/*
* Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
*
* 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 "memory/allocation.hpp"
#include "memory/universe.hpp"
#include "gc/shared/gcArguments.hpp"
#include "gc/shared/gcTimer.hpp"
#include "gc/shared/gcTraceTime.inline.hpp"
#include "gc/shared/locationPrinter.inline.hpp"
#include "gc/shared/memAllocator.hpp"
#include "gc/shared/plab.hpp"
#include "gc/shenandoah/shenandoahAllocTracker.hpp"
#include "gc/shenandoah/shenandoahBarrierSet.hpp"
#include "gc/shenandoah/shenandoahClosures.inline.hpp"
#include "gc/shenandoah/shenandoahCollectionSet.hpp"
#include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
#include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
#include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
#include "gc/shenandoah/shenandoahControlThread.hpp"
#include "gc/shenandoah/shenandoahFreeSet.hpp"
#include "gc/shenandoah/shenandoahPhaseTimings.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
#include "gc/shenandoah/shenandoahHeapRegion.hpp"
#include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
#include "gc/shenandoah/shenandoahMarkCompact.hpp"
#include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
#include "gc/shenandoah/shenandoahMemoryPool.hpp"
#include "gc/shenandoah/shenandoahMetrics.hpp"
#include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
#include "gc/shenandoah/shenandoahNormalMode.hpp"
#include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
#include "gc/shenandoah/shenandoahPacer.inline.hpp"
#include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
#include "gc/shenandoah/shenandoahPassiveMode.hpp"
#include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
#include "gc/shenandoah/shenandoahStringDedup.hpp"
#include "gc/shenandoah/shenandoahTaskqueue.hpp"
#include "gc/shenandoah/shenandoahTraversalMode.hpp"
#include "gc/shenandoah/shenandoahUtils.hpp"
#include "gc/shenandoah/shenandoahVerifier.hpp"
#include "gc/shenandoah/shenandoahCodeRoots.hpp"
#include "gc/shenandoah/shenandoahVMOperations.hpp"
#include "gc/shenandoah/shenandoahWorkGroup.hpp"
#include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
#if INCLUDE_JFR
#include "gc/shenandoah/shenandoahJfrSupport.hpp"
#endif
#include "memory/metaspace/classLoaderMetaspace.hpp"
#include "memory/metaspace/metaspaceEnums.hpp"
#include "oops/compressedOops.inline.hpp"
#include "runtime/globals.hpp"
#include "runtime/interfaceSupport.inline.hpp"
#include "runtime/safepointMechanism.hpp"
#include "runtime/vmThread.hpp"
#include "services/mallocTracker.hpp"
#ifdef ASSERT
template <class T>
void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
T o = RawAccess<>::oop_load(p);
if (! CompressedOops::is_null(o)) {
oop obj = CompressedOops::decode_not_null(o);
shenandoah_assert_not_forwarded(p, obj);
}
}
void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
#endif
class ShenandoahPretouchHeapTask : public AbstractGangTask {
private:
ShenandoahRegionIterator _regions;
const size_t _page_size;
public:
ShenandoahPretouchHeapTask(size_t page_size) :
AbstractGangTask("Shenandoah Pretouch Heap"),
_page_size(page_size) {}
virtual void work(uint worker_id) {
ShenandoahHeapRegion* r = _regions.next();
while (r != NULL) {
os::pretouch_memory(r->bottom(), r->end(), _page_size);
r = _regions.next();
}
}
};
class ShenandoahPretouchBitmapTask : public AbstractGangTask {
private:
ShenandoahRegionIterator _regions;
char* _bitmap_base;
const size_t _bitmap_size;
const size_t _page_size;
public:
ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
AbstractGangTask("Shenandoah Pretouch Bitmap"),
_bitmap_base(bitmap_base),
_bitmap_size(bitmap_size),
_page_size(page_size) {}
virtual void work(uint worker_id) {
ShenandoahHeapRegion* r = _regions.next();
while (r != NULL) {
size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
r = _regions.next();
}
}
};
jint ShenandoahHeap::initialize() {
initialize_heuristics();
//
// Figure out heap sizing
//
size_t init_byte_size = InitialHeapSize;
size_t min_byte_size = MinHeapSize;
size_t max_byte_size = MaxHeapSize;
size_t heap_alignment = HeapAlignment;
size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
if (ShenandoahAlwaysPreTouch) {
// Enabled pre-touch means the entire heap is committed right away.
init_byte_size = max_byte_size;
}
Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
_num_regions = ShenandoahHeapRegion::region_count();
size_t num_committed_regions = init_byte_size / reg_size_bytes;
num_committed_regions = MIN2(num_committed_regions, _num_regions);
assert(num_committed_regions <= _num_regions, "sanity");
_initial_size = num_committed_regions * reg_size_bytes;
size_t num_min_regions = min_byte_size / reg_size_bytes;
num_min_regions = MIN2(num_min_regions, _num_regions);
assert(num_min_regions <= _num_regions, "sanity");
_minimum_size = num_min_regions * reg_size_bytes;
_committed = _initial_size;
size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
//
// Reserve and commit memory for heap
//
ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
initialize_reserved_region(heap_rs);
_heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
_heap_region_special = heap_rs.special();
assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
"Misaligned heap: " PTR_FORMAT, p2i(base()));
#if SHENANDOAH_OPTIMIZED_OBJTASK
// The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
// Fail if we ever attempt to address more than we can.
if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
"but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
"VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
vm_exit_during_initialization("Fatal Error", buf);
}
#endif
ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
if (!_heap_region_special) {
os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
"Cannot commit heap memory");
}
//
// Reserve and commit memory for bitmap(s)
//
_bitmap_size = MarkBitMap::compute_size(heap_rs.size());
_bitmap_size = align_up(_bitmap_size, bitmap_page_size);
size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
guarantee(bitmap_bytes_per_region != 0,
"Bitmap bytes per region should not be zero");
guarantee(is_power_of_2(bitmap_bytes_per_region),
"Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
if (bitmap_page_size > bitmap_bytes_per_region) {
_bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
_bitmap_bytes_per_slice = bitmap_page_size;
} else {
_bitmap_regions_per_slice = 1;
_bitmap_bytes_per_slice = bitmap_bytes_per_region;
}
guarantee(_bitmap_regions_per_slice >= 1,
"Should have at least one region per slice: " SIZE_FORMAT,
_bitmap_regions_per_slice);
guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
"Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
_bitmap_bytes_per_slice, bitmap_page_size);
ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
_bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
_bitmap_region_special = bitmap.special();
size_t bitmap_init_commit = _bitmap_bytes_per_slice *
align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
if (!_bitmap_region_special) {
os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
"Cannot commit bitmap memory");
}
_marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
if (ShenandoahVerify) {
ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
if (!verify_bitmap.special()) {
os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
"Cannot commit verification bitmap memory");
}
MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
_verification_bit_map.initialize(_heap_region, verify_bitmap_region);
_verifier = new ShenandoahVerifier(this, &_verification_bit_map);
}
// Reserve aux bitmap for use in object_iterate(). We don't commit it here.
ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
_aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
_aux_bitmap_region_special = aux_bitmap.special();
_aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
//
// Create regions and region sets
//
_regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
_free_set = new ShenandoahFreeSet(this, _num_regions);
_collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
{
ShenandoahHeapLocker locker(lock());
size_t size_words = ShenandoahHeapRegion::region_size_words();
for (size_t i = 0; i < _num_regions; i++) {
HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
bool is_committed = i < num_committed_regions;
ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
_marking_context->initialize_top_at_mark_start(r);
_regions[i] = r;
assert(!collection_set()->is_in(i), "New region should not be in collection set");
}
// Initialize to complete
_marking_context->mark_complete();
_free_set->rebuild();
}
if (ShenandoahAlwaysPreTouch) {
assert(!AlwaysPreTouch, "Should have been overridden");
// For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
// before initialize() below zeroes it with initializing thread. For any given region,
// we touch the region and the corresponding bitmaps from the same thread.
ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
size_t pretouch_heap_page_size = heap_page_size;
size_t pretouch_bitmap_page_size = bitmap_page_size;
#ifdef LINUX
// UseTransparentHugePages would madvise that backing memory can be coalesced into huge
// pages. But, the kernel needs to know that every small page is used, in order to coalesce
// them into huge one. Therefore, we need to pretouch with smaller pages.
if (UseTransparentHugePages) {
pretouch_heap_page_size = (size_t)os::vm_page_size();
pretouch_bitmap_page_size = (size_t)os::vm_page_size();
}
#endif
// OS memory managers may want to coalesce back-to-back pages. Make their jobs
// simpler by pre-touching continuous spaces (heap and bitmap) separately.
log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
_num_regions, pretouch_bitmap_page_size);
ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
_workers->run_task(&bcl);
log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
_num_regions, pretouch_heap_page_size);
ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
_workers->run_task(&hcl);
}
//
// Initialize the rest of GC subsystems
//
_liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
for (uint worker = 0; worker < _max_workers; worker++) {
_liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
}
// There should probably be Shenandoah-specific options for these,
// just as there are G1-specific options.
