size_t ParallelScavengeHeap::used() const {
size_t value = young_gen()->used_in_bytes() + old_gen()->used_in_bytes();
return value;
}
void ParallelScavengeHeap::update_counters() {
young_gen()->update_counters();
old_gen()->update_counters();
MetaspaceCounters::update_performance_counters();
CompressedClassSpaceCounters::update_performance_counters();
}
size_t ParallelScavengeHeap::capacity() const {
size_t value = young_gen()->capacity_in_bytes() + old_gen()->capacity_in_bytes();
return value;
}
void ParallelScavengeHeap::object_iterate(ObjectClosure* cl) {
young_gen()->object_iterate(cl);
old_gen()->object_iterate(cl);
perm_gen()->object_iterate(cl);
}
void ParallelScavengeHeap::print_on(outputStream* st) const {
young_gen()->print_on(st);
old_gen()->print_on(st);
perm_gen()->print_on(st);
}
void ParallelScavengeHeap::update_counters() {
young_gen()->update_counters();
old_gen()->update_counters();
perm_gen()->update_counters();
}
// Basic allocation policy. Should never be called at a safepoint, or
// from the VM thread.
//
// This method must handle cases where many mem_allocate requests fail
// simultaneously. When that happens, only one VM operation will succeed,
// and the rest will not be executed. For that reason, this method loops
// during failed allocation attempts. If the java heap becomes exhausted,
// we rely on the size_policy object to force a bail out.
HeapWord* ParallelScavengeHeap::mem_allocate(size_t size, bool is_noref, bool is_tlab) {
assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");
assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
HeapWord* result = young_gen()->allocate(size, is_noref, is_tlab);
uint loop_count = 0;
uint gc_count = 0;
while (result == NULL) {
// We don't want to have multiple collections for a single filled generation.
// To prevent this, each thread tracks the total_collections() value, and if
// the count has changed, does not do a new collection.
//
// The collection count must be read only while holding the heap lock. VM
// operations also hold the heap lock during collections. There is a lock
// contention case where thread A blocks waiting on the Heap_lock, while
// thread B is holding it doing a collection. When thread A gets the lock,
// the collection count has already changed. To prevent duplicate collections,
// The policy MUST attempt allocations during the same period it reads the
// total_collections() value!
{
MutexLocker ml(Heap_lock);
gc_count = Universe::heap()->total_collections();
result = young_gen()->allocate(size, is_noref, is_tlab);
// In some cases, the requested object will be too large to easily
// fit in the young_gen. Rather than force a safepoint and collection
// for each one, try allocation in old_gen for objects likely to fail
// allocation in eden.
if (result == NULL && size >=
(young_gen()->eden_space()->capacity_in_words() / 2) && !is_tlab) {
result = old_gen()->allocate(size, is_noref, is_tlab);
}
}
if (result == NULL) {
// Exit the loop if if the gc time limit has been exceeded.
// The allocation must have failed above (result must be NULL),
// and the most recent collection must have exceeded the
// gc time limit. Exit the loop so that an out-of-memory
// will be thrown (returning a NULL will do that), but
// clear gc_time_limit_exceeded so that the next collection
// will succeeded if the applications decides to handle the
// out-of-memory and tries to go on.
if (size_policy()->gc_time_limit_exceeded()) {
size_policy()->set_gc_time_limit_exceeded(false);
if (PrintGCDetails && Verbose) {
gclog_or_tty->print_cr("ParallelScavengeHeap::mem_allocate: "
"return NULL because gc_time_limit_exceeded is set");
}
return NULL;
}
// Generate a VM operation
VM_ParallelGCFailedAllocation op(size, is_noref, is_tlab, gc_count);
VMThread::execute(&op);
// Did the VM operation execute? If so, return the result directly.
// This prevents us from looping until time out on requests that can
// not be satisfied.
if (op.prologue_succeeded()) {
assert(Universe::heap()->is_in_or_null(op.result()),
"result not in heap");
// If a NULL results is being returned, an out-of-memory
// will be thrown now. Clear the gc_time_limit_exceeded
// flag to avoid the following situation.
