// This method iterates over all objects in the young generation,
// unforwarding markOops. It then restores any preserved mark oops,
// and clears the _preserved_mark_stack.
void PSScavenge::clean_up_failed_promotion() {
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
assert(promotion_failed(), "Sanity");
PSYoungGen* young_gen = heap->young_gen();
{
ResourceMark rm;
// Unforward all pointers in the young gen.
PSPromotionFailedClosure unforward_closure;
young_gen->object_iterate(&unforward_closure);
if (PrintGC && Verbose) {
gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size());
}
// Restore any saved marks.
while (!_preserved_oop_stack.is_empty()) {
oop obj = _preserved_oop_stack.pop();
markOop mark = _preserved_mark_stack.pop();
obj->set_mark(mark);
}
// Clear the preserved mark and oop stack caches.
_preserved_mark_stack.clear(true);
_preserved_oop_stack.clear(true);
_promotion_failed = false;
}
// Reset the PromotionFailureALot counters.
NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
}
// This method iterates over all objects in the young generation,
// unforwarding markWords. It then restores any preserved mark oops,
// and clears the _preserved_mark_stack.
void PSScavenge::clean_up_failed_promotion() {
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
assert(promotion_failed(), "Sanity");
PSYoungGen* young_gen = heap->young_gen();
{
ResourceMark rm;
// Unforward all pointers in the young gen.
PSPromotionFailedClosure unforward_closure;
young_gen->object_iterate(&unforward_closure);
if (PrintGC && Verbose) {
gclog_or_tty->print_cr("Restoring %d marks",
_preserved_oop_stack->length());
}
// Restore any saved marks.
for (int i=0; i < _preserved_oop_stack->length(); i++) {
oop obj = _preserved_oop_stack->at(i);
markWord*mark=_preserved_mark_stack->at(i);
obj->set_mark(mark);
}
// Deallocate the preserved mark and oop stacks.
// The stacks were allocated as CHeap objects, so
// we must call delete to prevent mem leaks.
delete _preserved_mark_stack;
_preserved_mark_stack = NULL;
delete _preserved_oop_stack;
_preserved_oop_stack = NULL;
}
// Reset the PromotionFailureALot counters.
NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
}
// This method contains no policy. You should probably
// be calling invoke() instead.
bool PSScavenge::invoke_no_policy() {
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
elapsedTimer scavenge_time;
TimeStamp scavenge_entry;
TimeStamp scavenge_midpoint;
TimeStamp scavenge_exit;
scavenge_entry.update();
if (GC_locker::check_active_before_gc()) {
return false;
}
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
GCCause::Cause gc_cause = heap->gc_cause();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
// Check for potential problems.
if (!should_attempt_scavenge()) {
return false;
}
bool promotion_failure_occurred = false;
PSYoungGen* young_gen = heap->young_gen();
PSOldGen* old_gen = heap->old_gen();
PSPermGen* perm_gen = heap->perm_gen();
PSAdaptiveSizePolicy* size_policy = heap->size_policy();
heap->increment_total_collections();
AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
if ((gc_cause != GCCause::_java_lang_system_gc) ||
UseAdaptiveSizePolicyWithSystemGC) {
// Gather the feedback data for eden occupancy.
young_gen->eden_space()->accumulate_statistics();
}
// We need to track unique scavenge invocations as well.
_total_invocations++;
if (PrintHeapAtGC) {
Universe::print_heap_before_gc();
}
assert(!NeverTenure||_tenuring_threshold==markWord::max_age+1,"Sanity");
assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
size_t prev_used = heap->used();
assert(promotion_failed() == false, "Sanity");
// Fill in TLABs
heap->accumulate_statistics_all_tlabs();
heap->ensure_parsability(true); // retire TLABs
if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
gclog_or_tty->print(" VerifyBeforeGC:");
Universe::verify(true);
}
{
ResourceMark rm;
HandleMark hm;
gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
TraceTime t1("GC", PrintGC, !PrintGCDetails, gclog_or_tty);
TraceCollectorStats tcs(counters());
TraceMemoryManagerStats tms(false /* not full GC */);
if (TraceGen0Time) scavenge_time.start();
// Let the size policy know we're starting
size_policy->minor_collection_begin();
// Verify the object start arrays.
