegionRemSetClosure v_cl;
+ heap_region_iterate(&v_cl);
+ }
+
+ _verifier->verify_before_gc();
+
+ _verifier->check_bitmaps("GC Start");
+
+#if defined(COMPILER2) || INCLUDE_JVMCI
+ DerivedPointerTable::clear();
+#endif
+
+ // Please see comment in g1CollectedHeap.hpp and
+ // G1CollectedHeap::ref_processing_init() to see how
+ // reference processing currently works in G1.
+
+ // Enable discovery in the STW reference processor
+ if (g1_policy()->should_process_references()) {
+ ref_processor_stw()->enable_discovery();
+ } else {
+ ref_processor_stw()->disable_discovery();
+ }
+
+ {
+ // We want to temporarily turn off discovery by the
+ // CM ref processor, if necessary, and turn it back on
+ // on again later if we do. Using a scoped
+ // NoRefDiscovery object will do this.
+ NoRefDiscovery no_cm_discovery(ref_processor_cm());
+
+ // Forget the current alloc region (we might even choose it to be part
+ // of the collection set!).
+ _allocator->release_mutator_alloc_region();
+
+ // This timing is only used by the ergonomics to handle our pause target.
+ // It is unclear why this should not include the full pause. We will
+ // investigate this in CR 7178365.
+ //
+ // Preserving the old comment here if that helps the investigation:
+ //
+ // The elapsed time induced by the start time below deliberately elides
+ // the possible verification above.
+ double sample_start_time_sec = os::elapsedTime();
+
+ g1_policy()->record_collection_pause_start(sample_start_time_sec);
+
+ if (collector_state()->during_initial_mark_pause()) {
+ concurrent_mark()->checkpointRootsInitialPre();
+ }
+
+ g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
+
+ evacuation_info.set_collectionset_regions(collection_set()->region_length());
+
+ // Make sure the remembered sets are up to date. This needs to be
+ // done before register_humongous_regions_with_cset(), because the
+ // remembered sets are used there to choose eager reclaim candidates.
+ // If the remembered sets are not up to date we might miss some
+ // entries that need to be handled.
+ g1_rem_set()->cleanupHRRS();
+
+ register_humongous_regions_with_cset();
+
+ assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
+
+ // We call this after finalize_cset() to
+ // ensure that the CSet has been finalized.
+ _cm->verify_no_cset_oops();
+
+ if (_hr_printer.is_active()) {
+ G1PrintCollectionSetClosure cl(&_hr_printer);
+ _collection_set.iterate(&cl);
+ }
+
+ // Initialize the GC alloc regions.
+ _allocator->init_gc_alloc_regions(evacuation_info);
+
+ G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
+ pre_evacuate_collection_set();
+
+ // Actually do the work...
+ evacuate_collection_set(evacuation_info, &per_thread_states);
+
+ post_evacuate_collection_set(evacuation_info, &per_thread_states);
+
+ const size_t* surviving_young_words = per_thread_states.surviving_young_words();
+ free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
+
+ eagerly_reclaim_humongous_regions();
+
+ record_obj_copy_mem_stats();
+ _survivor_evac_stats.adjust_desired_plab_sz();
+ _old_evac_stats.adjust_desired_plab_sz();
+
+ double start = os::elapsedTime();
+ start_new_collection_set();
+ g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
+
+ if (evacuation_failed()) {
+ set_used(recalculate_used());
+ if (_archive_allocator != NULL) {
+ _archive_allocator->clear_used();
+ }
+ for (uint i = 0; i < ParallelGCThreads; i++) {
+ if (_evacuation_failed_info_array[i].has_failed()) {
+ _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
+ }
+ }
+ } else {
+ // The "used" of the the collection set have already been subtracted
+ // when they were freed. Add in the bytes evacuated.
+ increase_used(g1_policy()->bytes_copied_during_gc());
+ }
+
+ if (collector_state()->during_initial_mark_pause()) {
+ // We have to do this before we notify the CM threads that
+ // they can start working to make sure that all the
+ // appropriate initialization is done on the CM object.
+ concurrent_mark()->checkpointRootsInitialPost();
+ collector_state()->set_mark_in_progress(true);
+ // Note that we don't actually trigger the CM thread at
+ // this point. We do that later when we're sure that
+ // the current thread has completed its logging output.
+ }
+
+ allocate_dummy_regions();
+
+ _allocator->init_mutator_alloc_region();
+
+ {
+ size_t expand_bytes = _heap_sizing_policy->expansion_amount();
+ if (expand_bytes > 0) {
+ size_t bytes_before = capacity();
+ // No need for an ergo logging here,
+ // expansion_amount() does this when it returns a value > 0.
+ double expand_ms;
+ if (!expand(expand_bytes, _workers, &expand_ms)) {
+ // We failed to expand the heap. Cannot do anything about it.
+ }
+ g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
+ }
+ }
+
+ // We redo the verification but now wrt to the new CSet which
+ // has just got initialized after the previous CSet was freed.
+ _cm->verify_no_cset_oops();
+
+ // This timing is only used by the ergonomics to handle our pause target.
+ // It is unclear why this should not include the full pause. We will
+ // investigate this in CR 7178365.
+ double sample_end_time_sec = os::elapsedTime();
+ double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
+ size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
+ g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
+
+ evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
+ evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
+
+ if (VerifyRememberedSets) {
+ log_info(gc, verify)("[Verifying RemSets after GC]");
+ VerifyRegionRemSetClosure v_cl;
+ heap_region_iterate(&v_cl);
+ }
+
+ _verifier->verify_after_gc();
+ _verifier->check_bitmaps("GC End");
+
+ assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
+ ref_processor_stw()->verify_no_references_recorded();
+
+ // CM reference discovery will be re-enabled if necessary.
+ }
+
+#ifdef TRACESPINNING
+ ParallelTaskTerminator::print_termination_counts();
+#endif
+
+ gc_epilogue(false);
+ }
+
+ // Print the remainder of the GC log output.
+ if (evacuation_failed()) {
+ log_info(gc)("To-space exhausted");
+ }
+
+ g1_policy()->print_phases();
+ heap_transition.print();
+
+ // It is not yet to safe to tell the concurrent mark to
+ // start as we have some optional output below. We don't want the
+ // output from the concurrent mark thread interfering with this
+ // logging output either.
+
+ _hrm.verify_optional();
+ _verifier->verify_region_sets_optional();
+
+ TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
+ TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
+
+ print_heap_after_gc();
+ print_heap_regions();
+ trace_heap_after_gc(_gc_tracer_stw);
+
+ // We must call G1MonitoringSupport::update_sizes() in the same scoping level
+ // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
+ // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
+ // before any GC notifications are raised.
+ g1mm()->update_sizes();
+
+ _gc_tracer_stw->report_evacuation_info(&evacuation_info);
+ _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
+ _gc_timer_stw->register_gc_end();
+ _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
+ }
+ // It should now be safe to tell the concurrent mark thread to start
+ // without its logging output interfering with the logging output
+ // that came from the pause.
+
+ if (should_start_conc_mark) {
+ // CAUTION: after the doConcurrentMark() call below,
+ // the concurrent marking thread(s) could be running
+ // concurrently with us. Make sure that anything after
+ // this point does not assume that we are the only GC thread
+ // running. Note: of course, the actual marking work will
+ // not start until the safepoint itself is released in
+ // SuspendibleThreadSet::desynchronize().
+ doConcurrentMark();
+ }
+
+ return true;
+}
+
+void G1CollectedHeap::remove_self_forwarding_pointers() {
+ G1ParRemoveSelfForwardPtrsTask rsfp_task;
+ workers()->run_task(&rsfp_task);
+}
+
+void G1CollectedHeap::restore_after_evac_failure() {
+ double remove_self_forwards_start = os::elapsedTime();
+
+ remove_self_forwarding_pointers();
+ SharedRestorePreservedMarksTaskExecutor task_executor(workers());
+ _preserved_marks_set.restore(&task_executor);
+
+ g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
+}
+
+void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
+ if (!_evacuation_failed) {
+ _evacuation_failed = true;
+ }
+
+ _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
+ _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
+}
+
+bool G1ParEvacuateFollowersClosure::offer_termination() {
+ G1ParScanThreadState* const pss = par_scan_state();
+ start_term_time();
+ const bool res = terminator()->offer_termination();
+ end_term_time();
+ return res;
+}
+
+void G1ParEvacuateFollowersClosure::do_void() {
+ G1ParScanThreadState* const pss = par_scan_state();
+ pss->trim_queue();
+ do {
+ pss->steal_and_trim_queue(queues());
+ } while (!offer_termination());
+}
+
+class G1ParTask : public AbstractGangTask {
+protected:
+ G1CollectedHeap* _g1h;
+ G1ParScanThreadStateSet* _pss;
+ RefToScanQueueSet* _queues;
+ G1RootProcessor* _root_processor;
+ ParallelTaskTerminator _terminator;
+ uint _n_workers;
+
+public:
+ G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
+ : AbstractGangTask("G1 collection"),
+ _g1h(g1h),
+ _pss(per_thread_states),
+ _queues(task_queues),
+ _root_processor(root_processor),
+ _terminator(n_workers, _queues),
+ _n_workers(n_workers)
+ {}
+
+ void work(uint worker_id) {
+ if (worker_id >= _n_workers) return; // no work needed this round
+
+ double start_sec = os::elapsedTime();
+ _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
+
+ {
+ ResourceMark rm;
+ HandleMark hm;
+
+ ReferenceProcessor* rp = _g1h->ref_processor_stw();
+
+ G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
+ pss->set_ref_processor(rp);
+
+ double start_strong_roots_sec = os::elapsedTime();
+
+ _root_processor->evacuate_roots(pss->closures(), worker_id);
+
+ // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
+ // treating the nmethods visited to act as roots for concurrent marking.
