1 /* 2 * Copyright (c) 2015, 2018, 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 27 #include "aot/aotLoader.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "code/codeCache.hpp" 31 #include "gc/g1/bufferingOopClosure.hpp" 32 #include "gc/g1/g1BarrierSet.hpp" 33 #include "gc/g1/g1CodeBlobClosure.hpp" 34 #include "gc/g1/g1CollectedHeap.inline.hpp" 35 #include "gc/g1/g1CollectorState.hpp" 36 #include "gc/g1/g1GCPhaseTimes.hpp" 37 #include "gc/g1/g1Policy.hpp" 38 #include "gc/g1/g1RootClosures.hpp" 39 #include "gc/g1/g1RootProcessor.hpp" 40 #include "gc/g1/heapRegion.inline.hpp" 41 #include "gc/shared/referenceProcessor.hpp" 42 #include "gc/shared/weakProcessor.hpp" 43 #include "memory/allocation.inline.hpp" 44 #include "runtime/mutex.hpp" 45 #include "services/management.hpp" 46 #include "utilities/macros.hpp" 47 48 void G1RootProcessor::worker_has_discovered_all_strong_classes() { 49 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 50 51 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes); 52 if (new_value == n_workers()) { 53 // This thread is last. Notify the others. 54 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 55 _lock.notify_all(); 56 } 57 } 58 59 void G1RootProcessor::wait_until_all_strong_classes_discovered() { 60 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 61 62 if ((uint)_n_workers_discovered_strong_classes != n_workers()) { 63 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 64 while ((uint)_n_workers_discovered_strong_classes != n_workers()) { 65 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false); 66 } 67 } 68 } 69 70 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) : 71 _g1h(g1h), 72 _process_strong_tasks(G1RP_PS_NumElements), 73 _srs(n_workers), 74 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never), 75 _n_workers_discovered_strong_classes(0) {} 76 77 void G1RootProcessor::evacuate_roots(G1EvacuationRootClosures* closures, uint worker_i) { 78 double ext_roots_start = os::elapsedTime(); 79 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 80 81 process_java_roots(closures, phase_times, worker_i); 82 83 // This is the point where this worker thread will not find more strong CLDs/nmethods. 84 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing. 85 if (closures->trace_metadata()) { 86 worker_has_discovered_all_strong_classes(); 87 } 88 89 process_vm_roots(closures, phase_times, worker_i); 90 process_string_table_roots(closures, phase_times, worker_i); 91 92 { 93 // Now the CM ref_processor roots. 94 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_i); 95 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) { 96 // We need to treat the discovered reference lists of the 97 // concurrent mark ref processor as roots and keep entries 98 // (which are added by the marking threads) on them live 99 // until they can be processed at the end of marking. 100 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops()); 101 } 102 } 103 104 if (closures->trace_metadata()) { 105 { 106 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i); 107 // Barrier to make sure all workers passed 108 // the strong CLD and strong nmethods phases. 109 wait_until_all_strong_classes_discovered(); 110 } 111 112 // Now take the complement of the strong CLDs. 113 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i); 114 assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata."); 115 ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds()); 116 } else { 117 phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0); 118 phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0); 119 assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata."); 120 } 121 122 // Finish up any enqueued closure apps (attributed as object copy time). 123 closures->flush(); 124 125 double obj_copy_time_sec = closures->closure_app_seconds(); 126 127 phase_times->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec); 128 129 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec; 130 131 phase_times->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec); 132 133 // During conc marking we have to filter the per-thread SATB buffers 134 // to make sure we remove any oops into the CSet (which will show up 135 // as implicitly live). 136 { 137 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i); 138 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_or_rebuild_in_progress()) { 139 G1BarrierSet::satb_mark_queue_set().filter_thread_buffers(); 140 } 141 } 142 143 _process_strong_tasks.all_tasks_completed(n_workers()); 144 } 145 146 // Adaptor to pass the closures to the strong roots in the VM. 147 class StrongRootsClosures : public G1RootClosures { 148 OopClosure* _roots; 149 CLDClosure* _clds; 150 CodeBlobClosure* _blobs; 151 public: 152 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) : 153 _roots(roots), _clds(clds), _blobs(blobs) {} 154 155 OopClosure* weak_oops() { return NULL; } 156 OopClosure* strong_oops() { return _roots; } 157 158 CLDClosure* weak_clds() { return NULL; } 159 CLDClosure* strong_clds() { return _clds; } 160 161 CodeBlobClosure* strong_codeblobs() { return _blobs; } 162 }; 163 164 void G1RootProcessor::process_strong_roots(OopClosure* oops, 165 CLDClosure* clds, 166 CodeBlobClosure* blobs) { 167 StrongRootsClosures closures(oops, clds, blobs); 168 169 process_java_roots(&closures, NULL, 0); 170 process_vm_roots(&closures, NULL, 0); 171 172 _process_strong_tasks.all_tasks_completed(n_workers()); 173 } 174 175 // Adaptor to pass the closures to all the roots in the VM. 176 class AllRootsClosures : public G1RootClosures { 177 OopClosure* _roots; 178 CLDClosure* _clds; 179 public: 180 AllRootsClosures(OopClosure* roots, CLDClosure* clds) : 181 _roots(roots), _clds(clds) {} 182 183 OopClosure* weak_oops() { return _roots; } 184 OopClosure* strong_oops() { return _roots; } 185 186 // By returning the same CLDClosure for both weak and strong CLDs we ensure 187 // that a single walk of the CLDG will invoke the closure on all CLDs i the 188 // system. 