1 /* 2 * Copyright (c) 2005, 2013, 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 #ifndef USDT2 45 HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool); 46 HS_DTRACE_PROBE_DECL(hotspot, gc__end); 47 #endif /* !USDT2 */ 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 #ifndef USDT2 54 HS_DTRACE_PROBE1(hotspot, gc__begin, full); 55 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 56 #else /* USDT2 */ 57 HOTSPOT_GC_BEGIN( 58 full); 59 #endif /* USDT2 */ 60 } 61 62 void VM_GC_Operation::notify_gc_end() { 63 #ifndef USDT2 64 HS_DTRACE_PROBE(hotspot, gc__end); 65 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 66 #else /* USDT2 */ 67 HOTSPOT_GC_END( 68 ); 69 #endif /* USDT2 */ 70 } 71 72 void VM_GC_Operation::acquire_pending_list_lock() { 73 // we may enter this with pending exception set 74 InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock); 75 } 76 77 78 void VM_GC_Operation::release_and_notify_pending_list_lock() { 79 80 InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock); 81 } 82 83 // Allocations may fail in several threads at about the same time, 84 // resulting in multiple gc requests. We only want to do one of them. 85 // In case a GC locker is active and the need for a GC is already signalled, 86 // we want to skip this GC attempt altogether, without doing a futile 87 // safepoint operation. 88 bool VM_GC_Operation::skip_operation() const { 89 bool skip = (_gc_count_before != Universe::heap()->total_collections()); 90 if (_full && skip) { 91 skip = (_full_gc_count_before != Universe::heap()->total_full_collections()); 92 } 93 if (!skip && GC_locker::is_active_and_needs_gc()) { 94 skip = Universe::heap()->is_maximal_no_gc(); 95 assert(!(skip && (_gc_cause == GCCause::_gc_locker)), 96 "GC_locker cannot be active when initiating GC"); 97 } 98 return skip; 99 } 100 101 bool VM_GC_Operation::doit_prologue() { 102 assert(Thread::current()->is_Java_thread(), "just checking"); 103 assert(((_gc_cause != GCCause::_no_gc) && 104 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause"); 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 _res = gch->satisfy_failed_allocation(_size, _tlab); 188 assert(gch->is_in_reserved_or_null(_res), "result not in heap"); 189 190 if (_res == 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() { 204 SvcGCMarker sgcm(SvcGCMarker::FULL); 205 206 CollectedHeap* heap = Universe::heap(); 207 GCCauseSetter gccs(heap, _gc_cause); 208 209 // Check again if the space is available. Another thread 210 // may have similarly failed a metadata allocation and induced 211 // a GC that freed space for the allocation. 212 if (!MetadataAllocationFailALot) { 213 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 214 } 215 216 if (_result == NULL) { 217 if (UseConcMarkSweepGC) { 218 if (CMSClassUnloadingEnabled) { 219 MetaspaceGC::set_should_concurrent_collect(true); 220 } 221 // For CMS expand since the collection is going to be concurrent. 222 _result = 223 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 224 } 225 if (_result == NULL) { 226 // Don't clear the soft refs yet. 227 if (Verbose && PrintGCDetails && UseConcMarkSweepGC) { 228 gclog_or_tty->print_cr("\nCMS full GC for Metaspace"); 229 } 230 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold); 231 // After a GC try to allocate without expanding. Could fail 232 // and expansion will be tried below. 233 _result = 234 _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 235 } 236 if (_result == NULL) { 237 // If still failing, allow the Metaspace to expand. 238 // See delta_capacity_until_GC() for explanation of the 239 // amount of the expansion. 240 // This should work unless there really is no more space 241 // or a MaxMetaspaceSize has been specified on the command line. 242 _result = 243 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 244 if (_result == NULL) { 245 // If expansion failed, do a last-ditch collection and try allocating 246 // again. A last-ditch collection will clear softrefs. This 247 // behavior is similar to the last-ditch collection done for perm 248 // gen when it was full and a collection for failed allocation 249 // did not free perm gen space. 250 heap->collect_as_vm_thread(GCCause::_last_ditch_collection); 251 _result = 252 _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 253 } 254 } 255 if (Verbose && PrintGCDetails && _result == NULL) { 256 gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size " 257 SIZE_FORMAT, _size); 258 } 259 } 260 261 if (_result == NULL && GC_locker::is_active_and_needs_gc()) { 262 set_gc_locked(); 263 } 264 }