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/g1CodeBlobClosure.hpp" 32 #include "gc/g1/g1CollectedHeap.inline.hpp" 33 #include "gc/g1/g1CollectorState.hpp" 34 #include "gc/g1/g1GCPhaseTimes.hpp" 35 #include "gc/g1/g1ParScanThreadState.inline.hpp" 36 #include "gc/g1/g1Policy.hpp" 37 #include "gc/g1/g1RootClosures.hpp" 38 #include "gc/g1/g1RootProcessor.hpp" 39 #include "gc/g1/heapRegion.inline.hpp" 40 #include "gc/shared/weakProcessor.hpp" 41 #include "memory/allocation.inline.hpp" 42 #include "runtime/mutex.hpp" 43 #include "services/management.hpp" 44 #include "utilities/macros.hpp" 45 46 void G1RootProcessor::worker_has_discovered_all_strong_classes() { 47 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 48 49 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes); 50 if (new_value == n_workers()) { 51 // This thread is last. Notify the others. 52 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 53 _lock.notify_all(); 54 } 55 } 56 57 void G1RootProcessor::wait_until_all_strong_classes_discovered() { 58 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 59 60 if ((uint)_n_workers_discovered_strong_classes != n_workers()) { 61 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 62 while ((uint)_n_workers_discovered_strong_classes != n_workers()) { 63 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false); 64 } 65 } 66 } 67 68 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) : 69 _g1h(g1h), 70 _process_strong_tasks(G1RP_PS_NumElements), 71 _srs(n_workers), 72 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never), 73 _n_workers_discovered_strong_classes(0) {} 74 75 void G1RootProcessor::evacuate_roots(G1ParScanThreadState* pss, G1EvacuationRootClosures* closures, uint worker_i) { 76 double ext_roots_start = os::elapsedTime(); 77 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 78 79 process_java_roots(closures, phase_times, worker_i); 80 81 // This is the point where this worker thread will not find more strong CLDs/nmethods. 82 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing. 83 if (closures->trace_metadata()) { 84 worker_has_discovered_all_strong_classes(); 85 } 86 87 process_vm_roots(closures, phase_times, worker_i); 88 process_string_table_roots(closures, phase_times, worker_i); 89 90 { 91 // Now the CM ref_processor roots. 92 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_i); 93 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) { 94 // We need to treat the discovered reference lists of the 95 // concurrent mark ref processor as roots and keep entries 96 // (which are added by the marking threads) on them live 97 // until they can be processed at the end of marking. 98 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops()); 99 } 100 } 101 102 if (closures->trace_metadata()) { 103 { 104 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i); 105 // Barrier to make sure all workers passed 106 // the strong CLD and strong nmethods phases. 107 wait_until_all_strong_classes_discovered(); 108 } 109 110 // Now take the complement of the strong CLDs. 111 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i); 112 assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata."); 113 ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds()); 114 } else { 115 phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0); 116 phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0); 117 assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata."); 118 } 119 120 double const obj_copy_time_sec = TicksToTimeHelper::seconds(pss->trim_ticks_and_reset()); 121 122 phase_times->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec); 123 124 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec; 125 126 phase_times->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec); 127 128 // During conc marking we have to filter the per-thread SATB buffers 129 // to make sure we remove any oops into the CSet (which will show up 130 // as implicitly live). 131 { 132 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i); 133 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_or_rebuild_in_progress()) { 134 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 135 } 136 } 137 138 _process_strong_tasks.all_tasks_completed(n_workers()); 139 } 140 141 // Adaptor to pass the closures to the strong roots in the VM. 142 class StrongRootsClosures : public G1RootClosures { 143 OopClosure* _roots; 144 CLDClosure* _clds; 145 CodeBlobClosure* _blobs; 146 public: 147 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) : 148 _roots(roots), _clds(clds), _blobs(blobs) {} 149 150 OopClosure* weak_oops() { return NULL; } 151 OopClosure* strong_oops() { return _roots; } 152 153 CLDClosure* weak_clds() { return NULL; } 154 CLDClosure* strong_clds() { return _clds; } 155 156 CodeBlobClosure* strong_codeblobs() { return _blobs; } 157 }; 158 159 void G1RootProcessor::process_strong_roots(OopClosure* oops, 160 CLDClosure* clds, 161 CodeBlobClosure* blobs) { 162 StrongRootsClosures closures(oops, clds, blobs); 163 164 process_java_roots(&closures, NULL, 0); 165 process_vm_roots(&closures, NULL, 0); 166 167 _process_strong_tasks.all_tasks_completed(n_workers()); 168 } 169 170 // Adaptor to pass the closures to all the roots in the VM. 171 class AllRootsClosures : public G1RootClosures { 172 OopClosure* _roots; 173 CLDClosure* _clds; 174 public: 175 AllRootsClosures(OopClosure* roots, CLDClosure* clds) : 176 _roots(roots), _clds(clds) {} 177 178 OopClosure* weak_oops() { return _roots; } 179 OopClosure* strong_oops() { return _roots; } 180 181 // By returning the same CLDClosure for both weak and strong CLDs we ensure 182 // that a single walk of the CLDG will invoke the closure on all CLDs i the 183 // system. 