1 /* 2 * Copyright (c) 2005, 2015, 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_implementation/shared/vmGCOperations.hpp" 29 #include "memory/gcLocker.inline.hpp" 30 #include "memory/genCollectedHeap.hpp" 31 #include "memory/oopFactory.hpp" 32 #include "oops/instanceKlass.hpp" 33 #include "oops/instanceRefKlass.hpp" 34 #include "runtime/handles.inline.hpp" 35 #include "runtime/init.hpp" 36 #include "runtime/interfaceSupport.hpp" 37 #include "utilities/dtrace.hpp" 38 #include "utilities/preserveException.hpp" 39 #include "utilities/macros.hpp" 40 #if INCLUDE_ALL_GCS 41 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 42 #endif // INCLUDE_ALL_GCS 43 44 VM_GC_Operation::~VM_GC_Operation() { 45 CollectedHeap* ch = Universe::heap(); 46 ch->collector_policy()->set_all_soft_refs_clear(false); 47 } 48 49 // The same dtrace probe can't be inserted in two different files, so we 50 // have to call it here, so it's only in one file. Can't create new probes 51 // for the other file anymore. The dtrace probes have to remain stable. 52 void VM_GC_Operation::notify_gc_begin(bool full) { 53 HOTSPOT_GC_BEGIN( 54 full); 55 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 56 } 57 58 void VM_GC_Operation::notify_gc_end() { 59 HOTSPOT_GC_END(); 60 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 61 } 62 63 void VM_GC_Operation::acquire_pending_list_lock() { 64 // we may enter this with pending exception set 65 InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock); 66 } 67 68 69 void VM_GC_Operation::release_and_notify_pending_list_lock() { 70 71 InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock); 72 } 73 74 // Allocations may fail in several threads at about the same time, 75 // resulting in multiple gc requests. We only want to do one of them. 76 // In case a GC locker is active and the need for a GC is already signaled, 77 // we want to skip this GC attempt altogether, without doing a futile 78 // safepoint operation. 79 bool VM_GC_Operation::skip_operation() const { 80 bool skip = (_gc_count_before != Universe::heap()->total_collections()); 81 if (_full && skip) { 82 skip = (_full_gc_count_before != Universe::heap()->total_full_collections()); 83 } 84 if (!skip && GC_locker::is_active_and_needs_gc()) { 85 skip = Universe::heap()->is_maximal_no_gc(); 86 assert(!(skip && (_gc_cause == GCCause::_gc_locker)), 87 "GC_locker cannot be active when initiating GC"); 88 } 89 return skip; 90 } 91 92 bool VM_GC_Operation::doit_prologue() { 93 assert(Thread::current()->is_Java_thread(), "just checking"); 94 assert(((_gc_cause != GCCause::_no_gc) && 95 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause"); 96 97 // To be able to handle a GC the VM initialization needs to be completed. 98 if (!is_init_completed()) { 99 vm_exit_during_initialization( 100 err_msg("GC triggered before VM initialization completed. Try increasing " 101 "NewSize, current value " SIZE_FORMAT "%s.", 102 byte_size_in_proper_unit(NewSize), 103 proper_unit_for_byte_size(NewSize))); 104 } 105 106 acquire_pending_list_lock(); 107 // If the GC count has changed someone beat us to the collection 108 // Get the Heap_lock after the pending_list_lock. 109 Heap_lock->lock(); 110 111 // Check invocations 112 if (skip_operation()) { 113 // skip collection 114 Heap_lock->unlock(); 115 release_and_notify_pending_list_lock(); 116 _prologue_succeeded = false; 117 } else { 118 _prologue_succeeded = true; 119 SharedHeap* sh = SharedHeap::heap(); 120 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true; 121 } 122 return _prologue_succeeded; 123 } 124 125 126 void VM_GC_Operation::doit_epilogue() { 127 assert(Thread::current()->is_Java_thread(), "just checking"); 128 // Release the Heap_lock first. 