+ // We only want to make sure that the oops in the nmethods are adjusted with regard to the
+ // objects copied by the current evacuation.
+ _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
+ pss->closures()->weak_codeblobs(),
+ worker_id);
+
+ double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
+
+ double term_sec = 0.0;
+ size_t evac_term_attempts = 0;
+ {
+ double start = os::elapsedTime();
+ G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
+ evac.do_void();
+
+ evac_term_attempts = evac.term_attempts();
+ term_sec = evac.term_time();
+ double elapsed_sec = os::elapsedTime() - start;
+ _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
+ _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
+ _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
+ }
+
+ assert(pss->queue_is_empty(), "should be empty");
+
+ if (log_is_enabled(Debug, gc, task, stats)) {
+ MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
+ size_t lab_waste;
+ size_t lab_undo_waste;
+ pss->waste(lab_waste, lab_undo_waste);
+ _g1h->print_termination_stats(worker_id,
+ (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
+ strong_roots_sec * 1000.0, /* strong roots time */
+ term_sec * 1000.0, /* evac term time */
+ evac_term_attempts, /* evac term attempts */
+ lab_waste, /* alloc buffer waste */
+ lab_undo_waste /* undo waste */
+ );
+ }
+
+ // Close the inner scope so that the ResourceMark and HandleMark
+ // destructors are executed here and are included as part of the
+ // "GC Worker Time".
+ }
+ _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
+ }
+};
+
+void G1CollectedHeap::print_termination_stats_hdr() {
+ log_debug(gc, task, stats)("GC Termination Stats");
+ log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
+ log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
+ log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
+}
+
+void G1CollectedHeap::print_termination_stats(uint worker_id,
+ double elapsed_ms,
+ double strong_roots_ms,
+ double term_ms,
+ size_t term_attempts,
+ size_t alloc_buffer_waste,
+ size_t undo_waste) const {
+ log_debug(gc, task, stats)
+ ("%3d %9.2f %9.2f %6.2f "
+ "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
+ SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
+ worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
+ term_ms, term_ms * 100 / elapsed_ms, term_attempts,
+ (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
+ alloc_buffer_waste * HeapWordSize / K,
+ undo_waste * HeapWordSize / K);
+}
+
+class G1StringAndSymbolCleaningTask : public AbstractGangTask {
+private:
+ BoolObjectClosure* _is_alive;
+ G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
+
+ int _initial_string_table_size;
+ int _initial_symbol_table_size;
+
+ bool _process_strings;
+ int _strings_processed;
+ int _strings_removed;
+
+ bool _process_symbols;
+ int _symbols_processed;
+ int _symbols_removed;
+
+ bool _process_string_dedup;
+
+public:
+ G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
+ AbstractGangTask("String/Symbol Unlinking"),
+ _is_alive(is_alive),
+ _dedup_closure(is_alive, NULL, false),
+ _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
+ _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
+ _process_string_dedup(process_string_dedup) {
+
+ _initial_string_table_size = StringTable::the_table()->table_size();
+ _initial_symbol_table_size = SymbolTable::the_table()->table_size();
+ if (process_strings) {
+ StringTable::clear_parallel_claimed_index();
+ }
+ if (process_symbols) {
+ SymbolTable::clear_parallel_claimed_index();
+ }
+ }
+
+ ~G1StringAndSymbolCleaningTask() {
+ guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
+ "claim value %d after unlink less than initial string table size %d",
+ StringTable::parallel_claimed_index(), _initial_string_table_size);
+ guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
+ "claim value %d after unlink less than initial symbol table size %d",
+ SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
+
+ log_info(gc, stringtable)(
+ "Cleaned string and symbol table, "
+ "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
+ "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
+ strings_processed(), strings_removed(),
+ symbols_processed(), symbols_removed());
+ }
+
+ void work(uint worker_id) {
+ int strings_processed = 0;
+ int strings_removed = 0;
+ int symbols_processed = 0;
+ int symbols_removed = 0;
+ if (_process_strings) {
+ StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
+ Atomic::add(strings_processed, &_strings_processed);
+ Atomic::add(strings_removed, &_strings_removed);
+ }
+ if (_process_symbols) {
+ SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
+ Atomic::add(symbols_processed, &_symbols_processed);
+ Atomic::add(symbols_removed, &_symbols_removed);
+ }
+ if (_process_string_dedup) {
+ G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
+ }
+ }
+
+ size_t strings_processed() const { return (size_t)_strings_processed; }
+ size_t strings_removed() const { return (size_t)_strings_removed; }
+
+ size_t symbols_processed() const { return (size_t)_symbols_processed; }
+ size_t symbols_removed() const { return (size_t)_symbols_removed; }
+};
+
+class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
+private:
+ static Monitor* _lock;
+
+ BoolObjectClosure* const _is_alive;
+ const bool _unloading_occurred;
+ const uint _num_workers;
+
+ // Variables used to claim nmethods.
+ CompiledMethod* _first_nmethod;
+ volatile CompiledMethod* _claimed_nmethod;
+
+ // The list of nmethods that need to be processed by the second pass.
+ volatile CompiledMethod* _postponed_list;
+ volatile uint _num_entered_barrier;
+
+ public:
+ G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
+ _is_alive(is_alive),
+ _unloading_occurred(unloading_occurred),
+ _num_workers(num_workers),
+ _first_nmethod(NULL),
+ _claimed_nmethod(NULL),
+ _postponed_list(NULL),
+ _num_entered_barrier(0)
+ {
+ CompiledMethod::increase_unloading_clock();
+ // Get first alive nmethod
+ CompiledMethodIterator iter = CompiledMethodIterator();
+ if(iter.next_alive()) {
+ _first_nmethod = iter.method();
+ }
+ _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
+ }
+
+ ~G1CodeCacheUnloadingTask() {
+ CodeCache::verify_clean_inline_caches();
+
+ CodeCache::set_needs_cache_clean(false);
+ guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
+
+ CodeCache::verify_icholder_relocations();
+ }
+
+ private:
+ void add_to_postponed_list(CompiledMethod* nm) {
+ CompiledMethod* old;
+ do {
+ old = (CompiledMethod*)_postponed_list;
+ nm->set_unloading_next(old);
+ } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
+ }
+
+ void clean_nmethod(CompiledMethod* nm) {
+ bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
+
+ if (postponed) {
+ // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
+ add_to_postponed_list(nm);
+ }
+
+ // Mark that this thread has been cleaned/unloaded.
+ // After this call, it will be safe to ask if this nmethod was unloaded or not.
+ nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
+ }
+
+ void clean_nmethod_postponed(CompiledMethod* nm) {
+ nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
+ }
+
+ static const int MaxClaimNmethods = 16;
+
+ void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
+ CompiledMethod* first;
+ CompiledMethodIterator last;
+
+ do {
+ *num_claimed_nmethods = 0;
+
+ first = (CompiledMethod*)_claimed_nmethod;
+ last = CompiledMethodIterator(first);
+
+ if (first != NULL) {
+
+ for (int i = 0; i < MaxClaimNmethods; i++) {
+ if (!last.next_alive()) {
+ break;
+ }
+ claimed_nmethods[i] = last.method();
+ (*num_claimed_nmethods)++;
+ }
+ }
+
+ } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
+ }
+
+ CompiledMethod* claim_postponed_nmethod() {
+ CompiledMethod* claim;
+ CompiledMethod* next;
+
+ do {
+ claim = (CompiledMethod*)_postponed_list;
+ if (claim == NULL) {
+ return NULL;
+ }
+
+ next = claim->unloading_next();
+
+ } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
+
+ return claim;
+ }
+
+ public:
+ // Mark that we're done with the first pass of nmethod cleaning.
+ void barrier_mark(uint worker_id) {
+ MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
+ _num_entered_barrier++;
+ if (_num_entered_barrier == _num_workers) {
+ ml.notify_all();
+ }
+ }
+
+ // See if we have to wait for the other workers to
+ // finish their first-pass nmethod cleaning work.
