/**
* 标记清除的方式回收内存堆的垃圾对象
* 1.第一步: 标记所有存活的对象
* 2.第二步: 计算存活的对象在其内存区压缩后的偏移位置
* 3.第三步: 遍历所有存活的对象并修改其对应的地址映射表
* 4.第四步: 移动存活的对象压缩内存区
*/
void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp,
bool clear_all_softrefs) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
GenCollectedHeap* gch = GenCollectedHeap::heap();
#ifdef ASSERT
if (gch->collector_policy()->should_clear_all_soft_refs()) {
assert(clear_all_softrefs, "Policy should have been checked earlier");
}
#endif
// hook up weak ref data so it can be used during Mark-Sweep
assert(ref_processor() == NULL, "no stomping");
assert(rp != NULL, "should be non-NULL");
_ref_processor = rp;
rp->setup_policy(clear_all_softrefs);
TraceTime t1("Full GC", PrintGC && !PrintGCDetails, true, gclog_or_tty);
// When collecting the permanent generation methodOops may be moving,
// so we either have to flush all bcp data or convert it into bci.
CodeCache::gc_prologue();
Threads::gc_prologue();
// Increment the invocation count for the permanent generation, since it is
// implicitly collected whenever we do a full mark sweep collection.
gch->perm_gen()->stat_record()->invocations++;
//本次Gc之前内存堆的使用量
size_t gch_prev_used = gch->used();
// Some of the card table updates below assume that the perm gen is
// also being collected.
assert(level == gch->n_gens() - 1, "All generations are being collected, ergo perm gen too.");
// Capture used regions for each generation that will be
// subject to collection, so that card table adjustments can
// be made intelligently (see clear / invalidate further below).
gch->save_used_regions(level, true /* perm */);
allocate_stacks();
mark_sweep_phase1(level, clear_all_softrefs);
mark_sweep_phase2();
// Don't add any more derived pointers during phase3
COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
mark_sweep_phase3(level);
VALIDATE_MARK_SWEEP_ONLY(
if (ValidateMarkSweep) {
guarantee(_root_refs_stack->length() == 0, "should be empty by now");
}
)
void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
bool clear_all_softrefs) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
SharedHeap* sh = SharedHeap::heap();
#ifdef ASSERT
if (sh->collector_policy()->should_clear_all_soft_refs()) {
assert(clear_all_softrefs, "Policy should have been checked earler");
}
#endif
// hook up weak ref data so it can be used during Mark-Sweep
assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
assert(rp != NULL, "should be non-NULL");
assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Precondition");
GenMarkSweep::_ref_processor = rp;
rp->setup_policy(clear_all_softrefs);
// When collecting the permanent generation Method*s may be moving,
// so we either have to flush all bcp data or convert it into bci.
CodeCache::gc_prologue();
Threads::gc_prologue();
bool marked_for_unloading = false;
allocate_stacks();
// We should save the marks of the currently locked biased monitors.
// The marking doesn't preserve the marks of biased objects.
BiasedLocking::preserve_marks();
mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
mark_sweep_phase2();
// Don't add any more derived pointers during phase3
COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
mark_sweep_phase3();
mark_sweep_phase4();
GenMarkSweep::restore_marks();
BiasedLocking::restore_marks();
GenMarkSweep::deallocate_stacks();
// "free at last gc" is calculated from these.
// CHF: cheating for now!!!
// Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
// Universe::set_heap_used_at_last_gc(Universe::heap()->used());
Threads::gc_epilogue();
CodeCache::gc_epilogue();
JvmtiExport::gc_epilogue();
// refs processing: clean slate
GenMarkSweep::_ref_processor = NULL;
}
oop MarkSweep::collect(oop p) {
FlagSetting fl(GCInProgress, true);
EventMarker em("Garbage Collect");
ResourceMark rm;
TraceTime t("Garbage collection", PrintGC);
int old_used = Universe::old_gen.used();
if (VerifyBeforeScavenge || VerifyBeforeGC) Universe::verify();
// Clear all vm inline caches
DeltaCallCache::clearAll();
// clear remembered set; it is used for object sizes
Universe::remembered_set->clear();
allocate(); // allocate stack for traversal
mark_sweep_phase1(&p);
mark_sweep_phase2();
mark_sweep_phase3();
deallocate(); // clear allocated structures
// clear the remember set; we have no pointers from old to new
Universe::remembered_set->clear();
lookupCache::flush();
if (VerifyAfterScavenge || VerifyAfterGC) Universe::verify();
if (PrintGC) {
std->print(" %.1fM -> %.1fM",
(double) old_used / (double) (1024 * 1024),
(double) Universe::old_gen.used() / (double) (1024 * 1024));
}
return p;
}
void GenMarkSweep::invoke_at_safepoint(ReferenceProcessor* rp, bool clear_all_softrefs) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
GenCollectedHeap* gch = GenCollectedHeap::heap();
#ifdef ASSERT
if (gch->collector_policy()->should_clear_all_soft_refs()) {
assert(clear_all_softrefs, "Policy should have been checked earlier");
}
#endif
// hook up weak ref data so it can be used during Mark-Sweep
assert(ref_processor() == NULL, "no stomping");
assert(rp != NULL, "should be non-NULL");
set_ref_processor(rp);
rp->setup_policy(clear_all_softrefs);
gch->trace_heap_before_gc(_gc_tracer);
// When collecting the permanent generation Method*s may be moving,
// so we either have to flush all bcp data or convert it into bci.
CodeCache::gc_prologue();
// Increment the invocation count
_total_invocations++;
// Capture used regions for each generation that will be
// subject to collection, so that card table adjustments can
// be made intelligently (see clear / invalidate further below).
gch->save_used_regions();
allocate_stacks();
mark_sweep_phase1(clear_all_softrefs);
mark_sweep_phase2();
// Don't add any more derived pointers during phase3
#if defined(COMPILER2) || INCLUDE_JVMCI
assert(DerivedPointerTable::is_active(), "Sanity");
DerivedPointerTable::set_active(false);
#endif
mark_sweep_phase3();
mark_sweep_phase4();
restore_marks();
// Set saved marks for allocation profiler (and other things? -- dld)
// (Should this be in general part?)
gch->save_marks();
deallocate_stacks();
// If compaction completely evacuated the young generation then we
// can clear the card table. Otherwise, we must invalidate
// it (consider all cards dirty). In the future, we might consider doing
// compaction within generations only, and doing card-table sliding.
CardTableRS* rs = gch->rem_set();
Generation* old_gen = gch->old_gen();
// Clear/invalidate below make use of the "prev_used_regions" saved earlier.
if (gch->young_gen()->used() == 0) {
// We've evacuated the young generation.
rs->clear_into_younger(old_gen);
} else {
// Invalidate the cards corresponding to the currently used
// region and clear those corresponding to the evacuated region.
rs->invalidate_or_clear(old_gen);
}
CodeCache::gc_epilogue();
JvmtiExport::gc_epilogue();
// refs processing: clean slate
set_ref_processor(NULL);
// Update heap occupancy information which is used as
// input to soft ref clearing policy at the next gc.
Universe::update_heap_info_at_gc();
// Update time of last gc for all generations we collected
// (which currently is all the generations in the heap).
// We need to use a monotonically non-decreasing time in ms
// or we will see time-warp warnings and os::javaTimeMillis()
// does not guarantee monotonicity.
jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
gch->update_time_of_last_gc(now);
gch->trace_heap_after_gc(_gc_tracer);
}
// This method contains no policy. You should probably
// be calling invoke() instead.
void PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
assert(ref_processor() != NULL, "Sanity");
if (GC_locker::check_active_before_gc()) {
return;
}
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
GCCause::Cause gc_cause = heap->gc_cause();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
PSAdaptiveSizePolicy* size_policy = heap->size_policy();
PSYoungGen* young_gen = heap->young_gen();
PSOldGen* old_gen = heap->old_gen();
PSPermGen* perm_gen = heap->perm_gen();
// Increment the invocation count
heap->increment_total_collections(true /* full */);
// Save information needed to minimize mangling
heap->record_gen_tops_before_GC();
// We need to track unique mark sweep invocations as well.
