/*
* Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
# include "incls/_precompiled.incl"
# include "incls/_collectorPolicy.cpp.incl"
// CollectorPolicy methods.
void CollectorPolicy::initialize_flags() {
if (PermSize > MaxPermSize) {
MaxPermSize = PermSize;
}
PermSize = align_size_down(PermSize, min_alignment());
MaxPermSize = align_size_up(MaxPermSize, max_alignment());
MinPermHeapExpansion = align_size_down(MinPermHeapExpansion, min_alignment());
MaxPermHeapExpansion = align_size_down(MaxPermHeapExpansion, min_alignment());
MinHeapDeltaBytes = align_size_up(MinHeapDeltaBytes, min_alignment());
SharedReadOnlySize = align_size_up(SharedReadOnlySize, max_alignment());
SharedReadWriteSize = align_size_up(SharedReadWriteSize, max_alignment());
SharedMiscDataSize = align_size_up(SharedMiscDataSize, max_alignment());
assert(PermSize % min_alignment() == 0, "permanent space alignment");
assert(MaxPermSize % max_alignment() == 0, "maximum permanent space alignment");
assert(SharedReadOnlySize % max_alignment() == 0, "read-only space alignment");
assert(SharedReadWriteSize % max_alignment() == 0, "read-write space alignment");
assert(SharedMiscDataSize % max_alignment() == 0, "misc-data space alignment");
if (PermSize < M) {
vm_exit_during_initialization("Too small initial permanent heap");
}
}
void CollectorPolicy::initialize_size_info() {
// User inputs from -mx and ms are aligned
_initial_heap_byte_size = align_size_up(Arguments::initial_heap_size(),
min_alignment());
_min_heap_byte_size = align_size_up(Arguments::min_heap_size(),
min_alignment());
_max_heap_byte_size = align_size_up(MaxHeapSize, max_alignment());
// Check validity of heap parameters from launcher
if (_initial_heap_byte_size == 0) {
_initial_heap_byte_size = NewSize + OldSize;
} else {
Universe::check_alignment(_initial_heap_byte_size, min_alignment(),
"initial heap");
}
if (_min_heap_byte_size == 0) {
_min_heap_byte_size = NewSize + OldSize;
} else {
Universe::check_alignment(_min_heap_byte_size, min_alignment(),
"initial heap");
}
// Check heap parameter properties
if (_initial_heap_byte_size < M) {
vm_exit_during_initialization("Too small initial heap");
}
// Check heap parameter properties
if (_min_heap_byte_size < M) {
vm_exit_during_initialization("Too small minimum heap");
}
if (_initial_heap_byte_size <= NewSize) {
// make sure there is at least some room in old space
vm_exit_during_initialization("Too small initial heap for new size specified");
}
if (_max_heap_byte_size < _min_heap_byte_size) {
vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
}
if (_initial_heap_byte_size < _min_heap_byte_size) {
vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
}
if (_max_heap_byte_size < _initial_heap_byte_size) {
vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
}
}
void CollectorPolicy::initialize_perm_generation(PermGen::Name pgnm) {
_permanent_generation =
new PermanentGenerationSpec(pgnm, PermSize, MaxPermSize,
SharedReadOnlySize,
SharedReadWriteSize,
SharedMiscDataSize,
SharedMiscCodeSize);
if (_permanent_generation == NULL) {
vm_exit_during_initialization("Unable to allocate gen spec");
}
}
GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap,
int max_covered_regions) {
switch (rem_set_name()) {
case GenRemSet::CardTable: {
if (barrier_set_name() != BarrierSet::CardTableModRef)
vm_exit_during_initialization("Mismatch between RS and BS.");
CardTableRS* res = new CardTableRS(whole_heap, max_covered_regions);
return res;
}
default:
guarantee(false, "unrecognized GenRemSet::Name");
return NULL;
}
}
// GenCollectorPolicy methods.
void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
size_t init_promo_size,
size_t init_survivor_size) {
double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;
_size_policy = new AdaptiveSizePolicy(init_eden_size,
init_promo_size,
init_survivor_size,
max_gc_minor_pause_sec,
GCTimeRatio);
}
size_t GenCollectorPolicy::compute_max_alignment() {
// The card marking array and the offset arrays for old generations are
// committed in os pages as well. Make sure they are entirely full (to
// avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
// byte entry and the os page size is 4096, the maximum heap size should
// be 512*4096 = 2MB aligned.
