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 // The same dtrace probe can't be inserted in two different files, so we 45 // have to call it here, so it's only in one file. Can't create new probes 46 // for the other file anymore. The dtrace probes have to remain stable. 47 void VM_GC_Operation::notify_gc_begin(bool full) { 48 HOTSPOT_GC_BEGIN( 49 full); 50 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 51 } 52 53 void VM_GC_Operation::notify_gc_end() { 54 HOTSPOT_GC_END(); 55 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG(); 56 } 57 58 void VM_GC_Operation::acquire_pending_list_lock() { 59 // we may enter this with pending exception set 60 InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock); 61 } 62 63 64 void VM_GC_Operation::release_and_notify_pending_list_lock() { 65 66 InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock); 67 } 68 69 // Allocations may fail in several threads at about the same time, 70 // resulting in multiple gc requests. We only want to do one of them. 71 // In case a GC locker is active and the need for a GC is already signaled, 72 // we want to skip this GC attempt altogether, without doing a futile 73 // safepoint operation. 74 bool VM_GC_Operation::skip_operation() const { 75 bool skip = (_gc_count_before != Universe::heap()->total_collections()); 76 if (_full && skip) { 77 skip = (_full_gc_count_before != Universe::heap()->total_full_collections()); 78 } 79 if (!skip && GC_locker::is_active_and_needs_gc()) { 80 skip = Universe::heap()->is_maximal_no_gc(); 81 assert(!(skip && (_gc_cause == GCCause::_gc_locker)), 82 "GC_locker cannot be active when initiating GC"); 83 } 84 return skip; 85 } 86 87 bool VM_GC_Operation::doit_prologue() { 88 assert(Thread::current()->is_Java_thread(), "just checking"); 89 assert(((_gc_cause != GCCause::_no_gc) && 90 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause"); 91 92 // To be able to handle a GC the VM initialization needs to be completed. 93 if (!is_init_completed()) { 94 vm_exit_during_initialization( 95 err_msg("GC triggered before VM initialization completed. Try increasing " 96 "NewSize, current value " UINTX_FORMAT "%s.", 97 byte_size_in_proper_unit(NewSize), 98 proper_unit_for_byte_size(NewSize))); 99 } 100 101 acquire_pending_list_lock(); 102 // If the GC count has changed someone beat us to the collection 103 // Get the Heap_lock after the pending_list_lock. 104 Heap_lock->lock(); 105 106 // Check invocations 107 if (skip_operation()) { 108 // skip collection 109 Heap_lock->unlock(); 110 release_and_notify_pending_list_lock(); 111 _prologue_succeeded = false; 112 } else { 113 _prologue_succeeded = true; 114 SharedHeap* sh = SharedHeap::heap(); 115 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true; 116 } 117 return _prologue_succeeded; 118 } 119 120 121 void VM_GC_Operation::doit_epilogue() { 122 assert(Thread::current()->is_Java_thread(), "just checking"); 123 // Release the Heap_lock first. 124 SharedHeap* sh = SharedHeap::heap(); 125 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false; 126 Heap_lock->unlock(); 127 release_and_notify_pending_list_lock(); 128 } 129 130 bool VM_GC_HeapInspection::doit_prologue() { 131 if (Universe::heap()->supports_heap_inspection()) { 132 return VM_GC_Operation::doit_prologue(); 133 } else { 134 return false; 135 } 136 } 137 138 bool VM_GC_HeapInspection::skip_operation() const { 139 assert(Universe::heap()->supports_heap_inspection(), "huh?"); 140 return false; 141 } 142 143 bool VM_GC_HeapInspection::collect() { 144 if (GC_locker::is_active()) { 145 return false; 146 } 147 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection); 148 return true; 149 } 150 151 void VM_GC_HeapInspection::doit() { 152 HandleMark hm; 153 Universe::heap()->ensure_parsability(false); // must happen, even if collection does 154 // not happen (e.g. due to GC_locker) 155 // or _full_gc being false 156 if (_full_gc) { 157 if (!collect()) { 158 // The collection attempt was skipped because the gc locker is held. 159 // The following dump may then be a tad misleading to someone expecting 160 // only live objects to show up in the dump (see CR 6944195). Just issue 161 // a suitable warning in that case and do not attempt to do a collection. 