1 /* 2 * Copyright (c) 2015, 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_implementation/g1/bufferingOopClosure.hpp" 31 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 32 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 33 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 34 #include "gc_implementation/g1/g1RemSet.inline.hpp" 35 #include "gc_implementation/g1/g1RootProcessor.hpp" 36 #include "memory/allocation.inline.hpp" 37 #include "runtime/fprofiler.hpp" 38 #include "runtime/mutex.hpp" 39 #include "services/management.hpp" 40 41 class G1CodeBlobClosure : public CodeBlobClosure { 42 class HeapRegionGatheringOopClosure : public OopClosure { 43 G1CollectedHeap* _g1h; 44 OopClosure* _work; 45 nmethod* _nm; 46 47 template <typename T> 48 void do_oop_work(T* p) { 49 _work->do_oop(p); 50 T oop_or_narrowoop = oopDesc::load_heap_oop(p); 51 if (!oopDesc::is_null(oop_or_narrowoop)) { 52 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop); 53 HeapRegion* hr = _g1h->heap_region_containing_raw(o); 54 assert(!_g1h->obj_in_cs(o) || hr->rem_set()->strong_code_roots_list_contains(_nm), "if o still in CS then evacuation failed and nm must already be in the remset"); 55 hr->add_strong_code_root(_nm); 56 } 57 } 58 59 public: 60 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {} 61 62 void do_oop(oop* o) { 63 do_oop_work(o); 64 } 65 66 void do_oop(narrowOop* o) { 67 do_oop_work(o); 68 } 69 70 void set_nm(nmethod* nm) { 71 _nm = nm; 72 } 73 }; 74 75 HeapRegionGatheringOopClosure _oc; 76 public: 77 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {} 78 79 void do_code_blob(CodeBlob* cb) { 80 nmethod* nm = cb->as_nmethod_or_null(); 81 if (nm != NULL) { 82 if (!nm->test_set_oops_do_mark()) { 83 _oc.set_nm(nm); 84 nm->oops_do(&_oc); 85 nm->fix_oop_relocations(); 86 } 87 } 88 } 89 }; 90 91 92 void G1RootProcessor::worker_has_discovered_all_strong_classes() { 93 uint n_workers = _g1h->n_par_threads(); 94 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 95 96 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes); 97 if (new_value == n_workers) { 98 // This thread is last. Notify the others. 99 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 100 _lock.notify_all(); 101 } 102 } 103 104 void G1RootProcessor::wait_until_all_strong_classes_discovered() { 105 uint n_workers = _g1h->n_par_threads(); 106 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading"); 107 108 if ((uint)_n_workers_discovered_strong_classes != n_workers) { 109 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag); 110 while ((uint)_n_workers_discovered_strong_classes != n_workers) { 111 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false); 112 } 113 } 114 } 115 116 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, bool trace_metadata) : 117 _g1h(g1h), 118 _process_strong_tasks(new SubTasksDone(G1RP_PS_NumElements)), 119 _srs(g1h), 120 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never), 121 _n_workers_discovered_strong_classes(0), 122 _trace_metadata(trace_metadata) {} 123 124 void G1RootProcessor::evacuate_roots(OopClosure* scan_non_heap_roots, 125 OopClosure* scan_non_heap_weak_roots, 126 CLDClosure* scan_strong_clds, 127 CLDClosure* scan_weak_clds, 128 uint worker_i) { 129 // First scan the shared roots. 130 double ext_roots_start = os::elapsedTime(); 131 132 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 133 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots); 134 135 OopClosure* const weak_roots = &buf_scan_non_heap_weak_roots; 136 OopClosure* const strong_roots = &buf_scan_non_heap_roots; 137 138 // CodeBlobClosures are not interoperable with BufferingOopClosures 139 G1CodeBlobClosure root_code_blobs(scan_non_heap_roots); 140 141 process_java_roots(strong_roots, 142 _trace_metadata ? scan_strong_clds : NULL, 143 scan_strong_clds, 144 _trace_metadata ? NULL : scan_weak_clds, 145 &root_code_blobs); 146 147 // This is the point where this worker thread will not find more strong CLDs/nmethods. 148 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing. 149 if (_trace_metadata) { 150 worker_has_discovered_all_strong_classes(); 151 } 152 153 process_vm_roots(strong_roots, weak_roots); 154 155 // Now the CM ref_processor roots. 156 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_refProcessor_oops_do)) { 157 // We need to treat the discovered reference lists of the 158 // concurrent mark ref processor as roots and keep entries 159 // (which are added by the marking threads) on them live 160 // until they can be processed at the end of marking. 