jdk8-mips64-public/hotspot: src/share/vm/memory/genCollectedHeap.cpp@9f28a4cac6d9 (annotated)

src/share/vm/memory/genCollectedHeap.cpp@9f28a4cac6d9 (annotated)

src/share/vm/memory/genCollectedHeap.cpp

Wed, 31 Jul 2019 14:28:51 -0400

author: kbarrett
date: Wed, 31 Jul 2019 14:28:51 -0400
changeset 9787: 9f28a4cac6d9
parent 9665: a8441ccaff15
child 9806: 758c07667682
child 9896: 1b8c45b8216a
permissions: -rw-r--r--

8048556: Unnecessary GCLocker-initiated young GCs
Summary: Fixed recognition of unnecessary GCLocker collections.
Reviewed-by: pliden, tschatzl
Contributed-by: johnc@azul.com

 /*
  * Copyright (c) 2000, 2016, 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
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "classfile/symbolTable.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmSymbols.hpp"
 #include "code/codeCache.hpp"
 #include "code/icBuffer.hpp"
 #include "gc_implementation/shared/collectorCounters.hpp"
 #include "gc_implementation/shared/gcTrace.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/management.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 root scanning.
 enum GCH_strong_roots_tasks {
   GCH_PS_Universe_oops_do,
   GCH_PS_JNIHandles_oops_do,
   GCH_PS_ObjectSynchronizer_oops_do,
   GCH_PS_FlatProfiler_oops_do,
   GCH_PS_Management_oops_do,
   GCH_PS_SystemDictionary_oops_do,
   GCH_PS_ClassLoaderDataGraph_oops_do,
   GCH_PS_jvmti_oops_do,
   GCH_PS_CodeCache_oops_do,
   GCH_PS_younger_gens,
   // Leave this one last.
   GCH_PS_NumElements
 };
 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
   SharedHeap(policy),
   _gen_policy(policy),
   _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
   _full_collections_completed(0)
 {
   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::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";
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
     // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
     // so we can assume here that the next GC id is what we want.
     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
     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
         // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
         // so we can assume here that the next GC id is what we want.
         GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
         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);
   set_n_termination(t);
 }
 void GenCollectedHeap::set_n_termination(uint t) {
   _process_strong_tasks->set_n_threads(t);
 }
 #ifdef ASSERT
 class AssertNonScavengableClosure: public OopClosure {
 public:
   virtual void do_oop(oop* p) {
     assert(!Universe::heap()->is_in_partial_collection(*p),
       "Referent should not be scavengable.");  }
   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 };
 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 #endif
 void GenCollectedHeap::process_roots(bool activate_scope,
                                      ScanningOption so,
                                      OopClosure* strong_roots,
                                      OopClosure* weak_roots,
                                      CLDClosure* strong_cld_closure,
                                      CLDClosure* weak_cld_closure,
                                      CodeBlobToOopClosure* code_roots) {
   StrongRootsScope srs(this, activate_scope);
   // General roots.
   assert(_strong_roots_parity != 0, "must have called prologue code");
   assert(code_roots != NULL, "code root closure should always be set");
   // _n_termination for _process_strong_tasks should be set up stream
   // in a method not running in a GC worker.  Otherwise the GC worker
   // could be trying to change the termination condition while the task
   // is executing in another GC worker.
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
     ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
   }
   // Some CLDs contained in the thread frames should be considered strong.
   // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
   CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
   // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
   CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
   Threads::possibly_parallel_oops_do(strong_roots, roots_from_clds_p, roots_from_code_p);
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
     Universe::oops_do(strong_roots);
   }
   // Global (strong) JNI handles
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
     JNIHandles::oops_do(strong_roots);
   }
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
     ObjectSynchronizer::oops_do(strong_roots);
   }
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
     FlatProfiler::oops_do(strong_roots);
   }
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
     Management::oops_do(strong_roots);
   }
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
     JvmtiExport::oops_do(strong_roots);
   }
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
     SystemDictionary::roots_oops_do(strong_roots, weak_roots);
   }
   // All threads execute the following. A specific chunk of buckets
   // from the StringTable are the individual tasks.
   if (weak_roots != NULL) {
     if (CollectedHeap::use_parallel_gc_threads()) {
       StringTable::possibly_parallel_oops_do(weak_roots);
     } else {
       StringTable::oops_do(weak_roots);
     }
   }
   if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
     if (so & SO_ScavengeCodeCache) {
       assert(code_roots != NULL, "must supply closure for code cache");
       // We only visit parts of the CodeCache when scavenging.
       CodeCache::scavenge_root_nmethods_do(code_roots);
     }
     if (so & SO_AllCodeCache) {
       assert(code_roots != NULL, "must supply closure for code cache");
       // CMSCollector uses this to do intermediate-strength collections.
       // We scan the entire code cache, since CodeCache::do_unloading is not called.
       CodeCache::blobs_do(code_roots);
     }
     // Verify that the code cache contents are not subject to
     // movement by a scavenging collection.
     DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
     DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
   }
 }
 void GenCollectedHeap::gen_process_roots(int level,
                                          bool younger_gens_as_roots,
                                          bool activate_scope,
                                          ScanningOption so,
                                          bool only_strong_roots,
                                          OopsInGenClosure* not_older_gens,
                                          OopsInGenClosure* older_gens,
                                          CLDClosure* cld_closure) {
   const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
   bool is_moving_collection = false;
   if (level == 0 || is_adjust_phase) {
     // young collections are always moving
     is_moving_collection = true;
   }
   MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
   OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
   CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
   process_roots(activate_scope, so,
                 not_older_gens, weak_roots,
                 cld_closure, weak_cld_closure,
                 &mark_code_closure);
   if (younger_gens_as_roots) {
     if (!_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();
   }
   _process_strong_tasks->all_tasks_completed();
 }
 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
   JNIHandles::weak_oops_do(root_closure);
   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();
 }
 // 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 if ((cause == GCCause::_wb_young_gc) ||
              (cause == GCCause::_gc_locker)) {
     // minor collection for WhiteBox or GCLocker.
     // _gc_locker collections upgraded by GCLockerInvokesConcurrent
     // are handled above and never discarded.
     collect(cause, 0);
   } 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();
   if (GC_locker::should_discard(cause, gc_count_before)) {
     return;
   }
   {
     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) {
   do_collection(true                 /* full */,
                 clear_all_soft_refs  /* clear_all_soft_refs */,
 /* size */,
                 false                /* is_tlab */,
                 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 (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
     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 */,
 /* 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, p2i((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::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::tlab_used(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_used();
     }
   }
   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);
   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("%s", 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, (int64_t) retVal);)
     return 0;
   }
   return retVal;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/genCollectedHeap.cpp@9f28a4cac6d9 (annotated)

src/share/vm/memory/genCollectedHeap.cpp