Java example source code file (genCollectedHeap.cpp)
The genCollectedHeap.cpp Java example source code/*
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#include "precompiled.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "code/icBuffer.hpp"
#include "gc_implementation/shared/collectorCounters.hpp"
#include "gc_implementation/shared/gcTraceTime.hpp"
#include "gc_implementation/shared/vmGCOperations.hpp"
#include "gc_interface/collectedHeap.inline.hpp"
#include "memory/filemap.hpp"
#include "memory/gcLocker.inline.hpp"
#include "memory/genCollectedHeap.hpp"
#include "memory/genOopClosures.inline.hpp"
#include "memory/generation.inline.hpp"
#include "memory/generationSpec.hpp"
#include "memory/resourceArea.hpp"
#include "memory/sharedHeap.hpp"
#include "memory/space.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oop.inline2.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/fprofiler.hpp"
#include "runtime/handles.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/java.hpp"
#include "runtime/vmThread.hpp"
#include "services/memoryService.hpp"
#include "utilities/vmError.hpp"
#include "utilities/workgroup.hpp"
#include "utilities/macros.hpp"
#if INCLUDE_ALL_GCS
#include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
#include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
#endif // INCLUDE_ALL_GCS
GenCollectedHeap* GenCollectedHeap::_gch;
NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
// The set of potentially parallel tasks in strong root scanning.
enum GCH_process_strong_roots_tasks {
// We probably want to parallelize both of these internally, but for now...
GCH_PS_younger_gens,
// Leave this one last.
GCH_PS_NumElements
};
GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
SharedHeap(policy),
_gen_policy(policy),
_gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
_full_collections_completed(0)
{
if (_gen_process_strong_tasks == NULL ||
!_gen_process_strong_tasks->valid()) {
vm_exit_during_initialization("Failed necessary allocation.");
}
assert(policy != NULL, "Sanity check");
}
jint GenCollectedHeap::initialize() {
CollectedHeap::pre_initialize();
int i;
_n_gens = gen_policy()->number_of_generations();
// While there are no constraints in the GC code that HeapWordSize
// be any particular value, there are multiple other areas in the
// system which believe this to be true (e.g. oop->object_size in some
// cases incorrectly returns the size in wordSize units rather than
// HeapWordSize).
guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
// The heap must be at least as aligned as generations.
size_t gen_alignment = Generation::GenGrain;
_gen_specs = gen_policy()->generations();
// Make sure the sizes are all aligned.
for (i = 0; i < _n_gens; i++) {
_gen_specs[i]->align(gen_alignment);
}
// Allocate space for the heap.
char* heap_address;
size_t total_reserved = 0;
int n_covered_regions = 0;
ReservedSpace heap_rs;
size_t heap_alignment = collector_policy()->heap_alignment();
heap_address = allocate(heap_alignment, &total_reserved,
&n_covered_regions, &heap_rs);
if (!heap_rs.is_reserved()) {
vm_shutdown_during_initialization(
"Could not reserve enough space for object heap");
return JNI_ENOMEM;
}
_reserved = MemRegion((HeapWord*)heap_rs.base(),
(HeapWord*)(heap_rs.base() + heap_rs.size()));
// It is important to do this in a way such that concurrent readers can't
// temporarily think somethings in the heap. (Seen this happen in asserts.)
_reserved.set_word_size(0);
_reserved.set_start((HeapWord*)heap_rs.base());
size_t actual_heap_size = heap_rs.size();
_reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
_rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
set_barrier_set(rem_set()->bs());
_gch = this;
for (i = 0; i < _n_gens; i++) {
ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), false, false);
_gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
}
clear_incremental_collection_failed();
#if INCLUDE_ALL_GCS
// If we are running CMS, create the collector responsible
// for collecting the CMS generations.
if (collector_policy()->is_concurrent_mark_sweep_policy()) {
bool success = create_cms_collector();
if (!success) return JNI_ENOMEM;
}
#endif // INCLUDE_ALL_GCS
return JNI_OK;
}
char* GenCollectedHeap::allocate(size_t alignment,
size_t* _total_reserved,
int* _n_covered_regions,
ReservedSpace* heap_rs){
const char overflow_msg[] = "The size of the object heap + VM data exceeds "
"the maximum representable size";
// Now figure out the total size.
