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 void VM_GC_Operation::acquire_pending_list_lock() { 66 _pending_list_locker.lock(); 67 } 68 69 void VM_GC_Operation::release_and_notify_pending_list_lock() { 70 _pending_list_locker.unlock(); 71 } 72 73 // Allocations may fail in several threads at about the same time, 74 // resulting in multiple gc requests. We only want to do one of them. 75 // In case a GC locker is active and the need for a GC is already signaled, 76 // we want to skip this GC attempt altogether, without doing a futile 77 // safepoint operation. 78 bool VM_GC_Operation::skip_operation() const { 79 bool skip = (_gc_count_before != Universe::heap()->total_collections()); 80 if (_full && skip) { 81 skip = (_full_gc_count_before != Universe::heap()->total_full_collections()); 82 } 83 if (!skip && GCLocker::is_active_and_needs_gc()) { 84 skip = Universe::heap()->is_maximal_no_gc(); 85 assert(!(skip && (_gc_cause == GCCause::_gc_locker)), 86 "GCLocker cannot be active when initiating GC"); 87 } 88 return skip; 89 } 90 91 bool VM_GC_Operation::doit_prologue() { 92 assert(Thread::current()->is_Java_thread(), "just checking"); 93 assert(((_gc_cause != GCCause::_no_gc) && 94 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause"); 95 96 // To be able to handle a GC the VM initialization needs to be completed. 97 if (!is_init_completed()) { 98 vm_exit_during_initialization( 99 err_msg("GC triggered before VM initialization completed. Try increasing " 100 "NewSize, current value " SIZE_FORMAT "%s.", 101 byte_size_in_proper_unit(NewSize), 102 proper_unit_for_byte_size(NewSize))); 103 } 104 105 acquire_pending_list_lock(); 106 // If the GC count has changed someone beat us to the collection 107 // Get the Heap_lock after the pending_list_lock. 108 Heap_lock->lock(); 109 110 // Check invocations 111 if (skip_operation()) { 112 // skip collection 113 Heap_lock->unlock(); 114 release_and_notify_pending_list_lock(); 115 _prologue_succeeded = false; 116 } else { 117 _prologue_succeeded = true; 118 } 119 return _prologue_succeeded; 120 } 121 122 123 void VM_GC_Operation::doit_epilogue() { 124 assert(Thread::current()->is_Java_thread(), "just checking"); 125 // Release the Heap_lock first. 126 Heap_lock->unlock(); 127 release_and_notify_pending_list_lock(); 128 } 129 130 bool VM_GC_HeapInspection::skip_operation() const { 131 return false; 132 } 133 134 bool VM_GC_HeapInspection::collect() { 135 if (GCLocker::is_active()) { 136 return false; 137 } 138 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection); 139 return true; 140 } 141 142 void VM_GC_HeapInspection::doit() { 143 HandleMark hm; 144 Universe::heap()->ensure_parsability(false); // must happen, even if collection does 145 // not happen (e.g. due to GCLocker) 146 // or _full_gc being false 147 if (_full_gc) { 148 if (!collect()) { 149 // The collection attempt was skipped because the gc locker is held. 150 // The following dump may then be a tad misleading to someone expecting 151 // only live objects to show up in the dump (see CR 6944195). Just issue 152 // a suitable warning in that case and do not attempt to do a collection. 153 // The latter is a subtle point, because even a failed attempt 154 // to GC will, in fact, induce one in the future, which we 155 // probably want to avoid in this case because the GC that we may 156 // be about to attempt holds value for us only 157 // if it happens now and not if it happens in the eventual 158 // future. 159 log_warning(gc)("GC locker is held; pre-dump GC was skipped"); 160 } 161 } 162 HeapInspection inspect(_csv_format, _print_help, _print_class_stats, 163 _columns); 164 inspect.heap_inspection(_out); 165 } 166 167 168 void VM_GenCollectForAllocation::doit() { 169 SvcGCMarker sgcm(SvcGCMarker::MINOR); 170 171 GenCollectedHeap* gch = GenCollectedHeap::heap(); 172 GCCauseSetter gccs(gch, _gc_cause); 173 _result = gch->satisfy_failed_allocation(_word_size, _tlab); 174 assert(gch->is_in_reserved_or_null(_result), "result not in heap"); 175 176 if (_result == NULL && GCLocker::is_active_and_needs_gc()) { 177 set_gc_locked(); 