// gc_time_limit_exceeded is set during a collection
// the collection fails to return enough space and an OOM is thrown
// the next GC is skipped because the gc_time_limit_exceeded
// flag is set and another OOM is thrown
if (op.result() == NULL) {
size_policy()->set_gc_time_limit_exceeded(false);
}
return op.result();
}
}
// The policy object will prevent us from looping forever. If the
// time spent in gc crosses a threshold, we will bail out.
loop_count++;
if ((result == NULL) && (QueuedAllocationWarningCount > 0) &&
(loop_count % QueuedAllocationWarningCount == 0)) {
warning("ParallelScavengeHeap::mem_allocate retries %d times \n\t"
" size=%d %s", loop_count, size, is_tlab ? "(TLAB)" : "");
}
}
return result;
}
void ParallelScavengeHeap::initialize() {
// Cannot be initialized until after the flags are parsed
GenerationSizer flag_parser;
const size_t alignment = min_alignment();
// Check alignments
// NEEDS_CLEANUP The default TwoGenerationCollectorPolicy uses
// NewRatio; it should check UseAdaptiveSizePolicy. Changes from
// generationSizer could move to the common code.
size_t young_size = align_size_up(flag_parser.young_gen_size(), alignment);
size_t max_young_size = align_size_up(flag_parser.max_young_gen_size(),
alignment);
size_t old_size = align_size_up(flag_parser.old_gen_size(), alignment);
size_t max_old_size = align_size_up(flag_parser.max_old_gen_size(),
alignment);
size_t perm_size = align_size_up(flag_parser.perm_gen_size(), alignment);
size_t max_perm_size = align_size_up(flag_parser.max_perm_gen_size(),
alignment);
// Calculate the total size.
size_t total_reserved = max_young_size + max_old_size + max_perm_size;
if (UseISM || UsePermISM) {
total_reserved = round_to(total_reserved, LargePageSizeInBytes);
}
ReservedSpace heap_rs(total_reserved, alignment, UseISM || UsePermISM);
if (!heap_rs.is_reserved()) {
vm_exit_during_initialization("Could not reserve enough space for "
"object heap");
}
_reserved = MemRegion((HeapWord*)heap_rs.base(),
(HeapWord*)(heap_rs.base() + heap_rs.size()));
HeapWord* boundary = (HeapWord*)(heap_rs.base() + max_young_size);
CardTableExtension* card_table_barrier_set = new CardTableExtension(_reserved, 3);
_barrier_set = card_table_barrier_set;
oopDesc::set_bs(_barrier_set);
if (_barrier_set == NULL) {
vm_exit_during_initialization("Could not reserve enough space for "
"barrier set");
}
// Initial young gen size is 4 Mb
size_t init_young_size = align_size_up(4 * M, alignment);
init_young_size = MAX2(MIN2(init_young_size, max_young_size), young_size);
ReservedSpace generation_rs = heap_rs.first_part(max_young_size);
_young_gen = new PSYoungGen(generation_rs,
init_young_size,
young_size,
max_young_size);
heap_rs = heap_rs.last_part(max_young_size);
generation_rs = heap_rs.first_part(max_old_size);
_old_gen = new PSOldGen(generation_rs,
old_size,
old_size,
max_old_size,
"old", 1);
heap_rs = heap_rs.last_part(max_old_size);
_perm_gen = new PSPermGen(heap_rs,
perm_size,
perm_size,
max_perm_size,
"perm", 2);
_size_policy = new AdaptiveSizePolicy(young_gen()->eden_space()->capacity_in_bytes(),
old_gen()->capacity_in_bytes(),
young_gen()->to_space()->capacity_in_bytes(),
max_young_size,
max_old_size,
alignment);
// initialize the policy counters - 2 collectors, 3 generations
_gc_policy_counters = new GCPolicyCounters(PERF_GC, "ParScav:MSC", 2, 3);
}
jint ParallelScavengeHeap::initialize() {
// Cannot be initialized until after the flags are parsed
GenerationSizer flag_parser;
size_t max_young_size = flag_parser.max_young_gen_size();
size_t max_old_size = flag_parser.max_old_gen_size();
if (UseMPSS && max_young_size + max_old_size >= LargePageHeapSizeThreshold) {
set_generation_alignment(LargePageSizeInBytes);
}
const size_t alignment = generation_alignment();
// Check alignments
// NEEDS_CLEANUP The default TwoGenerationCollectorPolicy uses
// NewRatio; it should check UseAdaptiveSizePolicy. Changes from
// generationSizer could move to the common code.
