jdk8-mips64-public/hotspot: src/share/vm/memory/defNewGeneration.cpp@2c6ef90f030a (annotated)

src/share/vm/memory/defNewGeneration.cpp@2c6ef90f030a (annotated)

src/share/vm/memory/defNewGeneration.cpp

Mon, 07 Jul 2014 10:12:40 +0200

author: stefank
date: Mon, 07 Jul 2014 10:12:40 +0200
changeset 6992: 2c6ef90f030a
parent 6971: 7426d8d76305
child 7031: ee019285a52c
permissions: -rw-r--r--

8049421: G1 Class Unloading after completing a concurrent mark cycle
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
Contributed-by: stefan.karlsson@oracle.com, mikael.gerdin@oracle.com

 /*
  * 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
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "gc_implementation/shared/collectorCounters.hpp"
 #include "gc_implementation/shared/gcPolicyCounters.hpp"
 #include "gc_implementation/shared/gcHeapSummary.hpp"
 #include "gc_implementation/shared/gcTimer.hpp"
 #include "gc_implementation/shared/gcTraceTime.hpp"
 #include "gc_implementation/shared/gcTrace.hpp"
 #include "gc_implementation/shared/spaceDecorator.hpp"
 #include "memory/defNewGeneration.inline.hpp"
 #include "memory/gcLocker.inline.hpp"
 #include "memory/genCollectedHeap.hpp"
 #include "memory/genOopClosures.inline.hpp"
 #include "memory/genRemSet.hpp"
 #include "memory/generationSpec.hpp"
 #include "memory/iterator.hpp"
 #include "memory/referencePolicy.hpp"
 #include "memory/space.inline.hpp"
 #include "oops/instanceRefKlass.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/java.hpp"
 #include "runtime/prefetch.inline.hpp"
 #include "runtime/thread.inline.hpp"
 #include "utilities/copy.hpp"
 #include "utilities/stack.inline.hpp"
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 //
 // DefNewGeneration functions.
 // Methods of protected closure types.
 DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* g) : _g(g) {
   assert(g->level() == 0, "Optimized for youngest gen.");
 }
 bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) {
   return (HeapWord*)p >= _g->reserved().end() || p->is_forwarded();
 }
 DefNewGeneration::KeepAliveClosure::
 KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) {
   GenRemSet* rs = GenCollectedHeap::heap()->rem_set();
   assert(rs->rs_kind() == GenRemSet::CardTable, "Wrong rem set kind.");
   _rs = (CardTableRS*)rs;
 }
 void DefNewGeneration::KeepAliveClosure::do_oop(oop* p)       { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
 void DefNewGeneration::KeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
 DefNewGeneration::FastKeepAliveClosure::
 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) :
   DefNewGeneration::KeepAliveClosure(cl) {
   _boundary = g->reserved().end();
 }
 void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p)       { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
 void DefNewGeneration::FastKeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
 DefNewGeneration::EvacuateFollowersClosure::
 EvacuateFollowersClosure(GenCollectedHeap* gch, int level,
                          ScanClosure* cur, ScanClosure* older) :
   _gch(gch), _level(level),
   _scan_cur_or_nonheap(cur), _scan_older(older)
 {}
 void DefNewGeneration::EvacuateFollowersClosure::do_void() {
   do {
     _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
                                        _scan_older);
   } while (!_gch->no_allocs_since_save_marks(_level));
 }
 DefNewGeneration::FastEvacuateFollowersClosure::
 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level,
                              DefNewGeneration* gen,
                              FastScanClosure* cur, FastScanClosure* older) :
   _gch(gch), _level(level), _gen(gen),
   _scan_cur_or_nonheap(cur), _scan_older(older)
 {}
 void DefNewGeneration::FastEvacuateFollowersClosure::do_void() {
   do {
     _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
                                        _scan_older);
   } while (!_gch->no_allocs_since_save_marks(_level));
   guarantee(_gen->promo_failure_scan_is_complete(), "Failed to finish scan");
 }
 ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) :
     OopsInKlassOrGenClosure(g), _g(g), _gc_barrier(gc_barrier)
 {
   assert(_g->level() == 0, "Optimized for youngest generation");
   _boundary = _g->reserved().end();
 }
 void ScanClosure::do_oop(oop* p)       { ScanClosure::do_oop_work(p); }
 void ScanClosure::do_oop(narrowOop* p) { ScanClosure::do_oop_work(p); }
 FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) :
     OopsInKlassOrGenClosure(g), _g(g), _gc_barrier(gc_barrier)
 {
   assert(_g->level() == 0, "Optimized for youngest generation");
   _boundary = _g->reserved().end();
 }
 void FastScanClosure::do_oop(oop* p)       { FastScanClosure::do_oop_work(p); }
 void FastScanClosure::do_oop(narrowOop* p) { FastScanClosure::do_oop_work(p); }
 void KlassScanClosure::do_klass(Klass* klass) {
 #ifndef PRODUCT
   if (TraceScavenge) {
     ResourceMark rm;
     gclog_or_tty->print_cr("KlassScanClosure::do_klass %p, %s, dirty: %s",
                            klass,
                            klass->external_name(),
                            klass->has_modified_oops() ? "true" : "false");
   }
 #endif
   // If the klass has not been dirtied we know that there's
   // no references into  the young gen and we can skip it.
   if (klass->has_modified_oops()) {
     if (_accumulate_modified_oops) {
       klass->accumulate_modified_oops();
     }
     // Clear this state since we're going to scavenge all the metadata.
     klass->clear_modified_oops();
     // Tell the closure which Klass is being scanned so that it can be dirtied
     // if oops are left pointing into the young gen.
