Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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  */

 #include "precompiled.hpp"

 #include "gc_implementation/parallelScavenge/adjoiningGenerations.hpp"

 #include "gc_implementation/parallelScavenge/adjoiningVirtualSpaces.hpp"

 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"

 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"

 #include "gc_implementation/parallelScavenge/generationSizer.hpp"

 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp"

 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"

 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"

 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"

 #include "gc_implementation/parallelScavenge/psPromotionManager.hpp"

 #include "gc_implementation/parallelScavenge/psScavenge.hpp"

 #include "gc_implementation/parallelScavenge/vmPSOperations.hpp"

 #include "gc_implementation/shared/gcHeapSummary.hpp"

 #include "gc_implementation/shared/gcWhen.hpp"

 #include "memory/gcLocker.inline.hpp"

 #include "oops/oop.inline.hpp"

 #include "runtime/handles.inline.hpp"

 #include "runtime/java.hpp"

 #include "runtime/vmThread.hpp"

 #include "services/memTracker.hpp"

 #include "utilities/vmError.hpp"

 PSYoungGen*  ParallelScavengeHeap::_young_gen = NULL;

 PSOldGen*    ParallelScavengeHeap::_old_gen = NULL;

 PSAdaptiveSizePolicy* ParallelScavengeHeap::_size_policy = NULL;

 PSGCAdaptivePolicyCounters* ParallelScavengeHeap::_gc_policy_counters = NULL;

 ParallelScavengeHeap* ParallelScavengeHeap::_psh = NULL;

 GCTaskManager* ParallelScavengeHeap::_gc_task_manager = NULL;

 jint ParallelScavengeHeap::initialize() {

   CollectedHeap::pre_initialize();

   // Initialize collector policy

   _collector_policy = new GenerationSizer();

   _collector_policy->initialize_all();

   const size_t heap_size = _collector_policy->max_heap_byte_size();

   ReservedSpace heap_rs = Universe::reserve_heap(heap_size, _collector_policy->heap_alignment());

   MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtJavaHeap);

   os::trace_page_sizes("ps main", _collector_policy->min_heap_byte_size(),

                        heap_size, generation_alignment(),

                        heap_rs.base(),

                        heap_rs.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->initialize();

   _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;

   }

   // 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(heap_rs, _collector_policy, generation_alignment());

   _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(),

                              _collector_policy->gen_alignment(),

                              max_gc_pause_sec,

                              max_gc_minor_pause_sec,

                              GCTimeRatio

                              );

   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;

 }

 void ParallelScavengeHeap::post_initialize() {

   // Need to init the tenuring threshold

   PSScavenge::initialize();

   if (UseParallelOldGC) {

     PSParallelCompact::post_initialize();

   } else {

     PSMarkSweep::initialize();

   }

   PSPromotionManager::initialize();

 }

 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;

 }

 size_t ParallelScavengeHeap::used() const {

   size_t value = young_gen()->used_in_bytes() + old_gen()->used_in_bytes();

   return value;

 }

 bool ParallelScavengeHeap::is_maximal_no_gc() const {

   return old_gen()->is_maximal_no_gc() && young_gen()->is_maximal_no_gc();

 }

 size_t ParallelScavengeHeap::max_capacity() const {

   size_t estimated = reserved_region().byte_size();

   if (UseAdaptiveSizePolicy) {

     estimated -= _size_policy->max_survivor_size(young_gen()->max_size());

   } else {

     estimated -= young_gen()->to_space()->capacity_in_bytes();

   }

   return MAX2(estimated, capacity());

 }

 bool ParallelScavengeHeap::is_in(const void* p) const {

   if (young_gen()->is_in(p)) {

     return true;

   }

   if (old_gen()->is_in(p)) {

     return true;

   }

   return false;

 }

 bool ParallelScavengeHeap::is_in_reserved(const void* p) const {

   if (young_gen()->is_in_reserved(p)) {

     return true;

   }

   if (old_gen()->is_in_reserved(p)) {

     return true;

   }

   return false;

 }

 bool ParallelScavengeHeap::is_scavengable(const void* addr) {

   return is_in_young((oop)addr);

 }

 #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 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 old (low addr), young (high addr)

   return p >= old_gen()->reserved().end();

 }

 #endif

 // There are two levels of allocation policy here.

 //

 // When an allocation request fails, the requesting thread must invoke a VM

 // operation, transfer control to the VM thread, and await the results of a

 // garbage collection. That is quite expensive, and we should avoid doing it

 // multiple times if possible.

 //

 // To accomplish this, we have a basic allocation policy, and also a

 // failed allocation policy.

