author | jcoomes |
Tue, 28 Sep 2010 15:56:15 -0700 | |
changeset 6762 | f8d1b560700e |
parent 5547 | f4b087cbb361 |
child 7397 | 5b173b4ca846 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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* |
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*/ |
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#include "incls/_precompiled.incl" |
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#include "incls/_g1MarkSweep.cpp.incl" |
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class HeapRegion; |
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void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp, |
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bool clear_all_softrefs) { |
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assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); |
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||
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SharedHeap* sh = SharedHeap::heap(); |
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#ifdef ASSERT |
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if (sh->collector_policy()->should_clear_all_soft_refs()) { |
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assert(clear_all_softrefs, "Policy should have been checked earler"); |
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} |
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#endif |
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// hook up weak ref data so it can be used during Mark-Sweep |
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assert(GenMarkSweep::ref_processor() == NULL, "no stomping"); |
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assert(rp != NULL, "should be non-NULL"); |
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GenMarkSweep::_ref_processor = rp; |
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rp->setup_policy(clear_all_softrefs); |
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// When collecting the permanent generation methodOops may be moving, |
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// so we either have to flush all bcp data or convert it into bci. |
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CodeCache::gc_prologue(); |
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Threads::gc_prologue(); |
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// Increment the invocation count for the permanent generation, since it is |
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// implicitly collected whenever we do a full mark sweep collection. |
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sh->perm_gen()->stat_record()->invocations++; |
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bool marked_for_unloading = false; |
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allocate_stacks(); |
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// We should save the marks of the currently locked biased monitors. |
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// The marking doesn't preserve the marks of biased objects. |
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BiasedLocking::preserve_marks(); |
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mark_sweep_phase1(marked_for_unloading, clear_all_softrefs); |
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if (VerifyDuringGC) { |
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G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
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g1h->checkConcurrentMark(); |
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} |
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mark_sweep_phase2(); |
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// Don't add any more derived pointers during phase3 |
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COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); |
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mark_sweep_phase3(); |
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mark_sweep_phase4(); |
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GenMarkSweep::restore_marks(); |
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BiasedLocking::restore_marks(); |
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GenMarkSweep::deallocate_stacks(); |
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// We must invalidate the perm-gen rs, so that it gets rebuilt. |
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GenRemSet* rs = sh->rem_set(); |
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rs->invalidate(sh->perm_gen()->used_region(), true /*whole_heap*/); |
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// "free at last gc" is calculated from these. |
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// CHF: cheating for now!!! |
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// Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity()); |
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// Universe::set_heap_used_at_last_gc(Universe::heap()->used()); |
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Threads::gc_epilogue(); |
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CodeCache::gc_epilogue(); |
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// refs processing: clean slate |
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GenMarkSweep::_ref_processor = NULL; |
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} |
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void G1MarkSweep::allocate_stacks() { |
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GenMarkSweep::_preserved_count_max = 0; |
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GenMarkSweep::_preserved_marks = NULL; |
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GenMarkSweep::_preserved_count = 0; |
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} |
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void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading, |
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bool clear_all_softrefs) { |
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// Recursively traverse all live objects and mark them |
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EventMark m("1 mark object"); |
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TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty); |
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GenMarkSweep::trace(" 1"); |
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SharedHeap* sh = SharedHeap::heap(); |
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sh->process_strong_roots(true, // activeate StrongRootsScope |
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true, // Collecting permanent generation. |
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SharedHeap::SO_SystemClasses, |
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&GenMarkSweep::follow_root_closure, |
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&GenMarkSweep::follow_code_root_closure, |
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&GenMarkSweep::follow_root_closure); |
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// Process reference objects found during marking |
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ReferenceProcessor* rp = GenMarkSweep::ref_processor(); |
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rp->setup_policy(clear_all_softrefs); |
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rp->process_discovered_references(&GenMarkSweep::is_alive, |
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&GenMarkSweep::keep_alive, |
