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/g1CodeBlobClosure.hpp" 33#include "gc/g1/g1CollectedHeap.inline.hpp" 34#include "gc/g1/g1CollectorState.hpp" 35#include "gc/g1/g1GCPhaseTimes.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 "memory/allocation.inline.hpp" 41#include "runtime/fprofiler.hpp" 42#include "runtime/mutex.hpp" 43#include "services/management.hpp" 44 45void G1RootProcessor::worker_has_discovered_all_strong_classes() { 46 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 47 48 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes); 49 if (new_value == n_workers()) { 50 // This thread is last. Notify the others. 51 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 52 _lock.notify_all(); 53 } 54} 55 56void G1RootProcessor::wait_until_all_strong_classes_discovered() { 57 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 58 59 if ((uint)_n_workers_discovered_strong_classes != n_workers()) { 60 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 61 while ((uint)_n_workers_discovered_strong_classes != n_workers()) { 62 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false); 63 } 64 } 65} 66 67G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) : 68 _g1h(g1h), 69 _process_strong_tasks(G1RP_PS_NumElements), 70 _srs(n_workers), 71 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never), 72 _n_workers_discovered_strong_classes(0) {} 73 74void G1RootProcessor::evacuate_roots(G1EvacuationRootClosures* closures, uint worker_i) { 75 double ext_roots_start = os::elapsedTime(); 76 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 77 78 process_java_roots(closures, phase_times, worker_i); 79 80 // This is the point where this worker thread will not find more strong CLDs/nmethods. 81 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing. 82 if (closures->trace_metadata()) { 83 worker_has_discovered_all_strong_classes(); 84 } 85 86 process_vm_roots(closures, phase_times, worker_i); 87 process_string_table_roots(closures, phase_times, worker_i); 88 89 { 90 // Now the CM ref_processor roots. 91 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_i); 92 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) { 93 // We need to treat the discovered reference lists of the 94 // concurrent mark ref processor as roots and keep entries 95 // (which are added by the marking threads) on them live 96 // until they can be processed at the end of marking. 97 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops()); 98 } 99 } 100 101 if (closures->trace_metadata()) { 102 { 103 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i); 104 // Barrier to make sure all workers passed 105 // the strong CLD and strong nmethods phases. 106 wait_until_all_strong_classes_discovered(); 107 } 108 109 // Now take the complement of the strong CLDs. 110 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i); 111 assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata."); 112 ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds()); 113 } else { 114 phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0); 115 phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0); 116 assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata."); 117 } 118 119 // Finish up any enqueued closure apps (attributed as object copy time). 120 closures->flush(); 121 122 double obj_copy_time_sec = closures->closure_app_seconds(); 123 124 phase_times->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec); 125 126 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec; 127 128 phase_times->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec); 129 130 // During conc marking we have to filter the per-thread SATB buffers 131 // to make sure we remove any oops into the CSet (which will show up 132 // as implicitly live). 133 { 134 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i); 135 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_in_progress()) { 136 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 137 } 138 } 139 140 _process_strong_tasks.all_tasks_completed(n_workers()); 141} 142 143// Adaptor to pass the closures to the strong roots in the VM. 144class StrongRootsClosures : public G1RootClosures { 145 OopClosure* _roots; 146 CLDClosure* _clds; 147 CodeBlobClosure* _blobs; 148public: 149 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) : 150 _roots(roots), _clds(clds), _blobs(blobs) {} 151 152 OopClosure* weak_oops() { return NULL; } 153 OopClosure* strong_oops() { return _roots; } 154 155 CLDClosure* weak_clds() { return NULL; } 156 CLDClosure* strong_clds() { return _clds; } 157 158 CodeBlobClosure* strong_codeblobs() { return _blobs; } 159}; 160 161void G1RootProcessor::process_strong_roots(OopClosure* oops, 162 CLDClosure* clds, 163 CodeBlobClosure* blobs) { 164 StrongRootsClosures closures(oops, clds, blobs); 165 166 process_java_roots(&closures, NULL, 0); 167 process_vm_roots(&closures, NULL, 0); 168 169 _process_strong_tasks.all_tasks_completed(n_workers()); 170} 171 172// Adaptor to pass the closures to all the roots in the VM. 173class AllRootsClosures : public G1RootClosures { 174 OopClosure* _roots; 175 CLDClosure* _clds; 176public: 177 AllRootsClosures(OopClosure* roots, CLDClosure* clds) : 178 _roots(roots), _clds(clds) {} 179 180 OopClosure* weak_oops() { return _roots; } 181 OopClosure* strong_oops() { return _roots; } 182 183 // By returning the same CLDClosure for both weak and strong CLDs we ensure 184 // that a single walk of the CLDG will invoke the closure on all CLDs i the 185 // system. 