178 } 179 } 180 181 void VM_GenCollectFull::doit() { 182 SvcGCMarker sgcm(SvcGCMarker::FULL); 183 184 GenCollectedHeap* gch = GenCollectedHeap::heap(); 185 GCCauseSetter gccs(gch, _gc_cause); 186 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_generation); 187 } 188 189 VM_CollectForMetadataAllocation::VM_CollectForMetadataAllocation(ClassLoaderData* loader_data, 190 size_t size, 191 Metaspace::MetadataType mdtype, 192 uint gc_count_before, 193 uint full_gc_count_before, 194 GCCause::Cause gc_cause) 195 : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true), 196 _loader_data(loader_data), _size(size), _mdtype(mdtype), _result(NULL) { 197 assert(_size != 0, "An allocation should always be requested with this operation."); 198 AllocTracer::send_allocation_requiring_gc_event(_size * HeapWordSize, GCId::peek()); 199 } 200 201 // Returns true iff concurrent GCs unloads metadata. 202 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() { 203 #if INCLUDE_ALL_GCS 204 if (UseConcMarkSweepGC && ClassUnloadingWithConcurrentMark) { 205 MetaspaceGC::set_should_concurrent_collect(true); 206 return true; 207 } 208 209 if (UseG1GC && ClassUnloadingWithConcurrentMark) { 210 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 211 g1h->g1_policy()->collector_state()->set_initiate_conc_mark_if_possible(true); 212 213 GCCauseSetter x(g1h, _gc_cause); 214 215 // At this point we are supposed to start a concurrent cycle. We 216 // will do so if one is not already in progress. 217 bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause); 218 219 if (should_start) { 220 double pause_target = g1h->g1_policy()->max_pause_time_ms(); 221 g1h->do_collection_pause_at_safepoint(pause_target); 222 } 223 return true; 224 } 225 #endif 226 227 return false; 228 } 229 230 void VM_CollectForMetadataAllocation::doit() { 231 SvcGCMarker sgcm(SvcGCMarker::FULL); 232 233 CollectedHeap* heap = Universe::heap(); 234 GCCauseSetter gccs(heap, _gc_cause); 235 236 // Check again if the space is available. Another thread 237 // may have similarly failed a metadata allocation and induced 238 // a GC that freed space for the allocation. 239 if (!MetadataAllocationFailALot) { 240 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 241 if (_result != NULL) { 242 return; 243 } 244 } 245 246 if (initiate_concurrent_GC()) { 247 // For CMS and G1 expand since the collection is going to be concurrent. 248 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 249 if (_result != NULL) { 250 return; 251 } 252 253 log_debug(gc)("%s full GC for Metaspace", UseConcMarkSweepGC ? "CMS" : "G1"); 254 } 255 256 // Don't clear the soft refs yet. 257 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold); 258 // After a GC try to allocate without expanding. Could fail 259 // and expansion will be tried below. 260 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 261 if (_result != NULL) { 262 return; 263 } 264 265 // If still failing, allow the Metaspace to expand. 266 // See delta_capacity_until_GC() for explanation of the 267 // amount of the expansion. 268 // This should work unless there really is no more space 269 // or a MaxMetaspaceSize has been specified on the command line. 270 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 271 if (_result != NULL) { 272 return; 273 } 274 275 // If expansion failed, do a collection clearing soft references. 276 heap->collect_as_vm_thread(GCCause::_metadata_GC_clear_soft_refs); 277 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 278 if (_result != NULL) { 279 return; 280 } 281 282 log_debug(gc)("After Metaspace GC failed to allocate size " SIZE_FORMAT, _size); 283 284 if (GCLocker::is_active_and_needs_gc()) { 285 set_gc_locked(); 286 } 287 } 288 289 VM_CollectForAllocation::VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause) 290 : VM_GC_Operation(gc_count_before, cause), _result(NULL), _word_size(word_size) { 291 // Only report if operation was really caused by an allocation. 292 if (_word_size != 0) { 293 AllocTracer::send_allocation_requiring_gc_event(_word_size * HeapWordSize, GCId::peek()); 294 } 295 }