129 SharedHeap* sh = SharedHeap::heap(); 130 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false; 131 Heap_lock->unlock(); 132 release_and_notify_pending_list_lock(); 133 } 134 135 bool VM_GC_HeapInspection::doit_prologue() { 136 if (Universe::heap()->supports_heap_inspection()) { 137 return VM_GC_Operation::doit_prologue(); 138 } else { 139 return false; 140 } 141 } 142 143 bool VM_GC_HeapInspection::skip_operation() const { 144 assert(Universe::heap()->supports_heap_inspection(), "huh?"); 145 return false; 146 } 147 148 bool VM_GC_HeapInspection::collect() { 149 if (GC_locker::is_active()) { 150 return false; 151 } 152 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection); 153 return true; 154 } 155 156 void VM_GC_HeapInspection::doit() { 157 HandleMark hm; 158 Universe::heap()->ensure_parsability(false); // must happen, even if collection does 159 // not happen (e.g. due to GC_locker) 160 // or _full_gc being false 161 if (_full_gc) { 162 if (!collect()) { 163 // The collection attempt was skipped because the gc locker is held. 164 // The following dump may then be a tad misleading to someone expecting 165 // only live objects to show up in the dump (see CR 6944195). Just issue 166 // a suitable warning in that case and do not attempt to do a collection. 167 // The latter is a subtle point, because even a failed attempt 168 // to GC will, in fact, induce one in the future, which we 169 // probably want to avoid in this case because the GC that we may 170 // be about to attempt holds value for us only 171 // if it happens now and not if it happens in the eventual 172 // future. 173 warning("GC locker is held; pre-dump GC was skipped"); 174 } 175 } 176 HeapInspection inspect(_csv_format, _print_help, _print_class_stats, 177 _columns); 178 inspect.heap_inspection(_out); 179 } 180 181 182 void VM_GenCollectForAllocation::doit() { 183 SvcGCMarker sgcm(SvcGCMarker::MINOR); 184 185 GenCollectedHeap* gch = GenCollectedHeap::heap(); 186 GCCauseSetter gccs(gch, _gc_cause); 187 _result = gch->satisfy_failed_allocation(_word_size, _tlab); 188 assert(gch->is_in_reserved_or_null(_result), "result not in heap"); 189 190 if (_result == NULL && GC_locker::is_active_and_needs_gc()) { 191 set_gc_locked(); 192 } 193 } 194 195 void VM_GenCollectFull::doit() { 196 SvcGCMarker sgcm(SvcGCMarker::FULL); 197 198 GenCollectedHeap* gch = GenCollectedHeap::heap(); 199 GCCauseSetter gccs(gch, _gc_cause); 200 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level); 201 } 202 203 void VM_CollectForMetadataAllocation::doit_epilogue() { 204 AllocTracer::send_collect_for_allocation_event(_size * HeapWordSize, _gcid, _gc_attempt); 205 VM_GC_Operation::doit_epilogue(); 206 } 207 208 VM_CollectForMetadataAllocation::VM_CollectForMetadataAllocation(ClassLoaderData* loader_data, 209 size_t size, 210 Metaspace::MetadataType mdtype, 211 uint gc_count_before, 212 uint full_gc_count_before, 213 GCCause::Cause gc_cause, 214 uint gc_attempt) 215 : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true), 216 _loader_data(loader_data), _size(size), _mdtype(mdtype), _result(NULL), _gc_attempt(gc_attempt), _gcid(GCId::peek()) { 217 assert(_size != 0, "An allocation should always be requested with this operation."); 218 AllocTracer::send_allocation_requiring_gc_event(_size * HeapWordSize, _gcid, _gc_attempt); 219 } 220 221 // Returns true iff concurrent GCs unloads metadata. 222 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() { 223 #if INCLUDE_ALL_GCS 224 if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) { 225 MetaspaceGC::set_should_concurrent_collect(true); 226 return true; 227 } 228 229 if (UseG1GC && ClassUnloadingWithConcurrentMark) { 230 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 231 g1h->g1_policy()->set_initiate_conc_mark_if_possible(); 232 233 GCCauseSetter x(g1h, _gc_cause); 234 235 // At this point we are supposed to start a concurrent cycle. We 236 // will do so if one is not already in progress. 