     _scavenge_closure->set_scanned_klass(klass);
     klass->oops_do(_scavenge_closure);
     _scavenge_closure->set_scanned_klass(NULL);
   }
 }
 ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) :
   _g(g)
 {
   assert(_g->level() == 0, "Optimized for youngest generation");
   _boundary = _g->reserved().end();
 }
 void ScanWeakRefClosure::do_oop(oop* p)       { ScanWeakRefClosure::do_oop_work(p); }
 void ScanWeakRefClosure::do_oop(narrowOop* p) { ScanWeakRefClosure::do_oop_work(p); }
 void FilteringClosure::do_oop(oop* p)       { FilteringClosure::do_oop_work(p); }
 void FilteringClosure::do_oop(narrowOop* p) { FilteringClosure::do_oop_work(p); }
 KlassScanClosure::KlassScanClosure(OopsInKlassOrGenClosure* scavenge_closure,
                                    KlassRemSet* klass_rem_set)
     : _scavenge_closure(scavenge_closure),
       _accumulate_modified_oops(klass_rem_set->accumulate_modified_oops()) {}
 DefNewGeneration::DefNewGeneration(ReservedSpace rs,
                                    size_t initial_size,
                                    int level,
                                    const char* policy)
   : Generation(rs, initial_size, level),
     _promo_failure_drain_in_progress(false),
     _should_allocate_from_space(false)
 {
   MemRegion cmr((HeapWord*)_virtual_space.low(),
                 (HeapWord*)_virtual_space.high());
   Universe::heap()->barrier_set()->resize_covered_region(cmr);
   if (GenCollectedHeap::heap()->collector_policy()->has_soft_ended_eden()) {
     _eden_space = new ConcEdenSpace(this);
   } else {
     _eden_space = new EdenSpace(this);
   }
   _from_space = new ContiguousSpace();
   _to_space   = new ContiguousSpace();
   if (_eden_space == NULL || _from_space == NULL || _to_space == NULL)
     vm_exit_during_initialization("Could not allocate a new gen space");
   // Compute the maximum eden and survivor space sizes. These sizes
   // are computed assuming the entire reserved space is committed.
   // These values are exported as performance counters.
   uintx alignment = GenCollectedHeap::heap()->collector_policy()->space_alignment();
   uintx size = _virtual_space.reserved_size();
   _max_survivor_size = compute_survivor_size(size, alignment);
   _max_eden_size = size - (2*_max_survivor_size);
   // allocate the performance counters
   // Generation counters -- generation 0, 3 subspaces
   _gen_counters = new GenerationCounters("new", 0, 3, &_virtual_space);
   _gc_counters = new CollectorCounters(policy, 0);
   _eden_counters = new CSpaceCounters("eden", 0, _max_eden_size, _eden_space,
                                       _gen_counters);
   _from_counters = new CSpaceCounters("s0", 1, _max_survivor_size, _from_space,
                                       _gen_counters);
   _to_counters = new CSpaceCounters("s1", 2, _max_survivor_size, _to_space,
                                     _gen_counters);
   compute_space_boundaries(0, SpaceDecorator::Clear, SpaceDecorator::Mangle);
   update_counters();
   _next_gen = NULL;
   _tenuring_threshold = MaxTenuringThreshold;
   _pretenure_size_threshold_words = PretenureSizeThreshold >> LogHeapWordSize;
   _gc_timer = new (ResourceObj::C_HEAP, mtGC) STWGCTimer();
 }
 void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size,
                                                 bool clear_space,
                                                 bool mangle_space) {
   uintx alignment =
     GenCollectedHeap::heap()->collector_policy()->space_alignment();
   // If the spaces are being cleared (only done at heap initialization
   // currently), the survivor spaces need not be empty.