size_t total_reserved = 0;
int n_covered_regions = 0;
const size_t pageSize = UseLargePages ?
os::large_page_size() : os::vm_page_size();
assert(alignment % pageSize == 0, "Must be");
for (int i = 0; i < _n_gens; i++) {
total_reserved += _gen_specs[i]->max_size();
if (total_reserved < _gen_specs[i]->max_size()) {
vm_exit_during_initialization(overflow_msg);
}
n_covered_regions += _gen_specs[i]->n_covered_regions();
}
assert(total_reserved % alignment == 0,
err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
SIZE_FORMAT, total_reserved, alignment));
// Needed until the cardtable is fixed to have the right number
// of covered regions.
n_covered_regions += 2;
*_total_reserved = total_reserved;
*_n_covered_regions = n_covered_regions;
*heap_rs = Universe::reserve_heap(total_reserved, alignment);
return heap_rs->base();
}
void GenCollectedHeap::post_initialize() {
SharedHeap::post_initialize();
TwoGenerationCollectorPolicy *policy =
(TwoGenerationCollectorPolicy *)collector_policy();
guarantee(policy->is_two_generation_policy(), "Illegal policy type");
DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
assert(def_new_gen->kind() == Generation::DefNew ||
def_new_gen->kind() == Generation::ParNew ||
def_new_gen->kind() == Generation::ASParNew,
"Wrong generation kind");
Generation* old_gen = get_gen(1);
assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
old_gen->kind() == Generation::ASConcurrentMarkSweep ||
old_gen->kind() == Generation::MarkSweepCompact,
"Wrong generation kind");
policy->initialize_size_policy(def_new_gen->eden()->capacity(),
old_gen->capacity(),
def_new_gen->from()->capacity());
policy->initialize_gc_policy_counters();
}
void GenCollectedHeap::ref_processing_init() {
SharedHeap::ref_processing_init();
for (int i = 0; i < _n_gens; i++) {
_gens[i]->ref_processor_init();
}
}
size_t GenCollectedHeap::capacity() const {
size_t res = 0;
for (int i = 0; i < _n_gens; i++) {
res += _gens[i]->capacity();
}
return res;
}
size_t GenCollectedHeap::used() const {
size_t res = 0;
for (int i = 0; i < _n_gens; i++) {
res += _gens[i]->used();
}
return res;
}
// Save the "used_region" for generations level and lower.
void GenCollectedHeap::save_used_regions(int level) {
assert(level < _n_gens, "Illegal level parameter");
for (int i = level; i >= 0; i--) {
_gens[i]->save_used_region();
}
}
size_t GenCollectedHeap::max_capacity() const {
size_t res = 0;
for (int i = 0; i < _n_gens; i++) {
res += _gens[i]->max_capacity();
}
return res;
}
// Update the _full_collections_completed counter
// at the end of a stop-world full GC.
unsigned int GenCollectedHeap::update_full_collections_completed() {
MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
assert(_full_collections_completed <= _total_full_collections,
"Can't complete more collections than were started");
_full_collections_completed = _total_full_collections;
ml.notify_all();
return _full_collections_completed;
}
// Update the _full_collections_completed counter, as appropriate,
// at the end of a concurrent GC cycle. Note the conditional update
// below to allow this method to be called by a concurrent collector
// without synchronizing in any manner with the VM thread (which
// may already have initiated a STW full collection "concurrently").
unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
assert((_full_collections_completed <= _total_full_collections) &&
(count <= _total_full_collections),
"Can't complete more collections than were started");
if (count > _full_collections_completed) {
_full_collections_completed = count;
ml.notify_all();
}
return _full_collections_completed;
}
#ifndef PRODUCT
// Override of memory state checking method in CollectedHeap:
// Some collectors (CMS for example) can't have badHeapWordVal written
// in the first two words of an object. (For instance , in the case of
// CMS these words hold state used to synchronize between certain
// (concurrent) GC steps and direct allocating mutators.)