if (VerifyObjectStartArray &&
VerifyBeforeGC) {
old_gen->verify_object_start_array();
perm_gen->verify_object_start_array();
}
// Verify no unmarked old->young roots
if (VerifyRememberedSets) {
CardTableExtension::verify_all_young_refs_imprecise();
}
if (!ScavengeWithObjectsInToSpace) {
assert(young_gen->to_space()->is_empty(),
"Attempt to scavenge with live objects in to_space");
young_gen->to_space()->clear();
} else if (ZapUnusedHeapArea) {
young_gen->to_space()->mangle_unused_area();
}
save_to_space_top_before_gc();
NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
DerivedPointerTable::clear();
reference_processor()->enable_discovery();
// We track how much was promoted to the next generation for
// the AdaptiveSizePolicy.
size_t old_gen_used_before = old_gen->used_in_bytes();
// For PrintGCDetails
size_t young_gen_used_before = young_gen->used_in_bytes();
// Reset our survivor overflow.
set_survivor_overflow(false);
// We need to save the old/perm top values before
// creating the promotion_manager. We pass the top
// values to the card_table, to prevent it from
// straying into the promotion labs.
HeapWord* old_top = old_gen->object_space()->top();
HeapWord* perm_top = perm_gen->object_space()->top();
// Release all previously held resources
gc_task_manager()->release_all_resources();
PSPromotionManager::pre_scavenge();
// We'll use the promotion manager again later.
PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
{
// TraceTime("Roots");
GCTaskQueue* q = GCTaskQueue::create();
for(uint i=0; i<ParallelGCThreads; i++) {
q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i));
q->enqueue(new OldToYoungRootsTask(perm_gen,perm_top,i));
}
// q->enqueue(new SerialOldToYoungRootsTask(perm_gen, perm_top));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
// We scan the thread roots in parallel
// FIX ME! We should have a NoResourceMarkVerifier here!
Threads::create_thread_roots_tasks(q);
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
// NOTE! ArtaObjects are not normal roots. During scavenges, they are
// considered strong roots. During a mark sweep they are weak roots.
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::arta_objects));
ParallelTaskTerminator terminator(
gc_task_manager()->workers(),
promotion_manager->depth_first() ?
(TaskQueueSetSuper*)promotion_manager->stack_array_depth()
: (TaskQueueSetSuper*)promotion_manager->stack_array_breadth());
if (ParallelGCThreads>1) {
for (uint j=0; j<ParallelGCThreads; j++) {
q->enqueue(new StealTask(&terminator));
}
}
gc_task_manager()->execute_and_wait(q);
}
scavenge_midpoint.update();
// Process reference objects discovered during scavenge
{
ReferencePolicy *soft_ref_policy = new LRUMaxHeapPolicy();
PSKeepAliveClosure keep_alive(promotion_manager);
PSEvacuateFollowersClosure evac_followers(promotion_manager);
assert(soft_ref_policy != NULL,"No soft reference policy");
if (reference_processor()->processing_is_mt()) {
PSRefProcTaskExecutor task_executor;
reference_processor()->process_discovered_references(
soft_ref_policy, &_is_alive_closure, &keep_alive, &evac_followers,
&task_executor);
} else {
reference_processor()->process_discovered_references(
soft_ref_policy, &_is_alive_closure, &keep_alive, &evac_followers,
NULL);
}
}
// Enqueue reference objects discovered during scavenge.
if (reference_processor()->processing_is_mt()) {
PSRefProcTaskExecutor task_executor;
reference_processor()->enqueue_discovered_references(&task_executor);
} else {
reference_processor()->enqueue_discovered_references(NULL);
}
// Finally, flush the promotion_manager's labs, and deallocate its stacks.
assert(promotion_manager->claimed_stack_empty(), "Sanity");
PSPromotionManager::post_scavenge();
promotion_failure_occurred = promotion_failed();
if (promotion_failure_occurred) {
_total_promotion_failures++;
clean_up_failed_promotion();
if (PrintGC) {
gclog_or_tty->print("--");
}
}
// Let the size policy know we're done. Note that we count promotion
// failure cleanup time as part of the collection (otherwise, we're
// implicitly saying it's mutator time).