+ void barrier_wait(uint worker_id) {
+ if (_num_entered_barrier < _num_workers) {
+ MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
+ while (_num_entered_barrier < _num_workers) {
+ ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
+ }
+ }
+ }
+
+ // Cleaning and unloading of nmethods. Some work has to be postponed
+ // to the second pass, when we know which nmethods survive.
+ void work_first_pass(uint worker_id) {
+ // The first nmethods is claimed by the first worker.
+ if (worker_id == 0 && _first_nmethod != NULL) {
+ clean_nmethod(_first_nmethod);
+ _first_nmethod = NULL;
+ }
+
+ int num_claimed_nmethods;
+ CompiledMethod* claimed_nmethods[MaxClaimNmethods];
+
+ while (true) {
+ claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
+
+ if (num_claimed_nmethods == 0) {
+ break;
+ }
+
+ for (int i = 0; i < num_claimed_nmethods; i++) {
+ clean_nmethod(claimed_nmethods[i]);
+ }
+ }
+ }
+
+ void work_second_pass(uint worker_id) {
+ CompiledMethod* nm;
+ // Take care of postponed nmethods.
+ while ((nm = claim_postponed_nmethod()) != NULL) {
+ clean_nmethod_postponed(nm);
+ }
+ }
+};
+
+Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
+
+class G1KlassCleaningTask : public StackObj {
+ BoolObjectClosure* _is_alive;
+ volatile jint _clean_klass_tree_claimed;
+ ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
+
+ public:
+ G1KlassCleaningTask(BoolObjectClosure* is_alive) :
+ _is_alive(is_alive),
+ _clean_klass_tree_claimed(0),
+ _klass_iterator() {
+ }
+
+ private:
+ bool claim_clean_klass_tree_task() {
+ if (_clean_klass_tree_claimed) {
+ return false;
+ }
+
+ return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
+ }
+
+ InstanceKlass* claim_next_klass() {
+ Klass* klass;
+ do {
+ klass =_klass_iterator.next_klass();
+ } while (klass != NULL && !klass->is_instance_klass());
+
+ // this can be null so don't call InstanceKlass::cast
+ return static_cast<InstanceKlass*>(klass);
+ }
+
+public:
+
+ void clean_klass(InstanceKlass* ik) {
+ ik->clean_weak_instanceklass_links(_is_alive);
+ }
+
+ void work() {
+ ResourceMark rm;
+
+ // One worker will clean the subklass/sibling klass tree.
+ if (claim_clean_klass_tree_task()) {
+ Klass::clean_subklass_tree(_is_alive);
+ }
+
+ // All workers will help cleaning the classes,
+ InstanceKlass* klass;
+ while ((klass = claim_next_klass()) != NULL) {
+ clean_klass(klass);
+ }
+ }
+};
+
+class G1ResolvedMethodCleaningTask : public StackObj {
+ BoolObjectClosure* _is_alive;
+ volatile jint _resolved_method_task_claimed;
+public:
+ G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
+ _is_alive(is_alive), _resolved_method_task_claimed(0) {}
+
+ bool claim_resolved_method_task() {
+ if (_resolved_method_task_claimed) {
+ return false;
+ }
+ return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
+ }
+
+ // These aren't big, one thread can do it all.
+ void work() {
+ if (claim_resolved_method_task()) {
+ ResolvedMethodTable::unlink(_is_alive);
+ }
+ }
+};
+
+
+// To minimize the remark pause times, the tasks below are done in parallel.
+class G1ParallelCleaningTask : public AbstractGangTask {
+private:
+ G1StringAndSymbolCleaningTask _string_symbol_task;
+ G1CodeCacheUnloadingTask _code_cache_task;
+ G1KlassCleaningTask _klass_cleaning_task;
+ G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
+
+public:
+ // The constructor is run in the VMThread.
+ G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
+ AbstractGangTask("Parallel Cleaning"),
+ _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
+ _code_cache_task(num_workers, is_alive, unloading_occurred),
+ _klass_cleaning_task(is_alive),
+ _resolved_method_cleaning_task(is_alive) {
+ }
+
+ // The parallel work done by all worker threads.
+ void work(uint worker_id) {
+ // Do first pass of code cache cleaning.
+ _code_cache_task.work_first_pass(worker_id);
+
+ // Let the threads mark that the first pass is done.
+ _code_cache_task.barrier_mark(worker_id);
+
+ // Clean the Strings and Symbols.
+ _string_symbol_task.work(worker_id);
+
+ // Clean unreferenced things in the ResolvedMethodTable
+ _resolved_method_cleaning_task.work();
+
+ // Wait for all workers to finish the first code cache cleaning pass.
+ _code_cache_task.barrier_wait(worker_id);
+
+ // Do the second code cache cleaning work, which realize on
+ // the liveness information gathered during the first pass.
+ _code_cache_task.work_second_pass(worker_id);
+
+ // Clean all klasses that were not unloaded.
+ _klass_cleaning_task.work();
+ }
+};
+
+
+void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
+ bool class_unloading_occurred) {
+ uint n_workers = workers()->active_workers();
+
+ G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
+ workers()->run_task(&g1_unlink_task);
+}
+
+void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
+ bool process_strings,
+ bool process_symbols,
+ bool process_string_dedup) {
+ if (!process_strings && !process_symbols && !process_string_dedup) {
+ // Nothing to clean.
+ return;
+ }
+
+ G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
+ workers()->run_task(&g1_unlink_task);
+
+}
+
+class G1RedirtyLoggedCardsTask : public AbstractGangTask {
+ private:
+ DirtyCardQueueSet* _queue;
+ G1CollectedHeap* _g1h;
+ public:
+ G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
+ _queue(queue), _g1h(g1h) { }
+
+ virtual void work(uint worker_id) {
+ G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
+ G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
+
+ RedirtyLoggedCardTableEntryClosure cl(_g1h);
+ _queue->par_apply_closure_to_all_completed_buffers(&cl);
+
+ phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
+ }
+};
+
+void G1CollectedHeap::redirty_logged_cards() {
+ double redirty_logged_cards_start = os::elapsedTime();
+
+ G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
+ dirty_card_queue_set().reset_for_par_iteration();
+ workers()->run_task(&redirty_task);
+
+ DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
+ dcq.merge_bufferlists(&dirty_card_queue_set());
+ assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
+
+ g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
+}
+
+// Weak Reference Processing support
+
+// An always "is_alive" closure that is used to preserve referents.
+// If the object is non-null then it's alive. Used in the preservation
+// of referent objects that are pointed to by reference objects
+// discovered by the CM ref processor.
+class G1AlwaysAliveClosure: public BoolObjectClosure {
+ G1CollectedHeap* _g1;
+public:
+ G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
+ bool do_object_b(oop p) {
+ if (p != NULL) {
+ return true;
+ }
+ return false;
+ }
+};
+
+bool G1STWIsAliveClosure::do_object_b(oop p) {
+ // An object is reachable if it is outside the collection set,
+ // or is inside and copied.
+ return !_g1->is_in_cset(p) || p->is_forwarded();
+}
+
+// Non Copying Keep Alive closure
+class G1KeepAliveClosure: public OopClosure {
+ G1CollectedHeap* _g1;
+public:
+ G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
+ void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
+ void do_oop(oop* p) {
+ oop obj = *p;
+ assert(obj != NULL, "the caller should have filtered out NULL values");
+
+ const InCSetState cset_state = _g1->in_cset_state(obj);
+ if (!cset_state.is_in_cset_or_humongous()) {
+ return;
+ }
+ if (cset_state.is_in_cset()) {
+ assert( obj->is_forwarded(), "invariant" );
+ *p = obj->forwardee();
+ } else {
+ assert(!obj->is_forwarded(), "invariant" );
+ assert(cset_state.is_humongous(),
+ "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
+ _g1->set_humongous_is_live(obj);
+ }
+ }
+};
+
+// Copying Keep Alive closure - can be called from both
+// serial and parallel code as long as different worker
+// threads utilize different G1ParScanThreadState instances
+// and different queues.
+
+class G1CopyingKeepAliveClosure: public OopClosure {
+ G1CollectedHeap* _g1h;
+ OopClosure* _copy_non_heap_obj_cl;
+ G1ParScanThreadState* _par_scan_state;
+
+public:
+ G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
+ OopClosure* non_heap_obj_cl,
+ G1ParScanThreadState* pss):
+ _g1h(g1h),
+ _copy_non_heap_obj_cl(non_heap_obj_cl),
+ _par_scan_state(pss)
+ {}
+
+ virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+ virtual void do_oop( oop* p) { do_oop_work(p); }
+
+ template <class T> void do_oop_work(T* p) {
+ oop obj = oopDesc::load_decode_heap_oop(p);
+
+ if (_g1h->is_in_cset_or_humongous(obj)) {
+ // If the referent object has been forwarded (either copied
+ // to a new location or to itself in the event of an
+ // evacuation failure) then we need to update the reference
+ // field and, if both reference and referent are in the G1
+ // heap, update the RSet for the referent.