// The skip_header_HeapWords() method below, allows us to skip
// over the requisite number of HeapWord's. Note that (for
// generational collectors) this means that those many words are
// skipped in each object, irrespective of the generation in which
// that object lives. The resultant loss of precision seems to be
// harmless and the pain of avoiding that imprecision appears somewhat
// higher than we are prepared to pay for such rudimentary debugging
// support.
void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
size_t size) {
if (CheckMemoryInitialization && ZapUnusedHeapArea) {
// We are asked to check a size in HeapWords,
// but the memory is mangled in juint words.
juint* start = (juint*) (addr + skip_header_HeapWords());
juint* end = (juint*) (addr + size);
for (juint* slot = start; slot < end; slot += 1) {
assert(*slot == badHeapWordVal,
"Found non badHeapWordValue in pre-allocation check");
}
}
}
#endif
HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
bool is_tlab,
bool first_only) {
HeapWord* res;
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->should_allocate(size, is_tlab)) {
res = _gens[i]->allocate(size, is_tlab);
if (res != NULL) return res;
else if (first_only) break;
}
}
// Otherwise...
return NULL;
}
HeapWord* GenCollectedHeap::mem_allocate(size_t size,
bool* gc_overhead_limit_was_exceeded) {
return collector_policy()->mem_allocate_work(size,
false /* is_tlab */,
gc_overhead_limit_was_exceeded);
}
bool GenCollectedHeap::must_clear_all_soft_refs() {
return _gc_cause == GCCause::_last_ditch_collection;
}
bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
return UseConcMarkSweepGC &&
((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
(cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
}
void GenCollectedHeap::do_collection(bool full,
bool clear_all_soft_refs,
size_t size,
bool is_tlab,
int max_level) {
bool prepared_for_verification = false;
ResourceMark rm;
DEBUG_ONLY(Thread* my_thread = Thread::current();)
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(my_thread->is_VM_thread() ||
my_thread->is_ConcurrentGC_thread(),
"incorrect thread type capability");
assert(Heap_lock->is_locked(),
"the requesting thread should have the Heap_lock");
guarantee(!is_gc_active(), "collection is not reentrant");
assert(max_level < n_gens(), "sanity check");
if (GC_locker::check_active_before_gc()) {
return; // GC is disabled (e.g. JNI GetXXXCritical operation)
}
const bool do_clear_all_soft_refs = clear_all_soft_refs ||
collector_policy()->should_clear_all_soft_refs();
ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
const size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
print_heap_before_gc();
{
FlagSetting fl(_is_gc_active, true);
bool complete = full && (max_level == (n_gens()-1));
const char* gc_cause_prefix = complete ? "Full GC" : "GC";
gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL);
gc_prologue(complete);
increment_total_collections(complete);
size_t gch_prev_used = used();
int starting_level = 0;
if (full) {
// Search for the oldest generation which will collect all younger
// generations, and start collection loop there.
for (int i = max_level; i >= 0; i--) {
if (_gens[i]->full_collects_younger_generations()) {
starting_level = i;
break;
}
}
}
bool must_restore_marks_for_biased_locking = false;
int max_level_collected = starting_level;
for (int i = starting_level; i <= max_level; i++) {
if (_gens[i]->should_collect(full, size, is_tlab)) {
if (i == n_gens() - 1) { // a major collection is to happen
if (!complete) {
// The full_collections increment was missed above.
increment_total_full_collections();
}
pre_full_gc_dump(NULL); // do any pre full gc dumps
}
// Timer for individual generations. Last argument is false: no CR
// FIXME: We should try to start the timing earlier to cover more of the GC pause
GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL);
TraceCollectorStats tcs(_gens[i]->counters());
TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
size_t prev_used = _gens[i]->used();
_gens[i]->stat_record()->invocations++;
_gens[i]->stat_record()->accumulated_time.start();
// Must be done anew before each collection because
// a previous collection will do mangling and will
// change top of some spaces.
record_gen_tops_before_GC();
if (PrintGC && Verbose) {
gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
i,
_gens[i]->stat_record()->invocations,
size*HeapWordSize);
}
if (VerifyBeforeGC && i >= VerifyGCLevel &&
total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
if (!prepared_for_verification) {
prepare_for_verify();
prepared_for_verification = true;
}
Universe::verify(" VerifyBeforeGC:");
}
COMPILER2_PRESENT(DerivedPointerTable::clear());
if (!must_restore_marks_for_biased_locking &&
_gens[i]->performs_in_place_marking()) {
// We perform this mark word preservation work lazily
// because it's only at this point that we know whether we
// absolutely have to do it; we want to avoid doing it for
// scavenge-only collections where it's unnecessary
must_restore_marks_for_biased_locking = true;
BiasedLocking::preserve_marks();
}
// Do collection work
{
// Note on ref discovery: For what appear to be historical reasons,
// GCH enables and disabled (by enqueing) refs discovery.