161 _g1h->ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 162 } 163 164 if (_trace_metadata) { 165 // Barrier to make sure all workers passed 166 // the strong CLD and strong nmethods phases. 167 wait_until_all_strong_classes_discovered(); 168 169 // Now take the complement of the strong CLDs. 170 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds); 171 } 172 173 // Finish up any enqueued closure apps (attributed as object copy time). 174 buf_scan_non_heap_roots.done(); 175 buf_scan_non_heap_weak_roots.done(); 176 177 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() 178 + buf_scan_non_heap_weak_roots.closure_app_seconds(); 179 180 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 181 phase_times->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec); 182 183 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec; 184 185 phase_times->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec); 186 187 // During conc marking we have to filter the per-thread SATB buffers 188 // to make sure we remove any oops into the CSet (which will show up 189 // as implicitly live). 190 { 191 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i); 192 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->mark_in_progress()) { 193 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 194 } 195 } 196 197 _process_strong_tasks->all_tasks_completed(); 198 } 199 200 void G1RootProcessor::process_strong_roots(OopClosure* oops, 201 CLDClosure* clds, 202 CodeBlobClosure* blobs) { 203 204 process_java_roots(oops, clds, clds, NULL, blobs); 205 process_vm_roots(oops, NULL); 206 207 _process_strong_tasks->all_tasks_completed(); 208 } 209 210 void G1RootProcessor::process_all_roots(OopClosure* oops, 211 CLDClosure* clds, 212 CodeBlobClosure* blobs) { 213 214 process_java_roots(oops, NULL, clds, clds, NULL); 215 process_vm_roots(oops, oops); 216 217 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_CodeCache_oops_do)) { 218 CodeCache::blobs_do(blobs); 219 } 220 221 _process_strong_tasks->all_tasks_completed(); 222 } 223 224 void G1RootProcessor::process_java_roots(OopClosure* strong_roots, 225 CLDClosure* thread_stack_clds, 226 CLDClosure* strong_clds, 227 CLDClosure* weak_clds, 228 CodeBlobClosure* strong_code) { 229 assert(thread_stack_clds == NULL || weak_clds == NULL, "There is overlap between those, only one may be set"); 230 // Iterating over the CLDG and the Threads are done early to allow us to 231 // first process the strong CLDs and nmethods and then, after a barrier, 232 // let the thread process the weak CLDs and nmethods. 233 234 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) { 235 ClassLoaderDataGraph::roots_cld_do(strong_clds, weak_clds); 236 } 237 238 Threads::possibly_parallel_oops_do(strong_roots, thread_stack_clds, strong_code); 239 } 240 241 void G1RootProcessor::process_vm_roots(OopClosure* strong_roots, 242 OopClosure* weak_roots) { 243 244 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_Universe_oops_do)) { 245 Universe::oops_do(strong_roots); 246 } 247 248 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_JNIHandles_oops_do)) { 249 JNIHandles::oops_do(strong_roots); 250 } 251 252 if (!_process_strong_tasks-> is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) { 253 ObjectSynchronizer::oops_do(strong_roots); 254 } 255 256 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_FlatProfiler_oops_do)) { 257 FlatProfiler::oops_do(strong_roots); 258 } 259 260 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_Management_oops_do)) { 261 Management::oops_do(strong_roots); 262 } 263 264 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_jvmti_oops_do)) { 265 JvmtiExport::oops_do(strong_roots); 266 } 267 268 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) { 269 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 270 } 271 272 // All threads execute the following. A specific chunk of buckets 273 // from the StringTable are the individual tasks. 274 if (weak_roots != NULL) { 275 StringTable::possibly_parallel_oops_do(weak_roots); 276 } 277 } 278 279 void G1RootProcessor::scan_remembered_sets(G1ParPushHeapRSClosure* scan_rs, 280 OopClosure* scan_non_heap_weak_roots, 281 uint worker_i) { 282 // Now scan the complement of the collection set. 283 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots); 284 285 _g1h->g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i); 286 } 287 288 void G1RootProcessor::set_num_workers(int active_workers) { 289 _process_strong_tasks->set_n_threads(active_workers); 290 }