+ //
+ // If the referent has not been forwarded then we have to keep
+ // it alive by policy. Therefore we have copy the referent.
+ //
+ // If the reference field is in the G1 heap then we can push
+ // on the PSS queue. When the queue is drained (after each
+ // phase of reference processing) the object and it's followers
+ // will be copied, the reference field set to point to the
+ // new location, and the RSet updated. Otherwise we need to
+ // use the the non-heap or metadata closures directly to copy
+ // the referent object and update the pointer, while avoiding
+ // updating the RSet.
+
+ if (_g1h->is_in_g1_reserved(p)) {
+ _par_scan_state->push_on_queue(p);
+ } else {
+ assert(!Metaspace::contains((const void*)p),
+ "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
+ _copy_non_heap_obj_cl->do_oop(p);
+ }
+ }
+ }
+};
+
+// Serial drain queue closure. Called as the 'complete_gc'
+// closure for each discovered list in some of the
+// reference processing phases.
+
+class G1STWDrainQueueClosure: public VoidClosure {
+protected:
+ G1CollectedHeap* _g1h;
+ G1ParScanThreadState* _par_scan_state;
+
+ G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
+
+public:
+ G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
+ _g1h(g1h),
+ _par_scan_state(pss)
+ { }
+
+ void do_void() {
+ G1ParScanThreadState* const pss = par_scan_state();
+ pss->trim_queue();
+ }
+};
+
+// Parallel Reference Processing closures
+
+// Implementation of AbstractRefProcTaskExecutor for parallel reference
+// processing during G1 evacuation pauses.
+
+class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
+private:
+ G1CollectedHeap* _g1h;
+ G1ParScanThreadStateSet* _pss;
+ RefToScanQueueSet* _queues;
+ WorkGang* _workers;
+ uint _active_workers;
+
+public:
+ G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
+ G1ParScanThreadStateSet* per_thread_states,
+ WorkGang* workers,
+ RefToScanQueueSet *task_queues,
+ uint n_workers) :
+ _g1h(g1h),
+ _pss(per_thread_states),
+ _queues(task_queues),
+ _workers(workers),
+ _active_workers(n_workers)
+ {
+ g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
+ }
+
+ // Executes the given task using concurrent marking worker threads.
+ virtual void execute(ProcessTask& task);
+ virtual void execute(EnqueueTask& task);
+};
+
+// Gang task for possibly parallel reference processing
+
+class G1STWRefProcTaskProxy: public AbstractGangTask {
+ typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
+ ProcessTask& _proc_task;
+ G1CollectedHeap* _g1h;
+ G1ParScanThreadStateSet* _pss;
+ RefToScanQueueSet* _task_queues;
+ ParallelTaskTerminator* _terminator;
+
+public:
+ G1STWRefProcTaskProxy(ProcessTask& proc_task,
+ G1CollectedHeap* g1h,
+ G1ParScanThreadStateSet* per_thread_states,
+ RefToScanQueueSet *task_queues,
+ ParallelTaskTerminator* terminator) :
+ AbstractGangTask("Process reference objects in parallel"),
+ _proc_task(proc_task),
+ _g1h(g1h),
+ _pss(per_thread_states),
+ _task_queues(task_queues),
+ _terminator(terminator)
+ {}
+
+ virtual void work(uint worker_id) {
+ // The reference processing task executed by a single worker.
+ ResourceMark rm;
+ HandleMark hm;
+
+ G1STWIsAliveClosure is_alive(_g1h);
+
+ G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
+ pss->set_ref_processor(NULL);
+
+ // Keep alive closure.
+ G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
+
+ // Complete GC closure
+ G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
+
+ // Call the reference processing task's work routine.
+ _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
+
+ // Note we cannot assert that the refs array is empty here as not all
+ // of the processing tasks (specifically phase2 - pp2_work) execute
+ // the complete_gc closure (which ordinarily would drain the queue) so
+ // the queue may not be empty.
+ }
+};
+
+// Driver routine for parallel reference processing.
+// Creates an instance of the ref processing gang
+// task and has the worker threads execute it.
+void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
+ assert(_workers != NULL, "Need parallel worker threads.");
+
+ ParallelTaskTerminator terminator(_active_workers, _queues);
+ G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
+
+ _workers->run_task(&proc_task_proxy);
+}
+
+// Gang task for parallel reference enqueueing.
+
+class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
+ typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
+ EnqueueTask& _enq_task;
+
+public:
+ G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
+ AbstractGangTask("Enqueue reference objects in parallel"),
+ _enq_task(enq_task)
+ { }
+
+ virtual void work(uint worker_id) {
+ _enq_task.work(worker_id);
+ }
+};
+
+// Driver routine for parallel reference enqueueing.
+// Creates an instance of the ref enqueueing gang
+// task and has the worker threads execute it.
+
+void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
+ assert(_workers != NULL, "Need parallel worker threads.");
+
+ G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
+
+ _workers->run_task(&enq_task_proxy);
+}
+
+// End of weak reference support closures
+
+// Abstract task used to preserve (i.e. copy) any referent objects
+// that are in the collection set and are pointed to by reference
+// objects discovered by the CM ref processor.
+
+class G1ParPreserveCMReferentsTask: public AbstractGangTask {
+protected:
+ G1CollectedHeap* _g1h;
+ G1ParScanThreadStateSet* _pss;
+ RefToScanQueueSet* _queues;
+ ParallelTaskTerminator _terminator;
+ uint _n_workers;
+
+public:
+ G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
+ AbstractGangTask("ParPreserveCMReferents"),
+ _g1h(g1h),
+ _pss(per_thread_states),
+ _queues(task_queues),
+ _terminator(workers, _queues),
+ _n_workers(workers)
+ {
+ g1h->ref_processor_cm()->set_active_mt_degree(workers);
+ }
+
+ void work(uint worker_id) {
+ G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
+
+ ResourceMark rm;
+ HandleMark hm;
+
+ G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
+ pss->set_ref_processor(NULL);
+ assert(pss->queue_is_empty(), "both queue and overflow should be empty");
+
+ // Is alive closure
+ G1AlwaysAliveClosure always_alive(_g1h);
+
+ // Copying keep alive closure. Applied to referent objects that need
+ // to be copied.
+ G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
+
+ ReferenceProcessor* rp = _g1h->ref_processor_cm();
+
+ uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
+ uint stride = MIN2(MAX2(_n_workers, 1U), limit);
+
+ // limit is set using max_num_q() - which was set using ParallelGCThreads.
+ // So this must be true - but assert just in case someone decides to
+ // change the worker ids.
+ assert(worker_id < limit, "sanity");
+ assert(!rp->discovery_is_atomic(), "check this code");
+
+ // Select discovered lists [i, i+stride, i+2*stride,...,limit)
+ for (uint idx = worker_id; idx < limit; idx += stride) {
+ DiscoveredList& ref_list = rp->discovered_refs()[idx];
+
+ DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
+ while (iter.has_next()) {
+ // Since discovery is not atomic for the CM ref processor, we
+ // can see some null referent objects.
+ iter.load_ptrs(DEBUG_ONLY(true));
+ oop ref = iter.obj();
+
+ // This will filter nulls.
+ if (iter.is_referent_alive()) {
+ iter.make_referent_alive();
+ }
+ iter.move_to_next();
+ }
+ }
+
+ // Drain the queue - which may cause stealing
+ G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
+ drain_queue.do_void();
+ // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
+ assert(pss->queue_is_empty(), "should be");
+ }
+};
+
+void G1CollectedHeap::process_weak_jni_handles() {
+ double ref_proc_start = os::elapsedTime();
+
+ G1STWIsAliveClosure is_alive(this);
+ G1KeepAliveClosure keep_alive(this);
+ JNIHandles::weak_oops_do(&is_alive, &keep_alive);
+
+ double ref_proc_time = os::elapsedTime() - ref_proc_start;
+ g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
+}
+
+void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
+ // Any reference objects, in the collection set, that were 'discovered'
+ // by the CM ref processor should have already been copied (either by
+ // applying the external root copy closure to the discovered lists, or
+ // by following an RSet entry).
+ //
+ // But some of the referents, that are in the collection set, that these
+ // reference objects point to may not have been copied: the STW ref
+ // processor would have seen that the reference object had already
+ // been 'discovered' and would have skipped discovering the reference,
+ // but would not have treated the reference object as a regular oop.
+ // As a result the copy closure would not have been applied to the
+ // referent object.
+ //
+ // We need to explicitly copy these referent objects - the references
+ // will be processed at the end of remarking.