size_policy->minor_collection_end(gc_cause);
if (!promotion_failure_occurred) {
// Swap the survivor spaces.
young_gen->eden_space()->clear();
young_gen->from_space()->clear();
young_gen->swap_spaces();
size_t survived = young_gen->from_space()->used_in_bytes();
size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
size_policy->update_averages(_survivor_overflow, survived, promoted);
if (UseAdaptiveSizePolicy) {
// Calculate the new survivor size and tenuring threshold
if (PrintAdaptiveSizePolicy) {
gclog_or_tty->print("AdaptiveSizeStart: ");
gclog_or_tty->stamp();
gclog_or_tty->print_cr(" collection: %d ",
heap->total_collections());
if (Verbose) {
gclog_or_tty->print("old_gen_capacity: %zd young_gen_capacity: %zd"
" perm_gen_capacity: %zd ",
old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
perm_gen->capacity_in_bytes());
}
}
if (UsePerfData) {
PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
counters->update_old_eden_size(
size_policy->calculated_eden_size_in_bytes());
counters->update_old_promo_size(
size_policy->calculated_promo_size_in_bytes());
counters->update_old_capacity(old_gen->capacity_in_bytes());
counters->update_young_capacity(young_gen->capacity_in_bytes());
counters->update_survived(survived);
counters->update_promoted(promoted);
counters->update_survivor_overflowed(_survivor_overflow);
}
size_t survivor_limit =
size_policy->max_survivor_size(young_gen->max_size());
_tenuring_threshold =
size_policy->compute_survivor_space_size_and_threshold(
_survivor_overflow,
_tenuring_threshold,
survivor_limit);
if (PrintTenuringDistribution) {
gclog_or_tty->cr();
gclog_or_tty->print_cr("Desired survivor size %ld bytes, new threshold %d (max %ld)",
size_policy->calculated_survivor_size_in_bytes(),
_tenuring_threshold, MaxTenuringThreshold);
}
if (UsePerfData) {
PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
counters->update_tenuring_threshold(_tenuring_threshold);
counters->update_survivor_size_counters();
}
// Do call at minor collections?
// Don't check if the size_policy is ready at this
// level. Let the size_policy check that internally.
if (UseAdaptiveSizePolicy &&
UseAdaptiveGenerationSizePolicyAtMinorCollection &&
((gc_cause != GCCause::_java_lang_system_gc) ||
UseAdaptiveSizePolicyWithSystemGC)) {
// Calculate optimial free space amounts
assert(young_gen->max_size() >
young_gen->from_space()->capacity_in_bytes() +
young_gen->to_space()->capacity_in_bytes(),
"Sizes of space in young gen are out-of-bounds");
size_t max_eden_size = young_gen->max_size() -
young_gen->from_space()->capacity_in_bytes() -
young_gen->to_space()->capacity_in_bytes();
size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
young_gen->eden_space()->used_in_bytes(),
old_gen->used_in_bytes(),
perm_gen->used_in_bytes(),
young_gen->eden_space()->capacity_in_bytes(),
old_gen->max_gen_size(),
max_eden_size,
false /* full gc*/,
gc_cause);
}
// Resize the young generation at every collection
// even if new sizes have not been calculated. This is
// to allow resizes that may have been inhibited by the
// relative location of the "to" and "from" spaces.
// Resizing the old gen at minor collects can cause increases
// that don't feed back to the generation sizing policy until
// a major collection. Don't resize the old gen here.
heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
size_policy->calculated_survivor_size_in_bytes());
if (PrintAdaptiveSizePolicy) {
gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
heap->total_collections());
}
}
// Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
// cause the change of the heap layout. Make sure eden is reshaped if that's the case.
// Also update() will case adaptive NUMA chunk resizing.
assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
young_gen->eden_space()->update();
heap->gc_policy_counters()->update_counters();
heap->resize_all_tlabs();
assert(young_gen->to_space()->is_empty(), "to space should be empty now");
}
DerivedPointerTable::update_pointers();
NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
// Re-verify object start arrays
if (VerifyObjectStartArray &&
VerifyAfterGC) {
old_gen->verify_object_start_array();
perm_gen->verify_object_start_array();
}
// Verify all old -> young cards are now precise
if (VerifyRememberedSets) {
// Precise verification will give false positives. Until this is fixed,
// use imprecise verification.