// In the future this should be moved into the generation's
// collect method so that ref discovery and enqueueing concerns
// are local to a generation. The collect method could return
// an appropriate indication in the case that notification on
// the ref lock was needed. This will make the treatment of
// weak refs more uniform (and indeed remove such concerns
// from GCH). XXX
HandleMark hm; // Discard invalid handles created during gc
save_marks(); // save marks for all gens
// We want to discover references, but not process them yet.
// This mode is disabled in process_discovered_references if the
// generation does some collection work, or in
// enqueue_discovered_references if the generation returns
// without doing any work.
ReferenceProcessor* rp = _gens[i]->ref_processor();
// If the discovery of ("weak") refs in this generation is
// atomic wrt other collectors in this configuration, we
// are guaranteed to have empty discovered ref lists.
if (rp->discovery_is_atomic()) {
rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
rp->setup_policy(do_clear_all_soft_refs);
} else {
// collect() below will enable discovery as appropriate
}
_gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
if (!rp->enqueuing_is_done()) {
rp->enqueue_discovered_references();
} else {
rp->set_enqueuing_is_done(false);
}
rp->verify_no_references_recorded();
}
max_level_collected = i;
// Determine if allocation request was met.
if (size > 0) {
if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
size = 0;
}
}
}
COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
_gens[i]->stat_record()->accumulated_time.stop();
update_gc_stats(i, full);
if (VerifyAfterGC && i >= VerifyGCLevel &&
total_collections() >= VerifyGCStartAt) {
HandleMark hm; // Discard invalid handles created during verification
Universe::verify(" VerifyAfterGC:");
}
if (PrintGCDetails) {
gclog_or_tty->print(":");
_gens[i]->print_heap_change(prev_used);
}
}
}
// Update "complete" boolean wrt what actually transpired --
// for instance, a promotion failure could have led to
// a whole heap collection.
complete = complete || (max_level_collected == n_gens() - 1);
if (complete) { // We did a "major" collection
// FIXME: See comment at pre_full_gc_dump call
post_full_gc_dump(NULL); // do any post full gc dumps
}
if (PrintGCDetails) {
print_heap_change(gch_prev_used);
// Print metaspace info for full GC with PrintGCDetails flag.
if (complete) {
MetaspaceAux::print_metaspace_change(metadata_prev_used);
}
}
for (int j = max_level_collected; j >= 0; j -= 1) {
// Adjust generation sizes.
_gens[j]->compute_new_size();
}
if (complete) {
// Delete metaspaces for unloaded class loaders and clean up loader_data graph
ClassLoaderDataGraph::purge();
MetaspaceAux::verify_metrics();
// Resize the metaspace capacity after full collections
MetaspaceGC::compute_new_size();
update_full_collections_completed();
}
// Track memory usage and detect low memory after GC finishes
MemoryService::track_memory_usage();
gc_epilogue(complete);
if (must_restore_marks_for_biased_locking) {
BiasedLocking::restore_marks();
}
}
AdaptiveSizePolicy* sp = gen_policy()->size_policy();
AdaptiveSizePolicyOutput(sp, total_collections());
print_heap_after_gc();
#ifdef TRACESPINNING
ParallelTaskTerminator::print_termination_counts();
#endif
}
HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
return collector_policy()->satisfy_failed_allocation(size, is_tlab);
}
void GenCollectedHeap::set_par_threads(uint t) {
SharedHeap::set_par_threads(t);
_gen_process_strong_tasks->set_n_threads(t);
}
void GenCollectedHeap::
gen_process_strong_roots(int level,
bool younger_gens_as_roots,
bool activate_scope,
bool is_scavenging,
SharedHeap::ScanningOption so,
OopsInGenClosure* not_older_gens,
bool do_code_roots,
OopsInGenClosure* older_gens,
KlassClosure* klass_closure) {
// General strong roots.