size_t min_young_size =
align_size_up(flag_parser.min_young_gen_size(), alignment);
size_t young_size = align_size_up(flag_parser.young_gen_size(), alignment);
max_young_size = align_size_up(max_young_size, alignment);
size_t min_old_size =
align_size_up(flag_parser.min_old_gen_size(), alignment);
size_t old_size = align_size_up(flag_parser.old_gen_size(), alignment);
old_size = MAX2(old_size, min_old_size);
max_old_size = align_size_up(max_old_size, alignment);
size_t perm_size = align_size_up(flag_parser.perm_gen_size(), alignment);
size_t max_perm_size = align_size_up(flag_parser.max_perm_gen_size(),
alignment);
// Calculate the total size.
size_t total_reserved = max_young_size + max_old_size + max_perm_size;
if (UseISM || UsePermISM) {
total_reserved = round_to(total_reserved, LargePageSizeInBytes);
}
ReservedSpace heap_rs(total_reserved, alignment, UseISM || UsePermISM);
if (!heap_rs.is_reserved()) {
vm_shutdown_during_initialization(
"Could not reserve enough space for object heap");
return JNI_ENOMEM;
}
_reserved_byte_size = heap_rs.size();
_reserved = MemRegion((HeapWord*)heap_rs.base(),
(HeapWord*)(heap_rs.base() + heap_rs.size()));
HeapWord* boundary = (HeapWord*)(heap_rs.base() + max_young_size);
CardTableExtension* card_table_barrier_set = new CardTableExtension(_reserved, 3);
_barrier_set = card_table_barrier_set;
oopDesc::set_bs(_barrier_set);
if (_barrier_set == NULL) {
vm_shutdown_during_initialization(
"Could not reserve enough space for barrier set");
return JNI_ENOMEM;
}
// Initial young gen size is 4 Mb
size_t init_young_size = align_size_up(4 * M, alignment);
init_young_size = MAX2(MIN2(init_young_size, max_young_size), young_size);
// Divide up the reserved space: perm, old, young
ReservedSpace perm_rs = heap_rs.first_part(max_perm_size);
ReservedSpace old_young_rs
= heap_rs.last_part(max_perm_size);
ReservedSpace old_rs = old_young_rs.first_part(max_old_size);
heap_rs = old_young_rs.last_part(max_old_size);
ReservedSpace young_rs = heap_rs.first_part(max_young_size);
assert(young_rs.size() == heap_rs.size(), "Didn't reserve all of the heap");
// Make up the generations
// Calculate the maximum size that a generation can grow. This
// includes growth into the other generation. Note that the
// parameter _max_gen_size is kept as the maximum
// size of the generation as the boundaries currently stand.
// _max_gen_size is still used as that value.
double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0;
double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;
// Regarding SEPARATE_PATHS. If SEPARATE_PATHS is defined, then
// the generations are created without the use of AdjoiningGenerations
// in the case where boundary moving is not an option. This is
// being kept until the code review in case there is some desire
// to keep the new code out of the path of the previous code.
// One effect of using AdjoiningGenerations for both cases is that
// is that the generations in AdjoiningGenerations need to be
// PSOldGen and PSYoungGen as opposed to ASPSOldGen and ASPSYoungGen.
// This latter means that methods such as available_for_expansion()
// need to be defined in PSOldGen.
#undef SEPARATE_PATHS
#ifdef SEPARATE_PATHS
if (UseAdaptiveSizePolicy && UseAdaptiveGCBoundary) {
#endif
_gens = new AdjoiningGenerations(old_young_rs,
old_size,
min_old_size,
max_old_size,
init_young_size,
min_young_size,
max_young_size,
alignment);
_old_gen = _gens->old_gen();
_young_gen = _gens->young_gen();
_size_policy =
new PSAdaptiveSizePolicy(young_gen()->eden_space()->capacity_in_bytes(),
old_gen()->capacity_in_bytes(),
young_gen()->to_space()->capacity_in_bytes(),
generation_alignment(),
intra_generation_alignment(),
max_gc_pause_sec,
max_gc_minor_pause_sec,
GCTimeRatio
);
#ifdef SEPARATE_PATHS
} else {
// Same as for case where boundary does not move.