{
ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
}
_monitoring_support = new ShenandoahMonitoringSupport(this);
_phase_timings = new ShenandoahPhaseTimings();
ShenandoahStringDedup::initialize();
ShenandoahCodeRoots::initialize();
if (ShenandoahAllocationTrace) {
_alloc_tracker = new ShenandoahAllocTracker();
}
if (ShenandoahPacing) {
_pacer = new ShenandoahPacer(this);
_pacer->setup_for_idle();
} else {
_pacer = NULL;
}
_traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
new ShenandoahTraversalGC(this, _num_regions) :
NULL;
_control_thread = new ShenandoahControlThread();
log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
);
log_info(gc, init)("Safepointing mechanism: %s",
SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
(SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
return JNI_OK;
}
void ShenandoahHeap::initialize_heuristics() {
if (ShenandoahGCMode != NULL) {
if (strcmp(ShenandoahGCMode, "traversal") == 0) {
_gc_mode = new ShenandoahTraversalMode();
} else if (strcmp(ShenandoahGCMode, "normal") == 0) {
_gc_mode = new ShenandoahNormalMode();
} else if (strcmp(ShenandoahGCMode, "passive") == 0) {
_gc_mode = new ShenandoahPassiveMode();
} else {
vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
}
} else {
ShouldNotReachHere();
}
_gc_mode->initialize_flags();
_heuristics = _gc_mode->initialize_heuristics();
if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
vm_exit_during_initialization(
err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
_heuristics->name()));
}
if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
vm_exit_during_initialization(
err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
_heuristics->name()));
}
log_info(gc, init)("Shenandoah heuristics: %s",
_heuristics->name());
}
#ifdef _MSC_VER
#pragma warning( push )
#pragma warning( disable:4355 ) // 'this' : used in base member initializer list
#endif
ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
CollectedHeap(),
_initial_size(0),
_used(0),
_committed(0),
_bytes_allocated_since_gc_start(0),
_max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
_workers(NULL),
_safepoint_workers(NULL),
_heap_region_special(false),
_num_regions(0),
_regions(NULL),
_update_refs_iterator(this),
_control_thread(NULL),
_shenandoah_policy(policy),
_heuristics(NULL),
_free_set(NULL),
_scm(new ShenandoahConcurrentMark()),
_traversal_gc(NULL),
_full_gc(new ShenandoahMarkCompact()),
_pacer(NULL),
_verifier(NULL),
_alloc_tracker(NULL),
_phase_timings(NULL),
_monitoring_support(NULL),
_memory_pool(NULL),
_stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
_cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
_gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
_soft_ref_policy(),
_log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
_ref_processor(NULL),
_marking_context(NULL),
_bitmap_size(0),
_bitmap_regions_per_slice(0),
_bitmap_bytes_per_slice(0),
_bitmap_region_special(false),
_aux_bitmap_region_special(false),
_liveness_cache(NULL),
_collection_set(NULL)
{
log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
_max_workers = MAX2(_max_workers, 1U);
_workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
/* are_GC_task_threads */ true,
/* are_ConcurrentGC_threads */ true);
if (_workers == NULL) {
vm_exit_during_initialization("Failed necessary allocation.");
} else {
_workers->initialize_workers();
}
if (ShenandoahParallelSafepointThreads > 1) {
_safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
ShenandoahParallelSafepointThreads,
/* are_GC_task_threads */ false,
/* are_ConcurrentGC_threads */ false);
_safepoint_workers->initialize_workers();
}
}
#ifdef _MSC_VER
#pragma warning( pop )
#endif
class ShenandoahResetBitmapTask : public AbstractGangTask {
private:
ShenandoahRegionIterator _regions;
public:
ShenandoahResetBitmapTask() :
AbstractGangTask("Parallel Reset Bitmap Task") {}
void work(uint worker_id) {
ShenandoahHeapRegion* region = _regions.next();
ShenandoahHeap* heap = ShenandoahHeap::heap();
ShenandoahMarkingContext* const ctx = heap->marking_context();
while (region != NULL) {
if (heap->is_bitmap_slice_committed(region)) {
ctx->clear_bitmap(region);
}
region = _regions.next();
}
}
};
void ShenandoahHeap::reset_mark_bitmap() {
assert_gc_workers(_workers->active_workers());
mark_incomplete_marking_context();
ShenandoahResetBitmapTask task;
_workers->run_task(&task);
}
void ShenandoahHeap::print_on(outputStream* st) const {
st->print_cr("Shenandoah Heap");
st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
num_regions(),
byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
st->print("Status: ");
if (has_forwarded_objects()) st->print("has forwarded objects, ");
if (is_concurrent_mark_in_progress()) st->print("marking, ");
if (is_evacuation_in_progress()) st->print("evacuating, ");
if (is_update_refs_in_progress()) st->print("updating refs, ");
if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
if (is_full_gc_in_progress()) st->print("full gc, ");
if (is_full_gc_move_in_progress()) st->print("full gc move, ");
if (cancelled_gc()) {
st->print("cancelled");
} else {
st->print("not cancelled");
}
st->cr();
st->print_cr("Reserved region:");
st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
p2i(reserved_region().start()),
p2i(reserved_region().end()));
ShenandoahCollectionSet* cset = collection_set();
st->print_cr("Collection set:");
if (cset != NULL) {
st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
} else {
st->print_cr(" (NULL)");
}
st->cr();
MetaspaceUtils::print_on(st);
if (Verbose) {
print_heap_regions_on(st);
}
}
class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
public:
void do_thread(Thread* thread) {
assert(thread != NULL, "Sanity");
assert(thread->is_Worker_thread(), "Only worker thread expected");
ShenandoahThreadLocalData::initialize_gclab(thread);
}
};
void ShenandoahHeap::post_initialize() {
CollectedHeap::post_initialize();
MutexLocker ml(Threads_lock);
ShenandoahInitWorkerGCLABClosure init_gclabs;
_workers->threads_do(&init_gclabs);
// gclab can not be initialized early during VM startup, as it can not determinate its max_size.
// Now, we will let WorkGang to initialize gclab when new worker is created.
_workers->set_initialize_gclab();
_scm->initialize(_max_workers);
_full_gc->initialize(_gc_timer);
ref_processing_init();
_heuristics->initialize();
JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
}
size_t ShenandoahHeap::used() const {
return OrderAccess::load_acquire(&_used);
}
size_t ShenandoahHeap::committed() const {
OrderAccess::acquire();
return _committed;
}
void ShenandoahHeap::increase_committed(size_t bytes) {
assert_heaplock_or_safepoint();
_committed += bytes;
}
void ShenandoahHeap::decrease_committed(size_t bytes) {
assert_heaplock_or_safepoint();
_committed -= bytes;
}
void ShenandoahHeap::increase_used(size_t bytes) {
Atomic::add(bytes, &_used);
}
void ShenandoahHeap::set_used(size_t bytes) {
OrderAccess::release_store_fence(&_used, bytes);
}
void ShenandoahHeap::decrease_used(size_t bytes) {
assert(used() >= bytes, "never decrease heap size by more than we've left");
Atomic::sub(bytes, &_used);
}
void ShenandoahHeap::increase_allocated(size_t bytes) {
Atomic::add(bytes, &_bytes_allocated_since_gc_start);
}
void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
size_t bytes = words * HeapWordSize;
if (!waste) {
increase_used(bytes);
}
increase_allocated(bytes);
if (ShenandoahPacing) {
control_thread()->pacing_notify_alloc(words);
if (waste) {
pacer()->claim_for_alloc(words, true);
}
}
}
size_t ShenandoahHeap::capacity() const {
return committed();
}
size_t ShenandoahHeap::max_capacity() const {
return _num_regions * ShenandoahHeapRegion::region_size_bytes();
}
size_t ShenandoahHeap::min_capacity() const {
return _minimum_size;
}
size_t ShenandoahHeap::initial_capacity() const {
return _initial_size;
}
bool ShenandoahHeap::is_in(const void* p) const {
HeapWord* heap_base = (HeapWord*) base();
HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
return p >= heap_base && p < last_region_end;
}
void ShenandoahHeap::op_uncommit(double shrink_before) {
assert (ShenandoahUncommit, "should be enabled");
// Application allocates from the beginning of the heap, and GC allocates at
// the end of it. It is more efficient to uncommit from the end, so that applications
// could enjoy the near committed regions. GC allocations are much less frequent,
// and therefore can accept the committing costs.
size_t count = 0;
for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
ShenandoahHeapRegion* r = get_region(i - 1);
if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
ShenandoahHeapLocker locker(lock());
if (r->is_empty_committed()) {
// Do not uncommit below minimal capacity
if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
break;
}
r->make_uncommitted();
count++;
}
}
SpinPause(); // allow allocators to take the lock
}
if (count > 0) {
control_thread()->notify_heap_changed();
}
}
HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
// New object should fit the GCLAB size
size_t min_size = MAX2(size, PLAB::min_size());
// Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
new_size = MIN2(new_size, PLAB::max_size());
new_size = MAX2(new_size, PLAB::min_size());
// Record new heuristic value even if we take any shortcut. This captures
// the case when moderately-sized objects always take a shortcut. At some point,
// heuristics should catch up with them.
ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
if (new_size < size) {
// New size still does not fit the object. Fall back to shared allocation.
// This avoids retiring perfectly good GCLABs, when we encounter a large object.
return NULL;
}
// Retire current GCLAB, and allocate a new one.
PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
gclab->retire();
size_t actual_size = 0;
HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
if (gclab_buf == NULL) {
return NULL;
}
assert (size <= actual_size, "allocation should fit");
if (ZeroTLAB) {
// ..and clear it.
Copy::zero_to_words(gclab_buf, actual_size);
} else {
// ...and zap just allocated object.
#ifdef ASSERT
// Skip mangling the space corresponding to the object header to
// ensure that the returned space is not considered parsable by
// any concurrent GC thread.
size_t hdr_size = oopDesc::header_size();
Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
#endif // ASSERT
}
gclab->set_buf(gclab_buf, actual_size);
return gclab->allocate(size);
}
HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
size_t requested_size,
size_t* actual_size) {
ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
HeapWord* res = allocate_memory(req);
if (res != NULL) {
*actual_size = req.actual_size();
} else {
*actual_size = 0;
}
return res;
}
HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
size_t word_size,
size_t* actual_size) {
ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
HeapWord* res = allocate_memory(req);
if (res != NULL) {
*actual_size = req.actual_size();
} else {
*actual_size = 0;
}
return res;
}
ShenandoahHeap* ShenandoahHeap::heap() {
CollectedHeap* heap = Universe::heap();
assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
return (ShenandoahHeap*) heap;
}
ShenandoahHeap* ShenandoahHeap::heap_no_check() {
CollectedHeap* heap = Universe::heap();
return (ShenandoahHeap*) heap;
}
HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
ShenandoahAllocTrace trace_alloc(req.size(), req.type());
intptr_t pacer_epoch = 0;
bool in_new_region = false;
HeapWord* result = NULL;
if (req.is_mutator_alloc()) {
if (ShenandoahPacing) {
pacer()->pace_for_alloc(req.size());
pacer_epoch = pacer()->epoch();
}
if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
result = allocate_memory_under_lock(req, in_new_region);
}
// Allocation failed, block until control thread reacted, then retry allocation.
//
// It might happen that one of the threads requesting allocation would unblock
// way later after GC happened, only to fail the second allocation, because
// other threads have already depleted the free storage. In this case, a better
// strategy is to try again, as long as GC makes progress.
//
// Then, we need to make sure the allocation was retried after at least one
// Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
size_t tries = 0;
while (result == NULL && _progress_last_gc.is_set()) {
tries++;
control_thread()->handle_alloc_failure(req.size());
result = allocate_memory_under_lock(req, in_new_region);
}
while (result == NULL && tries <= ShenandoahFullGCThreshold) {
tries++;
control_thread()->handle_alloc_failure(req.size());
result = allocate_memory_under_lock(req, in_new_region);
}
} else {
assert(req.is_gc_alloc(), "Can only accept GC allocs here");
result = allocate_memory_under_lock(req, in_new_region);
// Do not call handle_alloc_failure() here, because we cannot block.
// The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
}
if (in_new_region) {
control_thread()->notify_heap_changed();
}
if (result != NULL) {
size_t requested = req.size();
size_t actual = req.actual_size();
assert (req.is_lab_alloc() || (requested == actual),
"Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
if (req.is_mutator_alloc()) {
notify_mutator_alloc_words(actual, false);
// If we requested more than we were granted, give the rest back to pacer.
// This only matters if we are in the same pacing epoch: do not try to unpace
// over the budget for the other phase.
if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
}
} else {
increase_used(actual*HeapWordSize);
}
}
return result;
}
HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
ShenandoahHeapLocker locker(lock());
return _free_set->allocate(req, in_new_region);
}
HeapWord* ShenandoahHeap::mem_allocate(size_t size,
bool* gc_overhead_limit_was_exceeded) {
ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
return allocate_memory(req);
}
MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
size_t size,
Metaspace::MetadataType mdtype) {
MetaWord* result;
// Inform metaspace OOM to GC heuristics if class unloading is possible.
if (heuristics()->can_unload_classes()) {
ShenandoahHeuristics* h = heuristics();
h->record_metaspace_oom();
}
// Expand and retry allocation
result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
if (result != NULL) {
return result;
}
// Start full GC
collect(GCCause::_metadata_GC_clear_soft_refs);
// Retry allocation
result = loader_data->metaspace_non_null()->allocate(size, mdtype);
if (result != NULL) {
return result;
}
// Expand and retry allocation
result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
if (result != NULL) {
return result;
}
// Out of memory
return NULL;
}
class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
private:
ShenandoahHeap* const _heap;
Thread* const _thread;
public:
ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
_heap(heap), _thread(Thread::current()) {}
void do_object(oop p) {
shenandoah_assert_marked(NULL, p);
if (!p->is_forwarded()) {
_heap->evacuate_object(p, _thread);
}
}
};
class ShenandoahEvacuationTask : public AbstractGangTask {
private:
ShenandoahHeap* const _sh;
ShenandoahCollectionSet* const _cs;
bool _concurrent;
public:
ShenandoahEvacuationTask(ShenandoahHeap* sh,
ShenandoahCollectionSet* cs,
bool concurrent) :
AbstractGangTask("Parallel Evacuation Task"),
_sh(sh),
_cs(cs),
_concurrent(concurrent)
{}
void work(uint worker_id) {
if (_concurrent) {
ShenandoahConcurrentWorkerSession worker_session(worker_id);
ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
ShenandoahEvacOOMScope oom_evac_scope;
do_work();
} else {
ShenandoahParallelWorkerSession worker_session(worker_id);
ShenandoahEvacOOMScope oom_evac_scope;
do_work();
}
}
private:
void do_work() {
ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
ShenandoahHeapRegion* r;
while ((r =_cs->claim_next()) != NULL) {
assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->region_number());
_sh->marked_object_iterate(r, &cl);
if (ShenandoahPacing) {
_sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
}
if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
break;
}
}
}
};
void ShenandoahHeap::trash_cset_regions() {
ShenandoahHeapLocker locker(lock());
ShenandoahCollectionSet* set = collection_set();
ShenandoahHeapRegion* r;
set->clear_current_index();
while ((r = set->next()) != NULL) {
r->make_trash();
}
collection_set()->clear();
}
void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
st->print_cr("Heap Regions:");
st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
for (size_t i = 0; i < num_regions(); i++) {
get_region(i)->print_on(st);
}
}
void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
assert(start->is_humongous_start(), "reclaim regions starting with the first one");
oop humongous_obj = oop(start->bottom());
size_t size = humongous_obj->size();
size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
size_t index = start->region_number() + required_regions - 1;
assert(!start->has_live(), "liveness must be zero");
for(size_t i = 0; i < required_regions; i++) {
// Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
// as it expects that every region belongs to a humongous region starting with a humongous start region.
