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 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 60 #endif /* USDT2 */ 61 } 62 63 void VM_GC_Operation::notify_gc_end() { 64 #ifndef USDT2 65 HS_DTRACE_PROBE(hotspot, gc__end); 66 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 67 #else /* USDT2 */ 68 HOTSPOT_GC_END(); 69 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 70 #endif /* USDT2 */ 71 } 72 73 void VM_GC_Operation::acquire_pending_list_lock() { 74 // we may enter this with pending exception set 75 InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock); 76 } 77 78 79 void VM_GC_Operation::release_and_notify_pending_list_lock() { 80 81 InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock); 82 } 83 84 // Allocations may fail in several threads at about the same time, 85 // resulting in multiple gc requests. We only want to do one of them. 86 // In case a GC locker is active and the need for a GC is already signaled, 87 // we want to skip this GC attempt altogether, without doing a futile 88 // safepoint operation. 89 bool VM_GC_Operation::skip_operation() const { 90 bool skip = (_gc_count_before != Universe::heap()->total_collections()); 91 if (_full && skip) { 92 skip = (_full_gc_count_before != Universe::heap()->total_full_collections()); 93 } 94 if (!skip && GC_locker::is_active_and_needs_gc()) { 95 skip = Universe::heap()->is_maximal_no_gc(); 96 assert(!(skip && (_gc_cause == GCCause::_gc_locker)), 97 "GC_locker cannot be active when initiating GC"); 98 } 99 return skip; 100 } 101 102 bool VM_GC_Operation::doit_prologue() { 103 assert(Thread::current()->is_Java_thread(), "just checking"); 104 assert(((_gc_cause != GCCause::_no_gc) && 105 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause"); 106 107 acquire_pending_list_lock(); 108 // If the GC count has changed someone beat us to the collection 109 // Get the Heap_lock after the pending_list_lock. 110 Heap_lock->lock(); 111 112 // Check invocations 113 if (skip_operation()) { 114 // skip collection 115 Heap_lock->unlock(); 116 release_and_notify_pending_list_lock(); 117 _prologue_succeeded = false; 118 } else { 119 _prologue_succeeded = true; 120 SharedHeap* sh = SharedHeap::heap(); 121 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true; 122 } 123 return _prologue_succeeded; 124 } 125 126 127 void VM_GC_Operation::doit_epilogue() { 128 assert(Thread::current()->is_Java_thread(), "just checking"); 129 // Release the Heap_lock first. 130 SharedHeap* sh = SharedHeap::heap(); 131 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false; 132 Heap_lock->unlock(); 133 release_and_notify_pending_list_lock(); 134 } 135 136 bool VM_GC_HeapInspection::doit_prologue() { 137 if (Universe::heap()->supports_heap_inspection()) { 138 return VM_GC_Operation::doit_prologue(); 139 } else { 140 return false; 141 } 142 } 143 144 bool VM_GC_HeapInspection::skip_operation() const { 145 assert(Universe::heap()->supports_heap_inspection(), "huh?"); 146 return false; 147 } 148 149 bool VM_GC_HeapInspection::collect() { 150 if (GC_locker::is_active()) { 151 return false; 152 } 153 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection); 154 return true; 155 } 156 157 void VM_GC_HeapInspection::doit() { 158 HandleMark hm; 159 Universe::heap()->ensure_parsability(false); // must happen, even if collection does 160 // not happen (e.g. due to GC_locker) 161 // or _full_gc being false 162 if (_full_gc) { 163 if (!collect()) { 164 // The collection attempt was skipped because the gc locker is held. 165 // The following dump may then be a tad misleading to someone expecting 166 // only live objects to show up in the dump (see CR 6944195). Just issue 167 // a suitable warning in that case and do not attempt to do a collection. 168 // The latter is a subtle point, because even a failed attempt 169 // to GC will, in fact, induce one in the future, which we 170 // probably want to avoid in this case because the GC that we may 171 // be about to attempt holds value for us only 172 // if it happens now and not if it happens in the eventual 173 // future. 174 warning("GC locker is held; pre-dump GC was skipped"); 175 } 176 } 177 HeapInspection inspect(_csv_format, _print_help, _print_class_stats, 178 _columns); 179 inspect.heap_inspection(_out); 180 } 181 182 183 void VM_GenCollectForAllocation::doit() { 184 SvcGCMarker sgcm(SvcGCMarker::MINOR); 185 186 GenCollectedHeap* gch = GenCollectedHeap::heap(); 187 GCCauseSetter gccs(gch, _gc_cause); 188 _res = gch->satisfy_failed_allocation(_size, _tlab); 189 assert(gch->is_in_reserved_or_null(_res), "result not in heap"); 190 191 if (_res == NULL && GC_locker::is_active_and_needs_gc()) { 192 set_gc_locked(); 193 } 194 } 195 196 void VM_GenCollectFull::doit() { 197 SvcGCMarker sgcm(SvcGCMarker::FULL); 198 199 GenCollectedHeap* gch = GenCollectedHeap::heap(); 200 GCCauseSetter gccs(gch, _gc_cause); 201 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level); 202 } 203 204 void VM_CollectForMetadataAllocation::doit() { 205 SvcGCMarker sgcm(SvcGCMarker::FULL); 206 207 CollectedHeap* heap = Universe::heap(); 208 GCCauseSetter gccs(heap, _gc_cause); 209 210 // Check again if the space is available. Another thread 211 // may have similarly failed a metadata allocation and induced 212 // a GC that freed space for the allocation. 213 if (!MetadataAllocationFailALot) { 214 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 215 } 216 217 if (_result == NULL) { 218 if (UseConcMarkSweepGC) { 219 if (CMSClassUnloadingEnabled) { 220 MetaspaceGC::set_should_concurrent_collect(true); 221 } 222 // For CMS expand since the collection is going to be concurrent. 223 _result = 224 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 225 } 226 if (_result == NULL) { 227 // Don't clear the soft refs yet. 228 if (Verbose && PrintGCDetails && UseConcMarkSweepGC) { 229 gclog_or_tty->print_cr("\nCMS full GC for Metaspace"); 230 } 231 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold); 232 // After a GC try to allocate without expanding. Could fail 233 // and expansion will be tried below. 234 _result = 235 _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 236 } 237 if (_result == NULL) { 238 // If still failing, allow the Metaspace to expand. 239 // See delta_capacity_until_GC() for explanation of the 240 // amount of the expansion. 241 // This should work unless there really is no more space 242 // or a MaxMetaspaceSize has been specified on the command line. 243 _result = 244 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 245 if (_result == NULL) { 246 // If expansion failed, do a last-ditch collection and try allocating 247 // again. A last-ditch collection will clear softrefs. This 248 // behavior is similar to the last-ditch collection done for perm 249 // gen when it was full and a collection for failed allocation 250 // did not free perm gen space. 251 heap->collect_as_vm_thread(GCCause::_last_ditch_collection); 252 _result = 253 _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 254 } 255 } 256 if (Verbose && PrintGCDetails && _result == NULL) { 257 gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size " 258 SIZE_FORMAT, _size); 259 } 260 } 261 262 if (_result == NULL && GC_locker::is_active_and_needs_gc()) { 263 set_gc_locked(); 264 } 265 }