   // Otherwise, no care is taken for used areas in the survivor spaces
   // so check.
   assert(clear_space || (to()->is_empty() && from()->is_empty()),
     "Initialization of the survivor spaces assumes these are empty");
   // Compute sizes
   uintx size = _virtual_space.committed_size();
   uintx survivor_size = compute_survivor_size(size, alignment);
   uintx eden_size = size - (2*survivor_size);
   assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
   if (eden_size < minimum_eden_size) {
     // May happen due to 64Kb rounding, if so adjust eden size back up
     minimum_eden_size = align_size_up(minimum_eden_size, alignment);
     uintx maximum_survivor_size = (size - minimum_eden_size) / 2;
     uintx unaligned_survivor_size =
       align_size_down(maximum_survivor_size, alignment);
     survivor_size = MAX2(unaligned_survivor_size, alignment);
     eden_size = size - (2*survivor_size);
     assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
     assert(eden_size >= minimum_eden_size, "just checking");
   }
   char *eden_start = _virtual_space.low();
   char *from_start = eden_start + eden_size;
   char *to_start   = from_start + survivor_size;
   char *to_end     = to_start   + survivor_size;
   assert(to_end == _virtual_space.high(), "just checking");
   assert(Space::is_aligned((HeapWord*)eden_start), "checking alignment");
   assert(Space::is_aligned((HeapWord*)from_start), "checking alignment");
   assert(Space::is_aligned((HeapWord*)to_start),   "checking alignment");
   MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)from_start);
   MemRegion fromMR((HeapWord*)from_start, (HeapWord*)to_start);
   MemRegion toMR  ((HeapWord*)to_start, (HeapWord*)to_end);
   // A minimum eden size implies that there is a part of eden that
   // is being used and that affects the initialization of any
   // newly formed eden.
   bool live_in_eden = minimum_eden_size > 0;
   // If not clearing the spaces, do some checking to verify that
   // the space are already mangled.
   if (!clear_space) {
     // Must check mangling before the spaces are reshaped.  Otherwise,
     // the bottom or end of one space may have moved into another
     // a failure of the check may not correctly indicate which space
     // is not properly mangled.
     if (ZapUnusedHeapArea) {
       HeapWord* limit = (HeapWord*) _virtual_space.high();
       eden()->check_mangled_unused_area(limit);
       from()->check_mangled_unused_area(limit);
         to()->check_mangled_unused_area(limit);
     }
   }
   // Reset the spaces for their new regions.
   eden()->initialize(edenMR,
                      clear_space && !live_in_eden,
                      SpaceDecorator::Mangle);
   // If clear_space and live_in_eden, we will not have cleared any
   // portion of eden above its top. This can cause newly
   // expanded space not to be mangled if using ZapUnusedHeapArea.
   // We explicitly do such mangling here.
   if (ZapUnusedHeapArea && clear_space && live_in_eden && mangle_space) {
     eden()->mangle_unused_area();
   }
   from()->initialize(fromMR, clear_space, mangle_space);
   to()->initialize(toMR, clear_space, mangle_space);
   // Set next compaction spaces.
   eden()->set_next_compaction_space(from());
   // The to-space is normally empty before a compaction so need
   // not be considered.  The exception is during promotion
   // failure handling when to-space can contain live objects.
   from()->set_next_compaction_space(NULL);
 }
 void DefNewGeneration::swap_spaces() {
   ContiguousSpace* s = from();
   _from_space        = to();
   _to_space          = s;
   eden()->set_next_compaction_space(from());
   // The to-space is normally empty before a compaction so need
   // not be considered.  The exception is during promotion
   // failure handling when to-space can contain live objects.
   from()->set_next_compaction_space(NULL);
   if (UsePerfData) {
     CSpaceCounters* c = _from_counters;
     _from_counters = _to_counters;
     _to_counters = c;
   }
 }
 bool DefNewGeneration::expand(size_t bytes) {
   MutexLocker x(ExpandHeap_lock);
   HeapWord* prev_high = (HeapWord*) _virtual_space.high();
   bool success = _virtual_space.expand_by(bytes);
   if (success && ZapUnusedHeapArea) {
     // Mangle newly committed space immediately because it
     // can be done here more simply that after the new
     // spaces have been computed.
     HeapWord* new_high = (HeapWord*) _virtual_space.high();
     MemRegion mangle_region(prev_high, new_high);
     SpaceMangler::mangle_region(mangle_region);
   }
   // Do not attempt an expand-to-the reserve size.  The
   // request should properly observe the maximum size of
   // the generation so an expand-to-reserve should be
   // unnecessary.  Also a second call to expand-to-reserve
   // value potentially can cause an undue expansion.
   // For example if the first expand fail for unknown reasons,
   // but the second succeeds and expands the heap to its maximum
   // value.
   if (GC_locker::is_active()) {
     if (PrintGC && Verbose) {
       gclog_or_tty->print_cr("Garbage collection disabled, "
         "expanded heap instead");
     }
   }
   return success;
 }
 void DefNewGeneration::compute_new_size() {
   // This is called after a gc that includes the following generation
   // (which is required to exist.)  So from-space will normally be empty.
   // Note that we check both spaces, since if scavenge failed they revert roles.
