jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1MarkSweep.cpp@2a1472c30599 (annotated)

src/share/vm/gc_implementation/g1/g1MarkSweep.cpp@2a1472c30599 (annotated)

src/share/vm/gc_implementation/g1/g1MarkSweep.cpp

Wed, 03 Mar 2010 14:48:26 -0800

author: jcoomes
date: Wed, 03 Mar 2010 14:48:26 -0800
changeset 1746: 2a1472c30599
parent 1428: 54b3b351d6f9
child 1822: 0bfd3fb24150
permissions: -rw-r--r--

4396719: Mark Sweep stack overflow on deeply nested Object arrays
Summary: Use an explicit stack for object arrays and process them in chunks.
Reviewed-by: iveresov, apetrusenko

 /*
  * Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 #include "incls/_precompiled.incl"
 #include "incls/_g1MarkSweep.cpp.incl"
 class HeapRegion;
 void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
                                       bool clear_all_softrefs) {
   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
   // hook up weak ref data so it can be used during Mark-Sweep
   assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
   assert(rp != NULL, "should be non-NULL");
   GenMarkSweep::_ref_processor = rp;
   rp->setup_policy(clear_all_softrefs);
   // When collecting the permanent generation methodOops may be moving,
   // so we either have to flush all bcp data or convert it into bci.
   CodeCache::gc_prologue();
   Threads::gc_prologue();
   // Increment the invocation count for the permanent generation, since it is
   // implicitly collected whenever we do a full mark sweep collection.
   SharedHeap* sh = SharedHeap::heap();
   sh->perm_gen()->stat_record()->invocations++;
   bool marked_for_unloading = false;
   allocate_stacks();
   // We should save the marks of the currently locked biased monitors.
   // The marking doesn't preserve the marks of biased objects.
   BiasedLocking::preserve_marks();
   mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
   if (VerifyDuringGC) {
       G1CollectedHeap* g1h = G1CollectedHeap::heap();
       g1h->checkConcurrentMark();
   }
   mark_sweep_phase2();
   // Don't add any more derived pointers during phase3
   COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
   mark_sweep_phase3();
   mark_sweep_phase4();
   GenMarkSweep::restore_marks();
   BiasedLocking::restore_marks();
   GenMarkSweep::deallocate_stacks();
   // We must invalidate the perm-gen rs, so that it gets rebuilt.
   GenRemSet* rs = sh->rem_set();
   rs->invalidate(sh->perm_gen()->used_region(), true /*whole_heap*/);
   // "free at last gc" is calculated from these.
   // CHF: cheating for now!!!
   //  Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
   //  Universe::set_heap_used_at_last_gc(Universe::heap()->used());
   Threads::gc_epilogue();
   CodeCache::gc_epilogue();
   // refs processing: clean slate
   GenMarkSweep::_ref_processor = NULL;
 }
 void G1MarkSweep::allocate_stacks() {
   GenMarkSweep::_preserved_count_max = 0;
   GenMarkSweep::_preserved_marks = NULL;
   GenMarkSweep::_preserved_count = 0;
   GenMarkSweep::_preserved_mark_stack = NULL;
   GenMarkSweep::_preserved_oop_stack = NULL;
   GenMarkSweep::_marking_stack =
     new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
   GenMarkSweep::_objarray_stack =
     new (ResourceObj::C_HEAP) GrowableArray<ObjArrayTask>(50, true);
   int size = SystemDictionary::number_of_classes() * 2;
   GenMarkSweep::_revisit_klass_stack =
     new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
   // (#klass/k)^2 for k ~ 10 appears a better fit, but this will have to do
   // for now until we have a chance to work out a more optimal setting.
   GenMarkSweep::_revisit_mdo_stack =
     new (ResourceObj::C_HEAP) GrowableArray<DataLayout*>(size*2, true);
 }
 void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
                                     bool clear_all_softrefs) {
   // Recursively traverse all live objects and mark them
   EventMark m("1 mark object");
   TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty);
   GenMarkSweep::trace(" 1");
   SharedHeap* sh = SharedHeap::heap();
   sh->process_strong_roots(true,  // activeate StrongRootsScope
                            true,  // Collecting permanent generation.