+ //
+ // We also need to do this copying before we process the reference
+ // objects discovered by the STW ref processor in case one of these
+ // referents points to another object which is also referenced by an
+ // object discovered by the STW ref processor.
+ double preserve_cm_referents_time = 0.0;
+
+ // To avoid spawning task when there is no work to do, check that
+ // a concurrent cycle is active and that some references have been
+ // discovered.
+ if (concurrent_mark()->cmThread()->during_cycle() &&
+ ref_processor_cm()->has_discovered_references()) {
+ double preserve_cm_referents_start = os::elapsedTime();
+ uint no_of_gc_workers = workers()->active_workers();
+ G1ParPreserveCMReferentsTask keep_cm_referents(this,
+ per_thread_states,
+ no_of_gc_workers,
+ _task_queues);
+ workers()->run_task(&keep_cm_referents);
+ preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
+ }
+
+ g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
+}
+
+// Weak Reference processing during an evacuation pause (part 1).
+void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
+ double ref_proc_start = os::elapsedTime();
+
+ ReferenceProcessor* rp = _ref_processor_stw;
+ assert(rp->discovery_enabled(), "should have been enabled");
+
+ // Closure to test whether a referent is alive.
+ G1STWIsAliveClosure is_alive(this);
+
+ // Even when parallel reference processing is enabled, the processing
+ // of JNI refs is serial and performed serially by the current thread
+ // rather than by a worker. The following PSS will be used for processing
+ // JNI refs.
+
+ // Use only a single queue for this PSS.
+ G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
+ pss->set_ref_processor(NULL);
+ assert(pss->queue_is_empty(), "pre-condition");
+
+ // Keep alive closure.
+ G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
+
+ // Serial Complete GC closure
+ G1STWDrainQueueClosure drain_queue(this, pss);
+
+ // Setup the soft refs policy...
+ rp->setup_policy(false);
+
+ ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
+
+ ReferenceProcessorStats stats;
+ if (!rp->processing_is_mt()) {
+ // Serial reference processing...
+ stats = rp->process_discovered_references(&is_alive,
+ &keep_alive,
+ &drain_queue,
+ NULL,
+ pt);
+ } else {
+ uint no_of_gc_workers = workers()->active_workers();
+
+ // Parallel reference processing
+ assert(no_of_gc_workers <= rp->max_num_q(),
+ "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
+ no_of_gc_workers, rp->max_num_q());
+
+ G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
+ stats = rp->process_discovered_references(&is_alive,
+ &keep_alive,
+ &drain_queue,
+ &par_task_executor,
+ pt);
+ }
+
+ _gc_tracer_stw->report_gc_reference_stats(stats);
+
+ // We have completed copying any necessary live referent objects.
+ assert(pss->queue_is_empty(), "both queue and overflow should be empty");
+
+ double ref_proc_time = os::elapsedTime() - ref_proc_start;
+ g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
+}
+
+// Weak Reference processing during an evacuation pause (part 2).
+void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
+ double ref_enq_start = os::elapsedTime();
+
+ ReferenceProcessor* rp = _ref_processor_stw;
+ assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
+
+ ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
+
+ // Now enqueue any remaining on the discovered lists on to
+ // the pending list.
+ if (!rp->processing_is_mt()) {
+ // Serial reference processing...
+ rp->enqueue_discovered_references(NULL, pt);
+ } else {
+ // Parallel reference enqueueing
+
+ uint n_workers = workers()->active_workers();
+
+ assert(n_workers <= rp->max_num_q(),
+ "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
+ n_workers, rp->max_num_q());
+
+ G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
+ rp->enqueue_discovered_references(&par_task_executor, pt);
+ }
+
+ rp->verify_no_references_recorded();
+ assert(!rp->discovery_enabled(), "should have been disabled");
+
+ // If during an initial mark pause we install a pending list head which is not otherwise reachable
+ // ensure that it is marked in the bitmap for concurrent marking to discover.
+ if (collector_state()->during_initial_mark_pause()) {
+ oop pll_head = Universe::reference_pending_list();
+ if (pll_head != NULL) {
+ _cm->mark_in_next_bitmap(pll_head);
+ }
+ }
+
+ // FIXME
+ // CM's reference processing also cleans up the string and symbol tables.
+ // Should we do that here also? We could, but it is a serial operation
+ // and could significantly increase the pause time.
+
+ double ref_enq_time = os::elapsedTime() - ref_enq_start;
+ g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
+}
+
+void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
+ double merge_pss_time_start = os::elapsedTime();
+ per_thread_states->flush();
+ g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
+}
+
+void G1CollectedHeap::pre_evacuate_collection_set() {
+ _expand_heap_after_alloc_failure = true;
+ _evacuation_failed = false;
+
+ // Disable the hot card cache.
+ _hot_card_cache->reset_hot_cache_claimed_index();
+ _hot_card_cache->set_use_cache(false);
+
+ g1_rem_set()->prepare_for_oops_into_collection_set_do();
+ _preserved_marks_set.assert_empty();
+
+ G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
+
+ // InitialMark needs claim bits to keep track of the marked-through CLDs.
+ if (collector_state()->during_initial_mark_pause()) {
+ double start_clear_claimed_marks = os::elapsedTime();
+
+ ClassLoaderDataGraph::clear_claimed_marks();
+
+ double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
+ phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
+ }
+}
+
+void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
+ // Should G1EvacuationFailureALot be in effect for this GC?
+ NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
+
+ assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
+
+ G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
+
+ double start_par_time_sec = os::elapsedTime();
+ double end_par_time_sec;
+
+ {
+ const uint n_workers = workers()->active_workers();
+ G1RootProcessor root_processor(this, n_workers);
+ G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
+
+ print_termination_stats_hdr();
+
+ workers()->run_task(&g1_par_task);
+ end_par_time_sec = os::elapsedTime();
+
+ // Closing the inner scope will execute the destructor
+ // for the G1RootProcessor object. We record the current
+ // elapsed time before closing the scope so that time
+ // taken for the destructor is NOT included in the
+ // reported parallel time.
+ }
+
+ double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
+ phase_times->record_par_time(par_time_ms);
+
+ double code_root_fixup_time_ms =
+ (os::elapsedTime() - end_par_time_sec) * 1000.0;
+ phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
+}
+
+void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
+ // Process any discovered reference objects - we have
+ // to do this _before_ we retire the GC alloc regions
+ // as we may have to copy some 'reachable' referent
+ // objects (and their reachable sub-graphs) that were
+ // not copied during the pause.
+ if (g1_policy()->should_process_references()) {
+ preserve_cm_referents(per_thread_states);
+ process_discovered_references(per_thread_states);
+ } else {
+ ref_processor_stw()->verify_no_references_recorded();
+ process_weak_jni_handles();
+ }
+
+ if (G1StringDedup::is_enabled()) {
+ double fixup_start = os::elapsedTime();
+
+ G1STWIsAliveClosure is_alive(this);
+ G1KeepAliveClosure keep_alive(this);
+ G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
+
+ double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
+ g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
+ }
+
+ g1_rem_set()->cleanup_after_oops_into_collection_set_do();
+
+ if (evacuation_failed()) {
+ restore_after_evac_failure();
+
+ // Reset the G1EvacuationFailureALot counters and flags
+ // Note: the values are reset only when an actual
+ // evacuation failure occurs.
+ NOT_PRODUCT(reset_evacuation_should_fail();)
+ }
+
+ _preserved_marks_set.assert_empty();
+
+ // Enqueue any remaining references remaining on the STW
+ // reference processor's discovered lists. We need to do
+ // this after the card table is cleaned (and verified) as
+ // the act of enqueueing entries on to the pending list
+ // will log these updates (and dirty their associated
+ // cards). We need these updates logged to update any
+ // RSets.
+ if (g1_policy()->should_process_references()) {
+ enqueue_discovered_references(per_thread_states);
+ } else {
+ g1_policy()->phase_times()->record_ref_enq_time(0);
+ }
+
+ _allocator->release_gc_alloc_regions(evacuation_info);
+
+ merge_per_thread_state_info(per_thread_states);
+
+ // Reset and re-enable the hot card cache.
+ // Note the counts for the cards in the regions in the
+ // collection set are reset when the collection set is freed.
+ _hot_card_cache->reset_hot_cache();
+ _hot_card_cache->set_use_cache(true);
+
+ purge_code_root_memory();
+
+ redirty_logged_cards();
+#if defined(COMPILER2) || INCLUDE_JVMCI
+ double start = os::elapsedTime();
+ DerivedPointerTable::update_pointers();
+ g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
+#endif
+ g1_policy()->print_age_table();
+}
+
+void G1CollectedHeap::record_obj_copy_mem_stats() {
+ g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
+
+ _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
+ create_g1_evac_summary(&_old_evac_stats));
+}
+
+void G1CollectedHeap::free_region(HeapRegion* hr,
+ FreeRegionList* free_list,
+ bool skip_remset,
+ bool skip_hot_card_cache,
+ bool locked) {
+ assert(!hr->is_free(), "the region should not be free");
+ assert(!hr->is_empty(), "the region should not be empty");
+ assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
+ assert(free_list != NULL, "pre-condition");
+
+ if (G1VerifyBitmaps) {
+ MemRegion mr(hr->bottom(), hr->end());
+ concurrent_mark()->clearRangePrevBitmap(mr);
+ }
+
+ // Clear the card counts for this region.