   // If not we bail out (otherwise we would have to relocate the objects)
   if (!from()->is_empty() || !to()->is_empty()) {
     return;
   }
   int next_level = level() + 1;
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   assert(next_level < gch->_n_gens,
          "DefNewGeneration cannot be an oldest gen");
   Generation* next_gen = gch->_gens[next_level];
   size_t old_size = next_gen->capacity();
   size_t new_size_before = _virtual_space.committed_size();
   size_t min_new_size = spec()->init_size();
   size_t max_new_size = reserved().byte_size();
   assert(min_new_size <= new_size_before &&
          new_size_before <= max_new_size,
          "just checking");
   // All space sizes must be multiples of Generation::GenGrain.
   size_t alignment = Generation::GenGrain;
   // Compute desired new generation size based on NewRatio and
   // NewSizeThreadIncrease
   size_t desired_new_size = old_size/NewRatio;
   int threads_count = Threads::number_of_non_daemon_threads();
   size_t thread_increase_size = threads_count * NewSizeThreadIncrease;
   desired_new_size = align_size_up(desired_new_size + thread_increase_size, alignment);
   // Adjust new generation size
   desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size);
   assert(desired_new_size <= max_new_size, "just checking");
   bool changed = false;
   if (desired_new_size > new_size_before) {
     size_t change = desired_new_size - new_size_before;
     assert(change % alignment == 0, "just checking");
     if (expand(change)) {
        changed = true;
     }
     // If the heap failed to expand to the desired size,
     // "changed" will be false.  If the expansion failed
     // (and at this point it was expected to succeed),
     // ignore the failure (leaving "changed" as false).
   }
   if (desired_new_size < new_size_before && eden()->is_empty()) {
     // bail out of shrinking if objects in eden
     size_t change = new_size_before - desired_new_size;
     assert(change % alignment == 0, "just checking");
     _virtual_space.shrink_by(change);
     changed = true;
   }
   if (changed) {
     // The spaces have already been mangled at this point but
     // may not have been cleared (set top = bottom) and should be.
     // Mangling was done when the heap was being expanded.
     compute_space_boundaries(eden()->used(),
                              SpaceDecorator::Clear,
                              SpaceDecorator::DontMangle);
     MemRegion cmr((HeapWord*)_virtual_space.low(),
                   (HeapWord*)_virtual_space.high());
     Universe::heap()->barrier_set()->resize_covered_region(cmr);
     if (Verbose && PrintGC) {
       size_t new_size_after  = _virtual_space.committed_size();
       size_t eden_size_after = eden()->capacity();
       size_t survivor_size_after = from()->capacity();
       gclog_or_tty->print("New generation size " SIZE_FORMAT "K->"
         SIZE_FORMAT "K [eden="
         SIZE_FORMAT "K,survivor=" SIZE_FORMAT "K]",
         new_size_before/K, new_size_after/K,
         eden_size_after/K, survivor_size_after/K);
       if (WizardMode) {
         gclog_or_tty->print("[allowed " SIZE_FORMAT "K extra for %d threads]",
           thread_increase_size/K, threads_count);
       }
       gclog_or_tty->cr();
     }
   }
 }
 void DefNewGeneration::younger_refs_iterate(OopsInGenClosure* cl) {
   assert(false, "NYI -- are you sure you want to call this?");
 }
 size_t DefNewGeneration::capacity() const {
   return eden()->capacity()
        + from()->capacity();  // to() is only used during scavenge
 }
 size_t DefNewGeneration::used() const {
   return eden()->used()
        + from()->used();      // to() is only used during scavenge
 }
 size_t DefNewGeneration::free() const {
   return eden()->free()
        + from()->free();      // to() is only used during scavenge
 }
 size_t DefNewGeneration::max_capacity() const {
   const size_t alignment = GenCollectedHeap::heap()->collector_policy()->space_alignment();
   const size_t reserved_bytes = reserved().byte_size();
   return reserved_bytes - compute_survivor_size(reserved_bytes, alignment);
 }
 size_t DefNewGeneration::unsafe_max_alloc_nogc() const {
   return eden()->free();
 }
 size_t DefNewGeneration::capacity_before_gc() const {
   return eden()->capacity();
 }
 size_t DefNewGeneration::contiguous_available() const {
   return eden()->free();
 }
 HeapWord** DefNewGeneration::top_addr() const { return eden()->top_addr(); }
 HeapWord** DefNewGeneration::end_addr() const { return eden()->end_addr(); }
 void DefNewGeneration::object_iterate(ObjectClosure* blk) {
   eden()->object_iterate(blk);
   from()->object_iterate(blk);
 }
 void DefNewGeneration::space_iterate(SpaceClosure* blk,
                                      bool usedOnly) {
   blk->do_space(eden());
   blk->do_space(from());
   blk->do_space(to());
 }
 // The last collection bailed out, we are running out of heap space,
 // so we try to allocate the from-space, too.
 HeapWord* DefNewGeneration::allocate_from_space(size_t size) {
   HeapWord* result = NULL;
   if (Verbose && PrintGCDetails) {
     gclog_or_tty->print("DefNewGeneration::allocate_from_space(%u):"
                         "  will_fail: %s"
                         "  heap_lock: %s"
                         "  free: " SIZE_FORMAT,
                         size,
                         GenCollectedHeap::heap()->incremental_collection_will_fail(false /* don't consult_young */) ?
