1 /* 2 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "code/codeCache.hpp" 27 #include "gc/g1/g1CollectedHeap.hpp" 28 #include "gc/g1/g1CollectorPolicy.hpp" 29 #include "gc/g1/g1FullCollector.hpp" 30 #include "gc/g1/g1FullGCAdjustTask.hpp" 31 #include "gc/g1/g1FullGCCompactTask.hpp" 32 #include "gc/g1/g1FullGCMarker.inline.hpp" 33 #include "gc/g1/g1FullGCMarkTask.hpp" 34 #include "gc/g1/g1FullGCPrepareTask.hpp" 35 #include "gc/g1/g1FullGCReferenceProcessorExecutor.hpp" 36 #include "gc/g1/g1FullGCScope.hpp" 37 #include "gc/g1/g1OopClosures.hpp" 38 #include "gc/g1/g1Policy.hpp" 39 #include "gc/g1/g1StringDedup.hpp" 40 #include "gc/shared/gcTraceTime.inline.hpp" 41 #include "gc/shared/preservedMarks.hpp" 42 #include "gc/shared/referenceProcessor.hpp" 43 #include "gc/shared/weakProcessor.hpp" 44 #include "logging/log.hpp" 45 #include "runtime/biasedLocking.hpp" 46 #include "runtime/handles.inline.hpp" 47 #include "utilities/debug.hpp" 48 49 static void clear_and_activate_derived_pointers() { 50 #if COMPILER2_OR_JVMCI 51 DerivedPointerTable::clear(); 52 #endif 53 } 54 55 static void deactivate_derived_pointers() { 56 #if COMPILER2_OR_JVMCI 57 DerivedPointerTable::set_active(false); 58 #endif 59 } 60 61 static void update_derived_pointers() { 62 #if COMPILER2_OR_JVMCI 63 DerivedPointerTable::update_pointers(); 64 #endif 65 } 66 67 G1CMBitMap* G1FullCollector::mark_bitmap() { 68 return _heap->concurrent_mark()->next_mark_bitmap(); 69 } 70 71 ReferenceProcessor* G1FullCollector::reference_processor() { 72 return _heap->ref_processor_stw(); 73 } 74 75 G1FullCollector::G1FullCollector(G1CollectedHeap* heap, GCMemoryManager* memory_manager, bool explicit_gc, bool clear_soft_refs) : 76 _heap(heap), 77 _scope(memory_manager, explicit_gc, clear_soft_refs), 78 _num_workers(heap->workers()->active_workers()), 79 _oop_queue_set(_num_workers), 80 _array_queue_set(_num_workers), 81 _preserved_marks_set(true), 82 _serial_compaction_point(), 83 _is_alive(heap->concurrent_mark()->next_mark_bitmap()), 84 _is_alive_mutator(heap->ref_processor_stw(), &_is_alive) { 85 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 86 87 _preserved_marks_set.init(_num_workers); 88 _markers = NEW_C_HEAP_ARRAY(G1FullGCMarker*, _num_workers, mtGC); 89 _compaction_points = NEW_C_HEAP_ARRAY(G1FullGCCompactionPoint*, _num_workers, mtGC); 90 for (uint i = 0; i < _num_workers; i++) { 91 _markers[i] = new G1FullGCMarker(i, _preserved_marks_set.get(i), mark_bitmap()); 92 _compaction_points[i] = new G1FullGCCompactionPoint(); 93 _oop_queue_set.register_queue(i, marker(i)->oop_stack()); 94 _array_queue_set.register_queue(i, marker(i)->objarray_stack()); 95 } 96 } 97 98 G1FullCollector::~G1FullCollector() { 99 for (uint i = 0; i < _num_workers; i++) { 100 delete _markers[i]; 101 delete _compaction_points[i]; 102 } 103 FREE_C_HEAP_ARRAY(G1FullGCMarker*, _markers); 104 FREE_C_HEAP_ARRAY(G1FullGCCompactionPoint*, _compaction_points); 105 } 106 107 void G1FullCollector::prepare_collection() { 108 _heap->g1_policy()->record_full_collection_start(); 109 110 _heap->print_heap_before_gc(); 111 _heap->print_heap_regions(); 112 113 _heap->abort_concurrent_cycle(); 114 _heap->verify_before_full_collection(scope()->is_explicit_gc()); 115 116 _heap->gc_prologue(true); 117 _heap->prepare_heap_for_full_collection(); 118 119 reference_processor()->enable_discovery(); 120 reference_processor()->setup_policy(scope()->should_clear_soft_refs()); 121 122 // When collecting the permanent generation Method*s may be moving, 123 // so we either have to flush all bcp data or convert it into bci. 124 CodeCache::gc_prologue(); 125 126 // We should save the marks of the currently locked biased monitors. 127 // The marking doesn't preserve the marks of biased objects. 128 BiasedLocking::preserve_marks(); 129 130 // Clear and activate derived pointer collection. 131 clear_and_activate_derived_pointers(); 132 } 133 134 void G1FullCollector::collect() { 135 phase1_mark_live_objects(); 136 verify_after_marking(); 137 138 // Don't add any more derived pointers during later phases 139 deactivate_derived_pointers(); 140 141 phase2_prepare_compaction(); 142 143 phase3_adjust_pointers(); 144 145 phase4_do_compaction(); 146 } 147 148 void G1FullCollector::complete_collection() { 149 // Restore all marks. 150 restore_marks(); 151 152 // When the pointers have been adjusted and moved, we can 153 // update the derived pointer table. 