ShenandoahHeapRegion* region = get_region(index --);
assert(region->is_humongous(), "expect correct humongous start or continuation");
assert(!region->is_cset(), "Humongous region should not be in collection set");
region->make_trash_immediate();
}
}
class ShenandoahRetireGCLABClosure : public ThreadClosure {
public:
void do_thread(Thread* thread) {
PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
gclab->retire();
}
};
void ShenandoahHeap::make_parsable(bool retire_tlabs) {
if (UseTLAB) {
CollectedHeap::ensure_parsability(retire_tlabs);
}
ShenandoahRetireGCLABClosure cl;
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
cl.do_thread(t);
}
workers()->threads_do(&cl);
}
void ShenandoahHeap::resize_tlabs() {
CollectedHeap::resize_all_tlabs();
}
class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
private:
ShenandoahRootEvacuator* _rp;
public:
ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
AbstractGangTask("Shenandoah evacuate and update roots"),
_rp(rp) {}
void work(uint worker_id) {
ShenandoahParallelWorkerSession worker_session(worker_id);
ShenandoahEvacOOMScope oom_evac_scope;
ShenandoahEvacuateUpdateRootsClosure cl;
MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
_rp->roots_do(worker_id, &cl);
}
};
void ShenandoahHeap::evacuate_and_update_roots() {
#if COMPILER2_OR_JVMCI
DerivedPointerTable::clear();
#endif
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
{
// Include concurrent roots if current cycle can not process those roots concurrently
ShenandoahRootEvacuator rp(workers()->active_workers(),
ShenandoahPhaseTimings::init_evac,
!ShenandoahConcurrentRoots::should_do_concurrent_roots());
ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
workers()->run_task(&roots_task);
}
#if COMPILER2_OR_JVMCI
DerivedPointerTable::update_pointers();
#endif
}
// Returns size in bytes
size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
if (ShenandoahElasticTLAB) {
// With Elastic TLABs, return the max allowed size, and let the allocation path
// figure out the safe size for current allocation.
return ShenandoahHeapRegion::max_tlab_size_bytes();
} else {
return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
}
}
size_t ShenandoahHeap::max_tlab_size() const {
// Returns size in words
return ShenandoahHeapRegion::max_tlab_size_words();
}
class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
public:
void do_thread(Thread* thread) {
PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
gclab->retire();
if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
ShenandoahThreadLocalData::set_gclab_size(thread, 0);
}
}
};
void ShenandoahHeap::retire_and_reset_gclabs() {
ShenandoahRetireAndResetGCLABClosure cl;
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
cl.do_thread(t);
}
workers()->threads_do(&cl);
}
void ShenandoahHeap::collect(GCCause::Cause cause) {
control_thread()->request_gc(cause);
}
void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
//assert(false, "Shouldn't need to do full collections");
}
HeapWord* ShenandoahHeap::block_start(const void* addr) const {
Space* sp = heap_region_containing(addr);
if (sp != NULL) {
return sp->block_start(addr);
}
return NULL;
}
bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
Space* sp = heap_region_containing(addr);
return sp->block_is_obj(addr);
}
bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
}
jlong ShenandoahHeap::millis_since_last_gc() {
double v = heuristics()->time_since_last_gc() * 1000;
assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
return (jlong)v;
}
void ShenandoahHeap::prepare_for_verify() {
if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
make_parsable(false);
}
}
void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
workers()->print_worker_threads_on(st);
if (ShenandoahStringDedup::is_enabled()) {
ShenandoahStringDedup::print_worker_threads_on(st);
}
}
void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
workers()->threads_do(tcl);
if (_safepoint_workers != NULL) {
_safepoint_workers->threads_do(tcl);
}
if (ShenandoahStringDedup::is_enabled()) {
ShenandoahStringDedup::threads_do(tcl);
}
}
void ShenandoahHeap::print_tracing_info() const {
LogTarget(Info, gc, stats) lt;
if (lt.is_enabled()) {
ResourceMark rm;
LogStream ls(lt);
phase_timings()->print_on(&ls);
ls.cr();
ls.cr();
shenandoah_policy()->print_gc_stats(&ls);
ls.cr();
ls.cr();
if (ShenandoahPacing) {
pacer()->print_on(&ls);
}
ls.cr();
ls.cr();
if (ShenandoahAllocationTrace) {
assert(alloc_tracker() != NULL, "Must be");
alloc_tracker()->print_on(&ls);
} else {
ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
}
}
}
void ShenandoahHeap::verify(VerifyOption vo) {
if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
if (ShenandoahVerify) {
verifier()->verify_generic(vo);
} else {
// TODO: Consider allocating verification bitmaps on demand,
// and turn this on unconditionally.
}
}
}
size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
return _free_set->capacity();
}
class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
private:
MarkBitMap* _bitmap;
Stack<oop,mtGC>* _oop_stack;
template <class T>
void do_oop_work(T* p) {
T o = RawAccess<>::oop_load(p);
if (!CompressedOops::is_null(o)) {
oop obj = CompressedOops::decode_not_null(o);
oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
if (fwd == NULL) {
// There is an odd interaction with VM_HeapWalkOperation, see jvmtiTagMap.cpp.
//
// That operation walks the reachable objects on its own, storing the marking
// wavefront in the object marks. When it is done, it calls the CollectedHeap
// to iterate over all objects to clean up the mess. When it reaches here,
// the Shenandoah fwdptr resolution code encounters the marked objects with
// NULL forwardee. Trying to act on that would crash the VM. Or fail the
// asserts, should we go for resolve_forwarded_pointer(obj).
//
// Therefore, we have to dodge it by doing the raw access to forwardee, and
// assuming the object had no forwardee, if that thing is NULL.
} else {
obj = fwd;
}
assert(oopDesc::is_oop(obj), "must be a valid oop");
if (!_bitmap->is_marked((HeapWord*) obj)) {
_bitmap->mark((HeapWord*) obj);
_oop_stack->push(obj);
}
}
}
public:
ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
_bitmap(bitmap), _oop_stack(oop_stack) {}
void do_oop(oop* p) { do_oop_work(p); }
void do_oop(narrowOop* p) { do_oop_work(p); }
};
/*
* This is public API, used in preparation of object_iterate().
* Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
* need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
* control, we call SH::make_tlabs_parsable().
*/
void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
// No-op.
}
/*
* Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
*
* We cannot safely iterate objects by doing a linear scan at random points in time. Linear
* scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
* calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
* scanning therefore depends on having a valid marking bitmap to support it. However, we only
* have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
* marking bitmap during marking, after aborted marking or during/after cleanup (when we just
* wiped the bitmap in preparation for next marking).
*
* For all those reasons, we implement object iteration as a single marking traversal, reporting
* objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
* is allowed to report dead objects, but is not required to do so.
*/
void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
return;
}
// Reset bitmap
_aux_bit_map.clear();
Stack<oop,mtGC> oop_stack;
// First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
ShenandoahHeapIterationRootScanner rp;
ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
// If we are unloading classes right now, we should not touch weak roots,
// on the off-chance we would evacuate them and make them live accidentally.
// In other cases, we have to scan all roots.
if (is_evacuation_in_progress() && unload_classes()) {
rp.strong_roots_do(&oops);
} else {
rp.roots_do(&oops);
}
// Work through the oop stack to traverse heap.
while (! oop_stack.is_empty()) {
oop obj = oop_stack.pop();
assert(oopDesc::is_oop(obj), "must be a valid oop");
cl->do_object(obj);
obj->oop_iterate(&oops);
}
assert(oop_stack.is_empty(), "should be empty");
if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
}
}
void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) {
assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
object_iterate(cl);
}
void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
for (size_t i = 0; i < num_regions(); i++) {
ShenandoahHeapRegion* current = get_region(i);
blk->heap_region_do(current);
}
}
class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
private:
ShenandoahHeap* const _heap;
ShenandoahHeapRegionClosure* const _blk;
DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
volatile size_t _index;
DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
public:
ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
AbstractGangTask("Parallel Region Task"),
_heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
void work(uint worker_id) {
size_t stride = ShenandoahParallelRegionStride;
size_t max = _heap->num_regions();
while (_index < max) {
size_t cur = Atomic::add(stride, &_index) - stride;
size_t start = cur;
size_t end = MIN2(cur + stride, max);
if (start >= max) break;
for (size_t i = cur; i < end; i++) {
ShenandoahHeapRegion* current = _heap->get_region(i);
_blk->heap_region_do(current);
}
}
}
};
void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
assert(blk->is_thread_safe(), "Only thread-safe closures here");
if (num_regions() > ShenandoahParallelRegionStride) {
ShenandoahParallelHeapRegionTask task(blk);
workers()->run_task(&task);
} else {
heap_region_iterate(blk);
}
}
class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
private:
ShenandoahMarkingContext* const _ctx;
public:
ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
void heap_region_do(ShenandoahHeapRegion* r) {
if (r->is_active()) {
r->clear_live_data();
_ctx->capture_top_at_mark_start(r);
} else {
assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
assert(_ctx->top_at_mark_start(r) == r->top(),
"Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
}
}
bool is_thread_safe() { return true; }
};
void ShenandoahHeap::op_init_mark() {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
assert(!marking_context()->is_complete(), "should not be complete");
if (ShenandoahVerify) {
verifier()->verify_before_concmark();
}
if (VerifyBeforeGC) {
Universe::verify();
}
set_concurrent_mark_in_progress(true);
// We need to reset all TLABs because we'd lose marks on all objects allocated in them.