_total_invocations++;
AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
if (PrintHeapAtGC) {
Universe::print_heap_before_gc();
}
// 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);
}
// Verify object start arrays
if (VerifyObjectStartArray &&
VerifyBeforeGC) {
old_gen->verify_object_start_array();
perm_gen->verify_object_start_array();
}
heap->pre_full_gc_dump();
// Filled in below to track the state of the young gen after the collection.
bool eden_empty;
bool survivors_empty;
bool young_gen_empty;
{
HandleMark hm;
const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
// This is useful for debugging but don't change the output the
// the customer sees.
const char* gc_cause_str = "Full GC";
if (is_system_gc && PrintGCDetails) {
gc_cause_str = "Full GC (System)";
}
gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
TraceCollectorStats tcs(counters());
TraceMemoryManagerStats tms(true /* Full GC */);
if (TraceGen1Time) accumulated_time()->start();
// Let the size policy know we're starting
size_policy->major_collection_begin();
// When collecting the permanent generation methodOops may be moving,
// so we either have to flush all bcp data or convert it into bci.
CodeCache::gc_prologue();
Threads::gc_prologue();
BiasedLocking::preserve_marks();
// Capture heap size before collection for printing.
size_t prev_used = heap->used();
// Capture perm gen size before collection for sizing.
size_t perm_gen_prev_used = perm_gen->used_in_bytes();
// For PrintGCDetails
size_t old_gen_prev_used = old_gen->used_in_bytes();
size_t young_gen_prev_used = young_gen->used_in_bytes();
allocate_stacks();
NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
COMPILER2_PRESENT(DerivedPointerTable::clear());
ref_processor()->enable_discovery();
ref_processor()->setup_policy(clear_all_softrefs);
mark_sweep_phase1(clear_all_softrefs);
mark_sweep_phase2();
// Don't add any more derived pointers during phase3
COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
mark_sweep_phase3();
mark_sweep_phase4();
restore_marks();
deallocate_stacks();
if (ZapUnusedHeapArea) {
// Do a complete mangle (top to end) because the usage for
// scratch does not maintain a top pointer.
young_gen->to_space()->mangle_unused_area_complete();
}
eden_empty = young_gen->eden_space()->is_empty();
if (!eden_empty) {
eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
}
// Update heap occupancy information which is used as
// input to soft ref clearing policy at the next gc.
Universe::update_heap_info_at_gc();
survivors_empty = young_gen->from_space()->is_empty() &&
young_gen->to_space()->is_empty();
young_gen_empty = eden_empty && survivors_empty;
BarrierSet* bs = heap->barrier_set();
if (bs->is_a(BarrierSet::ModRef)) {
ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
MemRegion old_mr = heap->old_gen()->reserved();
MemRegion perm_mr = heap->perm_gen()->reserved();
assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
if (young_gen_empty) {
modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
} else {
modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
}
}
BiasedLocking::restore_marks();
Threads::gc_epilogue();
CodeCache::gc_epilogue();
COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
ref_processor()->enqueue_discovered_references(NULL);
// Update time of last GC
reset_millis_since_last_gc();
// Let the size policy know we're done
size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
if (UseAdaptiveSizePolicy) {
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: %d young_gen_capacity: %d"
" perm_gen_capacity: %d ",
old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
perm_gen->capacity_in_bytes());
}
}
// Don't check if the size_policy is ready here. Let
// the size_policy check that internally.
if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
((gc_cause != GCCause::_java_lang_system_gc) ||
UseAdaptiveSizePolicyWithSystemGC)) {
// Calculate optimal 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,
true /* full gc*/,
gc_cause);
heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
// Don't resize the young generation at an major collection. A
// desired young generation size may have been calculated but
// resizing the young generation complicates the code because the
// resizing of the old generation may have moved the boundary
// between the young generation and the old generation. Let the
// young generation resizing happen at the minor collections.
}
if (PrintAdaptiveSizePolicy) {
gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
heap->total_collections());
}
}
if (UsePerfData) {
heap->gc_policy_counters()->update_counters();
heap->gc_policy_counters()->update_old_capacity(
old_gen->capacity_in_bytes());
heap->gc_policy_counters()->update_young_capacity(
young_gen->capacity_in_bytes());
}
heap->resize_all_tlabs();
// We collected the perm gen, so we'll resize it here.
perm_gen->compute_new_size(perm_gen_prev_used);
if (TraceGen1Time) accumulated_time()->stop();
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_prev_used);
old_gen->print_used_change(old_gen_prev_used);
}
heap->print_heap_change(prev_used);
// Do perm gen after heap becase prev_used does
// not include the perm gen (done this way in the other
// collectors).