                           "true" : "false",
                         Heap_lock->is_locked() ? "locked" : "unlocked",
                         from()->free());
   }
   if (should_allocate_from_space() || GC_locker::is_active_and_needs_gc()) {
     if (Heap_lock->owned_by_self() ||
         (SafepointSynchronize::is_at_safepoint() &&
          Thread::current()->is_VM_thread())) {
       // If the Heap_lock is not locked by this thread, this will be called
       // again later with the Heap_lock held.
       result = from()->allocate(size);
     } else if (PrintGC && Verbose) {
       gclog_or_tty->print_cr("  Heap_lock is not owned by self");
     }
   } else if (PrintGC && Verbose) {
     gclog_or_tty->print_cr("  should_allocate_from_space: NOT");
   }
   if (PrintGC && Verbose) {
     gclog_or_tty->print_cr("  returns %s", result == NULL ? "NULL" : "object");
   }
   return result;
 }
 HeapWord* DefNewGeneration::expand_and_allocate(size_t size,
                                                 bool   is_tlab,
                                                 bool   parallel) {
   // We don't attempt to expand the young generation (but perhaps we should.)
   return allocate(size, is_tlab);
 }
 void DefNewGeneration::adjust_desired_tenuring_threshold() {
   // Set the desired survivor size to half the real survivor space
   _tenuring_threshold =
     age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize);
 }
 void DefNewGeneration::collect(bool   full,
                                bool   clear_all_soft_refs,
                                size_t size,
                                bool   is_tlab) {
   assert(full || size > 0, "otherwise we don't want to collect");
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   _gc_timer->register_gc_start();
   DefNewTracer gc_tracer;
   gc_tracer.report_gc_start(gch->gc_cause(), _gc_timer->gc_start());
   _next_gen = gch->next_gen(this);
   // If the next generation is too full to accommodate promotion
   // from this generation, pass on collection; let the next generation
   // do it.
   if (!collection_attempt_is_safe()) {
     if (Verbose && PrintGCDetails) {
       gclog_or_tty->print(" :: Collection attempt not safe :: ");
     }
     gch->set_incremental_collection_failed(); // Slight lie: we did not even attempt one
     return;
   }
   assert(to()->is_empty(), "Else not collection_attempt_is_safe");
   init_assuming_no_promotion_failure();
   GCTraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, gc_tracer.gc_id());
   // Capture heap used before collection (for printing).
   size_t gch_prev_used = gch->used();
   gch->trace_heap_before_gc(&gc_tracer);
   SpecializationStats::clear();
   // These can be shared for all code paths
   IsAliveClosure is_alive(this);
   ScanWeakRefClosure scan_weak_ref(this);
   age_table()->clear();
   to()->clear(SpaceDecorator::Mangle);
   gch->rem_set()->prepare_for_younger_refs_iterate(false);
   assert(gch->no_allocs_since_save_marks(0),
          "save marks have not been newly set.");
   // Not very pretty.
   CollectorPolicy* cp = gch->collector_policy();
   FastScanClosure fsc_with_no_gc_barrier(this, false);
   FastScanClosure fsc_with_gc_barrier(this, true);
   KlassScanClosure klass_scan_closure(&fsc_with_no_gc_barrier,
                                       gch->rem_set()->klass_rem_set());
   CLDToKlassAndOopClosure cld_scan_closure(&klass_scan_closure,
                                            &fsc_with_no_gc_barrier,
                                            false);
   set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
   FastEvacuateFollowersClosure evacuate_followers(gch, _level, this,
                                                   &fsc_with_no_gc_barrier,
                                                   &fsc_with_gc_barrier);
   assert(gch->no_allocs_since_save_marks(0),
          "save marks have not been newly set.");
   gch->gen_process_roots(_level,
                          true,  // Process younger gens, if any,
                                 // as strong roots.
                          true,  // activate StrongRootsScope
                          SharedHeap::SO_ScavengeCodeCache,
                          GenCollectedHeap::StrongAndWeakRoots,
                          &fsc_with_no_gc_barrier,
                          &fsc_with_gc_barrier,
                          &cld_scan_closure);
   // "evacuate followers".
   evacuate_followers.do_void();
   FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
   ReferenceProcessor* rp = ref_processor();
   rp->setup_policy(clear_all_soft_refs);
   const ReferenceProcessorStats& stats =
   rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers,
                                     NULL, _gc_timer, gc_tracer.gc_id());
   gc_tracer.report_gc_reference_stats(stats);
   if (!_promotion_failed) {
     // Swap the survivor spaces.
     eden()->clear(SpaceDecorator::Mangle);
     from()->clear(SpaceDecorator::Mangle);
     if (ZapUnusedHeapArea) {
       // This is now done here because of the piece-meal mangling which
       // can check for valid mangling at intermediate points in the
       // collection(s).  When a minor collection fails to collect
       // sufficient space resizing of the young generation can occur
       // an redistribute the spaces in the young generation.  Mangle
       // here so that unzapped regions don't get distributed to
       // other spaces.
       to()->mangle_unused_area();
     }
     swap_spaces();
     assert(to()->is_empty(), "to space should be empty now");
     adjust_desired_tenuring_threshold();
     // A successful scavenge should restart the GC time limit count which is
     // for full GC's.
     AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy();
     size_policy->reset_gc_overhead_limit_count();
     if (PrintGC && !PrintGCDetails) {
       gch->print_heap_change(gch_prev_used);
     }
     assert(!gch->incremental_collection_failed(), "Should be clear");
   } else {
     assert(_promo_failure_scan_stack.is_empty(), "post condition");
     _promo_failure_scan_stack.clear(true); // Clear cached segments.
     remove_forwarding_pointers();
     if (PrintGCDetails) {
       gclog_or_tty->print(" (promotion failed) ");
     }
     // Add to-space to the list of space to compact
     // when a promotion failure has occurred.  In that
     // case there can be live objects in to-space
     // as a result of a partial evacuation of eden
     // and from-space.
     swap_spaces();   // For uniformity wrt ParNewGeneration.
     from()->set_next_compaction_space(to());
     gch->set_incremental_collection_failed();
     // Inform the next generation that a promotion failure occurred.
     _next_gen->promotion_failure_occurred();
     gc_tracer.report_promotion_failed(_promotion_failed_info);
     // Reset the PromotionFailureALot counters.
     NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
   }
   // set new iteration safe limit for the survivor spaces
   from()->set_concurrent_iteration_safe_limit(from()->top());
   to()->set_concurrent_iteration_safe_limit(to()->top());
   SpecializationStats::print();
   // We need to use a monotonically non-decreasing time in ms
   // or we will see time-warp warnings and os::javaTimeMillis()
   // does not guarantee monotonicity.
   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
   update_time_of_last_gc(now);
   gch->trace_heap_after_gc(&gc_tracer);
   gc_tracer.report_tenuring_threshold(tenuring_threshold());
   _gc_timer->register_gc_end();
   gc_tracer.report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
 }
 class RemoveForwardPointerClosure: public ObjectClosure {
 public:
   void do_object(oop obj) {
     obj->init_mark();
   }
 };
 void DefNewGeneration::init_assuming_no_promotion_failure() {
   _promotion_failed = false;
   _promotion_failed_info.reset();
   from()->set_next_compaction_space(NULL);
 }
 void DefNewGeneration::remove_forwarding_pointers() {
   RemoveForwardPointerClosure rspc;
   eden()->object_iterate(&rspc);
   from()->object_iterate(&rspc);
   // Now restore saved marks, if any.
   assert(_objs_with_preserved_marks.size() == _preserved_marks_of_objs.size(),
          "should be the same");
   while (!_objs_with_preserved_marks.is_empty()) {
     oop obj   = _objs_with_preserved_marks.pop();
     markOop m = _preserved_marks_of_objs.pop();
     obj->set_mark(m);
   }
   _objs_with_preserved_marks.clear(true);
   _preserved_marks_of_objs.clear(true);
 }
 void DefNewGeneration::preserve_mark(oop obj, markOop m) {
   assert(_promotion_failed && m->must_be_preserved_for_promotion_failure(obj),
          "Oversaving!");
   _objs_with_preserved_marks.push(obj);
   _preserved_marks_of_objs.push(m);
 }
 void DefNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) {
   if (m->must_be_preserved_for_promotion_failure(obj)) {
     preserve_mark(obj, m);
   }
 }
 void DefNewGeneration::handle_promotion_failure(oop old) {
   if (PrintPromotionFailure && !_promotion_failed) {
     gclog_or_tty->print(" (promotion failure size = " SIZE_FORMAT ") ",
                         old->size());
   }
   _promotion_failed = true;
   _promotion_failed_info.register_copy_failure(old->size());
   preserve_mark_if_necessary(old, old->mark());
   // forward to self
   old->forward_to(old);
   _promo_failure_scan_stack.push(old);
   if (!_promo_failure_drain_in_progress) {
     // prevent recursion in copy_to_survivor_space()
     _promo_failure_drain_in_progress = true;
     drain_promo_failure_scan_stack();
     _promo_failure_drain_in_progress = false;
   }
 }
 oop DefNewGeneration::copy_to_survivor_space(oop old) {
   assert(is_in_reserved(old) && !old->is_forwarded(),
          "shouldn't be scavenging this oop");
   size_t s = old->size();
   oop obj = NULL;
   // Try allocating obj in to-space (unless too old)
   if (old->age() < tenuring_threshold()) {
     obj = (oop) to()->allocate(s);
   }
   // Otherwise try allocating obj tenured
   if (obj == NULL) {
     obj = _next_gen->promote(old, s);
     if (obj == NULL) {
       handle_promotion_failure(old);
       return old;
     }
   } else {
     // Prefetch beyond obj
     const intx interval = PrefetchCopyIntervalInBytes;
     Prefetch::write(obj, interval);
     // Copy obj
     Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)obj, s);
     // Increment age if obj still in new generation
     obj->incr_age();
     age_table()->add(obj, s);
   }
   // Done, insert forward pointer to obj in this header
   old->forward_to(obj);
   return obj;