size_t old_size_limit, young_size_limit;
old_size_limit = max_old_size;
young_size_limit = max_young_size;
_young_gen = new PSYoungGen(init_young_size,
min_young_size,
max_young_size);
_old_gen = new PSOldGen(old_size,
min_old_size,
max_old_size,
"old", 1);
_gens = 0;
_young_gen->initialize(young_rs, alignment);
_old_gen->initialize(old_rs, alignment, "old", 1);
_size_policy =
new PSAdaptiveSizePolicy(young_gen()->eden_space()->capacity_in_bytes(),
old_gen()->capacity_in_bytes(),
young_gen()->to_space()->capacity_in_bytes(),
generation_alignment(),
intra_generation_alignment(),
max_gc_pause_sec,
max_gc_minor_pause_sec,
GCTimeRatio
);
}
#endif
_perm_gen = new PSPermGen(perm_rs,
alignment,
perm_size,
perm_size,
max_perm_size,
"perm", 2);
assert(!UseAdaptiveGCBoundary ||
(old_gen()->virtual_space()->high_boundary() ==
young_gen()->virtual_space()->low_boundary()),
"Boundaries must meet");
// initialize the policy counters - 2 collectors, 3 generations
_gc_policy_counters =
new PSGCAdaptivePolicyCounters("ParScav:MSC", 2, 3, _size_policy);
_psh = this;
return JNI_OK;
}
jint ParallelScavengeHeap::initialize() {
CollectedHeap::pre_initialize();
// Cannot be initialized until after the flags are parsed
// GenerationSizer flag_parser;
_collector_policy = new GenerationSizer();
size_t yg_min_size = _collector_policy->min_young_gen_size();
size_t yg_max_size = _collector_policy->max_young_gen_size();
size_t og_min_size = _collector_policy->min_old_gen_size();
size_t og_max_size = _collector_policy->max_old_gen_size();
// Why isn't there a min_perm_gen_size()?
size_t pg_min_size = _collector_policy->perm_gen_size();
size_t pg_max_size = _collector_policy->max_perm_gen_size();
trace_gen_sizes("ps heap raw",
pg_min_size, pg_max_size,
og_min_size, og_max_size,
yg_min_size, yg_max_size);
// The ReservedSpace ctor used below requires that the page size for the perm
// gen is <= the page size for the rest of the heap (young + old gens).
const size_t og_page_sz = os::page_size_for_region(yg_min_size + og_min_size,
yg_max_size + og_max_size,
8);
const size_t pg_page_sz = MIN2(os::page_size_for_region(pg_min_size,
pg_max_size, 16),
og_page_sz);
const size_t pg_align = set_alignment(_perm_gen_alignment, pg_page_sz);
const size_t og_align = set_alignment(_old_gen_alignment, og_page_sz);
const size_t yg_align = set_alignment(_young_gen_alignment, og_page_sz);
// Update sizes to reflect the selected page size(s).
//
// NEEDS_CLEANUP. The default TwoGenerationCollectorPolicy uses NewRatio; it
// should check UseAdaptiveSizePolicy. Changes from generationSizer could
// move to the common code.
yg_min_size = align_size_up(yg_min_size, yg_align);
yg_max_size = align_size_up(yg_max_size, yg_align);
size_t yg_cur_size =
align_size_up(_collector_policy->young_gen_size(), yg_align);
yg_cur_size = MAX2(yg_cur_size, yg_min_size);
og_min_size = align_size_up(og_min_size, og_align);
// Align old gen size down to preserve specified heap size.
assert(og_align == yg_align, "sanity");
og_max_size = align_size_down(og_max_size, og_align);
og_max_size = MAX2(og_max_size, og_min_size);
size_t og_cur_size =
align_size_down(_collector_policy->old_gen_size(), og_align);
og_cur_size = MAX2(og_cur_size, og_min_size);
pg_min_size = align_size_up(pg_min_size, pg_align);
pg_max_size = align_size_up(pg_max_size, pg_align);
size_t pg_cur_size = pg_min_size;
trace_gen_sizes("ps heap rnd",
pg_min_size, pg_max_size,
og_min_size, og_max_size,
yg_min_size, yg_max_size);
const size_t total_reserved = pg_max_size + og_max_size + yg_max_size;
char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
// The main part of the heap (old gen + young gen) can often use a larger page
// size than is needed or wanted for the perm gen. Use the "compound
// alignment" ReservedSpace ctor to avoid having to use the same page size for
// all gens.