 //

 // The basic allocation policy controls how you allocate memory without

 // attempting garbage collection. It is okay to grab locks and

 // expand the heap, if that can be done without coming to a safepoint.

 // It is likely that the basic allocation policy will not be very

 // aggressive.

 //

 // The failed allocation policy is invoked from the VM thread after

 // the basic allocation policy is unable to satisfy a mem_allocate

 // request. This policy needs to cover the entire range of collection,

 // heap expansion, and out-of-memory conditions. It should make every

 // attempt to allocate the requested memory.

 // 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* 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);

   uint loop_count = 0;

   uint gc_count = 0;

   int gclocker_stalled_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);

       if (result != NULL) {

         return result;

       }

       // If certain conditions hold, try allocating from the old gen.

       result = mem_allocate_old_gen(size);

       if (result != NULL) {

         return result;

       }

       if (gclocker_stalled_count > GCLockerRetryAllocationCount) {

         return NULL;

       }

       // Failed to allocate without a gc.

       if (GC_locker::is_active_and_needs_gc()) {

         // 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();

           gclocker_stalled_count += 1;

           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, 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();

         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=" SIZE_FORMAT, loop_count, size);

     }

   }

   return result;

 }

 // A "death march" is a series of ultra-slow allocations in which a full gc is

 // done before each allocation, and after the full gc the allocation still

 // cannot be satisfied from the young gen.  This routine detects that condition;

 // it should be called after a full gc has been done and the allocation

 // attempted from the young gen. The parameter 'addr' should be the result of

 // that young gen allocation attempt.

 void

 ParallelScavengeHeap::death_march_check(HeapWord* const addr, size_t size) {

   if (addr != NULL) {

     _death_march_count = 0;  // death march has ended

   } else if (_death_march_count == 0) {

     if (should_alloc_in_eden(size)) {

       _death_march_count = 1;    // death march has started

     }

   }

 }

 HeapWord* ParallelScavengeHeap::mem_allocate_old_gen(size_t size) {

   if (!should_alloc_in_eden(size) || GC_locker::is_active_and_needs_gc()) {

     // Size is too big for eden, or gc is locked out.

     return old_gen()->allocate(size);

   }

   // If a "death march" is in progress, allocate from the old gen a limited

   // number of times before doing a GC.

   if (_death_march_count > 0) {

     if (_death_march_count < 64) {

       ++_death_march_count;

       return old_gen()->allocate(size);

     } else {

       _death_march_count = 0;

     }

   }

   return NULL;

 }

 void ParallelScavengeHeap::do_full_collection(bool clear_all_soft_refs) {

   if (UseParallelOldGC) {

     // The do_full_collection() parameter clear_all_soft_refs

     // is interpreted here as maximum_compaction which will

     // cause SoftRefs to be cleared.

     bool maximum_compaction = clear_all_soft_refs;

     PSParallelCompact::invoke(maximum_compaction);

   } else {

     PSMarkSweep::invoke(clear_all_soft_refs);

   }

 }

 // Failed allocation policy. Must be called from the VM thread, and

 // only at a safepoint! Note that this method has policy for allocation

 // flow, and NOT collection policy. So we do not check for gc collection

 // time over limit here, that is the responsibility of the heap specific

 // collection methods. This method decides where to attempt allocations,

 // and when to attempt collections, but no collection specific policy.

 HeapWord* ParallelScavengeHeap::failed_mem_allocate(size_t size) {

   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");

   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");

   assert(!Universe::heap()->is_gc_active(), "not reentrant");

   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");

   // We assume that allocation in eden will fail unless we collect.

   // First level allocation failure, scavenge and allocate in young gen.

   GCCauseSetter gccs(this, GCCause::_allocation_failure);

   const bool invoked_full_gc = PSScavenge::invoke();

   HeapWord* result = young_gen()->allocate(size);

   // Second level allocation failure.

   //   Mark sweep and allocate in young generation.

   if (result == NULL && !invoked_full_gc) {

     do_full_collection(false);

     result = young_gen()->allocate(size);

   }

   death_march_check(result, size);

   // Third level allocation failure.

   //   After mark sweep and young generation allocation failure,

   //   allocate in old generation.

   if (result == NULL) {

     result = old_gen()->allocate(size);

   }

   // Fourth level allocation failure. We're running out of memory.

   //   More complete mark sweep and allocate in young generation.

   if (result == NULL) {

     do_full_collection(true);

     result = young_gen()->allocate(size);

   }

   // Fifth level allocation failure.