if (PrintGCDetails) {
perm_gen->print_used_change(perm_gen_prev_used);
}
}
// Track memory usage and detect low memory
MemoryService::track_memory_usage();
heap->update_counters();
if (PrintGCDetails) {
if (size_policy->print_gc_time_limit_would_be_exceeded()) {
if (size_policy->gc_time_limit_exceeded()) {
gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit "
"of %d%%", GCTimeLimit);
} else {
gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit "
"of %d%%", GCTimeLimit);
}
}
size_policy->set_print_gc_time_limit_would_be_exceeded(false);
}
}
if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
gclog_or_tty->print(" VerifyAfterGC:");
Universe::verify(false);
}
// Re-verify object start arrays
if (VerifyObjectStartArray &&
VerifyAfterGC) {
old_gen->verify_object_start_array();
perm_gen->verify_object_start_array();
}
if (ZapUnusedHeapArea) {
old_gen->object_space()->check_mangled_unused_area_complete();
perm_gen->object_space()->check_mangled_unused_area_complete();
}
NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
if (PrintHeapAtGC) {
Universe::print_heap_after_gc();
}
heap->post_full_gc_dump();
#ifdef TRACESPINNING
ParallelTaskTerminator::print_termination_counts();
#endif
}
// This method contains no policy. You should probably
// be calling invoke() instead.
bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
assert(ref_processor() != NULL, "Sanity");
if (GC_locker::check_active_before_gc()) {
return false;
}
ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
GCCause::Cause gc_cause = heap->gc_cause();
_gc_timer->register_gc_start();
_gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
PSAdaptiveSizePolicy* size_policy = heap->size_policy();
// The scope of casr should end after code that can change
// CollectorPolicy::_should_clear_all_soft_refs.
ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
PSYoungGen* young_gen = heap->young_gen();
PSOldGen* old_gen = heap->old_gen();
// Increment the invocation count
heap->increment_total_collections(true /* full */);
// Save information needed to minimize mangling
heap->record_gen_tops_before_GC();
// We need to track unique mark sweep invocations as well.
_total_invocations++;
AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
heap->print_heap_before_gc();
heap->trace_heap_before_gc(_gc_tracer);
// 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
Universe::verify(" VerifyBeforeGC:");
}
// Verify object start arrays
if (VerifyObjectStartArray &&
VerifyBeforeGC) {
old_gen->verify_object_start_array();
}
heap->pre_full_gc_dump(_gc_timer);
// Filled in below to track the state of the young gen after the collection.
bool eden_empty;
bool survivors_empty;
bool young_gen_empty;
{
HandleMark hm;
TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer->gc_id());
TraceCollectorStats tcs(counters());
TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
if (TraceOldGenTime) accumulated_time()->start();
// Let the size policy know we're starting
size_policy->major_collection_begin();
CodeCache::gc_prologue();
BiasedLocking::preserve_marks();
// Capture heap size before collection for printing.
size_t prev_used = heap->used();
// Capture metadata size before collection for sizing.
size_t metadata_prev_used = MetaspaceAux::used_bytes();
// For PrintGCDetails
size_t old_gen_prev_used = old_gen->used_in_bytes();
size_t young_gen_prev_used = young_gen->used_in_bytes();
allocate_stacks();
COMPILER2_PRESENT(DerivedPointerTable::clear());
ref_processor()->enable_discovery();
ref_processor()->setup_policy(clear_all_softrefs);
mark_sweep_phase1(clear_all_softrefs);
mark_sweep_phase2();
// Don't add any more derived pointers during phase3
COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
mark_sweep_phase3();
mark_sweep_phase4();
restore_marks();
deallocate_stacks();
if (ZapUnusedHeapArea) {
// Do a complete mangle (top to end) because the usage for
// scratch does not maintain a top pointer.
young_gen->to_space()->mangle_unused_area_complete();
}
eden_empty = young_gen->eden_space()->is_empty();
if (!eden_empty) {
eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
}
// Update heap occupancy information which is used as
// input to soft ref clearing policy at the next gc.
