1 /* 2 * Copyright (c) 2005, 2016, 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.inline.hpp" 31 #include "gc/shared/genCollectedHeap.hpp" 32 #include "gc/shared/vmGCOperations.hpp" 33 #include "logging/log.hpp" 34 #include "memory/oopFactory.hpp" 35 #include "runtime/handles.inline.hpp" 36 #include "runtime/init.hpp" 37 #include "runtime/interfaceSupport.hpp" 38 #include "utilities/dtrace.hpp" 39 #include "utilities/macros.hpp" 40 #include "utilities/preserveException.hpp" 41 #if INCLUDE_ALL_GCS 42 #include "gc/g1/g1CollectedHeap.inline.hpp" 43 #include "gc/g1/g1Policy.hpp" 44 #endif // INCLUDE_ALL_GCS 45 46 VM_GC_Operation::~VM_GC_Operation() { 47 CollectedHeap* ch = Universe::heap(); 48 ch->collector_policy()->set_all_soft_refs_clear(false); 49 } 50 51 // The same dtrace probe can't be inserted in two different files, so we 52 // have to call it here, so it's only in one file. Can't create new probes 53 // for the other file anymore. The dtrace probes have to remain stable. 54 void VM_GC_Operation::notify_gc_begin(bool full) { 55 HOTSPOT_GC_BEGIN( 56 full); 57 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 58 } 59 60 void VM_GC_Operation::notify_gc_end() { 61 HOTSPOT_GC_END(); 62 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 63 } 64 65 // Allocations may fail in several threads at about the same time, 66 // resulting in multiple gc requests. We only want to do one of them. 67 // In case a GC locker is active and the need for a GC is already signaled, 68 // we want to skip this GC attempt altogether, without doing a futile 69 // safepoint operation. 70 bool VM_GC_Operation::skip_operation() const { 71 bool skip = (_gc_count_before != Universe::heap()->total_collections()); 72 if (_full && skip) { 73 skip = (_full_gc_count_before != Universe::heap()->total_full_collections()); 74 } 75 if (!skip && GCLocker::is_active_and_needs_gc()) { 76 skip = Universe::heap()->is_maximal_no_gc(); 77 assert(!(skip && (_gc_cause == GCCause::_gc_locker)), 78 "GCLocker cannot be active when initiating GC"); 79 } 80 return skip; 81 } 82 83 bool VM_GC_Operation::doit_prologue() { 84 assert(Thread::current()->is_Java_thread(), "just checking"); 85 assert(((_gc_cause != GCCause::_no_gc) && 86 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause"); 87 88 // To be able to handle a GC the VM initialization needs to be completed. 89 if (!is_init_completed()) { 90 vm_exit_during_initialization( 91 err_msg("GC triggered before VM initialization completed. Try increasing " 92 "NewSize, current value " SIZE_FORMAT "%s.", 93 byte_size_in_proper_unit(NewSize), 94 proper_unit_for_byte_size(NewSize))); 95 } 96 97 // If the GC count has changed someone beat us to the collection 98 Heap_lock->lock(); 99 100 // Check invocations 101 if (skip_operation()) { 102 // skip collection 103 Heap_lock->unlock(); 104 _prologue_succeeded = false; 105 } else { 106 _prologue_succeeded = true; 107 } 108 return _prologue_succeeded; 109 } 110 111 112 void VM_GC_Operation::doit_epilogue() { 113 assert(Thread::current()->is_Java_thread(), "just checking"); 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(_csv_format, _print_help, _print_class_stats, 153 _columns); 154 inspect.heap_inspection(_out); 155 } 156 157 158 void VM_GenCollectForAllocation::doit() { 159 SvcGCMarker sgcm(SvcGCMarker::MINOR); 160 161 GenCollectedHeap* gch = GenCollectedHeap::heap(); 162 GCCauseSetter gccs(gch, _gc_cause); 163 _result = gch->satisfy_failed_allocation(_word_size, _tlab); 164 assert(gch->is_in_reserved_or_null(_result), "result not in heap"); 165 166 if (_result == NULL && GCLocker::is_active_and_needs_gc()) { 167 set_gc_locked(); 168 } 169 } 170 171 void VM_GenCollectFull::doit() { 172 SvcGCMarker sgcm(SvcGCMarker::FULL); 173 174 GenCollectedHeap* gch = GenCollectedHeap::heap(); 175 GCCauseSetter gccs(gch, _gc_cause); 176 