   //   After more complete mark sweep, allocate in old generation.

   if (result == NULL) {

     result = old_gen()->allocate(size);

   }

   return result;

 }

 void ParallelScavengeHeap::ensure_parsability(bool retire_tlabs) {

   CollectedHeap::ensure_parsability(retire_tlabs);

   young_gen()->eden_space()->ensure_parsability();

 }

 size_t ParallelScavengeHeap::tlab_capacity(Thread* thr) const {

   return young_gen()->eden_space()->tlab_capacity(thr);

 }

 size_t ParallelScavengeHeap::tlab_used(Thread* thr) const {

   return young_gen()->eden_space()->tlab_used(thr);

 }

 size_t ParallelScavengeHeap::unsafe_max_tlab_alloc(Thread* thr) const {

   return young_gen()->eden_space()->unsafe_max_tlab_alloc(thr);

 }

 HeapWord* ParallelScavengeHeap::allocate_new_tlab(size_t size) {

   return young_gen()->allocate(size);

 }

 void ParallelScavengeHeap::accumulate_statistics_all_tlabs() {

   CollectedHeap::accumulate_statistics_all_tlabs();

 }

 void ParallelScavengeHeap::resize_all_tlabs() {

   CollectedHeap::resize_all_tlabs();

 }

 bool ParallelScavengeHeap::can_elide_initializing_store_barrier(oop new_obj) {

   // We don't need barriers for stores to objects in the

   // young gen and, a fortiori, for initializing stores to

   // objects therein.

   return is_in_young(new_obj);

 }

 // This method is used by System.gc() and JVMTI.

 void ParallelScavengeHeap::collect(GCCause::Cause cause) {

   assert(!Heap_lock->owned_by_self(),

     "this thread should not own the Heap_lock");

   unsigned int gc_count      = 0;

   unsigned int full_gc_count = 0;

   {

     MutexLocker ml(Heap_lock);

     // This value is guarded by the Heap_lock

     gc_count      = Universe::heap()->total_collections();

     full_gc_count = Universe::heap()->total_full_collections();

   }

   VM_ParallelGCSystemGC op(gc_count, full_gc_count, cause);

   VMThread::execute(&op);

 }

 void ParallelScavengeHeap::oop_iterate(ExtendedOopClosure* cl) {

   Unimplemented();

 }

 void ParallelScavengeHeap::object_iterate(ObjectClosure* cl) {

   young_gen()->object_iterate(cl);

   old_gen()->object_iterate(cl);

 }

 HeapWord* ParallelScavengeHeap::block_start(const void* addr) const {

   if (young_gen()->is_in_reserved(addr)) {

     assert(young_gen()->is_in(addr),

            "addr should be in allocated part of young gen");

     // called from os::print_location by find or VMError

     if (Debugging || VMError::fatal_error_in_progress())  return NULL;

     Unimplemented();

   } else if (old_gen()->is_in_reserved(addr)) {

     assert(old_gen()->is_in(addr),

            "addr should be in allocated part of old gen");

     return old_gen()->start_array()->object_start((HeapWord*)addr);

   }

   return 0;

 }

 size_t ParallelScavengeHeap::block_size(const HeapWord* addr) const {

   return oop(addr)->size();

 }

 bool ParallelScavengeHeap::block_is_obj(const HeapWord* addr) const {

   return block_start(addr) == addr;

 }

 jlong ParallelScavengeHeap::millis_since_last_gc() {

   return UseParallelOldGC ?

     PSParallelCompact::millis_since_last_gc() :

     PSMarkSweep::millis_since_last_gc();

 }

 void ParallelScavengeHeap::prepare_for_verify() {

   ensure_parsability(false);  // no need to retire TLABs for verification

 }

 PSHeapSummary ParallelScavengeHeap::create_ps_heap_summary() {

   PSOldGen* old = old_gen();

   HeapWord* old_committed_end = (HeapWord*)old->virtual_space()->committed_high_addr();

   VirtualSpaceSummary old_summary(old->reserved().start(), old_committed_end, old->reserved().end());

   SpaceSummary old_space(old->reserved().start(), old_committed_end, old->used_in_bytes());

   PSYoungGen* young = young_gen();

   VirtualSpaceSummary young_summary(young->reserved().start(),

     (HeapWord*)young->virtual_space()->committed_high_addr(), young->reserved().end());

   MutableSpace* eden = young_gen()->eden_space();

   SpaceSummary eden_space(eden->bottom(), eden->end(), eden->used_in_bytes());

   MutableSpace* from = young_gen()->from_space();

   SpaceSummary from_space(from->bottom(), from->end(), from->used_in_bytes());

   MutableSpace* to = young_gen()->to_space();

   SpaceSummary to_space(to->bottom(), to->end(), to->used_in_bytes());

   VirtualSpaceSummary heap_summary = create_heap_space_summary();

   return PSHeapSummary(heap_summary, used(), old_summary, old_space, young_summary, eden_space, from_space, to_space);