184 CLDClosure* weak_clds() { return _clds; } 185 CLDClosure* strong_clds() { return _clds; } 186 187 // We don't want to visit code blobs more than once, so we return NULL for the 188 // strong case and walk the entire code cache as a separate step. 189 CodeBlobClosure* strong_codeblobs() { return NULL; } 190 }; 191 192 void G1RootProcessor::process_all_roots(OopClosure* oops, 193 CLDClosure* clds, 194 CodeBlobClosure* blobs, 195 bool process_string_table) { 196 AllRootsClosures closures(oops, clds); 197 198 process_java_roots(&closures, NULL, 0); 199 process_vm_roots(&closures, NULL, 0); 200 201 if (process_string_table) { 202 process_string_table_roots(&closures, NULL, 0); 203 } 204 process_code_cache_roots(blobs, NULL, 0); 205 206 _process_strong_tasks.all_tasks_completed(n_workers()); 207 } 208 209 void G1RootProcessor::process_all_roots(OopClosure* oops, 210 CLDClosure* clds, 211 CodeBlobClosure* blobs) { 212 process_all_roots(oops, clds, blobs, true); 213 } 214 215 void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops, 216 CLDClosure* clds, 217 CodeBlobClosure* blobs) { 218 assert(!ClassUnloading, "Should only be used when class unloading is disabled"); 219 process_all_roots(oops, clds, blobs, false); 220 } 221 222 void G1RootProcessor::process_java_roots(G1RootClosures* closures, 223 G1GCPhaseTimes* phase_times, 224 uint worker_i) { 225 // Iterating over the CLDG and the Threads are done early to allow us to 226 // first process the strong CLDs and nmethods and then, after a barrier, 227 // let the thread process the weak CLDs and nmethods. 228 { 229 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i); 230 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) { 231 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds()); 232 } 233 } 234 235 { 236 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i); 237 bool is_par = n_workers() > 1; 238 Threads::possibly_parallel_oops_do(is_par, 239 closures->strong_oops(), 240 closures->strong_codeblobs()); 241 } 242 } 243 244 void G1RootProcessor::process_vm_roots(G1RootClosures* closures, 245 G1GCPhaseTimes* phase_times, 246 uint worker_i) { 247 OopClosure* strong_roots = closures->strong_oops(); 248 OopClosure* weak_roots = closures->weak_oops(); 249 250 { 251 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i); 252 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) { 253 Universe::oops_do(strong_roots); 254 } 255 } 256 257 { 258 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i); 259 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) { 260 JNIHandles::oops_do(strong_roots); 261 } 262 } 263 264 { 265 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i); 266 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) { 267 ObjectSynchronizer::oops_do(strong_roots); 268 } 269 } 270 271 { 272 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i); 273 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) { 274 Management::oops_do(strong_roots); 275 } 276 } 277 278 { 279 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i); 280 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) { 281 JvmtiExport::oops_do(strong_roots); 282 } 283 } 284 285 #if INCLUDE_AOT 286 if (UseAOT) { 287 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i); 288 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_aot_oops_do)) { 289 AOTLoader::oops_do(strong_roots); 290 } 291 } 292 #endif 293 294 { 295 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i); 296 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) { 297 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 298 } 299 } 300 } 301 302 void G1RootProcessor::process_string_table_roots(G1RootClosures* closures, 303 G1GCPhaseTimes* phase_times, 304 uint worker_i) { 305 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed"); 306 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i); 307 // All threads execute the following. A specific chunk of buckets 308 // from the StringTable are the individual tasks. 309 StringTable::possibly_parallel_oops_do(closures->weak_oops()); 310 } 311 312 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure, 313 G1GCPhaseTimes* phase_times, 314 uint worker_i) { 315 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) { 316 CodeCache::blobs_do(code_closure); 317 } 318 } 319 320 void G1RootProcessor::process_full_gc_weak_roots(OopClosure* oops) { 321 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) { 322 _g1h->ref_processor_stw()->weak_oops_do(oops); 323 } 324 325 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_weakProcessor_oops_do)) { 326 WeakProcessor::oops_do(oops); 327 } 328 } 329 330 uint G1RootProcessor::n_workers() const { 331 return _srs.n_threads(); 332 }