Mercurial > hg > truffle
view src/share/vm/memory/genMarkSweep.cpp @ 4974:ab906cea36f7
First round of minimizing diff vs OpenJDK.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Mon, 27 Feb 2012 15:15:59 +0100 |
parents | d903bf750e9f |
children | 9d679effd28c |
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/* * Copyright (c) 2001, 2012, 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/javaClasses.hpp" #include "classfile/symbolTable.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/vmSymbols.hpp" #include "code/codeCache.hpp" #include "code/icBuffer.hpp" #include "gc_interface/collectedHeap.inline.hpp" #include "memory/genCollectedHeap.hpp" #include "memory/genMarkSweep.hpp" #include "memory/genOopClosures.inline.hpp" #include "memory/generation.inline.hpp" #include "memory/modRefBarrierSet.hpp" #include "memory/referencePolicy.hpp" #include "memory/space.hpp" #include "oops/instanceRefKlass.hpp" #include "oops/oop.inline.hpp" #include "prims/jvmtiExport.hpp" #include "runtime/fprofiler.hpp" #include "runtime/handles.inline.hpp" #include "runtime/synchronizer.hpp" #include "runtime/vmThread.hpp" #include "utilities/copy.hpp" #include "utilities/events.hpp" #ifdef TARGET_OS_FAMILY_linux # include "thread_linux.inline.hpp" #endif #ifdef TARGET_OS_FAMILY_solaris # include "thread_solaris.inline.hpp" #endif #ifdef TARGET_OS_FAMILY_windows # include "thread_windows.inline.hpp" #endif #ifdef TARGET_OS_FAMILY_bsd # include "thread_bsd.inline.hpp" #endif void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp, bool clear_all_softrefs) { assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); GenCollectedHeap* gch = GenCollectedHeap::heap(); #ifdef ASSERT if (gch->collector_policy()->should_clear_all_soft_refs()) { assert(clear_all_softrefs, "Policy should have been checked earlier"); } #endif // hook up weak ref data so it can be used during Mark-Sweep assert(ref_processor() == NULL, "no stomping"); assert(rp != NULL, "should be non-NULL"); _ref_processor = rp; rp->setup_policy(clear_all_softrefs); TraceTime t1("Full GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); // 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. gch->perm_gen()->stat_record()->invocations++; // Capture heap size before collection for printing. size_t gch_prev_used = gch->used(); // Some of the card table updates below assume that the perm gen is // also being collected. assert(level == gch->n_gens() - 1, "All generations are being collected, ergo perm gen too."); // Capture used regions for each generation that will be // subject to collection, so that card table adjustments can // be made intelligently (see clear / invalidate further below). gch->save_used_regions(level, true /* perm */); allocate_stacks(); mark_sweep_phase1(level, clear_all_softrefs); mark_sweep_phase2(); // Don't add any more derived pointers during phase3 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); mark_sweep_phase3(level); VALIDATE_MARK_SWEEP_ONLY( if (ValidateMarkSweep) { guarantee(_root_refs_stack->length() == 0, "should be empty by now"); } ) mark_sweep_phase4(); VALIDATE_MARK_SWEEP_ONLY( if (ValidateMarkSweep) { guarantee(_live_oops->length() == _live_oops_moved_to->length(), "should be the same size"); } ) restore_marks(); // Set saved marks for allocation profiler (and other things? -- dld) // (Should this be in general part?) gch->save_marks(); deallocate_stacks(); // If compaction completely evacuated all generations younger than this // one, then we can clear the card table. Otherwise, we must invalidate // it (consider all cards dirty). In the future, we might consider doing // compaction within generations only, and doing card-table sliding. bool all_empty = true; for (int i = 0; all_empty && i < level; i++) { Generation* g = gch->get_gen(i); all_empty = all_empty && gch->get_gen(i)->used() == 0; } GenRemSet* rs = gch->rem_set(); // Clear/invalidate below make use of the "prev_used_regions" saved earlier. if (all_empty) { // We've evacuated all generations below us. Generation* g = gch->get_gen(level); rs->clear_into_younger(g, true /* perm */); } else { // Invalidate the cards corresponding to the currently used // region and clear those corresponding to the evacuated region // of all generations just collected (i.e. level and younger). rs->invalidate_or_clear(gch->get_gen(level), true /* younger */, true /* perm */); } Threads::gc_epilogue(); CodeCache::gc_epilogue(); JvmtiExport::gc_epilogue(); if (PrintGC && !PrintGCDetails) { gch->print_heap_change(gch_prev_used); } // refs processing: clean slate _ref_processor = NULL; // Update heap occupancy information which is used as // input to soft ref clearing policy at the next gc. Universe::update_heap_info_at_gc(); // Update time of last gc for all generations we collected // (which curently is all the generations in the heap). // We need to use a monotonically non-deccreasing time in ms // or we will see time-warp warnings and os::javaTimeMillis() // does not guarantee monotonicity. jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; gch->update_time_of_last_gc(now); } void GenMarkSweep::allocate_stacks() { GenCollectedHeap* gch = GenCollectedHeap::heap(); // Scratch request on behalf of oldest generation; will do no // allocation. ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0); // $$$ To cut a corner, we'll only use the first scratch block, and then // revert to malloc. if (scratch != NULL) { _preserved_count_max = scratch->num_words * HeapWordSize / sizeof(PreservedMark); } else { _preserved_count_max = 0; } _preserved_marks = (PreservedMark*)scratch; _preserved_count = 0; #ifdef VALIDATE_MARK_SWEEP if (ValidateMarkSweep) { _root_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); _other_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); _adjusted_pointers = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); _live_oops = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); _live_oops_moved_to = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); _live_oops_size = new (ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); } if (RecordMarkSweepCompaction) { if (_cur_gc_live_oops == NULL) { _cur_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); _cur_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); _cur_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); _last_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); _last_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); _last_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); } else { _cur_gc_live_oops->clear(); _cur_gc_live_oops_moved_to->clear(); _cur_gc_live_oops_size->clear(); } } #endif } void GenMarkSweep::deallocate_stacks() { if (!UseG1GC) { GenCollectedHeap* gch = GenCollectedHeap::heap(); gch->release_scratch(); } _preserved_mark_stack.clear(true); _preserved_oop_stack.clear(true); _marking_stack.clear(); _objarray_stack.clear(true); _revisit_klass_stack.clear(true); _revisit_mdo_stack.clear(true); #ifdef VALIDATE_MARK_SWEEP if (ValidateMarkSweep) { delete _root_refs_stack; delete _other_refs_stack; delete _adjusted_pointers; delete _live_oops; delete _live_oops_size; delete _live_oops_moved_to; _live_oops_index = 0; _live_oops_index_at_perm = 0; } #endif } void GenMarkSweep::mark_sweep_phase1(int level, bool clear_all_softrefs) { // Recursively traverse all live objects and mark them TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty); trace(" 1"); VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); GenCollectedHeap* gch = GenCollectedHeap::heap(); // Because follow_root_closure is created statically, cannot // use OopsInGenClosure constructor which takes a generation, // as the Universe has not been created when the static constructors // are run. follow_root_closure.set_orig_generation(gch->get_gen(level)); gch->gen_process_strong_roots(level, false, // Younger gens are not roots. true, // activate StrongRootsScope true, // Collecting permanent generation. SharedHeap::SO_SystemClasses, &follow_root_closure, true, // walk code active on stacks &follow_root_closure); // Process reference objects found during marking { ref_processor()->setup_policy(clear_all_softrefs); ref_processor()->process_discovered_references( &is_alive, &keep_alive, &follow_stack_closure, NULL); } // Follow system dictionary roots and unload classes bool purged_class = SystemDictionary::do_unloading(&is_alive); // Follow code cache roots CodeCache::do_unloading(&is_alive, &keep_alive, purged_class); follow_stack(); // Flush marking stack // Update subklass/sibling/implementor links of live klasses follow_weak_klass_links(); assert(_marking_stack.is_empty(), "just drained"); // Visit memoized MDO's and clear any unmarked weak refs follow_mdo_weak_refs(); assert(_marking_stack.is_empty(), "just drained"); // Visit interned string tables and delete unmarked oops StringTable::unlink(&is_alive); // Clean up unreferenced symbols in symbol table. SymbolTable::unlink(); assert(_marking_stack.is_empty(), "stack should be empty by now"); } void GenMarkSweep::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. GenCollectedHeap* gch = GenCollectedHeap::heap(); Generation* pg = gch->perm_gen(); TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty); trace("2"); VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); gch->prepare_for_compaction(); VALIDATE_MARK_SWEEP_ONLY(_live_oops_index_at_perm = _live_oops_index); CompactPoint perm_cp(pg, NULL, NULL); pg->prepare_for_compaction(&perm_cp); } class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure { public: void do_generation(Generation* gen) { gen->adjust_pointers(); } }; void GenMarkSweep::mark_sweep_phase3(int level) { GenCollectedHeap* gch = GenCollectedHeap::heap(); Generation* pg = gch->perm_gen(); // Adjust the pointers to reflect the new locations TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty); trace("3"); VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); // Needs to be done before the system dictionary is adjusted. pg->pre_adjust_pointers(); // Because the two closures below are created statically, cannot // use OopsInGenClosure constructor which takes a generation, // as the Universe has not been created when the static constructors // are run. adjust_root_pointer_closure.set_orig_generation(gch->get_gen(level)); adjust_pointer_closure.set_orig_generation(gch->get_gen(level)); gch->gen_process_strong_roots(level, false, // Younger gens are not roots. true, // activate StrongRootsScope true, // Collecting permanent generation. SharedHeap::SO_AllClasses, &adjust_root_pointer_closure, false, // do not walk code &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.) CodeBlobToOopClosure adjust_code_pointer_closure(&adjust_pointer_closure, /*do_marking=*/ false); gch->gen_process_weak_roots(&adjust_root_pointer_closure, &adjust_code_pointer_closure, &adjust_pointer_closure); adjust_marks(); GenAdjustPointersClosure blk; gch->generation_iterate(&blk, true); pg->adjust_pointers(); } class GenCompactClosure: public GenCollectedHeap::GenClosure { public: void do_generation(Generation* gen) { gen->compact(); } }; void GenMarkSweep::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. GenCollectedHeap* gch = GenCollectedHeap::heap(); Generation* pg = gch->perm_gen(); TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty); trace("4"); VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(true)); pg->compact(); VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); GenCompactClosure blk; gch->generation_iterate(&blk, true); VALIDATE_MARK_SWEEP_ONLY(compaction_complete()); pg->post_compact(); // Shared spaces verification. }