+ // Note: we only need to do this if the region is not young
+ // (since we don't refine cards in young regions).
+ if (!skip_hot_card_cache && !hr->is_young()) {
+ _hot_card_cache->reset_card_counts(hr);
+ }
+ hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
+ free_list->add_ordered(hr);
+}
+
+void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
+ FreeRegionList* free_list,
+ bool skip_remset) {
+ assert(hr->is_humongous(), "this is only for humongous regions");
+ assert(free_list != NULL, "pre-condition");
+ hr->clear_humongous();
+ free_region(hr, free_list, skip_remset);
+}
+
+void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
+ const uint humongous_regions_removed) {
+ if (old_regions_removed > 0 || humongous_regions_removed > 0) {
+ MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
+ _old_set.bulk_remove(old_regions_removed);
+ _humongous_set.bulk_remove(humongous_regions_removed);
+ }
+
+}
+
+void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
+ assert(list != NULL, "list can't be null");
+ if (!list->is_empty()) {
+ MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
+ _hrm.insert_list_into_free_list(list);
+ }
+}
+
+void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
+ decrease_used(bytes);
+}
+
+class G1ParScrubRemSetTask: public AbstractGangTask {
+protected:
+ G1RemSet* _g1rs;
+ HeapRegionClaimer _hrclaimer;
+
+public:
+ G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
+ AbstractGangTask("G1 ScrubRS"),
+ _g1rs(g1_rs),
+ _hrclaimer(num_workers) {
+ }
+
+ void work(uint worker_id) {
+ _g1rs->scrub(worker_id, &_hrclaimer);
+ }
+};
+
+void G1CollectedHeap::scrub_rem_set() {
+ uint num_workers = workers()->active_workers();
+ G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
+ workers()->run_task(&g1_par_scrub_rs_task);
+}
+
+class G1FreeCollectionSetTask : public AbstractGangTask {
+private:
+
+ // Closure applied to all regions in the collection set to do work that needs to
+ // be done serially in a single thread.
+ class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
+ private:
+ EvacuationInfo* _evacuation_info;
+ const size_t* _surviving_young_words;
+
+ // Bytes used in successfully evacuated regions before the evacuation.
+ size_t _before_used_bytes;
+ // Bytes used in unsucessfully evacuated regions before the evacuation
+ size_t _after_used_bytes;
+
+ size_t _bytes_allocated_in_old_since_last_gc;
+
+ size_t _failure_used_words;
+ size_t _failure_waste_words;
+
+ FreeRegionList _local_free_list;
+ public:
+ G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
+ HeapRegionClosure(),
+ _evacuation_info(evacuation_info),
+ _surviving_young_words(surviving_young_words),
+ _before_used_bytes(0),
+ _after_used_bytes(0),
+ _bytes_allocated_in_old_since_last_gc(0),
+ _failure_used_words(0),
+ _failure_waste_words(0),
+ _local_free_list("Local Region List for CSet Freeing") {
+ }
+
+ virtual bool doHeapRegion(HeapRegion* r) {
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
+ g1h->clear_in_cset(r);
+
+ if (r->is_young()) {
+ assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
+ "Young index %d is wrong for region %u of type %s with %u young regions",
+ r->young_index_in_cset(),
+ r->hrm_index(),
+ r->get_type_str(),
+ g1h->collection_set()->young_region_length());
+ size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
+ r->record_surv_words_in_group(words_survived);
+ }
+
+ if (!r->evacuation_failed()) {
+ assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
+ _before_used_bytes += r->used();
+ g1h->free_region(r,
+ &_local_free_list,
+ true, /* skip_remset */
+ true, /* skip_hot_card_cache */
+ true /* locked */);
+ } else {
+ r->uninstall_surv_rate_group();
+ r->set_young_index_in_cset(-1);
+ r->set_evacuation_failed(false);
+ // When moving a young gen region to old gen, we "allocate" that whole region
+ // there. This is in addition to any already evacuated objects. Notify the
+ // policy about that.
+ // Old gen regions do not cause an additional allocation: both the objects
+ // still in the region and the ones already moved are accounted for elsewhere.
+ if (r->is_young()) {
+ _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
+ }
+ // The region is now considered to be old.
+ r->set_old();
+ // Do some allocation statistics accounting. Regions that failed evacuation
+ // are always made old, so there is no need to update anything in the young
+ // gen statistics, but we need to update old gen statistics.
+ size_t used_words = r->marked_bytes() / HeapWordSize;
+
+ _failure_used_words += used_words;
+ _failure_waste_words += HeapRegion::GrainWords - used_words;
+
+ g1h->old_set_add(r);
+ _after_used_bytes += r->used();
+ }
+ return false;
+ }
+
+ void complete_work() {
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ _evacuation_info->set_regions_freed(_local_free_list.length());
+ _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
+
+ g1h->prepend_to_freelist(&_local_free_list);
+ g1h->decrement_summary_bytes(_before_used_bytes);
+
+ G1Policy* policy = g1h->g1_policy();
+ policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
+
+ g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
+ }
+ };
+
+ G1CollectionSet* _collection_set;
+ G1SerialFreeCollectionSetClosure _cl;
+ const size_t* _surviving_young_words;
+
+ size_t _rs_lengths;
+
+ volatile jint _serial_work_claim;
+
+ struct WorkItem {
+ uint region_idx;
+ bool is_young;
+ bool evacuation_failed;
+
+ WorkItem(HeapRegion* r) {
+ region_idx = r->hrm_index();
+ is_young = r->is_young();
+ evacuation_failed = r->evacuation_failed();
+ }
+ };
+
+ volatile size_t _parallel_work_claim;
+ size_t _num_work_items;
+ WorkItem* _work_items;
+
+ void do_serial_work() {
+ // Need to grab the lock to be allowed to modify the old region list.
+ MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
+ _collection_set->iterate(&_cl);
+ }
+
+ void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ HeapRegion* r = g1h->region_at(region_idx);
+ assert(!g1h->is_on_master_free_list(r), "sanity");
+
+ Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
+
+ if (!is_young) {
+ g1h->_hot_card_cache->reset_card_counts(r);
+ }
+
+ if (!evacuation_failed) {
+ r->rem_set()->clear_locked();
+ }
+ }
+
+ class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
+ private:
+ size_t _cur_idx;
+ WorkItem* _work_items;
+ public:
+ G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
+
+ virtual bool doHeapRegion(HeapRegion* r) {
+ _work_items[_cur_idx++] = WorkItem(r);
+ return false;
+ }
+ };
+
+ void prepare_work() {
+ G1PrepareFreeCollectionSetClosure cl(_work_items);
+ _collection_set->iterate(&cl);
+ }
+
+ void complete_work() {
+ _cl.complete_work();
+
+ G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
+ policy->record_max_rs_lengths(_rs_lengths);
+ policy->cset_regions_freed();
+ }
+public:
+ G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
+ AbstractGangTask("G1 Free Collection Set"),
+ _cl(evacuation_info, surviving_young_words),
+ _collection_set(collection_set),
+ _surviving_young_words(surviving_young_words),
+ _serial_work_claim(0),
+ _rs_lengths(0),
+ _parallel_work_claim(0),
+ _num_work_items(collection_set->region_length()),
+ _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
+ prepare_work();
+ }
+
+ ~G1FreeCollectionSetTask() {
+ complete_work();
+ FREE_C_HEAP_ARRAY(WorkItem, _work_items);
+ }
+
+ // Chunk size for work distribution. The chosen value has been determined experimentally
+ // to be a good tradeoff between overhead and achievable parallelism.
+ static uint chunk_size() { return 32; }
+
+ virtual void work(uint worker_id) {
+ G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
+
+ // Claim serial work.
+ if (_serial_work_claim == 0) {
+ jint value = Atomic::add(1, &_serial_work_claim) - 1;
+ if (value == 0) {
+ double serial_time = os::elapsedTime();
+ do_serial_work();
+ timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
+ }
+ }
+
+ // Start parallel work.