Universe::update_heap_info_at_gc();
survivors_empty = young_gen->from_space()->is_empty() &&
young_gen->to_space()->is_empty();
young_gen_empty = eden_empty && survivors_empty;
ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
MemRegion old_mr = heap->old_gen()->reserved();
if (young_gen_empty) {
modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
} else {
modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
}
// Delete metaspaces for unloaded class loaders and clean up loader_data graph
ClassLoaderDataGraph::purge();
MetaspaceAux::verify_metrics();
BiasedLocking::restore_marks();
CodeCache::gc_epilogue();
JvmtiExport::gc_epilogue();
COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
ref_processor()->enqueue_discovered_references(NULL);
// Update time of last GC
reset_millis_since_last_gc();
// Let the size policy know we're done
size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
if (UseAdaptiveSizePolicy) {
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: " SIZE_FORMAT
" young_gen_capacity: " SIZE_FORMAT,
old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
}
}
// Don't check if the size_policy is ready here. Let
// the size_policy check that internally.
if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
((gc_cause != GCCause::_java_lang_system_gc) ||
UseAdaptiveSizePolicyWithSystemGC)) {
// Swap the survivor spaces if from_space is empty. The
// resize_young_gen() called below is normally used after
// a successful young GC and swapping of survivor spaces;
// otherwise, it will fail to resize the young gen with
// the current implementation.
if (young_gen->from_space()->is_empty()) {
young_gen->from_space()->clear(SpaceDecorator::Mangle);
young_gen->swap_spaces();
}
// Calculate optimal 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 young_live = young_gen->used_in_bytes();
size_t eden_live = young_gen->eden_space()->used_in_bytes();
size_t old_live = old_gen->used_in_bytes();
size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
size_t max_old_gen_size = old_gen->max_gen_size();
size_t max_eden_size = young_gen->max_size() -
young_gen->from_space()->capacity_in_bytes() -
young_gen->to_space()->capacity_in_bytes();
// Used for diagnostics
size_policy->clear_generation_free_space_flags();
size_policy->compute_generations_free_space(young_live,
eden_live,
old_live,
cur_eden,
max_old_gen_size,
max_eden_size,
true /* full gc*/);
size_policy->check_gc_overhead_limit(young_live,
eden_live,
max_old_gen_size,
max_eden_size,
true /* full gc*/,
gc_cause,
heap->collector_policy());
size_policy->decay_supplemental_growth(true /* full gc*/);
heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
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());
}
}
if (UsePerfData) {
heap->gc_policy_counters()->update_counters();
heap->gc_policy_counters()->update_old_capacity(
old_gen->capacity_in_bytes());
heap->gc_policy_counters()->update_young_capacity(
young_gen->capacity_in_bytes());
}
heap->resize_all_tlabs();
// We collected the heap, recalculate the metaspace capacity
MetaspaceGC::compute_new_size();
if (TraceOldGenTime) accumulated_time()->stop();
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_prev_used);
old_gen->print_used_change(old_gen_prev_used);
}
heap->print_heap_change(prev_used);
if (PrintGCDetails) {
MetaspaceAux::print_metaspace_change(metadata_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
Universe::verify(" VerifyAfterGC:");
}
// Re-verify object start arrays
if (VerifyObjectStartArray &&
VerifyAfterGC) {
old_gen->verify_object_start_array();
}
if (ZapUnusedHeapArea) {
old_gen->object_space()->check_mangled_unused_area_complete();
}
NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
heap->print_heap_after_gc();
heap->trace_heap_after_gc(_gc_tracer);
heap->post_full_gc_dump(_gc_timer);
#ifdef TRACESPINNING
ParallelTaskTerminator::print_termination_counts();
#endif
_gc_timer->register_gc_end();
_gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
return true;
}
void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp, bool clear_all_softrefs) {
guarantee(level == 1, "We always collect both old and young.");
assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
GenCollectedHeap* gch = GenCollectedHeap::heap();
#ifdef ASSERT
if (gch->collector_policy()->should_clear_all_soft_refs()) {
assert(clear_all_softrefs, "Policy should have been checked earlier");
}
#endif
// hook up weak ref data so it can be used during Mark-Sweep
assert(ref_processor() == NULL, "no stomping");
assert(rp != NULL, "should be non-NULL");
_ref_processor = rp;
rp->setup_policy(clear_all_softrefs);
GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, _gc_tracer->gc_id());
gch->trace_heap_before_gc(_gc_tracer);
// When collecting the permanent generation Method*s may be moving,
// so we either have to flush all bcp data or convert it into bci.