// CardTableExtension::verify_all_young_refs_precise();
CardTableExtension::verify_all_young_refs_imprecise();
}
if (TraceGen0Time) {
scavenge_time.stop();
if (promotion_failure_occurred)
accumulated_undo_time()->add(scavenge_time);
else
accumulated_gc_time()->add(scavenge_time);
}
if (PrintGC) {
if (PrintGCDetails) {
// Don't print a GC timestamp here. This is after the GC so
// would be confusing.
young_gen->print_used_change(young_gen_used_before);
}
heap->print_heap_change(prev_used);
}
// Track memory usage and detect low memory
MemoryService::track_memory_usage();
heap->update_counters();
}
if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
gclog_or_tty->print(" VerifyAfterGC:");
Universe::verify(false);
}
if (PrintHeapAtGC) {
Universe::print_heap_after_gc();
}
scavenge_exit.update();
if (PrintGCTaskTimeStamps) {
tty->print_cr("VM-Thread %lld %lld %lld",
scavenge_entry.ticks(), scavenge_midpoint.ticks(),
scavenge_exit.ticks());
gc_task_manager()->print_task_time_stamps();
}
return !promotion_failure_occurred;
}
void DefNewGeneration::preserve_mark(oop obj, markOop m) {
assert(promotion_failed() && m->must_be_preserved_for_promotion_failure(obj),
"Oversaving!");
_objs_with_preserved_marks.push(obj);
_preserved_marks_of_objs.push(m);
}
void DefNewGeneration::collect(bool full,
bool clear_all_soft_refs,
size_t size,
bool is_tlab) {
assert(full || size > 0, "otherwise we don't want to collect");
GenCollectedHeap* gch = GenCollectedHeap::heap();
_next_gen = gch->next_gen(this);
assert(_next_gen != NULL,
"This must be the youngest gen, and not the only gen");
// If the next generation is too full to accomodate promotion
// from this generation, pass on collection; let the next generation
// do it.
if (!collection_attempt_is_safe()) {
if (Verbose && PrintGCDetails) {
gclog_or_tty->print(" :: Collection attempt not safe :: ");
}
gch->set_incremental_collection_failed(); // Slight lie: we did not even attempt one
return;
}
assert(to()->is_empty(), "Else not collection_attempt_is_safe");
init_assuming_no_promotion_failure();
TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty);
// Capture heap used before collection (for printing).
size_t gch_prev_used = gch->used();
SpecializationStats::clear();
// These can be shared for all code paths
IsAliveClosure is_alive(this);
ScanWeakRefClosure scan_weak_ref(this);
age_table()->clear();
to()->clear(SpaceDecorator::Mangle);
gch->rem_set()->prepare_for_younger_refs_iterate(false);
assert(gch->no_allocs_since_save_marks(0),
"save marks have not been newly set.");
// Not very pretty.
CollectorPolicy* cp = gch->collector_policy();
FastScanClosure fsc_with_no_gc_barrier(this, false);
FastScanClosure fsc_with_gc_barrier(this, true);
set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
FastEvacuateFollowersClosure evacuate_followers(gch, _level, this,
&fsc_with_no_gc_barrier,
&fsc_with_gc_barrier);
assert(gch->no_allocs_since_save_marks(0),
"save marks have not been newly set.");
gch->gen_process_strong_roots(_level,
true, // Process younger gens, if any,
// as strong roots.
true, // activate StrongRootsScope
false, // not collecting perm generation.