if (!do_code_roots) {
SharedHeap::process_strong_roots(activate_scope, is_scavenging, so,
not_older_gens, NULL, klass_closure);
} else {
bool do_code_marking = (activate_scope || nmethod::oops_do_marking_is_active());
CodeBlobToOopClosure code_roots(not_older_gens, /*do_marking=*/ do_code_marking);
SharedHeap::process_strong_roots(activate_scope, is_scavenging, so,
not_older_gens, &code_roots, klass_closure);
}
if (younger_gens_as_roots) {
if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
for (int i = 0; i < level; i++) {
not_older_gens->set_generation(_gens[i]);
_gens[i]->oop_iterate(not_older_gens);
}
not_older_gens->reset_generation();
}
}
// When collection is parallel, all threads get to cooperate to do
// older-gen scanning.
for (int i = level+1; i < _n_gens; i++) {
older_gens->set_generation(_gens[i]);
rem_set()->younger_refs_iterate(_gens[i], older_gens);
older_gens->reset_generation();
}
_gen_process_strong_tasks->all_tasks_completed();
}
void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
CodeBlobClosure* code_roots) {
SharedHeap::process_weak_roots(root_closure, code_roots);
// "Local" "weak" refs
for (int i = 0; i < _n_gens; i++) {
_gens[i]->ref_processor()->weak_oops_do(root_closure);
}
}
#define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
void GenCollectedHeap:: \
oop_since_save_marks_iterate(int level, \
OopClosureType* cur, \
OopClosureType* older) { \
_gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
for (int i = level+1; i < n_gens(); i++) { \
_gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
} \
}
ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
#undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
for (int i = level; i < _n_gens; i++) {
if (!_gens[i]->no_allocs_since_save_marks()) return false;
}
return true;
}
bool GenCollectedHeap::supports_inline_contig_alloc() const {
return _gens[0]->supports_inline_contig_alloc();
}
HeapWord** GenCollectedHeap::top_addr() const {
return _gens[0]->top_addr();
}
HeapWord** GenCollectedHeap::end_addr() const {
return _gens[0]->end_addr();
}
size_t GenCollectedHeap::unsafe_max_alloc() {
return _gens[0]->unsafe_max_alloc_nogc();
}
// public collection interfaces
void GenCollectedHeap::collect(GCCause::Cause cause) {
if (should_do_concurrent_full_gc(cause)) {
#if INCLUDE_ALL_GCS
// mostly concurrent full collection
collect_mostly_concurrent(cause);
#else // INCLUDE_ALL_GCS
ShouldNotReachHere();
#endif // INCLUDE_ALL_GCS
} else {
#ifdef ASSERT
if (cause == GCCause::_scavenge_alot) {
// minor collection only
collect(cause, 0);
} else {
// Stop-the-world full collection
collect(cause, n_gens() - 1);
}
#else
// Stop-the-world full collection
collect(cause, n_gens() - 1);
#endif
}
}
void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
// The caller doesn't have the Heap_lock
assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
MutexLocker ml(Heap_lock);
collect_locked(cause, max_level);
}
void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
// The caller has the Heap_lock
assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
collect_locked(cause, n_gens() - 1);
}
// this is the private collection interface
// The Heap_lock is expected to be held on entry.
void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
// Read the GC count while holding the Heap_lock
unsigned int gc_count_before = total_collections();
unsigned int full_gc_count_before = total_full_collections();
{
MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
VM_GenCollectFull op(gc_count_before, full_gc_count_before,
cause, max_level);
VMThread::execute(&op);
}
}
#if INCLUDE_ALL_GCS
bool GenCollectedHeap::create_cms_collector() {
assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
(_gens[1]->kind() == Generation::ASConcurrentMarkSweep)),
"Unexpected generation kinds");
// Skip two header words in the block content verification
NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
CMSCollector* collector = new CMSCollector(
(ConcurrentMarkSweepGeneration*)_gens[1],
_rem_set->as_CardTableRS(),
(ConcurrentMarkSweepPolicy*) collector_policy());
if (collector == NULL || !collector->completed_initialization()) {
if (collector) {
delete collector; // Be nice in embedded situation
}
vm_shutdown_during_initialization("Could not create CMS collector");
return false;
}
return true; // success
}
void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
MutexLocker ml(Heap_lock);
// Read the GC counts while holding the Heap_lock
unsigned int full_gc_count_before = total_full_collections();
unsigned int gc_count_before = total_collections();
{
MutexUnlocker mu(Heap_lock);
VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
VMThread::execute(&op);
}
}
#endif // INCLUDE_ALL_GCS
void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
do_full_collection(clear_all_soft_refs, _n_gens - 1);
}
void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
int max_level) {
int local_max_level;
if (!incremental_collection_will_fail(false /* don't consult_young */) &&
gc_cause() == GCCause::_gc_locker) {
local_max_level = 0;
} else {
local_max_level = max_level;
}
do_collection(true /* full */,
clear_all_soft_refs /* clear_all_soft_refs */,
0 /* size */,
false /* is_tlab */,
local_max_level /* max_level */);
// Hack XXX FIX ME !!!