                            SharedHeap::SO_SystemClasses,
                            &GenMarkSweep::follow_root_closure,
                            &GenMarkSweep::follow_code_root_closure,
                            &GenMarkSweep::follow_root_closure);
   // Process reference objects found during marking
   ReferenceProcessor* rp = GenMarkSweep::ref_processor();
   rp->setup_policy(clear_all_softrefs);
   rp->process_discovered_references(&GenMarkSweep::is_alive,
                                     &GenMarkSweep::keep_alive,
                                     &GenMarkSweep::follow_stack_closure,
                                     NULL);
   // Follow system dictionary roots and unload classes
   bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
   assert(GenMarkSweep::_marking_stack->is_empty(),
          "stack should be empty by now");
   // Follow code cache roots (has to be done after system dictionary,
   // assumes all live klasses are marked)
   CodeCache::do_unloading(&GenMarkSweep::is_alive,
                                    &GenMarkSweep::keep_alive,
                                    purged_class);
   GenMarkSweep::follow_stack();
   // Update subklass/sibling/implementor links of live klasses
   GenMarkSweep::follow_weak_klass_links();
   assert(GenMarkSweep::_marking_stack->is_empty(),
          "stack should be empty by now");
   // Visit memoized MDO's and clear any unmarked weak refs
   GenMarkSweep::follow_mdo_weak_refs();
   assert(GenMarkSweep::_marking_stack->is_empty(), "just drained");
   // Visit symbol and interned string tables and delete unmarked oops
   SymbolTable::unlink(&GenMarkSweep::is_alive);
   StringTable::unlink(&GenMarkSweep::is_alive);
   assert(GenMarkSweep::_marking_stack->is_empty(),
          "stack should be empty by now");
 }
 class G1PrepareCompactClosure: public HeapRegionClosure {
   ModRefBarrierSet* _mrbs;
   CompactPoint _cp;
   void free_humongous_region(HeapRegion* hr) {
     HeapWord* bot = hr->bottom();
     HeapWord* end = hr->end();
     assert(hr->startsHumongous(),
            "Only the start of a humongous region should be freed.");
     G1CollectedHeap::heap()->free_region(hr);
     hr->prepare_for_compaction(&_cp);
     // Also clear the part of the card table that will be unused after
     // compaction.
     _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
   }
 public:
   G1PrepareCompactClosure(CompactibleSpace* cs) :
     _cp(NULL, cs, cs->initialize_threshold()),
     _mrbs(G1CollectedHeap::heap()->mr_bs())
   {}
   bool doHeapRegion(HeapRegion* hr) {
     if (hr->isHumongous()) {
       if (hr->startsHumongous()) {
         oop obj = oop(hr->bottom());
         if (obj->is_gc_marked()) {
           obj->forward_to(obj);
         } else  {
           free_humongous_region(hr);
         }
       } else {
         assert(hr->continuesHumongous(), "Invalid humongous.");
       }
     } else {
       hr->prepare_for_compaction(&_cp);
       // Also clear the part of the card table that will be unused after
       // compaction.
       _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
     }
     return false;
   }
 };
 // Finds the first HeapRegion.
 class FindFirstRegionClosure: public HeapRegionClosure {
   HeapRegion* _a_region;
 public:
   FindFirstRegionClosure() : _a_region(NULL) {}
   bool doHeapRegion(HeapRegion* r) {
     _a_region = r;
     return true;
   }
   HeapRegion* result() { return _a_region; }
 };
 void G1MarkSweep::mark_sweep_phase2() {
   // Now all live objects are marked, compute the new object addresses.
   // It is imperative that we traverse perm_gen LAST. If dead space is
   // allowed a range of dead object may get overwritten by a dead int
   // array. If perm_gen is not traversed last a klassOop may get
   // overwritten. This is fine since it is dead, but if the class has dead
   // instances we have to skip them, and in order to find their size we
   // need the klassOop!
   //
   // It is not required that we traverse spaces in the same order in
   // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
   // tracking expects us to do so. See comment under phase4.