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&GenMarkSweep::follow_stack_closure, |
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NULL); |
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// Follow system dictionary roots and unload classes |
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bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive); |
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assert(GenMarkSweep::_marking_stack.is_empty(), |
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"stack should be empty by now"); |
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// Follow code cache roots (has to be done after system dictionary, |
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// assumes all live klasses are marked) |
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CodeCache::do_unloading(&GenMarkSweep::is_alive, |
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&GenMarkSweep::keep_alive, |
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purged_class); |
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GenMarkSweep::follow_stack(); |
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// Update subklass/sibling/implementor links of live klasses |
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GenMarkSweep::follow_weak_klass_links(); |
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assert(GenMarkSweep::_marking_stack.is_empty(), |
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"stack should be empty by now"); |
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// Visit memoized MDO's and clear any unmarked weak refs |
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GenMarkSweep::follow_mdo_weak_refs(); |
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assert(GenMarkSweep::_marking_stack.is_empty(), "just drained"); |
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// Visit symbol and interned string tables and delete unmarked oops |
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SymbolTable::unlink(&GenMarkSweep::is_alive); |
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StringTable::unlink(&GenMarkSweep::is_alive); |
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assert(GenMarkSweep::_marking_stack.is_empty(), |
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"stack should be empty by now"); |
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} |
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class G1PrepareCompactClosure: public HeapRegionClosure { |
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ModRefBarrierSet* _mrbs; |
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CompactPoint _cp; |
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void free_humongous_region(HeapRegion* hr) { |
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HeapWord* bot = hr->bottom(); |
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HeapWord* end = hr->end(); |
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assert(hr->startsHumongous(), |
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"Only the start of a humongous region should be freed."); |
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G1CollectedHeap::heap()->free_region(hr); |
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hr->prepare_for_compaction(&_cp); |
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// Also clear the part of the card table that will be unused after |
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// compaction. |
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_mrbs->clear(MemRegion(hr->compaction_top(), hr->end())); |
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} |
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public: |
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G1PrepareCompactClosure(CompactibleSpace* cs) : |
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_cp(NULL, cs, cs->initialize_threshold()), |
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_mrbs(G1CollectedHeap::heap()->mr_bs()) |
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{} |
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bool doHeapRegion(HeapRegion* hr) { |
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if (hr->isHumongous()) { |
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if (hr->startsHumongous()) { |
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oop obj = oop(hr->bottom()); |
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if (obj->is_gc_marked()) { |
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obj->forward_to(obj); |
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} else { |
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free_humongous_region(hr); |
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} |
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} else { |
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assert(hr->continuesHumongous(), "Invalid humongous."); |
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} |
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} else { |
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hr->prepare_for_compaction(&_cp); |
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// Also clear the part of the card table that will be unused after |
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// compaction. |
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_mrbs->clear(MemRegion(hr->compaction_top(), hr->end())); |
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} |
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return false; |
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} |
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}; |
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// Finds the first HeapRegion. |
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class FindFirstRegionClosure: public HeapRegionClosure { |
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HeapRegion* _a_region; |
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public: |
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FindFirstRegionClosure() : _a_region(NULL) {} |
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bool doHeapRegion(HeapRegion* r) { |
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_a_region = r; |
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return true; |
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} |
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HeapRegion* result() { return _a_region; } |
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}; |
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void G1MarkSweep::mark_sweep_phase2() { |
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// Now all live objects are marked, compute the new object addresses. |
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// It is imperative that we traverse perm_gen LAST. If dead space is |
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// allowed a range of dead object may get overwritten by a dead int |
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// array. If perm_gen is not traversed last a klassOop may get |
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// overwritten. This is fine since it is dead, but if the class has dead |
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// instances we have to skip them, and in order to find their size we |
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// need the klassOop! |
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// |
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// It is not required that we traverse spaces in the same order in |
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// phase2, phase3 and phase4, but the ValidateMarkSweep live oops |