189 CLDClosure* weak_clds() { return _clds; } 190 CLDClosure* strong_clds() { return _clds; } 191 192 // We don't want to visit code blobs more than once, so we return NULL for the 193 // strong case and walk the entire code cache as a separate step. 194 CodeBlobClosure* strong_codeblobs() { return NULL; } 195 }; 196 197 void G1RootProcessor::process_all_roots(OopClosure* oops, 198 CLDClosure* clds, 199 CodeBlobClosure* blobs, 200 bool process_string_table) { 201 AllRootsClosures closures(oops, clds); 202 203 process_java_roots(&closures, NULL, 0); 204 process_vm_roots(&closures, NULL, 0); 205 206 if (process_string_table) { 207 process_string_table_roots(&closures, NULL, 0); 208 } 209 process_code_cache_roots(blobs, NULL, 0); 210 211 _process_strong_tasks.all_tasks_completed(n_workers()); 212 } 213 214 void G1RootProcessor::process_all_roots(OopClosure* oops, 215 CLDClosure* clds, 216 CodeBlobClosure* blobs) { 217 process_all_roots(oops, clds, blobs, true); 218 } 219 220 void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops, 221 CLDClosure* clds, 222 CodeBlobClosure* blobs) { 223 assert(!ClassUnloading, "Should only be used when class unloading is disabled"); 224 process_all_roots(oops, clds, blobs, false); 225 } 226 227 void G1RootProcessor::process_java_roots(G1RootClosures* closures, 228 G1GCPhaseTimes* phase_times, 229 uint worker_i) { 230 // Iterating over the CLDG and the Threads are done early to allow us to 231 // first process the strong CLDs and nmethods and then, after a barrier, 232 // let the thread process the weak CLDs and nmethods. 233 { 234 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i); 235 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) { 236 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds()); 237 } 238 } 239 240 { 241 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i); 242 bool is_par = n_workers() > 1; 243 Threads::possibly_parallel_oops_do(is_par, 244 closures->strong_oops(), 245 closures->strong_codeblobs()); 246 } 247 } 248 249 void G1RootProcessor::process_vm_roots(G1RootClosures* closures, 250 G1GCPhaseTimes* phase_times, 251 uint worker_i) { 252 OopClosure* strong_roots = closures->strong_oops(); 253 OopClosure* weak_roots = closures->weak_oops(); 254 255 { 256 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i); 257 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) { 258 Universe::oops_do(strong_roots); 259 } 260 } 261 262 { 263 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i); 264 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) { 265 JNIHandles::oops_do(strong_roots); 266 } 267 } 268 269 { 270 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i); 271 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) { 272 ObjectSynchronizer::oops_do(strong_roots); 273 } 274 } 275 276 { 277 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i); 278 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) { 279 Management::oops_do(strong_roots); 280 } 281 } 282 283 { 284 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i); 285 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) { 286 JvmtiExport::oops_do(strong_roots); 287 } 288 } 289 290 #if INCLUDE_AOT 291 if (UseAOT) { 292 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i); 293 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_aot_oops_do)) { 294 AOTLoader::oops_do(strong_roots); 295 } 296 } 297 #endif 298 299 { 300 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i); 301 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) { 302 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 303 } 304 } 305 } 306 307 void G1RootProcessor::process_string_table_roots(G1RootClosures* closures, 308 G1GCPhaseTimes* phase_times, 309 uint worker_i) { 310 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed"); 311 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i); 312 // All threads execute the following. A specific chunk of buckets 313 // from the StringTable are the individual tasks. 314 StringTable::possibly_parallel_oops_do(closures->weak_oops()); 315 } 316 317 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure, 318 G1GCPhaseTimes* phase_times, 319 uint worker_i) { 320 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) { 321 CodeCache::blobs_do(code_closure); 322 } 323 } 324 325 void G1RootProcessor::process_full_gc_weak_roots(OopClosure* oops) { 326 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) { 327 _g1h->ref_processor_stw()->weak_oops_do(oops); 328 } 329 330 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_weakProcessor_oops_do)) { 331 WeakProcessor::oops_do(oops); 332 } 333 } 334 335 uint G1RootProcessor::n_workers() const { 336 return _srs.n_threads(); 337 }