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
make_parsable(true);
}
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
ShenandoahClearLivenessClosure clc;
parallel_heap_region_iterate(&clc);
}
// Make above changes visible to worker threads
OrderAccess::fence();
concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
if (UseTLAB) {
ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
resize_tlabs();
}
if (ShenandoahPacing) {
pacer()->setup_for_mark();
}
}
void ShenandoahHeap::op_mark() {
concurrent_mark()->mark_from_roots();
}
class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
private:
ShenandoahMarkingContext* const _ctx;
public:
ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
void heap_region_do(ShenandoahHeapRegion* r) {
if (r->is_active()) {
HeapWord *tams = _ctx->top_at_mark_start(r);
HeapWord *top = r->top();
if (top > tams) {
r->increase_live_data_alloc_words(pointer_delta(top, tams));
}
} else {
assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
assert(_ctx->top_at_mark_start(r) == r->top(),
"Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
}
}
bool is_thread_safe() { return true; }
};
void ShenandoahHeap::op_final_mark() {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
// It is critical that we
// evacuate roots right after finishing marking, so that we don't
// get unmarked objects in the roots.
if (!cancelled_gc()) {
concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
// Marking is completed, deactivate SATB barrier
set_concurrent_mark_in_progress(false);
mark_complete_marking_context();
parallel_cleaning(false /* full gc*/);
if (has_forwarded_objects()) {
// Degen may be caused by failed evacuation of roots
if (is_degenerated_gc_in_progress()) {
concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
} else {
concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots);
}
set_has_forwarded_objects(false);
}
if (ShenandoahVerify) {
verifier()->verify_roots_no_forwarded();
}
// All allocations past TAMS are implicitly live, adjust the region data.
// Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
ShenandoahCompleteLivenessClosure cl;
parallel_heap_region_iterate(&cl);
}
// Force the threads to reacquire their TLABs outside the collection set.
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
make_parsable(true);
}
// We are about to select the collection set, make sure it knows about
// current pinning status. Also, this allows trashing more regions that
// now have their pinning status dropped.
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
sync_pinned_region_status();
}
// Trash the collection set left over from previous cycle, if any.
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
trash_cset_regions();
}
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
ShenandoahHeapLocker locker(lock());
_collection_set->clear();
_free_set->clear();
heuristics()->choose_collection_set(_collection_set);
_free_set->rebuild();
}
// If collection set has candidates, start evacuation.
// Otherwise, bypass the rest of the cycle.
if (!collection_set()->is_empty()) {
ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
if (ShenandoahVerify) {
verifier()->verify_before_evacuation();
}
set_evacuation_in_progress(true);
// From here on, we need to update references.
set_has_forwarded_objects(true);
if (!is_degenerated_gc_in_progress()) {
evacuate_and_update_roots();
}
if (ShenandoahPacing) {
pacer()->setup_for_evac();
}
if (ShenandoahVerify) {
if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
verifier()->verify_roots_no_forwarded_except(types);
} else {
verifier()->verify_roots_no_forwarded();
}
verifier()->verify_during_evacuation();
}
} else {
if (ShenandoahVerify) {
verifier()->verify_after_concmark();
}
if (VerifyAfterGC) {
Universe::verify();
}
}
} else {
// If this cycle was updating references, we need to keep the has_forwarded_objects
// flag on, for subsequent phases to deal with it.
concurrent_mark()->cancel();
set_concurrent_mark_in_progress(false);
if (process_references()) {
// Abandon reference processing right away: pre-cleaning must have failed.
ReferenceProcessor *rp = ref_processor();
rp->disable_discovery();
rp->abandon_partial_discovery();
rp->verify_no_references_recorded();
}
}
}
void ShenandoahHeap::op_final_evac() {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
set_evacuation_in_progress(false);
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_retire_gclabs);
retire_and_reset_gclabs();
}
if (ShenandoahVerify) {
verifier()->verify_after_evacuation();
}
if (VerifyAfterGC) {
Universe::verify();
}
}
void ShenandoahHeap::op_conc_evac() {
ShenandoahEvacuationTask task(this, _collection_set, true);
workers()->run_task(&task);
}
void ShenandoahHeap::op_stw_evac() {
ShenandoahEvacuationTask task(this, _collection_set, false);
workers()->run_task(&task);
}
void ShenandoahHeap::op_updaterefs() {
update_heap_references(true);
}
void ShenandoahHeap::op_cleanup() {
free_set()->recycle_trash();
}
class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
private:
ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
public:
ShenandoahConcurrentRootsEvacUpdateTask() :
AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task") {
}
void work(uint worker_id) {
ShenandoahEvacOOMScope oom;
{
// jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
// may race against OopStorage::release() calls.
ShenandoahEvacUpdateOopStorageRootsClosure cl;
_vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
_weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
}
{
ShenandoahEvacuateUpdateRootsClosure cl;
CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
_cld_roots.cld_do(&clds);
}
}
};
void ShenandoahHeap::op_roots() {
if (is_evacuation_in_progress() &&
ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
ShenandoahConcurrentRootsEvacUpdateTask task;
workers()->run_task(&task);
}
}
void ShenandoahHeap::op_reset() {
reset_mark_bitmap();
}
void ShenandoahHeap::op_preclean() {
concurrent_mark()->preclean_weak_refs();
}
void ShenandoahHeap::op_init_traversal() {
traversal_gc()->init_traversal_collection();
}
void ShenandoahHeap::op_traversal() {
traversal_gc()->concurrent_traversal_collection();
}
void ShenandoahHeap::op_final_traversal() {
traversal_gc()->final_traversal_collection();
}
void ShenandoahHeap::op_full(GCCause::Cause cause) {
ShenandoahMetricsSnapshot metrics;
metrics.snap_before();
full_gc()->do_it(cause);
if (UseTLAB) {
ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
resize_all_tlabs();
}
metrics.snap_after();
if (metrics.is_good_progress()) {
_progress_last_gc.set();
} else {
// Nothing to do. Tell the allocation path that we have failed to make
// progress, and it can finally fail.
_progress_last_gc.unset();
}
}
void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
// Degenerated GC is STW, but it can also fail. Current mechanics communicates
// GC failure via cancelled_concgc() flag. So, if we detect the failure after
// some phase, we have to upgrade the Degenerate GC to Full GC.
clear_cancelled_gc();
ShenandoahMetricsSnapshot metrics;
metrics.snap_before();
switch (point) {
case _degenerated_traversal:
{
// Drop the collection set. Note: this leaves some already forwarded objects
// behind, which may be problematic, see comments for ShenandoahEvacAssist
// workarounds in ShenandoahTraversalHeuristics.
ShenandoahHeapLocker locker(lock());
collection_set()->clear_current_index();
for (size_t i = 0; i < collection_set()->count(); i++) {
ShenandoahHeapRegion* r = collection_set()->next();
r->make_regular_bypass();
}
collection_set()->clear();
}
op_final_traversal();
op_cleanup();
return;
// The cases below form the Duff's-like device: it describes the actual GC cycle,
// but enters it at different points, depending on which concurrent phase had
// degenerated.
case _degenerated_outside_cycle:
// We have degenerated from outside the cycle, which means something is bad with
// the heap, most probably heavy humongous fragmentation, or we are very low on free
// space. It makes little sense to wait for Full GC to reclaim as much as it can, when
// we can do the most aggressive degen cycle, which includes processing references and
// class unloading, unless those features are explicitly disabled.
//
// Note that we can only do this for "outside-cycle" degens, otherwise we would risk
// changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
set_process_references(heuristics()->can_process_references());
set_unload_classes(heuristics()->can_unload_classes());
if (is_traversal_mode()) {
// Not possible to degenerate from here, upgrade to Full GC right away.
cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
op_degenerated_fail();
return;
}
op_reset();
op_init_mark();
if (cancelled_gc()) {
op_degenerated_fail();
return;
}
case _degenerated_mark:
op_final_mark();
if (cancelled_gc()) {
op_degenerated_fail();
return;
}
op_cleanup();
case _degenerated_evac:
// If heuristics thinks we should do the cycle, this flag would be set,
// and we can do evacuation. Otherwise, it would be the shortcut cycle.
if (is_evacuation_in_progress()) {
// Degeneration under oom-evac protocol might have left some objects in
// collection set un-evacuated. Restart evacuation from the beginning to
// capture all objects. For all the objects that are already evacuated,
// it would be a simple check, which is supposed to be fast. This is also
// safe to do even without degeneration, as CSet iterator is at beginning
// in preparation for evacuation anyway.
//
// Before doing that, we need to make sure we never had any cset-pinned
// regions. This may happen if allocation failure happened when evacuating
// the about-to-be-pinned object, oom-evac protocol left the object in
// the collection set, and then the pin reached the cset region. If we continue
// the cycle here, we would trash the cset and alive objects in it. To avoid
// it, we fail degeneration right away and slide into Full GC to recover.