size_t alignment = GenRemSet::max_alignment_constraint(rem_set_name());
// Parallel GC does its own alignment of the generations to avoid requiring a
// large page (256M on some platforms) for the permanent generation. The
// other collectors should also be updated to do their own alignment and then
// this use of lcm() should be removed.
if (UseLargePages && !UseParallelGC) {
// in presence of large pages we have to make sure that our
// alignment is large page aware
alignment = lcm(os::large_page_size(), alignment);
}
return alignment;
}
void GenCollectorPolicy::initialize_flags() {
// All sizes must be multiples of the generation granularity.
set_min_alignment((uintx) Generation::GenGrain);
set_max_alignment(compute_max_alignment());
assert(max_alignment() >= min_alignment() &&
max_alignment() % min_alignment() == 0,
"invalid alignment constraints");
CollectorPolicy::initialize_flags();
// All generational heaps have a youngest gen; handle those flags here.
// Adjust max size parameters
if (NewSize > MaxNewSize) {
MaxNewSize = NewSize;
}
NewSize = align_size_down(NewSize, min_alignment());
MaxNewSize = align_size_down(MaxNewSize, min_alignment());
// Check validity of heap flags
assert(NewSize % min_alignment() == 0, "eden space alignment");
assert(MaxNewSize % min_alignment() == 0, "survivor space alignment");
if (NewSize < 3*min_alignment()) {
// make sure there room for eden and two survivor spaces
vm_exit_during_initialization("Too small new size specified");
}
if (SurvivorRatio < 1 || NewRatio < 1) {
vm_exit_during_initialization("Invalid heap ratio specified");
}
}
void TwoGenerationCollectorPolicy::initialize_flags() {
GenCollectorPolicy::initialize_flags();
OldSize = align_size_down(OldSize, min_alignment());
if (NewSize + OldSize > MaxHeapSize) {
MaxHeapSize = NewSize + OldSize;
}
MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
always_do_update_barrier = UseConcMarkSweepGC;
BlockOffsetArrayUseUnallocatedBlock =
BlockOffsetArrayUseUnallocatedBlock || ParallelGCThreads > 0;
// Check validity of heap flags
assert(OldSize % min_alignment() == 0, "old space alignment");
assert(MaxHeapSize % max_alignment() == 0, "maximum heap alignment");
}
void GenCollectorPolicy::initialize_size_info() {
CollectorPolicy::initialize_size_info();
// Minimum sizes of the generations may be different than
// the initial sizes.
if (!FLAG_IS_DEFAULT(NewSize)) {
_min_gen0_size = NewSize;
} else {
_min_gen0_size = align_size_down(_min_heap_byte_size / (NewRatio+1),
min_alignment());
// We bound the minimum size by NewSize below (since it historically
// would have been NewSize and because the NewRatio calculation could
// yield a size that is too small) and bound it by MaxNewSize above.
// This is not always best. The NewSize calculated by CMS (which has
// a fixed minimum of 16m) can sometimes be "too" large. Consider
// the case where -Xmx32m. The CMS calculated NewSize would be about
// half the entire heap which seems too large. But the counter
// example is seen when the client defaults for NewRatio are used.
// An initial young generation size of 640k was observed
// with -Xmx128m -XX:MaxNewSize=32m when NewSize was not used
// as a lower bound as with
// _min_gen0_size = MIN2(_min_gen0_size, MaxNewSize);
// and 640k seemed too small a young generation.
_min_gen0_size = MIN2(MAX2(_min_gen0_size, NewSize), MaxNewSize);
}
// Parameters are valid, compute area sizes.
size_t max_new_size = align_size_down(_max_heap_byte_size / (NewRatio+1),
min_alignment());
max_new_size = MIN2(MAX2(max_new_size, _min_gen0_size), MaxNewSize);
// desired_new_size is used to set the initial size. The
// initial size must be greater than the minimum size.