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_generation); 177 } 178 179 VM_CollectForMetadataAllocation::VM_CollectForMetadataAllocation(ClassLoaderData* loader_data, 180 size_t size, 181 Metaspace::MetadataType mdtype, 182 uint gc_count_before, 183 uint full_gc_count_before, 184 GCCause::Cause gc_cause) 185 : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true), 186 _loader_data(loader_data), _size(size), _mdtype(mdtype), _result(NULL) { 187 assert(_size != 0, "An allocation should always be requested with this operation."); 188 AllocTracer::send_allocation_requiring_gc_event(_size * HeapWordSize, GCId::peek()); 189 } 190 191 // Returns true iff concurrent GCs unloads metadata. 192 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() { 193 #if INCLUDE_ALL_GCS 194 if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) { 195 MetaspaceGC::set_should_concurrent_collect(true); 196 return true; 197 } 198 199 if (UseG1GC && ClassUnloadingWithConcurrentMark) { 200 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 201 g1h->g1_policy()->collector_state()->set_initiate_conc_mark_if_possible(true); 202 203 GCCauseSetter x(g1h, _gc_cause); 204 205 // At this point we are supposed to start a concurrent cycle. We 206 // will do so if one is not already in progress. 207 bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause); 208 209 if (should_start) { 210 double pause_target = g1h->g1_policy()->max_pause_time_ms(); 211 g1h->do_collection_pause_at_safepoint(pause_target); 212 } 213 return true; 214 } 215 #endif 216 217 return false; 218 } 219 220 void VM_CollectForMetadataAllocation::doit() { 221 SvcGCMarker sgcm(SvcGCMarker::FULL); 222 223 CollectedHeap* heap = Universe::heap(); 224 GCCauseSetter gccs(heap, _gc_cause); 225 226 // Check again if the space is available. Another thread 227 // may have similarly failed a metadata allocation and induced 228 // a GC that freed space for the allocation. 229 if (!MetadataAllocationFailALot) { 230 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 231 if (_result != NULL) { 232 return; 233 } 234 } 235 236 if (initiate_concurrent_GC()) { 237 // For CMS and G1 expand since the collection is going to be concurrent. 238 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 239 if (_result != NULL) { 240 return; 241 } 242 243 log_debug(gc)("%s full GC for Metaspace", UseConcMarkSweepGC ? "CMS" : "G1"); 244 } 245 246 // Don't clear the soft refs yet. 247 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold); 248 // After a GC try to allocate without expanding. Could fail 249 // and expansion will be tried below. 250 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 251 if (_result != NULL) { 252 return; 253 } 254 255 // If still failing, allow the Metaspace to expand. 256 // See delta_capacity_until_GC() for explanation of the 257 // amount of the expansion. 258 // This should work unless there really is no more space 259 // or a MaxMetaspaceSize has been specified on the command line. 260 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 261 if (_result != NULL) { 262 return; 263 } 264 265 // If expansion failed, do a collection clearing soft references. 266 heap->collect_as_vm_thread(GCCause::_metadata_GC_clear_soft_refs); 267 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 268 if (_result != NULL) { 269 return; 270 } 271 272 log_debug(gc)("After Metaspace GC failed to allocate size " SIZE_FORMAT, _size); 273 274 if (GCLocker::is_active_and_needs_gc()) { 275 set_gc_locked(); 276 } 277 } 278 279 VM_CollectForAllocation::VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause) 280 : VM_GC_Operation(gc_count_before, cause), _result(NULL), _word_size(word_size) { 281 // Only report if operation was really caused by an allocation. 282 if (_word_size != 0) { 283 AllocTracer::send_allocation_requiring_gc_event(_word_size * HeapWordSize, GCId::peek()); 284 } 285 }