237 bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause); 238 239 if (should_start) { 240 double pause_target = g1h->g1_policy()->max_pause_time_ms(); 241 g1h->do_collection_pause_at_safepoint(pause_target); 242 } 243 return true; 244 } 245 #endif 246 247 return false; 248 } 249 250 static void log_metaspace_alloc_failure_for_concurrent_GC() { 251 if (Verbose && PrintGCDetails) { 252 if (UseConcMarkSweepGC) { 253 gclog_or_tty->print_cr("\nCMS full GC for Metaspace"); 254 } else if (UseG1GC) { 255 gclog_or_tty->print_cr("\nG1 full GC for Metaspace"); 256 } 257 } 258 } 259 260 void VM_CollectForMetadataAllocation::doit() { 261 SvcGCMarker sgcm(SvcGCMarker::FULL); 262 263 CollectedHeap* heap = Universe::heap(); 264 GCCauseSetter gccs(heap, _gc_cause); 265 266 // Check again if the space is available. Another thread 267 // may have similarly failed a metadata allocation and induced 268 // a GC that freed space for the allocation. 269 if (!MetadataAllocationFailALot) { 270 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 271 if (_result != NULL) { 272 return; 273 } 274 } 275 276 if (initiate_concurrent_GC()) { 277 // For CMS and G1 expand since the collection is going to be concurrent. 278 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 279 if (_result != NULL) { 280 return; 281 } 282 283 log_metaspace_alloc_failure_for_concurrent_GC(); 284 } 285 286 // Don't clear the soft refs yet. 287 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold); 288 // After a GC try to allocate without expanding. Could fail 289 // and expansion will be tried below. 290 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 291 if (_result != NULL) { 292 return; 293 } 294 295 // If still failing, allow the Metaspace to expand. 296 // See delta_capacity_until_GC() for explanation of the 297 // amount of the expansion. 298 // This should work unless there really is no more space 299 // or a MaxMetaspaceSize has been specified on the command line. 300 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 301 if (_result != NULL) { 302 return; 303 } 304 305 // If expansion failed, do a last-ditch collection and try allocating 306 // again. A last-ditch collection will clear softrefs. This 307 // behavior is similar to the last-ditch collection done for perm 308 // gen when it was full and a collection for failed allocation 309 // did not free perm gen space. 310 heap->collect_as_vm_thread(GCCause::_last_ditch_collection); 311 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 312 if (_result != NULL) { 313 return; 314 } 315 316 if (Verbose && PrintGCDetails) { 317 gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size " 318 SIZE_FORMAT, _size); 319 } 320 321 if (GC_locker::is_active_and_needs_gc()) { 322 set_gc_locked(); 323 } 324 } 325 326 VM_CollectForAllocation::VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause, uint gc_attempt) 327 : VM_GC_Operation(gc_count_before, cause), _result(NULL), _word_size(word_size), _gc_attempt(gc_attempt), _gcid(GCId::peek()) { 328 // Only report if operation was really caused by an allocation. 329 if (_word_size != 0) { 330 AllocTracer::send_allocation_requiring_gc_event(_word_size * HeapWordSize, _gcid, _gc_attempt); 331 } 332 } 333 334 void VM_CollectForAllocation::doit_epilogue() { 335 // Only report if operation was caused by an allocation. 336 if (_word_size != 0) { 337 AllocTracer::send_collect_for_allocation_event(_word_size * HeapWordSize, _gcid, _gc_attempt); 338 } 339 VM_GC_Operation::doit_epilogue(); 340 }