--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/g1MarkSweep.cpp Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,364 @@
+/*
+ * Copyright (c) 2001, 2015, 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/javaClasses.hpp"
+#include "classfile/symbolTable.hpp"
+#include "classfile/systemDictionary.hpp"
+#include "classfile/vmSymbols.hpp"
+#include "code/codeCache.hpp"
+#include "code/icBuffer.hpp"
+#include "gc/g1/g1Log.hpp"
+#include "gc/g1/g1MarkSweep.hpp"
+#include "gc/g1/g1RootProcessor.hpp"
+#include "gc/g1/g1StringDedup.hpp"
+#include "gc/serial/markSweep.inline.hpp"
+#include "gc/shared/gcHeapSummary.hpp"
+#include "gc/shared/gcLocker.hpp"
+#include "gc/shared/gcTimer.hpp"
+#include "gc/shared/gcTrace.hpp"
+#include "gc/shared/gcTraceTime.hpp"
+#include "gc/shared/genCollectedHeap.hpp"
+#include "gc/shared/modRefBarrierSet.hpp"
+#include "gc/shared/referencePolicy.hpp"
+#include "gc/shared/space.hpp"
+#include "oops/instanceRefKlass.hpp"
+#include "oops/oop.inline.hpp"
+#include "prims/jvmtiExport.hpp"
+#include "runtime/atomic.inline.hpp"
+#include "runtime/biasedLocking.hpp"
+#include "runtime/fprofiler.hpp"
+#include "runtime/synchronizer.hpp"
+#include "runtime/thread.hpp"
+#include "runtime/vmThread.hpp"
+#include "utilities/copy.hpp"
+#include "utilities/events.hpp"
+
+class HeapRegion;
+
+void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
+ bool clear_all_softrefs) {
+ assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
+
+#ifdef ASSERT
+ if (G1CollectedHeap::heap()->collector_policy()->should_clear_all_soft_refs()) {
+ assert(clear_all_softrefs, "Policy should have been checked earler");
+ }
+#endif
+ // hook up weak ref data so it can be used during Mark-Sweep
+ assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
+ assert(rp != NULL, "should be non-NULL");
+ assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Precondition");
+
+ GenMarkSweep::_ref_processor = rp;
+ rp->setup_policy(clear_all_softrefs);
+
+ // When collecting the permanent generation Method*s may be moving,
+ // so we either have to flush all bcp data or convert it into bci.
+ CodeCache::gc_prologue();
+
+ bool marked_for_unloading = false;
+
+ allocate_stacks();
+
+ // We should save the marks of the currently locked biased monitors.
+ // The marking doesn't preserve the marks of biased objects.
+ BiasedLocking::preserve_marks();
+
+ mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
+
+ mark_sweep_phase2();
+
+ // Don't add any more derived pointers during phase3
+ COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
+
+ mark_sweep_phase3();
+
+ mark_sweep_phase4();
+
+ GenMarkSweep::restore_marks();
+ BiasedLocking::restore_marks();
+ GenMarkSweep::deallocate_stacks();
+
+ CodeCache::gc_epilogue();
+ JvmtiExport::gc_epilogue();
+
+ // refs processing: clean slate
+ GenMarkSweep::_ref_processor = NULL;
+}
+
+
+void G1MarkSweep::allocate_stacks() {
+ GenMarkSweep::_preserved_count_max = 0;
+ GenMarkSweep::_preserved_marks = NULL;
+ GenMarkSweep::_preserved_count = 0;
+}
+
+void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
+ bool clear_all_softrefs) {
+ // Recursively traverse all live objects and mark them
+ GCTraceTime tm("phase 1", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
+
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ // Need cleared claim bits for the roots processing
+ ClassLoaderDataGraph::clear_claimed_marks();
+
+ MarkingCodeBlobClosure follow_code_closure(&GenMarkSweep::follow_root_closure, !CodeBlobToOopClosure::FixRelocations);
+ {
+ G1RootProcessor root_processor(g1h);
+ root_processor.process_strong_roots(&GenMarkSweep::follow_root_closure,
+ &GenMarkSweep::follow_cld_closure,
+ &follow_code_closure);
+ }
+
+ // Process reference objects found during marking
+ ReferenceProcessor* rp = GenMarkSweep::ref_processor();
+ assert(rp == g1h->ref_processor_stw(), "Sanity");
+
+ rp->setup_policy(clear_all_softrefs);
+ const ReferenceProcessorStats& stats =
+ rp->process_discovered_references(&GenMarkSweep::is_alive,
+ &GenMarkSweep::keep_alive,
+ &GenMarkSweep::follow_stack_closure,
+ NULL,
+ gc_timer(),
+ gc_tracer()->gc_id());
+ gc_tracer()->report_gc_reference_stats(stats);
+
+
+ // This is the point where the entire marking should have completed.