CodeCache::gc_prologue();
Threads::gc_prologue();
// Increment the invocation count
_total_invocations++;
// Capture heap size before collection for printing.
size_t gch_prev_used = gch->used();
// Capture used regions for each generation that will be
// subject to collection, so that card table adjustments can
// be made intelligently (see clear / invalidate further below).
gch->save_used_regions(level);
allocate_stacks();
mark_sweep_phase1(level, clear_all_softrefs);
mark_sweep_phase2();
// Don't add any more derived pointers during phase3
COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
mark_sweep_phase3(level);
mark_sweep_phase4();
restore_marks();
// Set saved marks for allocation profiler (and other things? -- dld)
// (Should this be in general part?)
gch->save_marks();
deallocate_stacks();
// If compaction completely evacuated all generations younger than this
// one, then we can clear the card table. Otherwise, we must invalidate
// it (consider all cards dirty). In the future, we might consider doing
// compaction within generations only, and doing card-table sliding.
bool all_empty = true;
for (int i = 0; all_empty && i < level; i++) {
Generation* g = gch->get_gen(i);
all_empty = all_empty && gch->get_gen(i)->used() == 0;
}
GenRemSet* rs = gch->rem_set();
Generation* old_gen = gch->get_gen(level);
// Clear/invalidate below make use of the "prev_used_regions" saved earlier.
if (all_empty) {
// We've evacuated all generations below us.
rs->clear_into_younger(old_gen);
} else {
// Invalidate the cards corresponding to the currently used
// region and clear those corresponding to the evacuated region.
rs->invalidate_or_clear(old_gen);
}
Threads::gc_epilogue();
CodeCache::gc_epilogue();
JvmtiExport::gc_epilogue();
if (PrintGC && !PrintGCDetails) {
gch->print_heap_change(gch_prev_used);
}
// refs processing: clean slate
_ref_processor = NULL;
// Update heap occupancy information which is used as
// input to soft ref clearing policy at the next gc.
Universe::update_heap_info_at_gc();
// Update time of last gc for all generations we collected
// (which curently is all the generations in the heap).
// We need to use a monotonically non-deccreasing time in ms
// or we will see time-warp warnings and os::javaTimeMillis()
// does not guarantee monotonicity.
jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
gch->update_time_of_last_gc(now);
gch->trace_heap_after_gc(_gc_tracer);
}
void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
bool clear_all_softrefs) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
SharedHeap* sh = SharedHeap::heap();
#ifdef ASSERT
if (sh->collector_policy()->should_clear_all_soft_refs()) {
assert(clear_all_softrefs, "Policy should have been checked earler");
}
#endif
// hook up weak ref data so it can be used during Mark-Sweep
assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
assert(rp != NULL, "should be non-NULL");
GenMarkSweep::_ref_processor = rp;
rp->setup_policy(clear_all_softrefs);
// When collecting the permanent generation methodOops may be moving,
// so we either have to flush all bcp data or convert it into bci.
CodeCache::gc_prologue();
Threads::gc_prologue();
// Increment the invocation count for the permanent generation, since it is
// implicitly collected whenever we do a full mark sweep collection.
sh->perm_gen()->stat_record()->invocations++;
bool marked_for_unloading = false;
allocate_stacks();
// We should save the marks of the currently locked biased monitors.
// The marking doesn't preserve the marks of biased objects.
BiasedLocking::preserve_marks();
mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
if (VerifyDuringGC) {
G1CollectedHeap* g1h = G1CollectedHeap::heap();
g1h->checkConcurrentMark();
}
mark_sweep_phase2();
// Don't add any more derived pointers during phase3
COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
mark_sweep_phase3();
mark_sweep_phase4();
GenMarkSweep::restore_marks();
BiasedLocking::restore_marks();
GenMarkSweep::deallocate_stacks();
// We must invalidate the perm-gen rs, so that it gets rebuilt.
GenRemSet* rs = sh->rem_set();
rs->invalidate(sh->perm_gen()->used_region(), true /*whole_heap*/);
// "free at last gc" is calculated from these.