{
sync_pinned_region_status();
collection_set()->clear_current_index();
ShenandoahHeapRegion* r;
while ((r = collection_set()->next()) != NULL) {
if (r->is_pinned()) {
cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
op_degenerated_fail();
return;
}
}
collection_set()->clear_current_index();
}
op_stw_evac();
if (cancelled_gc()) {
op_degenerated_fail();
return;
}
}
// If heuristics thinks we should do the cycle, this flag would be set,
// and we need to do update-refs. Otherwise, it would be the shortcut cycle.
if (has_forwarded_objects()) {
op_init_updaterefs();
if (cancelled_gc()) {
op_degenerated_fail();
return;
}
}
case _degenerated_updaterefs:
if (has_forwarded_objects()) {
op_final_updaterefs();
if (cancelled_gc()) {
op_degenerated_fail();
return;
}
}
op_cleanup();
break;
default:
ShouldNotReachHere();
}
if (ShenandoahVerify) {
verifier()->verify_after_degenerated();
}
if (VerifyAfterGC) {
Universe::verify();
}
metrics.snap_after();
// Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
// because that probably means the heap is overloaded and/or fragmented.
if (!metrics.is_good_progress()) {
_progress_last_gc.unset();
cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
op_degenerated_futile();
} else {
_progress_last_gc.set();
}
}
void ShenandoahHeap::op_degenerated_fail() {
log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
shenandoah_policy()->record_degenerated_upgrade_to_full();
op_full(GCCause::_shenandoah_upgrade_to_full_gc);
}
void ShenandoahHeap::op_degenerated_futile() {
shenandoah_policy()->record_degenerated_upgrade_to_full();
op_full(GCCause::_shenandoah_upgrade_to_full_gc);
}
void ShenandoahHeap::force_satb_flush_all_threads() {
if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
// No need to flush SATBs
return;
}
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
ShenandoahThreadLocalData::set_force_satb_flush(t, true);
}
// The threads are not "acquiring" their thread-local data, but it does not
// hurt to "release" the updates here anyway.
OrderAccess::fence();
}
void ShenandoahHeap::set_gc_state_all_threads(char state) {
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
ShenandoahThreadLocalData::set_gc_state(t, state);
}
}
void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
_gc_state.set_cond(mask, value);
set_gc_state_all_threads(_gc_state.raw_value());
}
void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
if (has_forwarded_objects()) {
set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
} else {
set_gc_state_mask(MARKING, in_progress);
}
ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
}
void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
set_gc_state_mask(TRAVERSAL, in_progress);
ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
}
void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
set_gc_state_mask(EVACUATION, in_progress);
}
void ShenandoahHeap::ref_processing_init() {
assert(_max_workers > 0, "Sanity");
_ref_processor =
new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
ParallelRefProcEnabled, // MT processing
_max_workers, // Degree of MT processing
true, // MT discovery
_max_workers, // Degree of MT discovery
false, // Reference discovery is not atomic
NULL, // No closure, should be installed before use
true); // Scale worker threads
shenandoah_assert_rp_isalive_not_installed();
}
GCTracer* ShenandoahHeap::tracer() {
return shenandoah_policy()->tracer();
}
size_t ShenandoahHeap::tlab_used(Thread* thread) const {
return _free_set->used();
}
bool ShenandoahHeap::try_cancel_gc() {
while (true) {
jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
if (prev == CANCELLABLE) return true;
else if (prev == CANCELLED) return false;
assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
if (Thread::current()->is_Java_thread()) {
// We need to provide a safepoint here, otherwise we might
// spin forever if a SP is pending.
ThreadBlockInVM sp(JavaThread::current());
SpinPause();
}
}
}
void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
if (try_cancel_gc()) {
FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
log_info(gc)("%s", msg.buffer());
Events::log(Thread::current(), "%s", msg.buffer());
}
}
uint ShenandoahHeap::max_workers() {
return _max_workers;
}
void ShenandoahHeap::stop() {
// The shutdown sequence should be able to terminate when GC is running.
// Step 0. Notify policy to disable event recording.
_shenandoah_policy->record_shutdown();
// Step 1. Notify control thread that we are in shutdown.
// Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
// Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
control_thread()->prepare_for_graceful_shutdown();
// Step 2. Notify GC workers that we are cancelling GC.
cancel_gc(GCCause::_shenandoah_stop_vm);
// Step 3. Wait until GC worker exits normally.
control_thread()->stop();
// Step 4. Stop String Dedup thread if it is active
if (ShenandoahStringDedup::is_enabled()) {
ShenandoahStringDedup::stop();
}
}
void ShenandoahHeap::stw_unload_classes(bool full_gc) {
if (!unload_classes()) return;
bool purged_class;
// Unload classes and purge SystemDictionary.
{
ShenandoahGCPhase phase(full_gc ?
ShenandoahPhaseTimings::full_gc_purge_class_unload :
ShenandoahPhaseTimings::purge_class_unload);
purged_class = SystemDictionary::do_unloading(gc_timer());
}
{
ShenandoahGCPhase phase(full_gc ?
ShenandoahPhaseTimings::full_gc_purge_par :
ShenandoahPhaseTimings::purge_par);
ShenandoahIsAliveSelector is_alive;
uint num_workers = _workers->active_workers();
ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
_workers->run_task(&unlink_task);
}
{
ShenandoahGCPhase phase(full_gc ?
ShenandoahPhaseTimings::full_gc_purge_cldg :
ShenandoahPhaseTimings::purge_cldg);
ClassLoaderDataGraph::purge();
}
// Resize and verify metaspace
MetaspaceGC::compute_new_size();
}
// Process leftover weak oops: update them, if needed or assert they do not
// need updating otherwise.
// Weak processor API requires us to visit the oops, even if we are not doing
// anything to them.
void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
ShenandoahGCPhase root_phase(full_gc ?
ShenandoahPhaseTimings::full_gc_purge :
ShenandoahPhaseTimings::purge);
uint num_workers = _workers->active_workers();
ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
ShenandoahPhaseTimings::full_gc_purge_par :
ShenandoahPhaseTimings::purge_par;
// Cleanup weak roots
ShenandoahGCPhase phase(timing_phase);
if (has_forwarded_objects()) {
if (is_traversal_mode()) {
ShenandoahForwardedIsAliveClosure is_alive;
ShenandoahTraversalUpdateRefsClosure keep_alive;
ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahTraversalUpdateRefsClosure>
cleaning_task(&is_alive, &keep_alive, num_workers);
_workers->run_task(&cleaning_task);
} else {
ShenandoahForwardedIsAliveClosure is_alive;
ShenandoahUpdateRefsClosure keep_alive;
ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
cleaning_task(&is_alive, &keep_alive, num_workers);
_workers->run_task(&cleaning_task);
}
} else {
ShenandoahIsAliveClosure is_alive;
#ifdef ASSERT
ShenandoahAssertNotForwardedClosure verify_cl;
ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
cleaning_task(&is_alive, &verify_cl, num_workers);
#else
ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
cleaning_task(&is_alive, &do_nothing_cl, num_workers);
#endif
_workers->run_task(&cleaning_task);
}
}
void ShenandoahHeap::parallel_cleaning(bool full_gc) {
assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
stw_process_weak_roots(full_gc);
stw_unload_classes(full_gc);
}
void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
if (is_traversal_mode()) {
set_gc_state_mask(HAS_FORWARDED | UPDATEREFS, cond);
} else {
set_gc_state_mask(HAS_FORWARDED, cond);
}
}
void ShenandoahHeap::set_process_references(bool pr) {
_process_references.set_cond(pr);
}
void ShenandoahHeap::set_unload_classes(bool uc) {
_unload_classes.set_cond(uc);
}
bool ShenandoahHeap::process_references() const {
return _process_references.is_set();
}
bool ShenandoahHeap::unload_classes() const {
return _unload_classes.is_set();
}
address ShenandoahHeap::in_cset_fast_test_addr() {
ShenandoahHeap* heap = ShenandoahHeap::heap();
assert(heap->collection_set() != NULL, "Sanity");
return (address) heap->collection_set()->biased_map_address();
}
address ShenandoahHeap::cancelled_gc_addr() {
return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
}
address ShenandoahHeap::gc_state_addr() {
return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
}
size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
return OrderAccess::load_acquire(&_bytes_allocated_since_gc_start);
}
void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
OrderAccess::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
}
void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
_degenerated_gc_in_progress.set_cond(in_progress);
}
void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
_full_gc_in_progress.set_cond(in_progress);
}
void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
assert (is_full_gc_in_progress(), "should be");
_full_gc_move_in_progress.set_cond(in_progress);
}
void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
set_gc_state_mask(UPDATEREFS, in_progress);
}
void ShenandoahHeap::register_nmethod(nmethod* nm) {
ShenandoahCodeRoots::add_nmethod(nm);
}
void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
ShenandoahCodeRoots::remove_nmethod(nm);
}
oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
heap_region_containing(o)->record_pin();
return o;
}
void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
heap_region_containing(o)->record_unpin();
}
void ShenandoahHeap::sync_pinned_region_status() {
ShenandoahHeapLocker locker(lock());
for (size_t i = 0; i < num_regions(); i++) {