// A scavenge may not have been attempted, or may have
// been attempted and failed, because the old gen was too full
if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
incremental_collection_will_fail(false /* don't consult_young */)) {
if (PrintGCDetails) {
gclog_or_tty->print_cr("GC locker: Trying a full collection "
"because scavenge failed");
}
// This time allow the old gen to be collected as well
do_collection(true /* full */,
clear_all_soft_refs /* clear_all_soft_refs */,
0 /* size */,
false /* is_tlab */,
n_gens() - 1 /* max_level */);
}
}
bool GenCollectedHeap::is_in_young(oop p) {
bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
assert(result == _gens[0]->is_in_reserved(p),
err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, (void*)p));
return result;
}
// Returns "TRUE" iff "p" points into the committed areas of the heap.
bool GenCollectedHeap::is_in(const void* p) const {
#ifndef ASSERT
guarantee(VerifyBeforeGC ||
VerifyDuringGC ||
VerifyBeforeExit ||
VerifyDuringStartup ||
PrintAssembly ||
tty->count() != 0 || // already printing
VerifyAfterGC ||
VMError::fatal_error_in_progress(), "too expensive");
#endif
// This might be sped up with a cache of the last generation that
// answered yes.
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->is_in(p)) return true;
}
// Otherwise...
return false;
}
#ifdef ASSERT
// Don't implement this by using is_in_young(). This method is used
// in some cases to check that is_in_young() is correct.
bool GenCollectedHeap::is_in_partial_collection(const void* p) {
assert(is_in_reserved(p) || p == NULL,
"Does not work if address is non-null and outside of the heap");
return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
}
#endif
void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->oop_iterate(cl);
}
}
void GenCollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->oop_iterate(mr, cl);
}
}
void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->object_iterate(cl);
}
}
void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->safe_object_iterate(cl);
}
}
Space* GenCollectedHeap::space_containing(const void* addr) const {
for (int i = 0; i < _n_gens; i++) {
Space* res = _gens[i]->space_containing(addr);
if (res != NULL) return res;
}
// Otherwise...
assert(false, "Could not find containing space");
return NULL;
}
HeapWord* GenCollectedHeap::block_start(const void* addr) const {
assert(is_in_reserved(addr), "block_start of address outside of heap");
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->is_in_reserved(addr)) {
assert(_gens[i]->is_in(addr),
"addr should be in allocated part of generation");
return _gens[i]->block_start(addr);
}
}
assert(false, "Some generation should contain the address");
return NULL;
}
size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
assert(is_in_reserved(addr), "block_size of address outside of heap");
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->is_in_reserved(addr)) {
assert(_gens[i]->is_in(addr),
"addr should be in allocated part of generation");
return _gens[i]->block_size(addr);
}
}
assert(false, "Some generation should contain the address");
return 0;
}
bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
assert(block_start(addr) == addr, "addr must be a block start");
for (int i = 0; i < _n_gens; i++) {
if (_gens[i]->is_in_reserved(addr)) {
return _gens[i]->block_is_obj(addr);
}
}
assert(false, "Some generation should contain the address");
return false;
}
bool GenCollectedHeap::supports_tlab_allocation() const {
for (int i = 0; i < _n_gens; i += 1) {
if (_gens[i]->supports_tlab_allocation()) {
return true;
}
}
return false;
}
size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
size_t result = 0;
for (int i = 0; i < _n_gens; i += 1) {
if (_gens[i]->supports_tlab_allocation()) {
result += _gens[i]->tlab_capacity();
}
}
return result;
}
size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
size_t result = 0;
for (int i = 0; i < _n_gens; i += 1) {
if (_gens[i]->supports_tlab_allocation()) {
result += _gens[i]->unsafe_max_tlab_alloc();
}
}
return result;
}
HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
bool gc_overhead_limit_was_exceeded;
return collector_policy()->mem_allocate_work(size /* size */,
true /* is_tlab */,
&gc_overhead_limit_was_exceeded);
}
// Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
// from the list headed by "*prev_ptr".
static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
bool first = true;
size_t min_size = 0; // "first" makes this conceptually infinite.
