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