ReservedHeapSpace heap_rs(pg_max_size, pg_align, og_max_size + yg_max_size,
og_align, addr);
if (UseCompressedOops) {
if (addr != NULL && !heap_rs.is_reserved()) {
// Failed to reserve at specified address - the requested memory
// region is taken already, for example, by 'java' launcher.
// Try again to reserver heap higher.
addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
ReservedHeapSpace heap_rs0(pg_max_size, pg_align, og_max_size + yg_max_size,
og_align, addr);
if (addr != NULL && !heap_rs0.is_reserved()) {
// Failed to reserve at specified address again - give up.
addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
assert(addr == NULL, "");
ReservedHeapSpace heap_rs1(pg_max_size, pg_align, og_max_size + yg_max_size,
og_align, addr);
heap_rs = heap_rs1;
} else {
heap_rs = heap_rs0;
}
}
}
os::trace_page_sizes("ps perm", pg_min_size, pg_max_size, pg_page_sz,
heap_rs.base(), pg_max_size);
os::trace_page_sizes("ps main", og_min_size + yg_min_size,
og_max_size + yg_max_size, og_page_sz,
heap_rs.base() + pg_max_size,
heap_rs.size() - pg_max_size);
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()));
CardTableExtension* const barrier_set = new CardTableExtension(_reserved, 3);
_barrier_set = barrier_set;
oopDesc::set_bs(_barrier_set);
if (_barrier_set == NULL) {
vm_shutdown_during_initialization(
"Could not reserve enough space for barrier set");
return JNI_ENOMEM;
}
// Initial young gen size is 4 Mb
//
// XXX - what about flag_parser.young_gen_size()?
const size_t init_young_size = align_size_up(4 * M, yg_align);
yg_cur_size = MAX2(MIN2(init_young_size, yg_max_size), yg_cur_size);
// Split the reserved space into perm gen and the main heap (everything else).
// The main heap uses a different alignment.
ReservedSpace perm_rs = heap_rs.first_part(pg_max_size);
ReservedSpace main_rs = heap_rs.last_part(pg_max_size, og_align);
// Make up the generations
// Calculate the maximum size that a generation can grow. This
// includes growth into the other generation. Note that the
// parameter _max_gen_size is kept as the maximum
// size of the generation as the boundaries currently stand.
// _max_gen_size is still used as that value.
double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0;
double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;
_gens = new AdjoiningGenerations(main_rs,
og_cur_size,
og_min_size,
og_max_size,
yg_cur_size,
yg_min_size,
yg_max_size,
yg_align);
_old_gen = _gens->old_gen();
_young_gen = _gens->young_gen();
const size_t eden_capacity = _young_gen->eden_space()->capacity_in_bytes();
const size_t old_capacity = _old_gen->capacity_in_bytes();
const size_t initial_promo_size = MIN2(eden_capacity, old_capacity);
_size_policy =
new PSAdaptiveSizePolicy(eden_capacity,
initial_promo_size,
young_gen()->to_space()->capacity_in_bytes(),
intra_heap_alignment(),
max_gc_pause_sec,
max_gc_minor_pause_sec,
GCTimeRatio
);
_perm_gen = new PSPermGen(perm_rs,
pg_align,
pg_cur_size,
pg_cur_size,
pg_max_size,
"perm", 2);
assert(!UseAdaptiveGCBoundary ||
(old_gen()->virtual_space()->high_boundary() ==
young_gen()->virtual_space()->low_boundary()),
"Boundaries must meet");
// initialize the policy counters - 2 collectors, 3 generations
_gc_policy_counters =
new PSGCAdaptivePolicyCounters("ParScav:MSC", 2, 3, _size_policy);
_psh = this;
// Set up the GCTaskManager
_gc_task_manager = GCTaskManager::create(ParallelGCThreads);
if (UseParallelOldGC && !PSParallelCompact::initialize()) {
return JNI_ENOMEM;
}
return JNI_OK;
}
// Basic allocation policy. Should never be called at a safepoint, or
// from the VM thread.
//
// This method must handle cases where many mem_allocate requests fail
// simultaneously. When that happens, only one VM operation will succeed,
// and the rest will not be executed. For that reason, this method loops
// during failed allocation attempts. If the java heap becomes exhausted,
// we rely on the size_policy object to force a bail out.