ShenandoahHeapRegion *r = get_region(i);
if (r->is_active()) {
if (r->is_pinned()) {
if (r->pin_count() == 0) {
r->make_unpinned();
}
} else {
if (r->pin_count() > 0) {
r->make_pinned();
}
}
}
}
assert_pinned_region_status();
}
#ifdef ASSERT
void ShenandoahHeap::assert_pinned_region_status() {
for (size_t i = 0; i < num_regions(); i++) {
ShenandoahHeapRegion* r = get_region(i);
assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
"Region " SIZE_FORMAT " pinning status is inconsistent", i);
}
}
#endif
GCTimer* ShenandoahHeap::gc_timer() const {
return _gc_timer;
}
#ifdef ASSERT
void ShenandoahHeap::assert_gc_workers(uint nworkers) {
assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
if (UseDynamicNumberOfGCThreads ||
(FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
} else {
// Use ParallelGCThreads inside safepoints
assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
}
} else {
if (UseDynamicNumberOfGCThreads ||
(FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
} else {
// Use ConcGCThreads outside safepoints
assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
}
}
}
#endif
ShenandoahVerifier* ShenandoahHeap::verifier() {
guarantee(ShenandoahVerify, "Should be enabled");
assert (_verifier != NULL, "sanity");
return _verifier;
}
template<class T>
class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
private:
T cl;
ShenandoahHeap* _heap;
ShenandoahRegionIterator* _regions;
bool _concurrent;
public:
ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
AbstractGangTask("Concurrent Update References Task"),
cl(T()),
_heap(ShenandoahHeap::heap()),
_regions(regions),
_concurrent(concurrent) {
}
void work(uint worker_id) {
if (_concurrent) {
ShenandoahConcurrentWorkerSession worker_session(worker_id);
ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
do_work();
} else {
ShenandoahParallelWorkerSession worker_session(worker_id);
do_work();
}
}
private:
void do_work() {
ShenandoahHeapRegion* r = _regions->next();
ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
while (r != NULL) {
HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
assert (top_at_start_ur >= r->bottom(), "sanity");
if (r->is_active() && !r->is_cset()) {
_heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
}
if (ShenandoahPacing) {
_heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
}
if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
return;
}
r = _regions->next();
}
}
};
void ShenandoahHeap::update_heap_references(bool concurrent) {
ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
workers()->run_task(&task);
}
void ShenandoahHeap::op_init_updaterefs() {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
set_evacuation_in_progress(false);
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
retire_and_reset_gclabs();
}
if (ShenandoahVerify) {
if (!is_degenerated_gc_in_progress()) {
verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
}
verifier()->verify_before_updaterefs();
}
set_update_refs_in_progress(true);
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
make_parsable(true);
for (uint i = 0; i < num_regions(); i++) {
ShenandoahHeapRegion* r = get_region(i);
r->set_concurrent_iteration_safe_limit(r->top());
}
// Reset iterator.
_update_refs_iterator.reset();
}
if (ShenandoahPacing) {
pacer()->setup_for_updaterefs();
}
}
void ShenandoahHeap::op_final_updaterefs() {
assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
// Check if there is left-over work, and finish it
if (_update_refs_iterator.has_next()) {
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
// Finish updating references where we left off.
clear_cancelled_gc();
update_heap_references(false);
}
// Clear cancelled GC, if set. On cancellation path, the block before would handle
// everything. On degenerated paths, cancelled gc would not be set anyway.
if (cancelled_gc()) {
clear_cancelled_gc();
}
assert(!cancelled_gc(), "Should have been done right before");
if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
}
if (is_degenerated_gc_in_progress()) {
concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
} else {
concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
}
// Has to be done before cset is clear
if (ShenandoahVerify) {
verifier()->verify_roots_in_to_space();
}
// Drop unnecessary "pinned" state from regions that does not have CP marks
// anymore, as this would allow trashing them below.
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
sync_pinned_region_status();
}
{
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
trash_cset_regions();
}
set_has_forwarded_objects(false);
set_update_refs_in_progress(false);
if (ShenandoahVerify) {
verifier()->verify_after_updaterefs();
}
if (VerifyAfterGC) {
Universe::verify();
}
{
ShenandoahHeapLocker locker(lock());
_free_set->rebuild();
}
}
#ifdef ASSERT
void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
_lock.assert_owned_by_current_thread();
}
void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
_lock.assert_not_owned_by_current_thread();
}
void ShenandoahHeap::assert_heaplock_or_safepoint() {
_lock.assert_owned_by_current_thread_or_safepoint();
}
#endif
void ShenandoahHeap::print_extended_on(outputStream *st) const {
print_on(st);
print_heap_regions_on(st);
}
bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
size_t slice = r->region_number() / _bitmap_regions_per_slice;
size_t regions_from = _bitmap_regions_per_slice * slice;
size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
for (size_t g = regions_from; g < regions_to; g++) {
assert (g / _bitmap_regions_per_slice == slice, "same slice");
if (skip_self && g == r->region_number()) continue;
if (get_region(g)->is_committed()) {
return true;
}
}
return false;
}
bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
assert_heaplock_owned_by_current_thread();
// Bitmaps in special regions do not need commits
if (_bitmap_region_special) {
return true;
}
if (is_bitmap_slice_committed(r, true)) {
// Some other region from the group is already committed, meaning the bitmap
// slice is already committed, we exit right away.
return true;
}
// Commit the bitmap slice:
size_t slice = r->region_number() / _bitmap_regions_per_slice;
size_t off = _bitmap_bytes_per_slice * slice;
size_t len = _bitmap_bytes_per_slice;
if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
return false;
}
return true;
}
bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
assert_heaplock_owned_by_current_thread();
// Bitmaps in special regions do not need uncommits
if (_bitmap_region_special) {
return true;
}
if (is_bitmap_slice_committed(r, true)) {
// Some other region from the group is still committed, meaning the bitmap
// slice is should stay committed, exit right away.
return true;
}
// Uncommit the bitmap slice:
size_t slice = r->region_number() / _bitmap_regions_per_slice;
size_t off = _bitmap_bytes_per_slice * slice;
size_t len = _bitmap_bytes_per_slice;
if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
return false;
}
return true;
}
void ShenandoahHeap::safepoint_synchronize_begin() {
if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
SuspendibleThreadSet::synchronize();
}
}
void ShenandoahHeap::safepoint_synchronize_end() {
if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
SuspendibleThreadSet::desynchronize();
}
}
void ShenandoahHeap::vmop_entry_init_mark() {
TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
try_inject_alloc_failure();
VM_ShenandoahInitMark op;
VMThread::execute(&op); // jump to entry_init_mark() under safepoint
}
void ShenandoahHeap::vmop_entry_final_mark() {
TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
try_inject_alloc_failure();
VM_ShenandoahFinalMarkStartEvac op;
VMThread::execute(&op); // jump to entry_final_mark under safepoint
}
void ShenandoahHeap::vmop_entry_final_evac() {
TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
VM_ShenandoahFinalEvac op;
VMThread::execute(&op); // jump to entry_final_evac under safepoint
}
void ShenandoahHeap::vmop_entry_init_updaterefs() {
TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
try_inject_alloc_failure();
VM_ShenandoahInitUpdateRefs op;
VMThread::execute(&op);
}
void ShenandoahHeap::vmop_entry_final_updaterefs() {
TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
try_inject_alloc_failure();
VM_ShenandoahFinalUpdateRefs op;
VMThread::execute(&op);
}
void ShenandoahHeap::vmop_entry_init_traversal() {
TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
try_inject_alloc_failure();
VM_ShenandoahInitTraversalGC op;
VMThread::execute(&op);
}
void ShenandoahHeap::vmop_entry_final_traversal() {
TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
try_inject_alloc_failure();
VM_ShenandoahFinalTraversalGC op;
VMThread::execute(&op);
}
void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
try_inject_alloc_failure();
VM_ShenandoahFullGC op(cause);
VMThread::execute(&op);
}
void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
VMThread::execute(°enerated_gc);
}
void ShenandoahHeap::entry_init_mark() {
ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
const char* msg = init_mark_event_message();
GCTraceTime(Info, gc) time(msg, gc_timer());
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
"init marking");
op_init_mark();
}
void ShenandoahHeap::entry_final_mark() {
ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
const char* msg = final_mark_event_message();
GCTraceTime(Info, gc) time(msg, gc_timer());
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
"final marking");
op_final_mark();
}
void ShenandoahHeap::entry_final_evac() {
ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
static const char* msg = "Pause Final Evac";
GCTraceTime(Info, gc) time(msg, gc_timer());
EventMark em("%s", msg);
op_final_evac();
}