+ assert(GenMarkSweep::_marking_stack.is_empty(), "Marking should have completed");
+
+ // Unload classes and purge the SystemDictionary.
+ bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
+
+ // Unload nmethods.
+ CodeCache::do_unloading(&GenMarkSweep::is_alive, purged_class);
+
+ // Prune dead klasses from subklass/sibling/implementor lists.
+ Klass::clean_weak_klass_links(&GenMarkSweep::is_alive);
+
+ // Delete entries for dead interned string and clean up unreferenced symbols in symbol table.
+ g1h->unlink_string_and_symbol_table(&GenMarkSweep::is_alive);
+
+ if (VerifyDuringGC) {
+ HandleMark hm; // handle scope
+ COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact);
+ g1h->prepare_for_verify();
+ // Note: we can verify only the heap here. When an object is
+ // marked, the previous value of the mark word (including
+ // identity hash values, ages, etc) is preserved, and the mark
+ // word is set to markOop::marked_value - effectively removing
+ // any hash values from the mark word. These hash values are
+ // used when verifying the dictionaries and so removing them
+ // from the mark word can make verification of the dictionaries
+ // fail. At the end of the GC, the original mark word values
+ // (including hash values) are restored to the appropriate
+ // objects.
+ if (!VerifySilently) {
+ gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying ");
+ }
+ g1h->verify(VerifySilently, VerifyOption_G1UseMarkWord);
+ if (!VerifySilently) {
+ gclog_or_tty->print_cr("]");
+ }
+ }
+
+ gc_tracer()->report_object_count_after_gc(&GenMarkSweep::is_alive);
+}
+
+
+void G1MarkSweep::mark_sweep_phase2() {
+ // Now all live objects are marked, compute the new object addresses.
+
+ // It is not required that we traverse spaces in the same order in
+ // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
+ // tracking expects us to do so. See comment under phase4.
+
+ GCTraceTime tm("phase 2", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
+
+ prepare_compaction();
+}
+
+class G1AdjustPointersClosure: public HeapRegionClosure {
+ public:
+ bool doHeapRegion(HeapRegion* r) {
+ if (r->is_humongous()) {
+ if (r->is_starts_humongous()) {
+ // We must adjust the pointers on the single H object.
+ oop obj = oop(r->bottom());
+ // point all the oops to the new location
+ MarkSweep::adjust_pointers(obj);
+ }
+ } else {
+ // This really ought to be "as_CompactibleSpace"...
+ r->adjust_pointers();
+ }
+ return false;
+ }
+};
+
+class G1AlwaysTrueClosure: public BoolObjectClosure {
+public:
+ bool do_object_b(oop p) { return true; }
+};
+static G1AlwaysTrueClosure always_true;
+
+void G1MarkSweep::mark_sweep_phase3() {
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ // Adjust the pointers to reflect the new locations
+ GCTraceTime tm("phase 3", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
+
+ // Need cleared claim bits for the roots processing
+ ClassLoaderDataGraph::clear_claimed_marks();
+
+ CodeBlobToOopClosure adjust_code_closure(&GenMarkSweep::adjust_pointer_closure, CodeBlobToOopClosure::FixRelocations);
+ {
+ G1RootProcessor root_processor(g1h);
+ root_processor.process_all_roots(&GenMarkSweep::adjust_pointer_closure,
+ &GenMarkSweep::adjust_cld_closure,
+ &adjust_code_closure);
+ }
+
+ assert(GenMarkSweep::ref_processor() == g1h->ref_processor_stw(), "Sanity");
+ g1h->ref_processor_stw()->weak_oops_do(&GenMarkSweep::adjust_pointer_closure);
+
+ // Now adjust pointers in remaining weak roots. (All of which should
+ // have been cleared if they pointed to non-surviving objects.)