 }
 void DefNewGeneration::drain_promo_failure_scan_stack() {
   while (!_promo_failure_scan_stack.is_empty()) {
      oop obj = _promo_failure_scan_stack.pop();
      obj->oop_iterate(_promo_failure_scan_stack_closure);
   }
 }
 void DefNewGeneration::save_marks() {
   eden()->set_saved_mark();
   to()->set_saved_mark();
   from()->set_saved_mark();
 }
 void DefNewGeneration::reset_saved_marks() {
   eden()->reset_saved_mark();
   to()->reset_saved_mark();
   from()->reset_saved_mark();
 }
 bool DefNewGeneration::no_allocs_since_save_marks() {
   assert(eden()->saved_mark_at_top(), "Violated spec - alloc in eden");
   assert(from()->saved_mark_at_top(), "Violated spec - alloc in from");
   return to()->saved_mark_at_top();
 }
 #define DefNew_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
                                                                 \
 void DefNewGeneration::                                         \
 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) {   \
   cl->set_generation(this);                                     \
   eden()->oop_since_save_marks_iterate##nv_suffix(cl);          \
   to()->oop_since_save_marks_iterate##nv_suffix(cl);            \
   from()->oop_since_save_marks_iterate##nv_suffix(cl);          \
   cl->reset_generation();                                       \
   save_marks();                                                 \
 }
 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DEFN)
 #undef DefNew_SINCE_SAVE_MARKS_DEFN
 void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor,
                                          size_t max_alloc_words) {
   if (requestor == this || _promotion_failed) return;
   assert(requestor->level() > level(), "DefNewGeneration must be youngest");
   /* $$$ Assert this?  "trace" is a "MarkSweep" function so that's not appropriate.
   if (to_space->top() > to_space->bottom()) {
     trace("to_space not empty when contribute_scratch called");
   }
   */
   ContiguousSpace* to_space = to();
   assert(to_space->end() >= to_space->top(), "pointers out of order");
   size_t free_words = pointer_delta(to_space->end(), to_space->top());
   if (free_words >= MinFreeScratchWords) {
     ScratchBlock* sb = (ScratchBlock*)to_space->top();
     sb->num_words = free_words;
     sb->next = list;
     list = sb;
   }
 }
 void DefNewGeneration::reset_scratch() {
   // If contributing scratch in to_space, mangle all of
   // to_space if ZapUnusedHeapArea.  This is needed because
   // top is not maintained while using to-space as scratch.
   if (ZapUnusedHeapArea) {
     to()->mangle_unused_area_complete();
   }
 }
 bool DefNewGeneration::collection_attempt_is_safe() {
   if (!to()->is_empty()) {
     if (Verbose && PrintGCDetails) {
       gclog_or_tty->print(" :: to is not empty :: ");
     }
     return false;
   }
   if (_next_gen == NULL) {
     GenCollectedHeap* gch = GenCollectedHeap::heap();
     _next_gen = gch->next_gen(this);
   }
   return _next_gen->promotion_attempt_is_safe(used());
 }
 void DefNewGeneration::gc_epilogue(bool full) {
   DEBUG_ONLY(static bool seen_incremental_collection_failed = false;)
   assert(!GC_locker::is_active(), "We should not be executing here");
   // Check if the heap is approaching full after a collection has
   // been done.  Generally the young generation is empty at
   // a minimum at the end of a collection.  If it is not, then
   // the heap is approaching full.
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   if (full) {
     DEBUG_ONLY(seen_incremental_collection_failed = false;)
     if (!collection_attempt_is_safe() && !_eden_space->is_empty()) {
       if (Verbose && PrintGCDetails) {
         gclog_or_tty->print("DefNewEpilogue: cause(%s), full, not safe, set_failed, set_alloc_from, clear_seen",
                             GCCause::to_string(gch->gc_cause()));
       }
       gch->set_incremental_collection_failed(); // Slight lie: a full gc left us in that state
       set_should_allocate_from_space(); // we seem to be running out of space
     } else {
       if (Verbose && PrintGCDetails) {
         gclog_or_tty->print("DefNewEpilogue: cause(%s), full, safe, clear_failed, clear_alloc_from, clear_seen",
                             GCCause::to_string(gch->gc_cause()));
       }
       gch->clear_incremental_collection_failed(); // We just did a full collection
       clear_should_allocate_from_space(); // if set
     }
   } else {
 #ifdef ASSERT
     // It is possible that incremental_collection_failed() == true
     // here, because an attempted scavenge did not succeed. The policy
     // is normally expected to cause a full collection which should
     // clear that condition, so we should not be here twice in a row
     // with incremental_collection_failed() == true without having done
     // a full collection in between.