size_t desired_new_size =
align_size_down(_initial_heap_byte_size / (NewRatio+1),
min_alignment());
size_t new_size = MIN2(MAX2(desired_new_size, _min_gen0_size), max_new_size);
_initial_gen0_size = new_size;
_max_gen0_size = max_new_size;
}
void TwoGenerationCollectorPolicy::initialize_size_info() {
GenCollectorPolicy::initialize_size_info();
// Minimum sizes of the generations may be different than
// the initial sizes. An inconsistently is permitted here
// in the total size that can be specified explicitly by
// command line specification of OldSize and NewSize and
// also a command line specification of -Xms. Issue a warning
// but allow the values to pass.
if (!FLAG_IS_DEFAULT(OldSize)) {
_min_gen1_size = OldSize;
// The generation minimums and the overall heap mimimum should
// be within one heap alignment.
if ((_min_gen1_size + _min_gen0_size + max_alignment()) <
_min_heap_byte_size) {
warning("Inconsistency between minimum heap size and minimum "
"generation sizes: using min heap = " SIZE_FORMAT,
_min_heap_byte_size);
}
} else {
_min_gen1_size = _min_heap_byte_size - _min_gen0_size;
}
_initial_gen1_size = _initial_heap_byte_size - _initial_gen0_size;
_max_gen1_size = _max_heap_byte_size - _max_gen0_size;
}
HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
bool is_tlab,
bool* gc_overhead_limit_was_exceeded) {
GenCollectedHeap *gch = GenCollectedHeap::heap();
debug_only(gch->check_for_valid_allocation_state());
assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
HeapWord* result = NULL;
// Loop until the allocation is satisified,
// or unsatisfied after GC.
for (int try_count = 1; /* return or throw */; try_count += 1) {
HandleMark hm; // discard any handles allocated in each iteration
// First allocation attempt is lock-free.
Generation *gen0 = gch->get_gen(0);
assert(gen0->supports_inline_contig_alloc(),
"Otherwise, must do alloc within heap lock");
if (gen0->should_allocate(size, is_tlab)) {
result = gen0->par_allocate(size, is_tlab);
if (result != NULL) {
assert(gch->is_in_reserved(result), "result not in heap");
return result;
}
}
unsigned int gc_count_before; // read inside the Heap_lock locked region
{
MutexLocker ml(Heap_lock);
if (PrintGC && Verbose) {
gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:"
" attempting locked slow path allocation");
}
// Note that only large objects get a shot at being
// allocated in later generations.
bool first_only = ! should_try_older_generation_allocation(size);
result = gch->attempt_allocation(size, is_tlab, first_only);
if (result != NULL) {
assert(gch->is_in_reserved(result), "result not in heap");
return result;
}
// There are NULL's returned for different circumstances below.
// 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;
if (GC_locker::is_active_and_needs_gc()) {
if (is_tlab) {
return NULL; // Caller will retry allocating individual object
}
if (!gch->is_maximal_no_gc()) {
// Try and expand heap to satisfy request
result = expand_heap_and_allocate(size, is_tlab);
// result could be null if we are out of space
if (result != NULL) {
return result;
}
}
// 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);
// Wait for JNI critical section to be exited
GC_locker::stall_until_clear();
continue;
} else {
if (CheckJNICalls) {
fatal("Possible deadlock due to allocating while"
" in jni critical section");
}
return NULL;
}
}
// Read the gc count while the heap lock is held.
gc_count_before = Universe::heap()->total_collections();
}
// Allocation has failed and a collection is about
// to be done. If the gc time limit was exceeded the
// last time a collection was done, return NULL so
// that an out-of-memory will be thrown. Clear
// gc_time_limit_exceeded so that subsequent attempts
// at a collection will be made.
if (size_policy()->gc_time_limit_exceeded()) {
*gc_overhead_limit_was_exceeded = true;
size_policy()->set_gc_time_limit_exceeded(false);
return NULL;
}
VM_GenCollectForAllocation op(size,
is_tlab,
gc_count_before);
VMThread::execute(&op);
if (op.prologue_succeeded()) {
result = op.result();
if (op.gc_locked()) {
assert(result == NULL, "must be NULL if gc_locked() is true");
continue; // retry and/or stall as necessary
}
assert(result == NULL || gch->is_in_reserved(result),
"result not in heap");
return result;
}
// Give a warning if we seem to be looping forever.