+ JNIHandles::weak_oops_do(&always_true, &GenMarkSweep::adjust_pointer_closure);
+
+ if (G1StringDedup::is_enabled()) {
+ G1StringDedup::oops_do(&GenMarkSweep::adjust_pointer_closure);
+ }
+
+ GenMarkSweep::adjust_marks();
+
+ G1AdjustPointersClosure blk;
+ g1h->heap_region_iterate(&blk);
+}
+
+class G1SpaceCompactClosure: public HeapRegionClosure {
+public:
+ G1SpaceCompactClosure() {}
+
+ bool doHeapRegion(HeapRegion* hr) {
+ if (hr->is_humongous()) {
+ if (hr->is_starts_humongous()) {
+ oop obj = oop(hr->bottom());
+ if (obj->is_gc_marked()) {
+ obj->init_mark();
+ } else {
+ assert(hr->is_empty(), "Should have been cleared in phase 2.");
+ }
+ hr->reset_during_compaction();
+ }
+ } else {
+ hr->compact();
+ }
+ return false;
+ }
+};
+
+void G1MarkSweep::mark_sweep_phase4() {
+ // All pointers are now adjusted, move objects accordingly
+
+ // The ValidateMarkSweep live oops tracking expects us to traverse spaces
+ // in the same order in phase2, phase3 and phase4. We don't quite do that
+ // here (code and comment not fixed for perm removal), so we tell the validate code
+ // to use a higher index (saved from phase2) when verifying perm_gen.
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ GCTraceTime tm("phase 4", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
+
+ G1SpaceCompactClosure blk;
+ g1h->heap_region_iterate(&blk);
+
+}
+
+void G1MarkSweep::prepare_compaction_work(G1PrepareCompactClosure* blk) {
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+ g1h->heap_region_iterate(blk);
+ blk->update_sets();
+}
+
+void G1PrepareCompactClosure::free_humongous_region(HeapRegion* hr) {
+ HeapWord* end = hr->end();
+ FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep");
+
+ assert(hr->is_starts_humongous(),
+ "Only the start of a humongous region should be freed.");
+
+ hr->set_containing_set(NULL);
+ _humongous_regions_removed.increment(1u, hr->capacity());
+
+ _g1h->free_humongous_region(hr, &dummy_free_list, false /* par */);
+ prepare_for_compaction(hr, end);
+ dummy_free_list.remove_all();
+}
+
+void G1PrepareCompactClosure::prepare_for_compaction(HeapRegion* hr, HeapWord* end) {
+ // If this is the first live region that we came across which we can compact,
+ // initialize the CompactPoint.
+ if (!is_cp_initialized()) {
+ _cp.space = hr;
+ _cp.threshold = hr->initialize_threshold();
+ }
+ prepare_for_compaction_work(&_cp, hr, end);
+}
+
+void G1PrepareCompactClosure::prepare_for_compaction_work(CompactPoint* cp,
+ HeapRegion* hr,
+ HeapWord* end) {
+ hr->prepare_for_compaction(cp);
+ // Also clear the part of the card table that will be unused after
+ // compaction.
+ _mrbs->clear(MemRegion(hr->compaction_top(), end));
+}
+
+void G1PrepareCompactClosure::update_sets() {
+ // We'll recalculate total used bytes and recreate the free list
+ // at the end of the GC, so no point in updating those values here.
+ HeapRegionSetCount empty_set;
+ _g1h->remove_from_old_sets(empty_set, _humongous_regions_removed);
+}
+
+bool G1PrepareCompactClosure::doHeapRegion(HeapRegion* hr) {
+ if (hr->is_humongous()) {
+ if (hr->is_starts_humongous()) {
+ oop obj = oop(hr->bottom());
+ if (obj->is_gc_marked()) {
+ obj->forward_to(obj);
+ } else {
+ free_humongous_region(hr);
+ }
+ } else {
+ assert(hr->is_continues_humongous(), "Invalid humongous.");
+ }
+ } else {
+ prepare_for_compaction(hr, hr->end());
+ }
+ return false;
+}