186 CLDClosure* weak_clds() { return _clds; } 187 CLDClosure* strong_clds() { return _clds; } 188 189 // We don't want to visit code blobs more than once, so we return NULL for the 190 // strong case and walk the entire code cache as a separate step. 191 CodeBlobClosure* strong_codeblobs() { return NULL; } 192}; 193 194void G1RootProcessor::process_all_roots(OopClosure* oops, 195 CLDClosure* clds, 196 CodeBlobClosure* blobs, 197 bool process_string_table) { 198 AllRootsClosures closures(oops, clds); 199 200 process_java_roots(&closures, NULL, 0); 201 process_vm_roots(&closures, NULL, 0); 202 203 if (process_string_table) { 204 process_string_table_roots(&closures, NULL, 0); 205 } 206 process_code_cache_roots(blobs, NULL, 0); 207 208 _process_strong_tasks.all_tasks_completed(n_workers()); 209} 210 211void G1RootProcessor::process_all_roots(OopClosure* oops, 212 CLDClosure* clds, 213 CodeBlobClosure* blobs) { 214 process_all_roots(oops, clds, blobs, true); 215} 216 217void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops, 218 CLDClosure* clds, 219 CodeBlobClosure* blobs) { 220 assert(!ClassUnloading, "Should only be used when class unloading is disabled"); 221 process_all_roots(oops, clds, blobs, false); 222} 223 224void G1RootProcessor::process_java_roots(G1RootClosures* closures, 225 G1GCPhaseTimes* phase_times, 226 uint worker_i) { 227 // Iterating over the CLDG and the Threads are done early to allow us to 228 // first process the strong CLDs and nmethods and then, after a barrier, 229 // let the thread process the weak CLDs and nmethods. 230 { 231 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i); 232 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) { 233 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds()); 234 } 235 } 236 237 { 238 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i); 239 bool is_par = n_workers() > 1; 240 Threads::possibly_parallel_oops_do(is_par, 241 closures->strong_oops(), 242 closures->strong_codeblobs()); 243 } 244} 245 246void G1RootProcessor::process_vm_roots(G1RootClosures* closures, 247 G1GCPhaseTimes* phase_times, 248 uint worker_i) { 249 OopClosure* strong_roots = closures->strong_oops(); 250 OopClosure* weak_roots = closures->weak_oops(); 251 252 { 253 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i); 254 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) { 255 Universe::oops_do(strong_roots); 256 } 257 } 258 259 { 260 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i); 261 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) { 262 JNIHandles::oops_do(strong_roots); 263 } 264 } 265 266 { 267 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i); 268 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) { 269 ObjectSynchronizer::oops_do(strong_roots); 270 } 271 } 272 273 { 274 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::FlatProfilerRoots, worker_i); 275 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_FlatProfiler_oops_do)) { 276 FlatProfiler::oops_do(strong_roots); 277 } 278 } 279 280 { 281 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i); 282 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) { 283 Management::oops_do(strong_roots); 284 } 285 } 286 287 { 288 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i); 289 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) { 290 JvmtiExport::oops_do(strong_roots); 291 } 292 } 293 294#if INCLUDE_AOT 295 if (UseAOT) { 296 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i); 297 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_aot_oops_do)) { 298 AOTLoader::oops_do(strong_roots); 299 } 300 } 301#endif 302 303 { 304 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i); 305 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) { 306 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 307 } 308 } 309} 310 311void G1RootProcessor::process_string_table_roots(G1RootClosures* closures, 312 G1GCPhaseTimes* phase_times, 313 uint worker_i) { 314 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed"); 315 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i); 316 // All threads execute the following. A specific chunk of buckets 317 // from the StringTable are the individual tasks. 318 StringTable::possibly_parallel_oops_do(closures->weak_oops()); 319} 320 321void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure, 322 G1GCPhaseTimes* phase_times, 323 uint worker_i) { 324 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) { 325 CodeCache::blobs_do(code_closure); 326 } 327} 328 329uint G1RootProcessor::n_workers() const { 330 return _srs.n_threads(); 331} 332