SharedHeap::SO_AllClasses,
&fsc_with_no_gc_barrier,
true, // walk *all* scavengable nmethods
&fsc_with_gc_barrier);
// "evacuate followers".
evacuate_followers.do_void();
FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
ReferenceProcessor* rp = ref_processor();
rp->setup_policy(clear_all_soft_refs);
rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers,
NULL);
if (!promotion_failed()) {
// Swap the survivor spaces.
eden()->clear(SpaceDecorator::Mangle);
from()->clear(SpaceDecorator::Mangle);
if (ZapUnusedHeapArea) {
// This is now done here because of the piece-meal mangling which
// can check for valid mangling at intermediate points in the
// collection(s). When a minor collection fails to collect
// sufficient space resizing of the young generation can occur
// an redistribute the spaces in the young generation. Mangle
// here so that unzapped regions don't get distributed to
// other spaces.
to()->mangle_unused_area();
}
swap_spaces();
assert(to()->is_empty(), "to space should be empty now");
// Set the desired survivor size to half the real survivor space
_tenuring_threshold =
age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize);
// A successful scavenge should restart the GC time limit count which is
// for full GC's.
AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy();
size_policy->reset_gc_overhead_limit_count();
if (PrintGC && !PrintGCDetails) {
gch->print_heap_change(gch_prev_used);
}
assert(!gch->incremental_collection_failed(), "Should be clear");
} else {
assert(_promo_failure_scan_stack.is_empty(), "post condition");
_promo_failure_scan_stack.clear(true); // Clear cached segments.
remove_forwarding_pointers();
if (PrintGCDetails) {
gclog_or_tty->print(" (promotion failed) ");
}
// Add to-space to the list of space to compact
// when a promotion failure has occurred. In that
// case there can be live objects in to-space
// as a result of a partial evacuation of eden
// and from-space.
swap_spaces(); // For uniformity wrt ParNewGeneration.
from()->set_next_compaction_space(to());
gch->set_incremental_collection_failed();
// Inform the next generation that a promotion failure occurred.
_next_gen->promotion_failure_occurred();
// Reset the PromotionFailureALot counters.
NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
}
// set new iteration safe limit for the survivor spaces
from()->set_concurrent_iteration_safe_limit(from()->top());
to()->set_concurrent_iteration_safe_limit(to()->top());
SpecializationStats::print();
update_time_of_last_gc(os::javaTimeMillis());
}
// This method contains no policy. You should probably
// be calling invoke() instead.
void PSScavenge::invoke_no_policy(bool& notify_ref_lock) {
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
TimeStamp scavenge_entry;
TimeStamp scavenge_midpoint;
TimeStamp scavenge_exit;
scavenge_entry.update();
if (GC_locker::is_active()) return;
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
// Check for potential problems.
if (!should_attempt_scavenge()) {
return;
}
PSYoungGen* young_gen = heap->young_gen();
PSOldGen* old_gen = heap->old_gen();
PSPermGen* perm_gen = heap->perm_gen();
AdaptiveSizePolicy* size_policy = heap->size_policy();
heap->increment_total_collections();
if (PrintHeapAtGC){
gclog_or_tty->print_cr(" {Heap before GC invocations=%d:", heap->total_collections());
Universe::print();
}
assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
size_t prev_used = heap->used();
assert(promotion_failed() == false, "Sanity");
// Fill in TLABs
heap->ensure_parseability();
if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
tty->print(" VerifyBeforeGC:");
Universe::verify(true);
}
{
ResourceMark rm;
HandleMark hm;
TraceTime t1("GC", PrintGC, true, gclog_or_tty);
TraceCollectorStats tcs(counters());
if (TraceGen0Time) accumulated_time()->start();
// Let the size policy know we're starting
size_policy->minor_collection_begin();
// Verify no unmarked old->young roots
if (VerifyRememberedSets) {
old_gen->verify_object_start_array();
perm_gen->verify_object_start_array();
CardTableExtension::verify_all_young_refs_imprecise();
}
assert(young_gen->to_space()->is_empty(), "Attempt to scavenge with live objects in to_space");
young_gen->to_space()->clear();
NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
COMPILER2_ONLY(DerivedPointerTable::clear(););
reference_processor()->enable_discovery();
// We track how much was promoted to the next generation for
// the AdaptiveSizePolicy.
size_t old_gen_used_before = old_gen->object_space()->used_in_bytes();
// Reset our survivor overflow.
set_survivor_overflow(false);
// We need to save the old/perm top values before
// creating the promotion_manager. We pass the top
// values to the card_table, to prevent it from
// straying into the promotion labs.
