1 /* 2 * Copyright (c) 2015, 2016, 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 "memory/allocation.inline.hpp" 42 #include "runtime/fprofiler.hpp" 43 #include "runtime/mutex.hpp" 44 #include "services/management.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(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 // Finish up any enqueued closure apps (attributed as object copy time). 121 closures->flush(); 122 123 double obj_copy_time_sec = closures->closure_app_seconds(); 124 125 phase_times->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec); 126 127 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec; 128 129 phase_times->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec); 130 131 // During conc marking we have to filter the per-thread SATB buffers 132 // to make sure we remove any oops into the CSet (which will show up 133 // as implicitly live). 134 { 135 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i); 136 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_in_progress()) { 137 G1BarrierSet::satb_mark_queue_set().filter_thread_buffers(); 138 } 139 } 140 141 _process_strong_tasks.all_tasks_completed(n_workers()); 142 } 143 144 // Adaptor to pass the closures to the strong roots in the VM. 145 class StrongRootsClosures : public G1RootClosures { 146 OopClosure* _roots; 147 CLDClosure* _clds; 148 CodeBlobClosure* _blobs; 149 public: 150 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) : 151 _roots(roots), _clds(clds), _blobs(blobs) {} 152 153 OopClosure* weak_oops() { return NULL; } 154 OopClosure* strong_oops() { return _roots; } 155 156 CLDClosure* weak_clds() { return NULL; } 157 CLDClosure* strong_clds() { return _clds; } 158 159 CodeBlobClosure* strong_codeblobs() { return _blobs; } 160 }; 161 162 void G1RootProcessor::process_strong_roots(OopClosure* oops, 163 CLDClosure* clds, 164 CodeBlobClosure* blobs) { 165 StrongRootsClosures closures(oops, clds, blobs); 166 167 process_java_roots(&closures, NULL, 0); 168 process_vm_roots(&closures, NULL, 0); 169 170 _process_strong_tasks.all_tasks_completed(n_workers()); 171 } 172 173 // Adaptor to pass the closures to all the roots in the VM. 174 class AllRootsClosures : public G1RootClosures { 175 OopClosure* _roots; 176 CLDClosure* _clds; 177 public: 178 AllRootsClosures(OopClosure* roots, CLDClosure* clds) : 179 _roots(roots), _clds(clds) {} 180 181 OopClosure* weak_oops() { return _roots; } 182 OopClosure* strong_oops() { return _roots; } 183 184 // By returning the same CLDClosure for both weak and strong CLDs we ensure 185 // that a single walk of the CLDG will invoke the closure on all CLDs i the 186 // system. 187 CLDClosure* weak_clds() { return _clds; } 188 CLDClosure* strong_clds() { return _clds; } 189 190 // We don't want to visit code blobs more than once, so we return NULL for the 191 // strong case and walk the entire code cache as a separate step. 192 CodeBlobClosure* strong_codeblobs() { return NULL; } 193 }; 194 195 void G1RootProcessor::process_all_roots(OopClosure* oops, 196 CLDClosure* clds, 197 CodeBlobClosure* blobs, 198 bool process_string_table) { 199 AllRootsClosures closures(oops, clds); 200 201 process_java_roots(&closures, NULL, 0); 202 process_vm_roots(&closures, NULL, 0); 203 204 if (process_string_table) { 205 process_string_table_roots(&closures, NULL, 0); 206 } 207 process_code_cache_roots(blobs, NULL, 0); 208 209 _process_strong_tasks.all_tasks_completed(n_workers()); 210 } 211 212 void G1RootProcessor::process_all_roots(OopClosure* oops, 213 CLDClosure* clds, 214 CodeBlobClosure* blobs) { 215 process_all_roots(oops, clds, blobs, true); 216 } 217 218 void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops, 219 CLDClosure* clds, 220 CodeBlobClosure* blobs) { 221 assert(!ClassUnloading, "Should only be used when class unloading is disabled"); 222 process_all_roots(oops, clds, blobs, false); 223 } 224 225 void G1RootProcessor::process_java_roots(G1RootClosures* closures, 226 G1GCPhaseTimes* phase_times, 227 uint worker_i) { 228 // Iterating over the CLDG and the Threads are done early to allow us to 229 // first process the strong CLDs and nmethods and then, after a barrier, 230 // let the thread process the weak CLDs and nmethods. 231 { 232 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i); 233 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) { 234 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds()); 235 } 236 } 237 238 { 239 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i); 240 bool is_par = n_workers() > 1; 241 Threads::possibly_parallel_oops_do(is_par, 242 closures->strong_oops(), 243 closures->strong_codeblobs()); 244 } 245 } 246 247 void G1RootProcessor::process_vm_roots(G1RootClosures* closures, 248 G1GCPhaseTimes* phase_times, 249 uint worker_i) { 250 OopClosure* strong_roots = closures->strong_oops(); 251 OopClosure* weak_roots = closures->weak_oops(); 252 253 { 254 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i); 255 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) { 256 Universe::oops_do(strong_roots); 257 } 258 } 259 260 { 261 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i); 262 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) { 263 JNIHandles::oops_do(strong_roots); 264 } 265 } 266 267 { 268 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i); 269 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) { 270 ObjectSynchronizer::oops_do(strong_roots); 271 } 272 } 273 274 { 275 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::FlatProfilerRoots, worker_i); 276 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_FlatProfiler_oops_do)) { 277 FlatProfiler::oops_do(strong_roots); 278 } 279 } 280 281 { 282 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i); 283 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) { 284 Management::oops_do(strong_roots); 285 } 286 } 287 288 { 289 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i); 290 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) { 291 JvmtiExport::oops_do(strong_roots); 292 } 293 } 294 295 #if INCLUDE_AOT 296 if (UseAOT) { 297 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i); 298 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_aot_oops_do)) { 299 AOTLoader::oops_do(strong_roots); 300 } 301 } 302 #endif 303 304 { 305 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i); 306 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) { 307 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 308 } 309 } 310 } 311 312 void G1RootProcessor::process_string_table_roots(G1RootClosures* closures, 313 G1GCPhaseTimes* phase_times, 314 uint worker_i) { 315 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed"); 316 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i); 317 // All threads execute the following. A specific chunk of buckets 318 // from the StringTable are the individual tasks. 319 StringTable::possibly_parallel_oops_do(closures->weak_oops()); 320 } 321 322 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure, 323 G1GCPhaseTimes* phase_times, 324 uint worker_i) { 325 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) { 326 CodeCache::blobs_do(code_closure); 327 } 328 } 329 330 uint G1RootProcessor::n_workers() const { 331 return _srs.n_threads(); 332 }