void ShenandoahHeap::entry_init_updaterefs() {
ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
static const char* msg = "Pause Init Update Refs";
GCTraceTime(Info, gc) time(msg, gc_timer());
EventMark em("%s", msg);
// No workers used in this phase, no setup required
op_init_updaterefs();
}
void ShenandoahHeap::entry_final_updaterefs() {
ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
static const char* msg = "Pause Final Update Refs";
GCTraceTime(Info, gc) time(msg, gc_timer());
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
"final reference update");
op_final_updaterefs();
}
void ShenandoahHeap::entry_init_traversal() {
ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
static const char* msg = "Pause Init Traversal";
GCTraceTime(Info, gc) time(msg, gc_timer());
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
"init traversal");
op_init_traversal();
}
void ShenandoahHeap::entry_final_traversal() {
ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
static const char* msg = "Pause Final Traversal";
GCTraceTime(Info, gc) time(msg, gc_timer());
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
"final traversal");
op_final_traversal();
}
void ShenandoahHeap::entry_full(GCCause::Cause cause) {
ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
static const char* msg = "Pause Full";
GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
"full gc");
op_full(cause);
}
void ShenandoahHeap::entry_degenerated(int point) {
ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
const char* msg = degen_event_message(dpoint);
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
"stw degenerated gc");
set_degenerated_gc_in_progress(true);
op_degenerated(dpoint);
set_degenerated_gc_in_progress(false);
}
void ShenandoahHeap::entry_mark() {
TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
const char* msg = conc_mark_event_message();
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
"concurrent marking");
try_inject_alloc_failure();
op_mark();
}
void ShenandoahHeap::entry_evac() {
ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
static const char* msg = "Concurrent evacuation";
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
"concurrent evacuation");
try_inject_alloc_failure();
op_conc_evac();
}
void ShenandoahHeap::entry_updaterefs() {
ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
static const char* msg = "Concurrent update references";
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
"concurrent reference update");
try_inject_alloc_failure();
op_updaterefs();
}
void ShenandoahHeap::entry_roots() {
ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
static const char* msg = "Concurrent roots processing";
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
"concurrent root processing");
try_inject_alloc_failure();
op_roots();
}
void ShenandoahHeap::entry_cleanup() {
ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
static const char* msg = "Concurrent cleanup";
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
// This phase does not use workers, no need for setup
try_inject_alloc_failure();
op_cleanup();
}
void ShenandoahHeap::entry_reset() {
ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
static const char* msg = "Concurrent reset";
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
"concurrent reset");
try_inject_alloc_failure();
op_reset();
}
void ShenandoahHeap::entry_preclean() {
if (ShenandoahPreclean && process_references()) {
static const char* msg = "Concurrent precleaning";
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
"concurrent preclean",
/* check_workers = */ false);
try_inject_alloc_failure();
op_preclean();
}
}
void ShenandoahHeap::entry_traversal() {
static const char* msg = "Concurrent traversal";
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
ShenandoahWorkerScope scope(workers(),
ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
"concurrent traversal");
try_inject_alloc_failure();
op_traversal();
}
void ShenandoahHeap::entry_uncommit(double shrink_before) {
static const char *msg = "Concurrent uncommit";
GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
EventMark em("%s", msg);
ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
op_uncommit(shrink_before);
}
void ShenandoahHeap::try_inject_alloc_failure() {
if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
_inject_alloc_failure.set();
os::naked_short_sleep(1);
if (cancelled_gc()) {
log_info(gc)("Allocation failure was successfully injected");
}
}
}
bool ShenandoahHeap::should_inject_alloc_failure() {
return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
}
void ShenandoahHeap::initialize_serviceability() {
_memory_pool = new ShenandoahMemoryPool(this);
_cycle_memory_manager.add_pool(_memory_pool);
_stw_memory_manager.add_pool(_memory_pool);
}
GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
GrowableArray<GCMemoryManager*> memory_managers(2);
memory_managers.append(&_cycle_memory_manager);
memory_managers.append(&_stw_memory_manager);
return memory_managers;
}
GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
GrowableArray<MemoryPool*> memory_pools(1);
memory_pools.append(_memory_pool);
return memory_pools;
}
MemoryUsage ShenandoahHeap::memory_usage() {
return _memory_pool->get_memory_usage();
}
void ShenandoahHeap::enter_evacuation() {
_oom_evac_handler.enter_evacuation();
}
void ShenandoahHeap::leave_evacuation() {
_oom_evac_handler.leave_evacuation();
}
ShenandoahRegionIterator::ShenandoahRegionIterator() :
_heap(ShenandoahHeap::heap()),
_index(0) {}
ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
_heap(heap),
_index(0) {}
void ShenandoahRegionIterator::reset() {
_index = 0;
}
bool ShenandoahRegionIterator::has_next() const {
return _index < _heap->num_regions();
}
char ShenandoahHeap::gc_state() const {
return _gc_state.raw_value();
}
void ShenandoahHeap::deduplicate_string(oop str) {
assert(java_lang_String::is_instance(str), "invariant");
if (ShenandoahStringDedup::is_enabled()) {
ShenandoahStringDedup::deduplicate(str);
}
}
const char* ShenandoahHeap::init_mark_event_message() const {
bool update_refs = has_forwarded_objects();
bool proc_refs = process_references();
bool unload_cls = unload_classes();
if (update_refs && proc_refs && unload_cls) {
return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
} else if (update_refs && proc_refs) {
return "Pause Init Mark (update refs) (process weakrefs)";
} else if (update_refs && unload_cls) {
return "Pause Init Mark (update refs) (unload classes)";
} else if (proc_refs && unload_cls) {
return "Pause Init Mark (process weakrefs) (unload classes)";
} else if (update_refs) {
return "Pause Init Mark (update refs)";
} else if (proc_refs) {
return "Pause Init Mark (process weakrefs)";
} else if (unload_cls) {
return "Pause Init Mark (unload classes)";
} else {
return "Pause Init Mark";
}
}
const char* ShenandoahHeap::final_mark_event_message() const {
bool update_refs = has_forwarded_objects();
bool proc_refs = process_references();
bool unload_cls = unload_classes();
if (update_refs && proc_refs && unload_cls) {
return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
} else if (update_refs && proc_refs) {
return "Pause Final Mark (update refs) (process weakrefs)";
} else if (update_refs && unload_cls) {
return "Pause Final Mark (update refs) (unload classes)";
} else if (proc_refs && unload_cls) {
return "Pause Final Mark (process weakrefs) (unload classes)";
} else if (update_refs) {
return "Pause Final Mark (update refs)";
} else if (proc_refs) {
return "Pause Final Mark (process weakrefs)";
} else if (unload_cls) {
return "Pause Final Mark (unload classes)";
} else {
return "Pause Final Mark";
}
}
const char* ShenandoahHeap::conc_mark_event_message() const {
bool update_refs = has_forwarded_objects();
bool proc_refs = process_references();
bool unload_cls = unload_classes();
if (update_refs && proc_refs && unload_cls) {
return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
} else if (update_refs && proc_refs) {
return "Concurrent marking (update refs) (process weakrefs)";
} else if (update_refs && unload_cls) {
return "Concurrent marking (update refs) (unload classes)";
} else if (proc_refs && unload_cls) {
return "Concurrent marking (process weakrefs) (unload classes)";
} else if (update_refs) {
return "Concurrent marking (update refs)";
} else if (proc_refs) {
return "Concurrent marking (process weakrefs)";
} else if (unload_cls) {
return "Concurrent marking (unload classes)";
} else {
return "Concurrent marking";
}
}
const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
switch (point) {
case _degenerated_unset:
return "Pause Degenerated GC (<UNSET>)";
case _degenerated_traversal:
return "Pause Degenerated GC (Traversal)";
case _degenerated_outside_cycle:
return "Pause Degenerated GC (Outside of Cycle)";
case _degenerated_mark:
return "Pause Degenerated GC (Mark)";
case _degenerated_evac:
return "Pause Degenerated GC (Evacuation)";
case _degenerated_updaterefs:
return "Pause Degenerated GC (Update Refs)";
default:
ShouldNotReachHere();
return "ERROR";
}
}
jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
#ifdef ASSERT
assert(_liveness_cache != NULL, "sanity");
assert(worker_id < _max_workers, "sanity");
for (uint i = 0; i < num_regions(); i++) {
assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
}
#endif
return _liveness_cache[worker_id];
}
void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
assert(worker_id < _max_workers, "sanity");
assert(_liveness_cache != NULL, "sanity");
jushort* ld = _liveness_cache[worker_id];
for (uint i = 0; i < num_regions(); i++) {
ShenandoahHeapRegion* r = get_region(i);
jushort live = ld[i];
if (live > 0) {
r->increase_live_data_gc_words(live);
ld[i] = 0;
}
}
}