1 /* 2 * Copyright (c) 2005, 2020, 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 "classfile/classLoader.hpp" 27 #include "classfile/javaClasses.hpp" 28 #include "gc/shared/allocTracer.hpp" 29 #include "gc/shared/gcId.hpp" 30 #include "gc/shared/gcLocker.hpp" 31 #include "gc/shared/gcVMOperations.hpp" 32 #include "gc/shared/genCollectedHeap.hpp" 33 #include "interpreter/oopMapCache.hpp" 34 #include "logging/log.hpp" 35 #include "memory/oopFactory.hpp" 36 #include "memory/universe.hpp" 37 #include "runtime/handles.inline.hpp" 38 #include "runtime/init.hpp" 39 #include "utilities/dtrace.hpp" 40 #include "utilities/macros.hpp" 41 #include "utilities/preserveException.hpp" 42 #if INCLUDE_G1GC 43 #include "gc/g1/g1CollectedHeap.inline.hpp" 44 #include "gc/g1/g1Policy.hpp" 45 #endif // INCLUDE_G1GC 46 47 VM_GC_Operation::~VM_GC_Operation() { 48 CollectedHeap* ch = Universe::heap(); 49 ch->soft_ref_policy()->set_all_soft_refs_clear(false); 50 } 51 52 // The same dtrace probe can't be inserted in two different files, so we 53 // have to call it here, so it's only in one file. Can't create new probes 54 // for the other file anymore. The dtrace probes have to remain stable. 55 void VM_GC_Operation::notify_gc_begin(bool full) { 56 HOTSPOT_GC_BEGIN( 57 full); 58 } 59 60 void VM_GC_Operation::notify_gc_end() { 61 HOTSPOT_GC_END(); 62 } 63 64 // Allocations may fail in several threads at about the same time, 65 // resulting in multiple gc requests. We only want to do one of them. 66 // In case a GC locker is active and the need for a GC is already signaled, 67 // we want to skip this GC attempt altogether, without doing a futile 68 // safepoint operation. 69 bool VM_GC_Operation::skip_operation() const { 70 bool skip = (_gc_count_before != Universe::heap()->total_collections()); 71 if (_full && skip) { 72 skip = (_full_gc_count_before != Universe::heap()->total_full_collections()); 73 } 74 if (!skip && GCLocker::is_active_and_needs_gc()) { 75 skip = Universe::heap()->is_maximal_no_gc(); 76 assert(!(skip && (_gc_cause == GCCause::_gc_locker)), 77 "GCLocker cannot be active when initiating GC"); 78 } 79 return skip; 80 } 81 82 bool VM_GC_Operation::doit_prologue() { 83 assert(((_gc_cause != GCCause::_no_gc) && 84 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause"); 85 86 // To be able to handle a GC the VM initialization needs to be completed. 87 if (!is_init_completed()) { 88 vm_exit_during_initialization( 89 err_msg("GC triggered before VM initialization completed. Try increasing " 90 "NewSize, current value " SIZE_FORMAT "%s.", 91 byte_size_in_proper_unit(NewSize), 92 proper_unit_for_byte_size(NewSize))); 93 } 94 95 // If the GC count has changed someone beat us to the collection 96 Heap_lock->lock(); 97 98 // Check invocations 99 if (skip_operation()) { 100 // skip collection 101 Heap_lock->unlock(); 102 _prologue_succeeded = false; 103 } else { 104 _prologue_succeeded = true; 105 } 106 return _prologue_succeeded; 107 } 108 109 110 void VM_GC_Operation::doit_epilogue() { 111 // Clean up old interpreter OopMap entries that were replaced 112 // during the GC thread root traversal. 113 OopMapCache::cleanup_old_entries(); 114 if (Universe::has_reference_pending_list()) { 115 Heap_lock->notify_all(); 116 } 117 Heap_lock->unlock(); 118 } 119 120 bool VM_GC_HeapInspection::skip_operation() const { 121 return false; 122 } 123 124 bool VM_GC_HeapInspection::collect() { 125 if (GCLocker::is_active()) { 126 return false; 127 } 128 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection); 129 return true; 130 } 131 132 void VM_GC_HeapInspection::doit() { 133 HandleMark hm; 134 Universe::heap()->ensure_parsability(false); // must happen, even if collection does 135 // not happen (e.g. due to GCLocker) 136 // or _full_gc being false 137 if (_full_gc) { 138 if (!collect()) { 139 // The collection attempt was skipped because the gc locker is held. 140 // The following dump may then be a tad misleading to someone expecting 141 // only live objects to show up in the dump (see CR 6944195). Just issue 142 // a suitable warning in that case and do not attempt to do a collection. 143 // The latter is a subtle point, because even a failed attempt 144 // to GC will, in fact, induce one in the future, which we 145 // probably want to avoid in this case because the GC that we may 146 // be about to attempt holds value for us only 147 // if it happens now and not if it happens in the eventual 148 // future. 