162 // The latter is a subtle point, because even a failed attempt 163 // to GC will, in fact, induce one in the future, which we 164 // probably want to avoid in this case because the GC that we may 165 // be about to attempt holds value for us only 166 // if it happens now and not if it happens in the eventual 167 // future. 168 warning("GC locker is held; pre-dump GC was skipped"); 169 } 170 } 171 HeapInspection inspect(_csv_format, _print_help, _print_class_stats, 172 _columns); 173 inspect.heap_inspection(_out); 174 } 175 176 177 void VM_GenCollectForAllocation::doit() { 178 SvcGCMarker sgcm(SvcGCMarker::MINOR); 179 180 GenCollectedHeap* gch = GenCollectedHeap::heap(); 181 GCCauseSetter gccs(gch, _gc_cause); 182 _res = gch->satisfy_failed_allocation(_size, _tlab); 183 assert(gch->is_in_reserved_or_null(_res), "result not in heap"); 184 185 if (_res == NULL && GC_locker::is_active_and_needs_gc()) { 186 set_gc_locked(); 187 } 188 } 189 190 void VM_GenCollectFull::doit() { 191 SvcGCMarker sgcm(SvcGCMarker::FULL); 192 193 GenCollectedHeap* gch = GenCollectedHeap::heap(); 194 GCCauseSetter gccs(gch, _gc_cause); 195 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level); 196 } 197 198 void VM_CollectForMetadataAllocation::doit() { 199 SvcGCMarker sgcm(SvcGCMarker::FULL); 200 201 CollectedHeap* heap = Universe::heap(); 202 GCCauseSetter gccs(heap, _gc_cause); 203 204 // Check again if the space is available. Another thread 205 // may have similarly failed a metadata allocation and induced 206 // a GC that freed space for the allocation. 207 if (!MetadataAllocationFailALot) { 208 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 209 } 210 211 if (_result == NULL) { 212 if (UseConcMarkSweepGC) { 213 if (CMSClassUnloadingEnabled) { 214 MetaspaceGC::set_should_concurrent_collect(true); 215 } 216 // For CMS expand since the collection is going to be concurrent. 217 _result = 218 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 219 } 220 if (_result == NULL) { 221 // Don't clear the soft refs yet. 222 if (Verbose && PrintGCDetails && UseConcMarkSweepGC) { 223 gclog_or_tty->print_cr("\nCMS full GC for Metaspace"); 224 } 225 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold); 226 // After a GC try to allocate without expanding. Could fail 227 // and expansion will be tried below. 228 _result = 229 _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 230 } 231 if (_result == NULL) { 232 // If still failing, allow the Metaspace to expand. 233 // See delta_capacity_until_GC() for explanation of the 234 // amount of the expansion. 235 // This should work unless there really is no more space 236 // or a MaxMetaspaceSize has been specified on the command line. 237 _result = 238 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype); 239 if (_result == NULL) { 240 // If expansion failed, do a last-ditch collection and try allocating 241 // again. A last-ditch collection will clear softrefs. This 242 // behavior is similar to the last-ditch collection done for perm 243 // gen when it was full and a collection for failed allocation 244 // did not free perm gen space. 245 heap->collect_as_vm_thread(GCCause::_last_ditch_collection); 246 _result = 247 _loader_data->metaspace_non_null()->allocate(_size, _mdtype); 248 } 249 } 250 if (Verbose && PrintGCDetails && _result == NULL) { 251 gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size " 252 SIZE_FORMAT, _size); 253 } 254 } 255 256 if (_result == NULL && GC_locker::is_active_and_needs_gc()) { 257 set_gc_locked(); 258 } 259 }