154 update_derived_pointers(); 155 156 BiasedLocking::restore_marks(); 157 CodeCache::gc_epilogue(); 158 JvmtiExport::gc_epilogue(); 159 160 _heap->prepare_heap_for_mutators(); 161 162 _heap->g1_policy()->record_full_collection_end(); 163 _heap->gc_epilogue(true); 164 165 _heap->verify_after_full_collection(); 166 167 _heap->print_heap_after_full_collection(scope()->heap_transition()); 168 } 169 170 void G1FullCollector::phase1_mark_live_objects() { 171 // Recursively traverse all live objects and mark them. 172 GCTraceTime(Info, gc, phases) info("Phase 1: Mark live objects", scope()->timer()); 173 174 // Do the actual marking. 175 G1FullGCMarkTask marking_task(this); 176 run_task(&marking_task); 177 178 // Process references discovered during marking. 179 G1FullGCReferenceProcessingExecutor reference_processing(this); 180 reference_processing.execute(scope()->timer(), scope()->tracer()); 181 182 // Weak oops cleanup. 183 { 184 GCTraceTime(Debug, gc, phases) trace("Phase 1: Weak Processing", scope()->timer()); 185 WeakProcessor::weak_oops_do(&_is_alive, &do_nothing_cl); 186 } 187 188 // Class unloading and cleanup. 189 if (ClassUnloading) { 190 GCTraceTime(Debug, gc, phases) debug("Phase 1: Class Unloading and Cleanup", scope()->timer()); 191 // Unload classes and purge the SystemDictionary. 192 bool purged_class = SystemDictionary::do_unloading(&_is_alive, scope()->timer()); 193 _heap->complete_cleaning(&_is_alive, purged_class); 194 } else { 195 GCTraceTime(Debug, gc, phases) debug("Phase 1: String and Symbol Tables Cleanup", scope()->timer()); 196 // If no class unloading just clean out strings and symbols. 197 _heap->partial_cleaning(&_is_alive, true, true, G1StringDedup::is_enabled()); 198 } 199 200 scope()->tracer()->report_object_count_after_gc(&_is_alive); 201 } 202 203 void G1FullCollector::phase2_prepare_compaction() { 204 GCTraceTime(Info, gc, phases) info("Phase 2: Prepare for compaction", scope()->timer()); 205 G1FullGCPrepareTask task(this); 206 run_task(&task); 207 208 // To avoid OOM when there is memory left. 209 if (!task.has_freed_regions()) { 210 task.prepare_serial_compaction(); 211 } 212 } 213 214 void G1FullCollector::phase3_adjust_pointers() { 215 // Adjust the pointers to reflect the new locations 216 GCTraceTime(Info, gc, phases) info("Phase 3: Adjust pointers and remembered sets", scope()->timer()); 217 218 G1FullGCAdjustTask task(this); 219 run_task(&task); 220 } 221 222 void G1FullCollector::phase4_do_compaction() { 223 // Compact the heap using the compaction queues created in phase 2. 224 GCTraceTime(Info, gc, phases) info("Phase 4: Compact heap", scope()->timer()); 225 G1FullGCCompactTask task(this); 226 run_task(&task); 227 228 // Serial compact to avoid OOM when very few free regions. 229 if (serial_compaction_point()->has_regions()) { 230 task.serial_compaction(); 231 } 232 } 233 234 void G1FullCollector::restore_marks() { 235 SharedRestorePreservedMarksTaskExecutor task_executor(_heap->workers()); 236 _preserved_marks_set.restore(&task_executor); 237 _preserved_marks_set.reclaim(); 238 } 239 240 void G1FullCollector::run_task(AbstractGangTask* task) { 241 _heap->workers()->run_task(task, _num_workers); 242 } 243 244 void G1FullCollector::verify_after_marking() { 245 if (!VerifyDuringGC || !_heap->verifier()->should_verify(G1HeapVerifier::G1VerifyFull)) { 246 // Only do verification if VerifyDuringGC and G1VerifyFull is set. 247 return; 248 } 249 250 HandleMark hm; // handle scope 251 #if COMPILER2_OR_JVMCI 252 DerivedPointerTableDeactivate dpt_deact; 253 #endif 254 _heap->prepare_for_verify(); 255 // Note: we can verify only the heap here. When an object is 256 // marked, the previous value of the mark word (including 257 // identity hash values, ages, etc) is preserved, and the mark 258 // word is set to markOop::marked_value - effectively removing 259 // any hash values from the mark word. These hash values are 260 // used when verifying the dictionaries and so removing them 261 // from the mark word can make verification of the dictionaries 262 // fail. At the end of the GC, the original mark word values 263 // (including hash values) are restored to the appropriate 264 // objects. 265 GCTraceTime(Info, gc, verify)("Verifying During GC (full)"); 266 _heap->verify(VerifyOption_G1UseFullMarking); 267 }