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 // Returns true iff concurrent GCs unloads metadata. 204 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() { 205 #if INCLUDE_ALL_GCS 206 if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) { 207 MetaspaceGC::set_should_concurrent_collect(true); 208 return true; 209 } 210 211 if (UseG1GC && ClassUnloadingWithConcurrentMark) { 212 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 213 g1h->g1_policy()->set_initiate_conc_mark_if_possible(); 214 215 GCCauseSetter x(g1h, _gc_cause); 216 217 // At this point we are supposed to start a concurrent cycle. We 218 // will do so if one is not already in progress. 219 bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause); 220 221 if (should_start) { 222 double pause_target = g1h->g1_policy()->max_pause_time_ms(); 223 g1h->do_collection_pause_at_safepoint(pause_target); 224 } 225 return true; 226 } 227 #endif 228 229 return false; 230 } 231 232 static void log_metaspace_alloc_failure_for_concurrent_GC() { 233 if (Verbose && PrintGCDetails) { 234 if (UseConcMarkSweepGC) { 235 gclog_or_tty->print_cr("\nCMS full GC for Metaspace"); 236 } else if (UseG1GC) { 237 gclog_or_tty->print_cr("\nG1 full GC for Metaspace"); 238 } 239 } 240 } 241 242 void VM_CollectForMetadataAllocation::doit() { 243 SvcGCMarker sgcm(SvcGCMarker::FULL); 244 245 CollectedHeap* heap = Universe::heap(); 246 GCCauseSetter gccs(heap, _gc_cause); 247 248 // Check again if the space is available. Another thread 249 // may have similarly failed a metadata allocation and induced 250 // a GC that freed space for the allocation. 251 if (!MetadataAllocationFailALot) { 252 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 253 if (_result != NULL) { 254 return; 255 } 256 } 257 258 if (initiate_concurrent_GC()) { 259 // For CMS and G1 expand since the collection is going to be concurrent. 260 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 261 if (_result != NULL) { 262 return; 263 } 264 265 log_metaspace_alloc_failure_for_concurrent_GC(); 266 } 267 268 // Don't clear the soft refs yet. 269 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold); 270 // After a GC try to allocate without expanding. Could fail 271 // and expansion will be tried below. 272 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 273 if (_result != NULL) { 274 return; 275 } 276 277 // If still failing, allow the Metaspace to expand. 278 // See delta_capacity_until_GC() for explanation of the 279 // amount of the expansion. 280 // This should work unless there really is no more space 281 // or a MaxMetaspaceSize has been specified on the command line. 282 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 283 if (_result != NULL) { 284 return; 285 } 286 287 // If expansion failed, do a last-ditch collection and try allocating 288 // again. A last-ditch collection will clear softrefs. This 289 // behavior is similar to the last-ditch collection done for perm 290 // gen when it was full and a collection for failed allocation 291 // did not free perm gen space. 292 heap->collect_as_vm_thread(GCCause::_last_ditch_collection); 293 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 294 if (_result != NULL) { 295 return; 296 } 297 298 if (Verbose && PrintGCDetails) { 299 gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size " 300 SIZE_FORMAT, _size); 301 } 302 303 if (GC_locker::is_active_and_needs_gc()) { 304 set_gc_locked(); 305 } 306 }