+ double young_time = 0.0;
+ bool has_young_time = false;
+ double non_young_time = 0.0;
+ bool has_non_young_time = false;
+
+ while (true) {
+ size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
+ size_t cur = end - chunk_size();
+
+ if (cur >= _num_work_items) {
+ break;
+ }
+
+ double start_time = os::elapsedTime();
+
+ end = MIN2(end, _num_work_items);
+
+ for (; cur < end; cur++) {
+ bool is_young = _work_items[cur].is_young;
+
+ do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
+
+ double end_time = os::elapsedTime();
+ double time_taken = end_time - start_time;
+ if (is_young) {
+ young_time += time_taken;
+ has_young_time = true;
+ } else {
+ non_young_time += time_taken;
+ has_non_young_time = true;
+ }
+ start_time = end_time;
+ }
+ }
+
+ if (has_young_time) {
+ timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
+ }
+ if (has_non_young_time) {
+ timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
+ }
+ }
+};
+
+void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
+ _eden.clear();
+
+ double free_cset_start_time = os::elapsedTime();
+
+ {
+ uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
+ uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
+
+ G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
+
+ log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
+ cl.name(),
+ num_workers,
+ _collection_set.region_length());
+ workers()->run_task(&cl, num_workers);
+ }
+ g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
+
+ collection_set->clear();
+}
+
+class G1FreeHumongousRegionClosure : public HeapRegionClosure {
+ private:
+ FreeRegionList* _free_region_list;
+ HeapRegionSet* _proxy_set;
+ uint _humongous_objects_reclaimed;
+ uint _humongous_regions_reclaimed;
+ size_t _freed_bytes;
+ public:
+
+ G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
+ _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
+ }
+
+ virtual bool doHeapRegion(HeapRegion* r) {
+ if (!r->is_starts_humongous()) {
+ return false;
+ }
+
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ oop obj = (oop)r->bottom();
+ G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
+
+ // The following checks whether the humongous object is live are sufficient.
+ // The main additional check (in addition to having a reference from the roots
+ // or the young gen) is whether the humongous object has a remembered set entry.
+ //
+ // A humongous object cannot be live if there is no remembered set for it
+ // because:
+ // - there can be no references from within humongous starts regions referencing
+ // the object because we never allocate other objects into them.
+ // (I.e. there are no intra-region references that may be missed by the
+ // remembered set)
+ // - as soon there is a remembered set entry to the humongous starts region
+ // (i.e. it has "escaped" to an old object) this remembered set entry will stay
+ // until the end of a concurrent mark.
+ //
+ // It is not required to check whether the object has been found dead by marking
+ // or not, in fact it would prevent reclamation within a concurrent cycle, as
+ // all objects allocated during that time are considered live.
+ // SATB marking is even more conservative than the remembered set.
+ // So if at this point in the collection there is no remembered set entry,
+ // nobody has a reference to it.
+ // At the start of collection we flush all refinement logs, and remembered sets
+ // are completely up-to-date wrt to references to the humongous object.
+ //
+ // Other implementation considerations:
+ // - never consider object arrays at this time because they would pose
+ // considerable effort for cleaning up the the remembered sets. This is
+ // required because stale remembered sets might reference locations that
+ // are currently allocated into.
+ uint region_idx = r->hrm_index();
+ if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
+ !r->rem_set()->is_empty()) {
+ log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
+ region_idx,
+ (size_t)obj->size() * HeapWordSize,
+ p2i(r->bottom()),
+ r->rem_set()->occupied(),
+ r->rem_set()->strong_code_roots_list_length(),
+ next_bitmap->is_marked(r->bottom()),
+ g1h->is_humongous_reclaim_candidate(region_idx),
+ obj->is_typeArray()
+ );
+ return false;
+ }
+
+ guarantee(obj->is_typeArray(),
+ "Only eagerly reclaiming type arrays is supported, but the object "
+ PTR_FORMAT " is not.", p2i(r->bottom()));
+
+ log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
+ region_idx,
+ (size_t)obj->size() * HeapWordSize,
+ p2i(r->bottom()),
+ r->rem_set()->occupied(),
+ r->rem_set()->strong_code_roots_list_length(),
+ next_bitmap->is_marked(r->bottom()),
+ g1h->is_humongous_reclaim_candidate(region_idx),
+ obj->is_typeArray()
+ );
+
+ // Need to clear mark bit of the humongous object if already set.
+ if (next_bitmap->is_marked(r->bottom())) {
+ next_bitmap->clear(r->bottom());
+ }
+ _humongous_objects_reclaimed++;
+ do {
+ HeapRegion* next = g1h->next_region_in_humongous(r);
+ _freed_bytes += r->used();
+ r->set_containing_set(NULL);
+ _humongous_regions_reclaimed++;
+ g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
+ r = next;
+ } while (r != NULL);
+
+ return false;
+ }
+
+ uint humongous_objects_reclaimed() {
+ return _humongous_objects_reclaimed;
+ }
+
+ uint humongous_regions_reclaimed() {
+ return _humongous_regions_reclaimed;
+ }
+
+ size_t bytes_freed() const {
+ return _freed_bytes;
+ }
+};
+
+void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
+ assert_at_safepoint(true);
+
+ if (!G1EagerReclaimHumongousObjects ||
+ (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
+ g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
+ return;
+ }
+
+ double start_time = os::elapsedTime();
+
+ FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
+
+ G1FreeHumongousRegionClosure cl(&local_cleanup_list);
+ heap_region_iterate(&cl);
+
+ remove_from_old_sets(0, cl.humongous_regions_reclaimed());
+
+ G1HRPrinter* hrp = hr_printer();
+ if (hrp->is_active()) {
+ FreeRegionListIterator iter(&local_cleanup_list);
+ while (iter.more_available()) {
+ HeapRegion* hr = iter.get_next();
+ hrp->cleanup(hr);
+ }
+ }
+
+ prepend_to_freelist(&local_cleanup_list);
+ decrement_summary_bytes(cl.bytes_freed());
+
+ g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
+ cl.humongous_objects_reclaimed());
+}
+
+class G1AbandonCollectionSetClosure : public HeapRegionClosure {
+public:
+ virtual bool doHeapRegion(HeapRegion* r) {
+ assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
+ G1CollectedHeap::heap()->clear_in_cset(r);
+ r->set_young_index_in_cset(-1);
+ return false;
+ }
+};
+
+void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
+ G1AbandonCollectionSetClosure cl;
+ collection_set->iterate(&cl);
+
+ collection_set->clear();
+ collection_set->stop_incremental_building();
+}
+
+void G1CollectedHeap::set_free_regions_coming() {
+ log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
+
+ assert(!free_regions_coming(), "pre-condition");
+ _free_regions_coming = true;
+}
+
+void G1CollectedHeap::reset_free_regions_coming() {
+ assert(free_regions_coming(), "pre-condition");
+
+ {
+ MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
+ _free_regions_coming = false;
+ SecondaryFreeList_lock->notify_all();
+ }
+
+ log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
+}
+
+void G1CollectedHeap::wait_while_free_regions_coming() {
+ // Most of the time we won't have to wait, so let's do a quick test
+ // first before we take the lock.
+ if (!free_regions_coming()) {
+ return;
+ }
+
+ log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
+
+ {
+ MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
+ while (free_regions_coming()) {
+ SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
+ }
+ }
+
+ log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
+}
+
+bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
+ return _allocator->is_retained_old_region(hr);
+}
+
+void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
+ _eden.add(hr);
+ _g1_policy->set_region_eden(hr);
+}
+
+#ifdef ASSERT
+
+class NoYoungRegionsClosure: public HeapRegionClosure {
+private:
+ bool _success;
+public:
+ NoYoungRegionsClosure() : _success(true) { }
+ bool doHeapRegion(HeapRegion* r) {
+ if (r->is_young()) {
+ log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
+ p2i(r->bottom()), p2i(r->end()));
+ _success = false;
+ }
+ return false;
+ }
+ bool success() { return _success; }
+};
+
+bool G1CollectedHeap::check_young_list_empty() {
+ bool ret = (young_regions_count() == 0);
+
+ NoYoungRegionsClosure closure;
+ heap_region_iterate(&closure);
+ ret = ret && closure.success();
+
+ return ret;
+}
+
+#endif // ASSERT
+
+class TearDownRegionSetsClosure : public HeapRegionClosure {
+private:
+ HeapRegionSet *_old_set;
+
+public:
+ TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
+
+ bool doHeapRegion(HeapRegion* r) {
+ if (r->is_old()) {
+ _old_set->remove(r);
+ } else if(r->is_young()) {
+ r->uninstall_surv_rate_group();
+ } else {
+ // We ignore free regions, we'll empty the free list afterwards.
+ // We ignore humongous regions, we're not tearing down the
+ // humongous regions set.
+ assert(r->is_free() || r->is_humongous(),
+ "it cannot be another type");
+ }
+ return false;
+ }
+
+ ~TearDownRegionSetsClosure() {
+ assert(_old_set->is_empty(), "post-condition");
+ }
+};
+
+void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+
+ if (!free_list_only) {
+ TearDownRegionSetsClosure cl(&_old_set);
+ heap_region_iterate(&cl);
+
+ // Note that emptying the _young_list is postponed and instead done as
+ // the first step when rebuilding the regions sets again. The reason for
+ // this is that during a full GC string deduplication needs to know if
+ // a collected region was young or old when the full GC was initiated.