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   Generation* pg = g1h->perm_gen();
   EventMark m("2 compute new addresses");
   TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty);
   GenMarkSweep::trace("2");
   FindFirstRegionClosure cl;
   g1h->heap_region_iterate(&cl);
   HeapRegion *r = cl.result();
   CompactibleSpace* sp = r;
   if (r->isHumongous() && oop(r->bottom())->is_gc_marked()) {
     sp = r->next_compaction_space();
   }
   G1PrepareCompactClosure blk(sp);
   g1h->heap_region_iterate(&blk);
   CompactPoint perm_cp(pg, NULL, NULL);
   pg->prepare_for_compaction(&perm_cp);
 }
 class G1AdjustPointersClosure: public HeapRegionClosure {
  public:
   bool doHeapRegion(HeapRegion* r) {
     if (r->isHumongous()) {
       if (r->startsHumongous()) {
         // We must adjust the pointers on the single H object.
         oop obj = oop(r->bottom());
         debug_only(GenMarkSweep::track_interior_pointers(obj));
         // point all the oops to the new location
         obj->adjust_pointers();
         debug_only(GenMarkSweep::check_interior_pointers());
       }
     } else {
       // This really ought to be "as_CompactibleSpace"...
       r->adjust_pointers();
     }
     return false;
   }
 };
 void G1MarkSweep::mark_sweep_phase3() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   Generation* pg = g1h->perm_gen();
   // Adjust the pointers to reflect the new locations
   EventMark m("3 adjust pointers");
   TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty);
   GenMarkSweep::trace("3");
   SharedHeap* sh = SharedHeap::heap();
   sh->process_strong_roots(true,  // activate StrongRootsScope
                            true,  // Collecting permanent generation.
                            SharedHeap::SO_AllClasses,
                            &GenMarkSweep::adjust_root_pointer_closure,
                            NULL,  // do not touch code cache here
                            &GenMarkSweep::adjust_pointer_closure);
   g1h->ref_processor()->weak_oops_do(&GenMarkSweep::adjust_root_pointer_closure);
   // Now adjust pointers in remaining weak roots.  (All of which should
   // have been cleared if they pointed to non-surviving objects.)
   g1h->g1_process_weak_roots(&GenMarkSweep::adjust_root_pointer_closure,
                              &GenMarkSweep::adjust_pointer_closure);
   GenMarkSweep::adjust_marks();
   G1AdjustPointersClosure blk;
   g1h->heap_region_iterate(&blk);
   pg->adjust_pointers();
 }
 class G1SpaceCompactClosure: public HeapRegionClosure {
 public:
   G1SpaceCompactClosure() {}
   bool doHeapRegion(HeapRegion* hr) {
     if (hr->isHumongous()) {
       if (hr->startsHumongous()) {
         oop obj = oop(hr->bottom());
         if (obj->is_gc_marked()) {
           obj->init_mark();
         } else {
           assert(hr->is_empty(), "Should have been cleared in phase 2.");
         }
         hr->reset_during_compaction();
       }
     } else {
       hr->compact();
     }
     return false;
   }
 };
 void G1MarkSweep::mark_sweep_phase4() {
   // All pointers are now adjusted, move objects accordingly
   // It is imperative that we traverse perm_gen first in phase4. All
   // classes must be allocated earlier than their instances, and traversing
   // perm_gen first makes sure that all klassOops have moved to their new
   // location before any instance does a dispatch through it's klass!
   // The ValidateMarkSweep live oops tracking expects us to traverse spaces
   // in the same order in phase2, phase3 and phase4. We don't quite do that
   // here (perm_gen first rather than last), so we tell the validate code
   // to use a higher index (saved from phase2) when verifying perm_gen.
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   Generation* pg = g1h->perm_gen();
   EventMark m("4 compact heap");
   TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty);
   GenMarkSweep::trace("4");
   pg->compact();
   G1SpaceCompactClosure blk;
   g1h->heap_region_iterate(&blk);
 }
 // Local Variables: ***
 // c-indentation-style: gnu ***
 // End: ***

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1MarkSweep.cpp@2a1472c30599 (annotated)

src/share/vm/gc_implementation/g1/g1MarkSweep.cpp