1 /* 2 * Copyright (c) 2000, 2014, 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 #include "classfile/stringTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "code/codeCache.hpp" 29 #include "gc_interface/collectedHeap.inline.hpp" 30 #include "memory/sharedHeap.hpp" 31 #include "oops/oop.inline.hpp" 32 #include "runtime/atomic.inline.hpp" 33 #include "runtime/fprofiler.hpp" 34 #include "runtime/java.hpp" 35 #include "services/management.hpp" 36 #include "utilities/copy.hpp" 37 #include "utilities/workgroup.hpp" 38 39 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 40 41 SharedHeap* SharedHeap::_sh; 42 43 // The set of potentially parallel tasks in root scanning. 44 enum SH_process_roots_tasks { 45 SH_PS_Universe_oops_do, 46 SH_PS_JNIHandles_oops_do, 47 SH_PS_ObjectSynchronizer_oops_do, 48 SH_PS_FlatProfiler_oops_do, 49 SH_PS_Management_oops_do, 50 SH_PS_SystemDictionary_oops_do, 51 SH_PS_ClassLoaderDataGraph_oops_do, 52 SH_PS_jvmti_oops_do, 53 SH_PS_CodeCache_oops_do, 54 // Leave this one last. 55 SH_PS_NumElements 56 }; 57 58 SharedHeap::SharedHeap(CollectorPolicy* policy_) : 59 CollectedHeap(), 60 _collector_policy(policy_), 61 _rem_set(NULL), 62 _strong_roots_scope(NULL), 63 _strong_roots_parity(0), 64 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)), 65 _workers(NULL) 66 { 67 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 68 vm_exit_during_initialization("Failed necessary allocation."); 69 } 70 _sh = this; // ch is static, should be set only once. 71 if ((UseParNewGC || 72 (UseConcMarkSweepGC && (CMSParallelInitialMarkEnabled || 73 CMSParallelRemarkEnabled)) || 74 UseG1GC) && 75 ParallelGCThreads > 0) { 76 _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads, 77 /* are_GC_task_threads */true, 78 /* are_ConcurrentGC_threads */false); 79 if (_workers == NULL) { 80 vm_exit_during_initialization("Failed necessary allocation."); 81 } else { 82 _workers->initialize_workers(); 83 } 84 } 85 } 86 87 int SharedHeap::n_termination() { 88 return _process_strong_tasks->n_threads(); 89 } 90 91 void SharedHeap::set_n_termination(int t) { 92 _process_strong_tasks->set_n_threads(t); 93 } 94 95 bool SharedHeap::heap_lock_held_for_gc() { 96 Thread* t = Thread::current(); 97 return Heap_lock->owned_by_self() 98 || ( (t->is_GC_task_thread() || t->is_VM_thread()) 99 && _thread_holds_heap_lock_for_gc); 100 } 101 102 void SharedHeap::set_par_threads(uint t) { 103 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads"); 104 _n_par_threads = t; 105 _process_strong_tasks->set_n_threads(t); 106 } 107 108 #ifdef ASSERT 109 class AssertNonScavengableClosure: public OopClosure { 110 public: 111 virtual void do_oop(oop* p) { 112 assert(!Universe::heap()->is_in_partial_collection(*p), 113 "Referent should not be scavengable."); } 114 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 115 }; 116 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 117 #endif 118 119 SharedHeap::StrongRootsScope* SharedHeap::active_strong_roots_scope() const { 120 return _strong_roots_scope; 121 } 122 void SharedHeap::register_strong_roots_scope(SharedHeap::StrongRootsScope* scope) { 123 assert(_strong_roots_scope == NULL, "Should only have one StrongRootsScope active"); 124 assert(scope != NULL, "Illegal argument"); 125 _strong_roots_scope = scope; 126 } 127 void SharedHeap::unregister_strong_roots_scope(SharedHeap::StrongRootsScope* scope) { 128 assert(_strong_roots_scope == scope, "Wrong scope unregistered"); 129 _strong_roots_scope = NULL; 130 } 131 132 void SharedHeap::change_strong_roots_parity() { 133 // Also set the new collection parity. 134 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2, 135 "Not in range."); 136 _strong_roots_parity++; 137 if (_strong_roots_parity == 3) _strong_roots_parity = 1; 138 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2, 139 "Not in range."); 140 } 141 142 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* heap, bool activate) 143 : MarkScope(activate), _sh(heap), _n_workers_done_with_threads(0) 144 { 145 if (_active) { 146 _sh->register_strong_roots_scope(this); 147 _sh->change_strong_roots_parity(); 148 // Zero the claimed high water mark in the StringTable 149 StringTable::clear_parallel_claimed_index(); 150 } 151 } 152 153 SharedHeap::StrongRootsScope::~StrongRootsScope() { 154 if (_active) { 155 _sh->unregister_strong_roots_scope(this); 156 } 157 } 158 159 Monitor* SharedHeap::StrongRootsScope::_lock = new Monitor(Mutex::leaf, "StrongRootsScope lock", false); 160 161 void SharedHeap::StrongRootsScope::mark_worker_done_with_threads(uint n_workers) { 162 #if INCLUDE_ALL_GCS 163 // The Thread work barrier is only needed by G1 Class Unloading. 164 // No need to use the barrier if this is single-threaded code. 165 if (UseG1GC && G1ClassUnloadingEnabled && n_workers > 0) { 166 uint new_value = (uint)Atomic::add(1, &_n_workers_done_with_threads); 167 if (new_value == n_workers) { 168 // This thread is last. Notify the others. 169 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 170 _lock->notify_all(); 171 } 172 } 173 #endif 174 } 175 176 void SharedHeap::StrongRootsScope::wait_until_all_workers_done_with_threads(uint n_workers) { 177 #if INCLUDE_ALL_GCS 178 assert(UseG1GC, "Currently only used by G1"); 179 assert(G1ClassUnloadingEnabled, "Currently only needed when doing G1 Class Unloading"); 180 181 // No need to use the barrier if this is single-threaded code. 182 if (n_workers > 0 && (uint)_n_workers_done_with_threads != n_workers) { 183 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 184 while ((uint)_n_workers_done_with_threads != n_workers) { 185 _lock->wait(Mutex::_no_safepoint_check_flag, 0, false); 186 } 187 } 188 #endif 189 } 190 191 void SharedHeap::process_roots(bool activate_scope, 192 ScanningOption so, 193 OopClosure* strong_roots, 194 OopClosure* weak_roots, 195 CLDClosure* strong_cld_closure, 196 CLDClosure* weak_cld_closure, 197 CodeBlobClosure* code_roots) { 198 StrongRootsScope srs(this, activate_scope); 199 200 // General roots. 