// CHF: cheating for now!!!
// Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
// Universe::set_heap_used_at_last_gc(Universe::heap()->used());
Threads::gc_epilogue();
CodeCache::gc_epilogue();
// refs processing: clean slate
GenMarkSweep::_ref_processor = NULL;
}
// This method contains no policy. You should probably
// be calling invoke() instead.
void PSMarkSweep::invoke_no_policy(bool& notify_ref_lock, bool clear_all_softrefs) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
assert(ref_processor() != NULL, "Sanity");
if (GC_locker::is_active()) return;
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
PSYoungGen* young_gen = heap->young_gen();
PSOldGen* old_gen = heap->old_gen();
PSPermGen* perm_gen = heap->perm_gen();
// Increment the invocation count
heap->increment_total_collections();
// We need to track unique mark sweep invocations as well.
_total_invocations++;
if (PrintHeapAtGC) {
gclog_or_tty->print_cr(" {Heap before GC invocations=%d:", heap->total_collections());
Universe::print();
}
// 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);
}
{
HandleMark hm;
TraceTime t1("Full GC", PrintGC, true, gclog_or_tty);
TraceCollectorStats tcs(counters());
if (TraceGen1Time) accumulated_time()->start();
// Let the size policy know we're starting
AdaptiveSizePolicy* size_policy = heap->size_policy();
size_policy->major_collection_begin();
// When collecting the permanent generation methodOops may be moving,
// so we either have to flush all bcp data or convert it into bci.
NOT_CORE(CodeCache::gc_prologue());
Threads::gc_prologue();
// Capture heap size before collection for printing.
size_t prev_used = heap->used();
// Capture perm gen size before collection for sizing.
size_t perm_gen_prev_used = perm_gen->used_in_bytes();
bool marked_for_unloading = false;
allocate_stacks();
NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
COMPILER2_ONLY(DerivedPointerTable::clear());
ref_processor()->enable_discovery();
mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
mark_sweep_phase2();
// Don't add any more derived pointers during phase3
COMPILER2_ONLY(assert(DerivedPointerTable::is_active(), "Sanity"));
COMPILER2_ONLY(DerivedPointerTable::set_active(false));
mark_sweep_phase3();
mark_sweep_phase4();
restore_marks();
deallocate_stacks();
// "free at last gc" is calculated from these.
Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
Universe::set_heap_used_at_last_gc(Universe::heap()->used());
bool all_empty = young_gen->eden_space()->is_empty() &&
young_gen->from_space()->is_empty() &&
young_gen->to_space()->is_empty();
BarrierSet* bs = heap->barrier_set();
if (bs->is_a(BarrierSet::ModRef)) {
ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
MemRegion old_mr = heap->old_gen()->reserved();
MemRegion perm_mr = heap->perm_gen()->reserved();
assert(old_mr.end() <= perm_mr.start(), "Generations out of order");
if (all_empty) {
modBS->clear(MemRegion(old_mr.start(), perm_mr.end()));
} else {
modBS->invalidate(MemRegion(old_mr.start(), perm_mr.end()));
}
}
Threads::gc_epilogue();
NOT_CORE(CodeCache::gc_epilogue());
COMPILER2_ONLY(DerivedPointerTable::update_pointers());
notify_ref_lock |= ref_processor()->enqueue_discovered_references();
// Update time of last GC
reset_millis_since_last_gc();
// Let the size policy know we're done
size_policy->major_collection_end(old_gen->used_in_bytes());
if (UseAdaptiveSizePolicy) {
if (PrintAdaptiveSizePolicy) {
tty->print_cr("AdaptiveSizeStart: collection: %d ",
heap->total_collections());
}
// 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(),
true /* full gc*/);
// Resize 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());
}
}
// We collected the perm gen, so we'll resize it here.
perm_gen->compute_new_size(perm_gen_prev_used);
if (TraceGen1Time) accumulated_time()->stop();
if (PrintGC) {
heap->print_heap_change(prev_used);
}
heap->update_counters();
}
if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
tty->print(" VerifyAfterGC:");
Universe::verify(false);
}
NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
if (PrintHeapAtGC) {
gclog_or_tty->print_cr(" Heap after GC invocations=%d:", heap->total_collections());
Universe::print();
gclog_or_tty->print("} ");
}
}