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 "classfile/stringTable.hpp" 28 #include "classfile/systemDictionary.hpp" 29 #include "code/codeCache.hpp" 30 #include "gc/g1/bufferingOopClosure.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/g1Policy.hpp" 36 #include "gc/g1/g1RootClosures.hpp" 37 #include "gc/g1/g1RootProcessor.hpp" 38 #include "gc/g1/heapRegion.inline.hpp" 39 #include "memory/allocation.inline.hpp" 40 #include "runtime/fprofiler.hpp" 41 #include "runtime/mutex.hpp" 42 #include "services/management.hpp" 43 44 void G1RootProcessor::worker_has_discovered_all_strong_classes() { 45 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 46 47 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes); 48 if (new_value == n_workers()) { 49 // This thread is last. Notify the others. 50 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 51 _lock.notify_all(); 52 } 53 } 54 55 void G1RootProcessor::wait_until_all_strong_classes_discovered() { 56 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 57 58 if ((uint)_n_workers_discovered_strong_classes != n_workers()) { 59 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 60 while ((uint)_n_workers_discovered_strong_classes != n_workers()) { 61 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false); 62 } 63 } 64 } 65 66 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) : 67 _g1h(g1h), 68 _process_strong_tasks(G1RP_PS_NumElements), 69 _srs(n_workers), 70 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never), 71 _n_workers_discovered_strong_classes(0) {} 72 73 void G1RootProcessor::evacuate_roots(G1EvacuationRootClosures* closures, uint worker_i) { 74 double ext_roots_start = os::elapsedTime(); 75 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 76 77 process_java_roots(closures, phase_times, worker_i); 78 79 // This is the point where this worker thread will not find more strong CLDs/nmethods. 80 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing. 81 if (closures->trace_metadata()) { 82 worker_has_discovered_all_strong_classes(); 83 } 84 85 process_vm_roots(closures, phase_times, worker_i); 86 process_string_table_roots(closures, phase_times, worker_i); 87 88 { 89 // Now the CM ref_processor roots. 90 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_i); 91 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) { 92 // We need to treat the discovered reference lists of the 93 // concurrent mark ref processor as roots and keep entries 94 // (which are added by the marking threads) on them live 95 // until they can be processed at the end of marking. 96 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops()); 97 } 98 } 99 100 if (closures->trace_metadata()) { 101 { 102 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i); 103 // Barrier to make sure all workers passed 104 // the strong CLD and strong nmethods phases. 105 wait_until_all_strong_classes_discovered(); 106 } 107 108 // Now take the complement of the strong CLDs. 109 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i); 110 assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata."); 111 ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds()); 112 } else { 113 phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0); 114 phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0); 115 assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata."); 116 } 117 118 // Finish up any enqueued closure apps (attributed as object copy time). 119 closures->flush(); 120 121 double obj_copy_time_sec = closures->closure_app_seconds(); 122 123 phase_times->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec); 124 125 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec; 126 127 phase_times->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec); 128 129 // During conc marking we have to filter the per-thread SATB buffers 130 // to make sure we remove any oops into the CSet (which will show up 131 // as implicitly live). 132 { 133 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i); 134 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_in_progress()) { 135 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 136 } 137 } 138 139 _process_strong_tasks.all_tasks_completed(n_workers()); 140 } 141 142 // Adaptor to pass the closures to the strong roots in the VM. 143 class StrongRootsClosures : public G1RootClosures { 144 OopClosure* _roots; 145 CLDClosure* _clds; 146 CodeBlobClosure* _blobs; 147 public: 148 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) : 149 _roots(roots), _clds(clds), _blobs(blobs) {} 150 151 OopClosure* weak_oops() { return NULL; } 152 OopClosure* strong_oops() { return _roots; } 153 154 CLDClosure* weak_clds() { return NULL; } 155 CLDClosure* strong_clds() { return _clds; } 156 157 CodeBlobClosure* strong_codeblobs() { return _blobs; } 158 }; 159 160 void G1RootProcessor::process_strong_roots(OopClosure* oops, 161 CLDClosure* clds, 162 CodeBlobClosure* blobs) { 163 StrongRootsClosures closures(oops, clds, blobs); 164 165 process_java_roots(&closures, NULL, 0); 166 process_vm_roots(&closures, NULL, 0); 167 168 _process_strong_tasks.all_tasks_completed(n_workers()); 169 } 170 171 // Adaptor to pass the closures to all the roots in the VM. 172 class AllRootsClosures : public G1RootClosures { 173 OopClosure* _roots; 174 CLDClosure* _clds; 175 public: 176 AllRootsClosures(OopClosure* roots, CLDClosure* clds) : 177 _roots(roots), _clds(clds) {} 178 179 OopClosure* weak_oops() { return _roots; } 180 OopClosure* strong_oops() { return _roots; } 181 182 // By returning the same CLDClosure for both weak and strong CLDs we ensure 183 // that a single walk of the CLDG will invoke the closure on all CLDs i the 184 // system. 