149 log_warning(gc)("GC locker is held; pre-dump GC was skipped"); 150 } 151 } 152 HeapInspection inspect; 153 inspect.heap_inspection(_out, _parallel_thread_num); 154 } 155 156 157 void VM_GenCollectForAllocation::doit() { 158 SvcGCMarker sgcm(SvcGCMarker::MINOR); 159 160 GenCollectedHeap* gch = GenCollectedHeap::heap(); 161 GCCauseSetter gccs(gch, _gc_cause); 162 _result = gch->satisfy_failed_allocation(_word_size, _tlab); 163 assert(_result == NULL || gch->is_in_reserved(_result), "result not in heap"); 164 165 if (_result == NULL && GCLocker::is_active_and_needs_gc()) { 166 set_gc_locked(); 167 } 168 } 169 170 void VM_GenCollectFull::doit() { 171 SvcGCMarker sgcm(SvcGCMarker::FULL); 172 173 GenCollectedHeap* gch = GenCollectedHeap::heap(); 174 GCCauseSetter gccs(gch, _gc_cause); 175 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_generation); 176 } 177 178 VM_CollectForMetadataAllocation::VM_CollectForMetadataAllocation(ClassLoaderData* loader_data, 179 size_t size, 180 Metaspace::MetadataType mdtype, 181 uint gc_count_before, 182 uint full_gc_count_before, 183 GCCause::Cause gc_cause) 184 : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true), 185 _result(NULL), _size(size), _mdtype(mdtype), _loader_data(loader_data) { 186 assert(_size != 0, "An allocation should always be requested with this operation."); 187 AllocTracer::send_allocation_requiring_gc_event(_size * HeapWordSize, GCId::peek()); 188 } 189 190 // Returns true iff concurrent GCs unloads metadata. 191 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() { 192 #if INCLUDE_G1GC 193 if (UseG1GC && ClassUnloadingWithConcurrentMark) { 194 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 195 g1h->policy()->collector_state()->set_initiate_conc_mark_if_possible(true); 196 197 GCCauseSetter x(g1h, _gc_cause); 198 199 // At this point we are supposed to start a concurrent cycle. We 200 // will do so if one is not already in progress. 201 bool should_start = g1h->policy()->force_initial_mark_if_outside_cycle(_gc_cause); 202 203 if (should_start) { 204 double pause_target = g1h->policy()->max_pause_time_ms(); 205 g1h->do_collection_pause_at_safepoint(pause_target); 206 } 207 return true; 208 } 209 #endif 210 211 return false; 212 } 213 214 void VM_CollectForMetadataAllocation::doit() { 215 SvcGCMarker sgcm(SvcGCMarker::FULL); 216 217 CollectedHeap* heap = Universe::heap(); 218 GCCauseSetter gccs(heap, _gc_cause); 219 220 // Check again if the space is available. Another thread 221 // may have similarly failed a metadata allocation and induced 222 // a GC that freed space for the allocation. 223 if (!MetadataAllocationFailALot) { 224 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 225 if (_result != NULL) { 226 return; 227 } 228 } 229 230 if (initiate_concurrent_GC()) { 231 // For G1 expand since the collection is going to be concurrent. 232 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 233 if (_result != NULL) { 234 return; 235 } 236 237 log_debug(gc)("G1 full GC for Metaspace"); 238 } 239 240 // Don't clear the soft refs yet. 241 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold); 242 // After a GC try to allocate without expanding. Could fail 243 // and expansion will be tried below. 244 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 245 if (_result != NULL) { 246 return; 247 } 248 249 // If still failing, allow the Metaspace to expand. 250 // See delta_capacity_until_GC() for explanation of the 251 // amount of the expansion. 252 // This should work unless there really is no more space 253 // or a MaxMetaspaceSize has been specified on the command line. 254 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 255 if (_result != NULL) { 256 return; 257 } 258 259 // If expansion failed, do a collection clearing soft references. 260 heap->collect_as_vm_thread(GCCause::_metadata_GC_clear_soft_refs); 261 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 262 if (_result != NULL) { 263 return; 264 } 265 266 log_debug(gc)("After Metaspace GC failed to allocate size " SIZE_FORMAT, _size); 267 268 if (GCLocker::is_active_and_needs_gc()) { 269 set_gc_locked(); 270 } 271 } 272 273 VM_CollectForAllocation::VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause) 274 : VM_GC_Operation(gc_count_before, cause), _word_size(word_size), _result(NULL) { 275 // Only report if operation was really caused by an allocation. 276 if (_word_size != 0) { 277 AllocTracer::send_allocation_requiring_gc_event(_word_size * HeapWordSize, GCId::peek()); 278 } 279 }