HeapWord* ParallelScavengeHeap::mem_allocate(
size_t size,
bool is_noref,
bool is_tlab,
bool* gc_overhead_limit_was_exceeded) {
assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");
assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
// In general gc_overhead_limit_was_exceeded should be false so
// set it so here and reset it to true only if the gc time
// limit is being exceeded as checked below.
*gc_overhead_limit_was_exceeded = false;
HeapWord* result = young_gen()->allocate(size, is_tlab);
uint loop_count = 0;
uint gc_count = 0;
while (result == NULL) {
// We don't want to have multiple collections for a single filled generation.
// To prevent this, each thread tracks the total_collections() value, and if
// the count has changed, does not do a new collection.
//
// The collection count must be read only while holding the heap lock. VM
// operations also hold the heap lock during collections. There is a lock
// contention case where thread A blocks waiting on the Heap_lock, while
// thread B is holding it doing a collection. When thread A gets the lock,
// the collection count has already changed. To prevent duplicate collections,
// The policy MUST attempt allocations during the same period it reads the
// total_collections() value!
{
MutexLocker ml(Heap_lock);
gc_count = Universe::heap()->total_collections();
result = young_gen()->allocate(size, is_tlab);
// (1) If the requested object is too large to easily fit in the
// young_gen, or
// (2) If GC is locked out via GCLocker, young gen is full and
// the need for a GC already signalled to GCLocker (done
// at a safepoint),
// ... then, rather than force a safepoint and (a potentially futile)
// collection (attempt) for each allocation, try allocation directly
// in old_gen. For case (2) above, we may in the future allow
// TLAB allocation directly in the old gen.
if (result != NULL) {
return result;
}
if (!is_tlab &&
size >= (young_gen()->eden_space()->capacity_in_words(Thread::current()) / 2)) {
result = old_gen()->allocate(size, is_tlab);
if (result != NULL) {
return result;
}
}
if (GC_locker::is_active_and_needs_gc()) {
// GC is locked out. If this is a TLAB allocation,
// return NULL; the requestor will retry allocation
// of an idividual object at a time.
if (is_tlab) {
return NULL;
}
// If this thread is not in a jni critical section, we stall
// the requestor until the critical section has cleared and
// GC allowed. When the critical section clears, a GC is
// initiated by the last thread exiting the critical section; so
// we retry the allocation sequence from the beginning of the loop,
// rather than causing more, now probably unnecessary, GC attempts.
JavaThread* jthr = JavaThread::current();
if (!jthr->in_critical()) {
MutexUnlocker mul(Heap_lock);
GC_locker::stall_until_clear();
continue;
} else {
if (CheckJNICalls) {
fatal("Possible deadlock due to allocating while"
" in jni critical section");
}
return NULL;
}
}
}
if (result == NULL) {
// Generate a VM operation
VM_ParallelGCFailedAllocation op(size, is_tlab, gc_count);
VMThread::execute(&op);
// Did the VM operation execute? If so, return the result directly.
// This prevents us from looping until time out on requests that can
// not be satisfied.
if (op.prologue_succeeded()) {
assert(Universe::heap()->is_in_or_null(op.result()),
"result not in heap");
// If GC was locked out during VM operation then retry allocation
// and/or stall as necessary.
if (op.gc_locked()) {
assert(op.result() == NULL, "must be NULL if gc_locked() is true");
continue; // retry and/or stall as necessary
}
// Exit the loop if the gc time limit has been exceeded.
// The allocation must have failed above ("result" guarding
// this path is NULL) and the most recent collection has exceeded the
// gc overhead limit (although enough may have been collected to
// satisfy the allocation). Exit the loop so that an out-of-memory
// will be thrown (return a NULL ignoring the contents of
// op.result()),
// but clear gc_overhead_limit_exceeded so that the next collection
// starts with a clean slate (i.e., forgets about previous overhead
// excesses). Fill op.result() with a filler object so that the
// heap remains parsable.