ScratchBlock **smallest_ptr, *smallest;
ScratchBlock *cur = *prev_ptr;
while (cur) {
assert(*prev_ptr == cur, "just checking");
if (first || cur->num_words < min_size) {
smallest_ptr = prev_ptr;
smallest = cur;
min_size = smallest->num_words;
first = false;
}
prev_ptr = &cur->next;
cur = cur->next;
}
smallest = *smallest_ptr;
*smallest_ptr = smallest->next;
return smallest;
}
// Sort the scratch block list headed by res into decreasing size order,
// and set "res" to the result.
static void sort_scratch_list(ScratchBlock*& list) {
ScratchBlock* sorted = NULL;
ScratchBlock* unsorted = list;
while (unsorted) {
ScratchBlock *smallest = removeSmallestScratch(&unsorted);
smallest->next = sorted;
sorted = smallest;
}
list = sorted;
}
ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
size_t max_alloc_words) {
ScratchBlock* res = NULL;
for (int i = 0; i < _n_gens; i++) {
_gens[i]->contribute_scratch(res, requestor, max_alloc_words);
}
sort_scratch_list(res);
return res;
}
void GenCollectedHeap::release_scratch() {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->reset_scratch();
}
}
class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
void do_generation(Generation* gen) {
gen->prepare_for_verify();
}
};
void GenCollectedHeap::prepare_for_verify() {
ensure_parsability(false); // no need to retire TLABs
GenPrepareForVerifyClosure blk;
generation_iterate(&blk, false);
}
void GenCollectedHeap::generation_iterate(GenClosure* cl,
bool old_to_young) {
if (old_to_young) {
for (int i = _n_gens-1; i >= 0; i--) {
cl->do_generation(_gens[i]);
}
} else {
for (int i = 0; i < _n_gens; i++) {
cl->do_generation(_gens[i]);
}
}
}
void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->space_iterate(cl, true);
}
}
bool GenCollectedHeap::is_maximal_no_gc() const {
for (int i = 0; i < _n_gens; i++) {
if (!_gens[i]->is_maximal_no_gc()) {
return false;
}
}
return true;
}
void GenCollectedHeap::save_marks() {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->save_marks();
}
}
GenCollectedHeap* GenCollectedHeap::heap() {
assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
return _gch;
}
void GenCollectedHeap::prepare_for_compaction() {
guarantee(_n_gens = 2, "Wrong number of generations");
Generation* old_gen = _gens[1];
// Start by compacting into same gen.
CompactPoint cp(old_gen, NULL, NULL);
old_gen->prepare_for_compaction(&cp);
Generation* young_gen = _gens[0];
young_gen->prepare_for_compaction(&cp);
}
GCStats* GenCollectedHeap::gc_stats(int level) const {
return _gens[level]->gc_stats();
}
void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
for (int i = _n_gens-1; i >= 0; i--) {
Generation* g = _gens[i];
if (!silent) {
gclog_or_tty->print(g->name());
gclog_or_tty->print(" ");
}
g->verify();
}
if (!silent) {
gclog_or_tty->print("remset ");
}
rem_set()->verify();
}
void GenCollectedHeap::print_on(outputStream* st) const {
for (int i = 0; i < _n_gens; i++) {
_gens[i]->print_on(st);
}
MetaspaceAux::print_on(st);
}
void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
if (workers() != NULL) {
workers()->threads_do(tc);
}
#if INCLUDE_ALL_GCS
if (UseConcMarkSweepGC) {
ConcurrentMarkSweepThread::threads_do(tc);
}
#endif // INCLUDE_ALL_GCS
}
void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
#if INCLUDE_ALL_GCS
if (UseParNewGC) {
workers()->print_worker_threads_on(st);
}
if (UseConcMarkSweepGC) {
ConcurrentMarkSweepThread::print_all_on(st);
}
#endif // INCLUDE_ALL_GCS
}
void GenCollectedHeap::print_on_error(outputStream* st) const {
this->CollectedHeap::print_on_error(st);
#if INCLUDE_ALL_GCS
if (UseConcMarkSweepGC) {
st->cr();
CMSCollector::print_on_error(st);
}
#endif // INCLUDE_ALL_GCS
}
void GenCollectedHeap::print_tracing_info() const {
if (TraceGen0Time) {
get_gen(0)->print_summary_info();
}
if (TraceGen1Time) {
get_gen(1)->print_summary_info();