185 CLDClosure* weak_clds() { return _clds; } 186 CLDClosure* strong_clds() { return _clds; } 187 188 // We don't want to visit code blobs more than once, so we return NULL for the 189 // strong case and walk the entire code cache as a separate step. 190 CodeBlobClosure* strong_codeblobs() { return NULL; } 191 }; 192 193 void G1RootProcessor::process_all_roots(OopClosure* oops, 194 CLDClosure* clds, 195 CodeBlobClosure* blobs, 196 bool process_string_table) { 197 AllRootsClosures closures(oops, clds); 198 199 process_java_roots(&closures, NULL, 0); 200 process_vm_roots(&closures, NULL, 0); 201 202 if (process_string_table) { 203 process_string_table_roots(&closures, NULL, 0); 204 } 205 process_code_cache_roots(blobs, NULL, 0); 206 207 _process_strong_tasks.all_tasks_completed(n_workers()); 208 } 209 210 void G1RootProcessor::process_all_roots(OopClosure* oops, 211 CLDClosure* clds, 212 CodeBlobClosure* blobs) { 213 process_all_roots(oops, clds, blobs, true); 214 } 215 216 void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops, 217 CLDClosure* clds, 218 CodeBlobClosure* blobs) { 219 assert(!ClassUnloading, "Should only be used when class unloading is disabled"); 220 process_all_roots(oops, clds, blobs, false); 221 } 222 223 void G1RootProcessor::process_java_roots(G1RootClosures* closures, 224 G1GCPhaseTimes* phase_times, 225 uint worker_i) { 226 // Iterating over the CLDG and the Threads are done early to allow us to 227 // first process the strong CLDs and nmethods and then, after a barrier, 228 // let the thread process the weak CLDs and nmethods. 229 { 230 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i); 231 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) { 232 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds()); 233 } 234 } 235 236 { 237 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i); 238 bool is_par = n_workers() > 1; 239 Threads::possibly_parallel_oops_do(is_par, 240 closures->strong_oops(), 241 closures->strong_codeblobs()); 242 } 243 } 244 245 void G1RootProcessor::process_vm_roots(G1RootClosures* closures, 246 G1GCPhaseTimes* phase_times, 247 uint worker_i) { 248 OopClosure* strong_roots = closures->strong_oops(); 249 OopClosure* weak_roots = closures->weak_oops(); 250 251 { 252 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i); 253 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) { 254 Universe::oops_do(strong_roots); 255 } 256 } 257 258 { 259 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i); 260 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) { 261 JNIHandles::oops_do(strong_roots); 262 } 263 } 264 265 { 266 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i); 267 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) { 268 ObjectSynchronizer::oops_do(strong_roots); 269 } 270 } 271 272 { 273 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::FlatProfilerRoots, worker_i); 274 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_FlatProfiler_oops_do)) { 275 FlatProfiler::oops_do(strong_roots); 276 } 277 } 278 279 { 280 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i); 281 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) { 282 Management::oops_do(strong_roots); 283 } 284 } 285 286 { 287 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i); 288 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) { 289 JvmtiExport::oops_do(strong_roots); 290 } 291 } 292 293 { 294 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i); 295 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) { 296 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 297 } 298 } 299 } 300 301 void G1RootProcessor::process_string_table_roots(G1RootClosures* closures, 302 G1GCPhaseTimes* phase_times, 303 uint worker_i) { 304 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed"); 305 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i); 306 // All threads execute the following. A specific chunk of buckets 307 // from the StringTable are the individual tasks. 308 StringTable::possibly_parallel_oops_do(closures->weak_oops()); 309 } 310 311 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure, 312 G1GCPhaseTimes* phase_times, 313 uint worker_i) { 314 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) { 315 CodeCache::blobs_do(code_closure); 316 } 317 } 318 319 uint G1RootProcessor::n_workers() const { 320 return _srs.n_threads(); 321 }