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// tracking expects us to do so. See comment under phase4. |
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G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
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Generation* pg = g1h->perm_gen(); |
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EventMark m("2 compute new addresses"); |
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TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty); |
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GenMarkSweep::trace("2"); |
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FindFirstRegionClosure cl; |
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g1h->heap_region_iterate(&cl); |
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HeapRegion *r = cl.result(); |
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CompactibleSpace* sp = r; |
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if (r->isHumongous() && oop(r->bottom())->is_gc_marked()) { |
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sp = r->next_compaction_space(); |
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} |
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||
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G1PrepareCompactClosure blk(sp); |
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g1h->heap_region_iterate(&blk); |
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CompactPoint perm_cp(pg, NULL, NULL); |
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pg->prepare_for_compaction(&perm_cp); |
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} |
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class G1AdjustPointersClosure: public HeapRegionClosure { |
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public: |
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bool doHeapRegion(HeapRegion* r) { |
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if (r->isHumongous()) { |
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if (r->startsHumongous()) { |
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// We must adjust the pointers on the single H object. |
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oop obj = oop(r->bottom()); |
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debug_only(GenMarkSweep::track_interior_pointers(obj)); |
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// point all the oops to the new location |
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obj->adjust_pointers(); |
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debug_only(GenMarkSweep::check_interior_pointers()); |
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} |
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} else { |
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// This really ought to be "as_CompactibleSpace"... |
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r->adjust_pointers(); |
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} |
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return false; |
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} |
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}; |
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void G1MarkSweep::mark_sweep_phase3() { |
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G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
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Generation* pg = g1h->perm_gen(); |
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// Adjust the pointers to reflect the new locations |
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EventMark m("3 adjust pointers"); |
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TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty); |
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GenMarkSweep::trace("3"); |
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SharedHeap* sh = SharedHeap::heap(); |
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sh->process_strong_roots(true, // activate StrongRootsScope |
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true, // Collecting permanent generation. |
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SharedHeap::SO_AllClasses, |
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&GenMarkSweep::adjust_root_pointer_closure, |
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NULL, // do not touch code cache here |
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&GenMarkSweep::adjust_pointer_closure); |
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||
289 |
g1h->ref_processor()->weak_oops_do(&GenMarkSweep::adjust_root_pointer_closure); |
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// Now adjust pointers in remaining weak roots. (All of which should |
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// have been cleared if they pointed to non-surviving objects.) |
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g1h->g1_process_weak_roots(&GenMarkSweep::adjust_root_pointer_closure, |
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&GenMarkSweep::adjust_pointer_closure); |
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GenMarkSweep::adjust_marks(); |
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G1AdjustPointersClosure blk; |
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g1h->heap_region_iterate(&blk); |
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pg->adjust_pointers(); |
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} |
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303 |
class G1SpaceCompactClosure: public HeapRegionClosure { |
|
304 |
public: |
|
305 |
G1SpaceCompactClosure() {} |
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306 |
||
307 |
bool doHeapRegion(HeapRegion* hr) { |
|
308 |
if (hr->isHumongous()) { |
|
309 |
if (hr->startsHumongous()) { |
|
310 |
oop obj = oop(hr->bottom()); |
|
311 |
if (obj->is_gc_marked()) { |
|
312 |
obj->init_mark(); |
|
313 |
} else { |
|
314 |
assert(hr->is_empty(), "Should have been cleared in phase 2."); |
|
315 |
} |
|
316 |
hr->reset_during_compaction(); |
|
317 |
} |
|
318 |
} else { |
|
319 |
hr->compact(); |
|
320 |
} |
|
321 |
return false; |
|
322 |
} |
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323 |
}; |
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324 |
||
325 |
void G1MarkSweep::mark_sweep_phase4() { |
|
326 |
// All pointers are now adjusted, move objects accordingly |
|
327 |
||
328 |
// It is imperative that we traverse perm_gen first in phase4. All |
|
329 |
// classes must be allocated earlier than their instances, and traversing |
|
330 |
// perm_gen first makes sure that all klassOops have moved to their new |
|
331 |
// location before any instance does a dispatch through it's klass! |
|
332 |
||
333 |
// The ValidateMarkSweep live oops tracking expects us to traverse spaces |
|
334 |
// in the same order in phase2, phase3 and phase4. We don't quite do that |
|
335 |
// here (perm_gen first rather than last), so we tell the validate code |
|
336 |
// to use a higher index (saved from phase2) when verifying perm_gen. |
|
337 |
G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
|
338 |
Generation* pg = g1h->perm_gen(); |
|
339 |
||
340 |
EventMark m("4 compact heap"); |
|
341 |
TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty); |
|
342 |
GenMarkSweep::trace("4"); |
|
343 |
||
344 |
pg->compact(); |
|
345 |
||
346 |
G1SpaceCompactClosure blk; |
|
347 |
g1h->heap_region_iterate(&blk); |
|
348 |
||
349 |
} |
|
350 |
||
351 |
// Local Variables: *** |
|
352 |
// c-indentation-style: gnu *** |
|
353 |
// End: *** |