201 assert(_strong_roots_parity != 0, "must have called prologue code"); 202 assert(code_roots != NULL, "code root closure should always be set"); 203 // _n_termination for _process_strong_tasks should be set up stream 204 // in a method not running in a GC worker. Otherwise the GC worker 205 // could be trying to change the termination condition while the task 206 // is executing in another GC worker. 207 208 // Iterating over the CLDG and the Threads are done early to allow G1 to 209 // first process the strong CLDs and nmethods and then, after a barrier, 210 // let the thread process the weak CLDs and nmethods. 211 212 if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) { 213 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 214 } 215 216 // Some CLDs contained in the thread frames should be considered strong. 217 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 218 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 219 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 220 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 221 222 Threads::possibly_parallel_oops_do(strong_roots, roots_from_clds_p, roots_from_code_p); 223 224 // This is the point where this worker thread will not find more strong CLDs/nmethods. 225 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing. 226 active_strong_roots_scope()->mark_worker_done_with_threads(n_par_threads()); 227 228 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) { 229 Universe::oops_do(strong_roots); 230 } 231 // Global (strong) JNI handles 232 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do)) 233 JNIHandles::oops_do(strong_roots); 234 235 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do)) 236 ObjectSynchronizer::oops_do(strong_roots); 237 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do)) 238 FlatProfiler::oops_do(strong_roots); 239 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do)) 240 Management::oops_do(strong_roots); 241 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do)) 242 JvmtiExport::oops_do(strong_roots); 243 244 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) { 245 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 246 } 247 248 // All threads execute the following. A specific chunk of buckets 249 // from the StringTable are the individual tasks. 250 if (weak_roots != NULL) { 251 if (CollectedHeap::use_parallel_gc_threads()) { 252 StringTable::possibly_parallel_oops_do(weak_roots); 253 } else { 254 StringTable::oops_do(weak_roots); 255 } 256 } 257 258 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) { 259 if (so & SO_ScavengeCodeCache) { 260 assert(code_roots != NULL, "must supply closure for code cache"); 261 262 // We only visit parts of the CodeCache when scavenging. 263 CodeCache::scavenge_root_nmethods_do(code_roots); 264 } 265 if (so & SO_AllCodeCache) { 266 assert(code_roots != NULL, "must supply closure for code cache"); 267 268 // CMSCollector uses this to do intermediate-strength collections. 269 // We scan the entire code cache, since CodeCache::do_unloading is not called. 270 CodeCache::blobs_do(code_roots); 271 } 272 // Verify that the code cache contents are not subject to 273 // movement by a scavenging collection. 274 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 275 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 276 } 277 278 _process_strong_tasks->all_tasks_completed(); 279 } 280 281 void SharedHeap::process_all_roots(bool activate_scope, 282 ScanningOption so, 283 OopClosure* roots, 284 CLDClosure* cld_closure, 285 CodeBlobClosure* code_closure) { 286 process_roots(activate_scope, so, 287 roots, roots, 288 cld_closure, cld_closure, 289 code_closure); 290 } 291 292 void SharedHeap::process_strong_roots(bool activate_scope, 293 ScanningOption so, 294 OopClosure* roots, 295 CLDClosure* cld_closure, 296 CodeBlobClosure* code_closure) { 297 process_roots(activate_scope, so, 298 roots, NULL, 299 cld_closure, NULL, 300 code_closure); 301 } 302 303 304 class AlwaysTrueClosure: public BoolObjectClosure { 305 public: 306 bool do_object_b(oop p) { return true; } 307 }; 308 static AlwaysTrueClosure always_true; 309 310 void SharedHeap::process_weak_roots(OopClosure* root_closure) { 311 // Global (weak) JNI handles 312 JNIHandles::weak_oops_do(&always_true, root_closure); 313 } 314 315 void SharedHeap::set_barrier_set(BarrierSet* bs) { 316 _barrier_set = bs; 317 // Cached barrier set for fast access in oops 318 oopDesc::set_bs(bs); 319 } 320 321 void SharedHeap::post_initialize() { 322 CollectedHeap::post_initialize(); 323 ref_processing_init(); 324 } 325 326 void SharedHeap::ref_processing_init() {} 327 328 // Some utilities. 329 void SharedHeap::print_size_transition(outputStream* out, 330 size_t bytes_before, 331 size_t bytes_after, 332 size_t capacity) { 333 out->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)", 334 byte_size_in_proper_unit(bytes_before), 335 proper_unit_for_byte_size(bytes_before), 336 byte_size_in_proper_unit(bytes_after), 337 proper_unit_for_byte_size(bytes_after), 338 byte_size_in_proper_unit(capacity), 339 proper_unit_for_byte_size(capacity)); 340 }