+ }
+ _hrm.remove_all_free_regions();
+}
+
+void G1CollectedHeap::increase_used(size_t bytes) {
+ _summary_bytes_used += bytes;
+}
+
+void G1CollectedHeap::decrease_used(size_t bytes) {
+ assert(_summary_bytes_used >= bytes,
+ "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
+ _summary_bytes_used, bytes);
+ _summary_bytes_used -= bytes;
+}
+
+void G1CollectedHeap::set_used(size_t bytes) {
+ _summary_bytes_used = bytes;
+}
+
+class RebuildRegionSetsClosure : public HeapRegionClosure {
+private:
+ bool _free_list_only;
+ HeapRegionSet* _old_set;
+ HeapRegionManager* _hrm;
+ size_t _total_used;
+
+public:
+ RebuildRegionSetsClosure(bool free_list_only,
+ HeapRegionSet* old_set, HeapRegionManager* hrm) :
+ _free_list_only(free_list_only),
+ _old_set(old_set), _hrm(hrm), _total_used(0) {
+ assert(_hrm->num_free_regions() == 0, "pre-condition");
+ if (!free_list_only) {
+ assert(_old_set->is_empty(), "pre-condition");
+ }
+ }
+
+ bool doHeapRegion(HeapRegion* r) {
+ if (r->is_empty()) {
+ // Add free regions to the free list
+ r->set_free();
+ r->set_allocation_context(AllocationContext::system());
+ _hrm->insert_into_free_list(r);
+ } else if (!_free_list_only) {
+
+ if (r->is_humongous()) {
+ // We ignore humongous regions. We left the humongous set unchanged.
+ } else {
+ assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
+ // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
+ r->move_to_old();
+ _old_set->add(r);
+ }
+ _total_used += r->used();
+ }
+
+ return false;
+ }
+
+ size_t total_used() {
+ return _total_used;
+ }
+};
+
+void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+
+ if (!free_list_only) {
+ _eden.clear();
+ _survivor.clear();
+ }
+
+ RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
+ heap_region_iterate(&cl);
+
+ if (!free_list_only) {
+ set_used(cl.total_used());
+ if (_archive_allocator != NULL) {
+ _archive_allocator->clear_used();
+ }
+ }
+ assert(used_unlocked() == recalculate_used(),
+ "inconsistent used_unlocked(), "
+ "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
+ used_unlocked(), recalculate_used());
+}
+
+bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
+ HeapRegion* hr = heap_region_containing(p);
+ return hr->is_in(p);
+}
+
+// Methods for the mutator alloc region
+
+HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
+ bool force) {
+ assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
+ bool should_allocate = g1_policy()->should_allocate_mutator_region();
+ if (force || should_allocate) {
+ HeapRegion* new_alloc_region = new_region(word_size,
+ false /* is_old */,
+ false /* do_expand */);
+ if (new_alloc_region != NULL) {
+ set_region_short_lived_locked(new_alloc_region);
+ _hr_printer.alloc(new_alloc_region, !should_allocate);
+ _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
+ return new_alloc_region;
+ }
+ }
+ return NULL;
+}
+
+void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
+ size_t allocated_bytes) {
+ assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
+ assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
+
+ collection_set()->add_eden_region(alloc_region);
+ increase_used(allocated_bytes);
+ _hr_printer.retire(alloc_region);
+ // We update the eden sizes here, when the region is retired,
+ // instead of when it's allocated, since this is the point that its
+ // used space has been recored in _summary_bytes_used.
+ g1mm()->update_eden_size();
+}
+
+// Methods for the GC alloc regions
+
+bool G1CollectedHeap::has_more_regions(InCSetState dest) {
+ if (dest.is_old()) {
+ return true;
+ } else {
+ return survivor_regions_count() < g1_policy()->max_survivor_regions();
+ }
+}
+
+HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
+ assert(FreeList_lock->owned_by_self(), "pre-condition");
+
+ if (!has_more_regions(dest)) {
+ return NULL;
+ }
+
+ const bool is_survivor = dest.is_young();
+
+ HeapRegion* new_alloc_region = new_region(word_size,
+ !is_survivor,
+ true /* do_expand */);
+ if (new_alloc_region != NULL) {
+ // We really only need to do this for old regions given that we
+ // should never scan survivors. But it doesn't hurt to do it
+ // for survivors too.
+ new_alloc_region->record_timestamp();
+ if (is_survivor) {
+ new_alloc_region->set_survivor();
+ _survivor.add(new_alloc_region);
+ _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
+ } else {
+ new_alloc_region->set_old();
+ _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
+ }
+ _hr_printer.alloc(new_alloc_region);
+ bool during_im = collector_state()->during_initial_mark_pause();
+ new_alloc_region->note_start_of_copying(during_im);
+ return new_alloc_region;
+ }
+ return NULL;
+}
+
+void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
+ size_t allocated_bytes,
+ InCSetState dest) {
+ bool during_im = collector_state()->during_initial_mark_pause();
+ alloc_region->note_end_of_copying(during_im);
+ g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
+ if (dest.is_old()) {
+ _old_set.add(alloc_region);
+ }
+ _hr_printer.retire(alloc_region);
+}
+
+HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
+ bool expanded = false;
+ uint index = _hrm.find_highest_free(&expanded);
+
+ if (index != G1_NO_HRM_INDEX) {
+ if (expanded) {
+ log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
+ HeapRegion::GrainWords * HeapWordSize);
+ }
+ _hrm.allocate_free_regions_starting_at(index, 1);
+ return region_at(index);
+ }
+ return NULL;
+}
+
+// Optimized nmethod scanning
+
+class RegisterNMethodOopClosure: public OopClosure {
+ G1CollectedHeap* _g1h;
+ nmethod* _nm;
+
+ template <class T> void do_oop_work(T* p) {
+ T heap_oop = oopDesc::load_heap_oop(p);
+ if (!oopDesc::is_null(heap_oop)) {
+ oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
+ HeapRegion* hr = _g1h->heap_region_containing(obj);
+ assert(!hr->is_continues_humongous(),
+ "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
+ " starting at " HR_FORMAT,
+ p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
+
+ // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
+ hr->add_strong_code_root_locked(_nm);
+ }
+ }
+
+public:
+ RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
+ _g1h(g1h), _nm(nm) {}
+
+ void do_oop(oop* p) { do_oop_work(p); }
+ void do_oop(narrowOop* p) { do_oop_work(p); }
+};
+
+class UnregisterNMethodOopClosure: public OopClosure {
+ G1CollectedHeap* _g1h;
+ nmethod* _nm;
+
+ template <class T> void do_oop_work(T* p) {
+ T heap_oop = oopDesc::load_heap_oop(p);
+ if (!oopDesc::is_null(heap_oop)) {
+ oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
+ HeapRegion* hr = _g1h->heap_region_containing(obj);
+ assert(!hr->is_continues_humongous(),
+ "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
+ " starting at " HR_FORMAT,
+ p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
+
+ hr->remove_strong_code_root(_nm);
+ }
+ }
+
+public:
+ UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
+ _g1h(g1h), _nm(nm) {}
+
+ void do_oop(oop* p) { do_oop_work(p); }
+ void do_oop(narrowOop* p) { do_oop_work(p); }
+};
+
+void G1CollectedHeap::register_nmethod(nmethod* nm) {
+ CollectedHeap::register_nmethod(nm);
+
+ guarantee(nm != NULL, "sanity");
+ RegisterNMethodOopClosure reg_cl(this, nm);
+ nm->oops_do(®_cl);
+}
+
+void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
+ CollectedHeap::unregister_nmethod(nm);
+
+ guarantee(nm != NULL, "sanity");
+ UnregisterNMethodOopClosure reg_cl(this, nm);
+ nm->oops_do(®_cl, true);
+}
+
+void G1CollectedHeap::purge_code_root_memory() {
+ double purge_start = os::elapsedTime();
+ G1CodeRootSet::purge();
+ double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
+ g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
+}
+
+class RebuildStrongCodeRootClosure: public CodeBlobClosure {
+ G1CollectedHeap* _g1h;
+
+public:
+ RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
+ _g1h(g1h) {}
+
+ void do_code_blob(CodeBlob* cb) {
+ nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
+ if (nm == NULL) {
+ return;
+ }
+
+ if (ScavengeRootsInCode) {
+ _g1h->register_nmethod(nm);
+ }
+ }
+};
+
+void G1CollectedHeap::rebuild_strong_code_roots() {
+ RebuildStrongCodeRootClosure blob_cl(this);
+ CodeCache::blobs_do(&blob_cl);
+}