 }

 void ParallelScavengeHeap::print_on(outputStream* st) const {

   young_gen()->print_on(st);

   old_gen()->print_on(st);

   MetaspaceAux::print_on(st);

 }

 void ParallelScavengeHeap::print_on_error(outputStream* st) const {

   this->CollectedHeap::print_on_error(st);

   if (UseParallelOldGC) {

     st->cr();

     PSParallelCompact::print_on_error(st);

   }

 }

 void ParallelScavengeHeap::gc_threads_do(ThreadClosure* tc) const {

   PSScavenge::gc_task_manager()->threads_do(tc);

 }

 void ParallelScavengeHeap::print_gc_threads_on(outputStream* st) const {

   PSScavenge::gc_task_manager()->print_threads_on(st);

 }

 void ParallelScavengeHeap::print_tracing_info() const {

   if (TraceGen0Time) {

     double time = PSScavenge::accumulated_time()->seconds();

     tty->print_cr("[Accumulated GC generation 0 time %3.7f secs]", time);

   }

   if (TraceGen1Time) {

     double time = UseParallelOldGC ? PSParallelCompact::accumulated_time()->seconds() : PSMarkSweep::accumulated_time()->seconds();

     tty->print_cr("[Accumulated GC generation 1 time %3.7f secs]", time);

   }

 }

 void ParallelScavengeHeap::verify(bool silent, VerifyOption option /* ignored */) {

   // Why do we need the total_collections()-filter below?

   if (total_collections() > 0) {

     if (!silent) {

       gclog_or_tty->print("tenured ");

     }

     old_gen()->verify();

     if (!silent) {

       gclog_or_tty->print("eden ");

     }

     young_gen()->verify();

   }

 }

 void ParallelScavengeHeap::print_heap_change(size_t prev_used) {

   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);

   }

 }

 void ParallelScavengeHeap::trace_heap(GCWhen::Type when, GCTracer* gc_tracer) {

   const PSHeapSummary& heap_summary = create_ps_heap_summary();

   gc_tracer->report_gc_heap_summary(when, heap_summary);

   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();

   gc_tracer->report_metaspace_summary(when, metaspace_summary);

 }

 ParallelScavengeHeap* ParallelScavengeHeap::heap() {

   assert(_psh != NULL, "Uninitialized access to ParallelScavengeHeap::heap()");

   assert(_psh->kind() == CollectedHeap::ParallelScavengeHeap, "not a parallel scavenge heap");

   return _psh;

 }

 // Before delegating the resize to the young generation,

 // the reserved space for the young and old generations

 // may be changed to accomodate the desired resize.

 void ParallelScavengeHeap::resize_young_gen(size_t eden_size,

     size_t survivor_size) {

   if (UseAdaptiveGCBoundary) {

     if (size_policy()->bytes_absorbed_from_eden() != 0) {

       size_policy()->reset_bytes_absorbed_from_eden();

       return;  // The generation changed size already.

     }

     gens()->adjust_boundary_for_young_gen_needs(eden_size, survivor_size);

   }

   // Delegate the resize to the generation.

   _young_gen->resize(eden_size, survivor_size);

 }

 // Before delegating the resize to the old generation,

 // the reserved space for the young and old generations

 // may be changed to accomodate the desired resize.

 void ParallelScavengeHeap::resize_old_gen(size_t desired_free_space) {

   if (UseAdaptiveGCBoundary) {

     if (size_policy()->bytes_absorbed_from_eden() != 0) {

       size_policy()->reset_bytes_absorbed_from_eden();

       return;  // The generation changed size already.

     }

     gens()->adjust_boundary_for_old_gen_needs(desired_free_space);

   }

   // Delegate the resize to the generation.

   _old_gen->resize(desired_free_space);

 }

 ParallelScavengeHeap::ParStrongRootsScope::ParStrongRootsScope() {

   // nothing particular

 }

 ParallelScavengeHeap::ParStrongRootsScope::~ParStrongRootsScope() {

   // nothing particular

 }

 #ifndef PRODUCT

 void ParallelScavengeHeap::record_gen_tops_before_GC() {

   if (ZapUnusedHeapArea) {

     young_gen()->record_spaces_top();

     old_gen()->record_spaces_top();

   }

 }

 void ParallelScavengeHeap::gen_mangle_unused_area() {

   if (ZapUnusedHeapArea) {

     young_gen()->eden_space()->mangle_unused_area();

     young_gen()->to_space()->mangle_unused_area();

     young_gen()->from_space()->mangle_unused_area();

     old_gen()->object_space()->mangle_unused_area();

   }

 }

 #endif