HeapWord* old_top = old_gen->object_space()->top();
HeapWord* perm_top = perm_gen->object_space()->top();
// Release all previously held resources
gc_task_manager()->release_all_resources();
PSPromotionManager::pre_scavenge();
// We'll use the promotion manager again later.
PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
{
// TraceTime("Roots");
GCTaskQueue* q = GCTaskQueue::create();
for(uint i=0; i<ParallelGCThreads; i++) {
q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i));
}
q->enqueue(new SerialOldToYoungRootsTask(perm_gen, perm_top));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
// We scan the thread roots in parallel
Threads::create_thread_roots_tasks(q);
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
if (ParallelGCThreads>1) {
for (uint j=0; j<ParallelGCThreads-1; j++) {
q->enqueue(new StealTask(false));
}
q->enqueue(new StealTask(true));
}
WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
q->enqueue(fin);
gc_task_manager()->add_list(q);
fin->wait_for();
// We have to release the barrier tasks!
WaitForBarrierGCTask::destroy(fin);
}
scavenge_midpoint.update();
NOT_COMPILER2(ReferencePolicy *soft_ref_policy = new LRUCurrentHeapPolicy());
COMPILER2_ONLY(ReferencePolicy *soft_ref_policy = new LRUMaxHeapPolicy());
PSIsAliveClosure is_alive;
PSKeepAliveClosure keep_alive(promotion_manager);
PSEvacuateFollowersClosure evac_followers(promotion_manager);
// Process reference objects discovered during scavenge
reference_processor()->process_discovered_references(soft_ref_policy, &is_alive,
&keep_alive, &evac_followers);
// Enqueue reference objects discovered during scavenge.
notify_ref_lock = reference_processor()->enqueue_discovered_references();
// Finally, flush the promotion_manager's labs, and deallocate its stacks.
assert(promotion_manager->claimed_stack()->size() == 0, "Sanity");
PSPromotionManager::post_scavenge();
bool scavenge_promotion_failure = promotion_failed();
if (scavenge_promotion_failure) {
clean_up_failed_promotion();
if (PrintGC) {
gclog_or_tty->print("--");
}
}
// Let the size policy know we're done. Note that we count promotion
// failure cleanup time as part of the collection (otherwise, we're implicitly
// saying it's mutator time).
size_policy->minor_collection_end();
if (!scavenge_promotion_failure) {
// Swap the survivor spaces.
young_gen->eden_space()->clear();
young_gen->from_space()->clear();
young_gen->swap_spaces();
if (UseAdaptiveSizePolicy) {
// Calculate the new survivor size and tenuring threshold
size_t survived = young_gen->from_space()->used_in_bytes();
size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
if (PrintAdaptiveSizePolicy) {
tty->print_cr("AdaptiveSizeStart: collection: %d ",
heap->total_collections());
}
size_t survivor_limit =
size_policy->max_survivor_size(young_gen->max_size());
_tenuring_threshold =
size_policy->compute_survivor_space_size_and_threshold(survived,
promoted,
_survivor_overflow,
_tenuring_threshold,
survivor_limit);
// Calculate optimial free space amounts
size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
old_gen->used_in_bytes(),
perm_gen->used_in_bytes(),
false /* full gc*/);
// Resize the old and young generations
old_gen->resize(size_policy->calculated_old_free_size_in_bytes());
young_gen->resize(size_policy->calculated_eden_size_in_bytes(),
size_policy->calculated_survivor_size_in_bytes());
if (PrintAdaptiveSizePolicy) {
tty->print_cr("AdaptiveSizeStop: collection: %d ",
heap->total_collections());
}
}
assert(young_gen->to_space()->is_empty(), "to space should be empty now");
}
COMPILER2_ONLY(DerivedPointerTable::update_pointers());
NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
// Verify all old -> young cards are now precise
if (VerifyRememberedSets) {
// Precise verification will give false positives. Until this is fixed,
// use imprecise verification.
// CardTableExtension::verify_all_young_refs_precise();
CardTableExtension::verify_all_young_refs_imprecise();
}
if (TraceGen0Time) accumulated_time()->stop();
if (PrintGC) {
heap->print_heap_change(prev_used);
}
heap->update_counters();
}