const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
const bool softrefs_clear = collector_policy()->all_soft_refs_clear();
assert(!limit_exceeded || softrefs_clear, "Should have been cleared");
if (limit_exceeded && softrefs_clear) {
*gc_overhead_limit_was_exceeded = true;
size_policy()->set_gc_overhead_limit_exceeded(false);
if (PrintGCDetails && Verbose) {
gclog_or_tty->print_cr("ParallelScavengeHeap::mem_allocate: "
"return NULL because gc_overhead_limit_exceeded is set");
}
if (op.result() != NULL) {
CollectedHeap::fill_with_object(op.result(), size);
}
return NULL;
}
return op.result();
}
}
// The policy object will prevent us from looping forever. If the
// time spent in gc crosses a threshold, we will bail out.
loop_count++;
if ((result == NULL) && (QueuedAllocationWarningCount > 0) &&
(loop_count % QueuedAllocationWarningCount == 0)) {
warning("ParallelScavengeHeap::mem_allocate retries %d times \n\t"
" size=%d %s", loop_count, size, is_tlab ? "(TLAB)" : "");
}
}
return result;
}
// 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 ParallelScavengeHeap::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");
// The order of the generations is perm (low addr), old, young (high addr)
return p >= old_gen()->reserved().end();
}
bool ParallelScavengeHeap::is_maximal_no_gc() const {
return old_gen()->is_maximal_no_gc() && young_gen()->is_maximal_no_gc();
}
AdjoiningGenerations::AdjoiningGenerations(ReservedSpace old_young_rs,
size_t init_low_byte_size,
size_t min_low_byte_size,
size_t max_low_byte_size,
size_t init_high_byte_size,
size_t min_high_byte_size,
size_t max_high_byte_size,
size_t alignment) :
_virtual_spaces(old_young_rs, min_low_byte_size,
min_high_byte_size, alignment) {
assert(min_low_byte_size <= init_low_byte_size &&
init_low_byte_size <= max_low_byte_size, "Parameter check");
assert(min_high_byte_size <= init_high_byte_size &&
init_high_byte_size <= max_high_byte_size, "Parameter check");
// Create the generations differently based on the option to
// move the boundary.
if (UseAdaptiveGCBoundary) {
// Initialize the adjoining virtual spaces. Then pass the
// a virtual to each generation for initialization of the
// generation.
// Does the actual creation of the virtual spaces
_virtual_spaces.initialize(max_low_byte_size,
init_low_byte_size,
init_high_byte_size);
// Place the young gen at the high end. Passes in the virtual space.
_young_gen = new ASPSYoungGen(_virtual_spaces.high(),
_virtual_spaces.high()->committed_size(),
min_high_byte_size,
_virtual_spaces.high_byte_size_limit());
// Place the old gen at the low end. Passes in the virtual space.
_old_gen = new ASPSOldGen(_virtual_spaces.low(),
_virtual_spaces.low()->committed_size(),
min_low_byte_size,
_virtual_spaces.low_byte_size_limit(),
"old", 1);
young_gen()->initialize_work();
assert(young_gen()->reserved().byte_size() <= young_gen()->gen_size_limit(),
"Consistency check");
assert(old_young_rs.size() >= young_gen()->gen_size_limit(),
"Consistency check");
old_gen()->initialize_work("old", 1);
assert(old_gen()->reserved().byte_size() <= old_gen()->gen_size_limit(),
"Consistency check");
assert(old_young_rs.size() >= old_gen()->gen_size_limit(),
"Consistency check");
} else {
// Layout the reserved space for the generations.
ReservedSpace old_rs =
virtual_spaces()->reserved_space().first_part(max_low_byte_size);
ReservedSpace heap_rs =
virtual_spaces()->reserved_space().last_part(max_low_byte_size);
ReservedSpace young_rs = heap_rs.first_part(max_high_byte_size);
assert(young_rs.size() == heap_rs.size(), "Didn't reserve all of the heap");
// Create the generations. Virtual spaces are not passed in.
_young_gen = new PSYoungGen(init_high_byte_size,
min_high_byte_size,
max_high_byte_size);
_old_gen = new PSOldGen(init_low_byte_size,
min_low_byte_size,
max_low_byte_size,
"old", 1);
// The virtual spaces are created by the initialization of the gens.
_young_gen->initialize(young_rs, alignment);
assert(young_gen()->gen_size_limit() == young_rs.size(),
"Consistency check");
_old_gen->initialize(old_rs, alignment, "old", 1);
assert(old_gen()->gen_size_limit() == old_rs.size(), "Consistency check");
}
}