     if (!seen_incremental_collection_failed &&
         gch->incremental_collection_failed()) {
       if (Verbose && PrintGCDetails) {
         gclog_or_tty->print("DefNewEpilogue: cause(%s), not full, not_seen_failed, failed, set_seen_failed",
                             GCCause::to_string(gch->gc_cause()));
       }
       seen_incremental_collection_failed = true;
     } else if (seen_incremental_collection_failed) {
       if (Verbose && PrintGCDetails) {
         gclog_or_tty->print("DefNewEpilogue: cause(%s), not full, seen_failed, will_clear_seen_failed",
                             GCCause::to_string(gch->gc_cause()));
       }
       assert(gch->gc_cause() == GCCause::_scavenge_alot ||
              (gch->gc_cause() == GCCause::_java_lang_system_gc && UseConcMarkSweepGC && ExplicitGCInvokesConcurrent) ||
              !gch->incremental_collection_failed(),
              "Twice in a row");
       seen_incremental_collection_failed = false;
     }
 #endif // ASSERT
   }
   if (ZapUnusedHeapArea) {
     eden()->check_mangled_unused_area_complete();
     from()->check_mangled_unused_area_complete();
     to()->check_mangled_unused_area_complete();
   }
   if (!CleanChunkPoolAsync) {
     Chunk::clean_chunk_pool();
   }
   // update the generation and space performance counters
   update_counters();
   gch->collector_policy()->counters()->update_counters();
 }
 void DefNewGeneration::record_spaces_top() {
   assert(ZapUnusedHeapArea, "Not mangling unused space");
   eden()->set_top_for_allocations();
   to()->set_top_for_allocations();
   from()->set_top_for_allocations();
 }
 void DefNewGeneration::ref_processor_init() {
   Generation::ref_processor_init();
 }
 void DefNewGeneration::update_counters() {
   if (UsePerfData) {
     _eden_counters->update_all();
     _from_counters->update_all();
     _to_counters->update_all();
     _gen_counters->update_all();
   }
 }
 void DefNewGeneration::verify() {
   eden()->verify();
   from()->verify();
     to()->verify();
 }
 void DefNewGeneration::print_on(outputStream* st) const {
   Generation::print_on(st);
   st->print("  eden");
   eden()->print_on(st);
   st->print("  from");
   from()->print_on(st);
   st->print("  to  ");
   to()->print_on(st);
 }
 const char* DefNewGeneration::name() const {
   return "def new generation";
 }
 // Moved from inline file as they are not called inline
 CompactibleSpace* DefNewGeneration::first_compaction_space() const {
   return eden();
 }
 HeapWord* DefNewGeneration::allocate(size_t word_size,
                                      bool is_tlab) {
   // This is the slow-path allocation for the DefNewGeneration.
   // Most allocations are fast-path in compiled code.
   // We try to allocate from the eden.  If that works, we are happy.
   // Note that since DefNewGeneration supports lock-free allocation, we
   // have to use it here, as well.
   HeapWord* result = eden()->par_allocate(word_size);
   if (result != NULL) {
     if (CMSEdenChunksRecordAlways && _next_gen != NULL) {
       _next_gen->sample_eden_chunk();
     }
     return result;
   }
   do {
     HeapWord* old_limit = eden()->soft_end();
     if (old_limit < eden()->end()) {
       // Tell the next generation we reached a limit.
       HeapWord* new_limit =
         next_gen()->allocation_limit_reached(eden(), eden()->top(), word_size);
       if (new_limit != NULL) {
         Atomic::cmpxchg_ptr(new_limit, eden()->soft_end_addr(), old_limit);
       } else {
         assert(eden()->soft_end() == eden()->end(),
                "invalid state after allocation_limit_reached returned null");
       }
     } else {
       // The allocation failed and the soft limit is equal to the hard limit,
       // there are no reasons to do an attempt to allocate
       assert(old_limit == eden()->end(), "sanity check");
       break;
     }
     // Try to allocate until succeeded or the soft limit can't be adjusted
     result = eden()->par_allocate(word_size);
   } while (result == NULL);
   // If the eden is full and the last collection bailed out, we are running
   // out of heap space, and we try to allocate the from-space, too.
   // allocate_from_space can't be inlined because that would introduce a
   // circular dependency at compile time.
   if (result == NULL) {
     result = allocate_from_space(word_size);
   } else if (CMSEdenChunksRecordAlways && _next_gen != NULL) {
     _next_gen->sample_eden_chunk();
   }
   return result;
 }
 HeapWord* DefNewGeneration::par_allocate(size_t word_size,
                                          bool is_tlab) {
   HeapWord* res = eden()->par_allocate(word_size);
   if (CMSEdenChunksRecordAlways && _next_gen != NULL) {
     _next_gen->sample_eden_chunk();
   }
   return res;
 }
 void DefNewGeneration::gc_prologue(bool full) {
   // Ensure that _end and _soft_end are the same in eden space.
   eden()->set_soft_end(eden()->end());
 }
 size_t DefNewGeneration::tlab_capacity() const {
   return eden()->capacity();
 }
 size_t DefNewGeneration::tlab_used() const {
   return eden()->used();
 }
 size_t DefNewGeneration::unsafe_max_tlab_alloc() const {
   return unsafe_max_alloc_nogc();
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/defNewGeneration.cpp@2c6ef90f030a (annotated)

src/share/vm/memory/defNewGeneration.cpp