}
}
void GenCollectedHeap::print_heap_change(size_t prev_used) const {
if (PrintGCDetails && Verbose) {
gclog_or_tty->print(" " SIZE_FORMAT
"->" SIZE_FORMAT
"(" SIZE_FORMAT ")",
prev_used, used(), capacity());
} else {
gclog_or_tty->print(" " SIZE_FORMAT "K"
"->" SIZE_FORMAT "K"
"(" SIZE_FORMAT "K)",
prev_used / K, used() / K, capacity() / K);
}
}
class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
private:
bool _full;
public:
void do_generation(Generation* gen) {
gen->gc_prologue(_full);
}
GenGCPrologueClosure(bool full) : _full(full) {};
};
void GenCollectedHeap::gc_prologue(bool full) {
assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
always_do_update_barrier = false;
// Fill TLAB's and such
CollectedHeap::accumulate_statistics_all_tlabs();
ensure_parsability(true); // retire TLABs
// Walk generations
GenGCPrologueClosure blk(full);
generation_iterate(&blk, false); // not old-to-young.
};
class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
private:
bool _full;
public:
void do_generation(Generation* gen) {
gen->gc_epilogue(_full);
}
GenGCEpilogueClosure(bool full) : _full(full) {};
};
void GenCollectedHeap::gc_epilogue(bool full) {
#ifdef COMPILER2
assert(DerivedPointerTable::is_empty(), "derived pointer present");
size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
#endif /* COMPILER2 */
resize_all_tlabs();
GenGCEpilogueClosure blk(full);
generation_iterate(&blk, false); // not old-to-young.
if (!CleanChunkPoolAsync) {
Chunk::clean_chunk_pool();
}
MetaspaceCounters::update_performance_counters();
CompressedClassSpaceCounters::update_performance_counters();
always_do_update_barrier = UseConcMarkSweepGC;
};
#ifndef PRODUCT
class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
private:
public:
void do_generation(Generation* gen) {
gen->record_spaces_top();
}
};
void GenCollectedHeap::record_gen_tops_before_GC() {
if (ZapUnusedHeapArea) {
GenGCSaveTopsBeforeGCClosure blk;
generation_iterate(&blk, false); // not old-to-young.
}
}
#endif // not PRODUCT
class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
public:
void do_generation(Generation* gen) {
gen->ensure_parsability();
}
};
void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
CollectedHeap::ensure_parsability(retire_tlabs);
GenEnsureParsabilityClosure ep_cl;
generation_iterate(&ep_cl, false);
}
oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
oop obj,
size_t obj_size) {
guarantee(old_gen->level() == 1, "We only get here with an old generation");
assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
HeapWord* result = NULL;
result = old_gen->expand_and_allocate(obj_size, false);
if (result != NULL) {
Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
}
return oop(result);
}
class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
jlong _time; // in ms
jlong _now; // in ms
public:
GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
jlong time() { return _time; }
void do_generation(Generation* gen) {
_time = MIN2(_time, gen->time_of_last_gc(_now));
}
};
jlong GenCollectedHeap::millis_since_last_gc() {
// We need a monotonically non-deccreasing time in ms but
// os::javaTimeMillis() does not guarantee monotonicity.
jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
GenTimeOfLastGCClosure tolgc_cl(now);
// iterate over generations getting the oldest
// time that a generation was collected
generation_iterate(&tolgc_cl, false);
// javaTimeNanos() is guaranteed to be monotonically non-decreasing
// provided the underlying platform provides such a time source
// (and it is bug free). So we still have to guard against getting
// back a time later than 'now'.
jlong retVal = now - tolgc_cl.time();
if (retVal < 0) {
NOT_PRODUCT(warning("time warp: "INT64_FORMAT, retVal);)
return 0;
}
return retVal;
}
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