if ((QueuedAllocationWarningCount > 0) &&
(try_count % QueuedAllocationWarningCount == 0)) {
warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t"
" size=%d %s", try_count, size, is_tlab ? "(TLAB)" : "");
}
}
}
HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
bool is_tlab) {
GenCollectedHeap *gch = GenCollectedHeap::heap();
HeapWord* result = NULL;
for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) {
Generation *gen = gch->get_gen(i);
if (gen->should_allocate(size, is_tlab)) {
result = gen->expand_and_allocate(size, is_tlab);
}
}
assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
return result;
}
HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
bool is_tlab) {
GenCollectedHeap *gch = GenCollectedHeap::heap();
GCCauseSetter x(gch, GCCause::_allocation_failure);
HeapWord* result = NULL;
assert(size != 0, "Precondition violated");
if (GC_locker::is_active_and_needs_gc()) {
// GC locker is active; instead of a collection we will attempt
// to expand the heap, if there's room for expansion.
if (!gch->is_maximal_no_gc()) {
result = expand_heap_and_allocate(size, is_tlab);
}
return result; // could be null if we are out of space
} else if (!gch->incremental_collection_will_fail()) {
// The gc_prologues have not executed yet. The value
// for incremental_collection_will_fail() is the remanent
// of the last collection.
// Do an incremental collection.
gch->do_collection(false /* full */,
false /* clear_all_soft_refs */,
size /* size */,
is_tlab /* is_tlab */,
number_of_generations() - 1 /* max_level */);
} else {
// Try a full collection; see delta for bug id 6266275
// for the original code and why this has been simplified
// with from-space allocation criteria modified and
// such allocation moved out of the safepoint path.
gch->do_collection(true /* full */,
false /* clear_all_soft_refs */,
size /* size */,
is_tlab /* is_tlab */,
number_of_generations() - 1 /* max_level */);
}
result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
if (result != NULL) {
assert(gch->is_in_reserved(result), "result not in heap");
return result;
}
// OK, collection failed, try expansion.
result = expand_heap_and_allocate(size, is_tlab);
if (result != NULL) {
return result;
}
// If we reach this point, we're really out of memory. Try every trick
// we can to reclaim memory. Force collection of soft references. Force
// a complete compaction of the heap. Any additional methods for finding
// free memory should be here, especially if they are expensive. If this
// attempt fails, an OOM exception will be thrown.
{
IntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
gch->do_collection(true /* full */,
true /* clear_all_soft_refs */,
size /* size */,
is_tlab /* is_tlab */,
number_of_generations() - 1 /* max_level */);
}
result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
if (result != NULL) {
assert(gch->is_in_reserved(result), "result not in heap");
return result;
}
// What else? We might try synchronous finalization later. If the total
// space available is large enough for the allocation, then a more
// complete compaction phase than we've tried so far might be
// appropriate.
return NULL;
}
size_t GenCollectorPolicy::large_typearray_limit() {
return FastAllocateSizeLimit;
}
// Return true if any of the following is true:
// . the allocation won't fit into the current young gen heap
// . gc locker is occupied (jni critical section)
// . heap memory is tight -- the most recent previous collection
// was a full collection because a partial collection (would
// have) failed and is likely to fail again
bool GenCollectorPolicy::should_try_older_generation_allocation(
size_t word_size) const {
GenCollectedHeap* gch = GenCollectedHeap::heap();
size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
return (word_size > heap_word_size(gen0_capacity))
|| (GC_locker::is_active_and_needs_gc())
|| ( gch->last_incremental_collection_failed()
&& gch->incremental_collection_will_fail());
}
//
// MarkSweepPolicy methods
//
MarkSweepPolicy::MarkSweepPolicy() {
initialize_all();
}
void MarkSweepPolicy::initialize_generations() {
initialize_perm_generation(PermGen::MarkSweepCompact);
_generations = new GenerationSpecPtr[number_of_generations()];
if (_generations == NULL)
vm_exit_during_initialization("Unable to allocate gen spec");
if (UseParNewGC && ParallelGCThreads > 0) {
_generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size);
} else {
_generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size);
}
_generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size);
if (_generations[0] == NULL || _generations[1] == NULL)
vm_exit_during_initialization("Unable to allocate gen spec");
}
void MarkSweepPolicy::initialize_gc_policy_counters() {
// initialize the policy counters - 2 collectors, 3 generations
if (UseParNewGC && ParallelGCThreads > 0) {
_gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3);
}
else {
_gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
}
}