1 /* 2 * Copyright (c) 2000, 2010, 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/symbolTable.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/fprofiler.hpp" 33 #include "runtime/java.hpp" 34 #include "services/management.hpp" 35 #include "utilities/copy.hpp" 36 #include "utilities/workgroup.hpp" 37 38 SharedHeap* SharedHeap::_sh; 39 40 // The set of potentially parallel tasks in strong root scanning. 41 enum SH_process_strong_roots_tasks { 42 SH_PS_Universe_oops_do, 43 SH_PS_JNIHandles_oops_do, 44 SH_PS_ObjectSynchronizer_oops_do, 45 SH_PS_FlatProfiler_oops_do, 46 SH_PS_Management_oops_do, 47 SH_PS_SystemDictionary_oops_do, 48 SH_PS_jvmti_oops_do, 49 SH_PS_vmSymbols_oops_do, 50 SH_PS_SymbolTable_oops_do, 51 SH_PS_StringTable_oops_do, 52 SH_PS_CodeCache_oops_do, 53 // Leave this one last. 54 SH_PS_NumElements 55 }; 56 57 SharedHeap::SharedHeap(CollectorPolicy* policy_) : 58 CollectedHeap(), 59 _collector_policy(policy_), 60 _perm_gen(NULL), _rem_set(NULL), 61 _strong_roots_parity(0), 62 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)), 63 _n_par_threads(0), 64 _workers(NULL) 65 { 66 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 67 vm_exit_during_initialization("Failed necessary allocation."); 68 } 69 _sh = this; // ch is static, should be set only once. 70 if ((UseParNewGC || 71 (UseConcMarkSweepGC && CMSParallelRemarkEnabled) || 72 UseG1GC) && 73 ParallelGCThreads > 0) { 74 _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads, 75 /* are_GC_task_threads */true, 76 /* are_ConcurrentGC_threads */false); 77 if (_workers == NULL) { 78 vm_exit_during_initialization("Failed necessary allocation."); 79 } else { 80 _workers->initialize_workers(); 81 } 82 } 83 } 84 85 bool SharedHeap::heap_lock_held_for_gc() { 86 Thread* t = Thread::current(); 87 return Heap_lock->owned_by_self() 88 || ( (t->is_GC_task_thread() || t->is_VM_thread()) 89 && _thread_holds_heap_lock_for_gc); 90 } 91 92 void SharedHeap::set_par_threads(int t) { 93 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads"); 94 _n_par_threads = t; 95 _process_strong_tasks->set_n_threads(t); 96 } 97 98 class AssertIsPermClosure: public OopClosure { 99 public: 100 virtual void do_oop(oop* p) { 101 assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm."); 102 } 103 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 104 }; 105 static AssertIsPermClosure assert_is_perm_closure; 106 107 void SharedHeap::change_strong_roots_parity() { 108 // Also set the new collection parity. 109 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2, 110 "Not in range."); 111 _strong_roots_parity++; 112 if (_strong_roots_parity == 3) _strong_roots_parity = 1; 113 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2, 114 "Not in range."); 115 } 116 117 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate) 118 : MarkScope(activate) 119 { 120 if (_active) { 121 outer->change_strong_roots_parity(); 122 } 123 } 124 125 SharedHeap::StrongRootsScope::~StrongRootsScope() { 126 // nothing particular 127 } 128 129 void SharedHeap::process_strong_roots(bool activate_scope, 130 bool collecting_perm_gen, 131 ScanningOption so, 132 OopClosure* roots, 133 CodeBlobClosure* code_roots, 134 OopsInGenClosure* perm_blk) { 135 StrongRootsScope srs(this, activate_scope); 136 // General strong roots. 137 assert(_strong_roots_parity != 0, "must have called prologue code"); 138 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) { 139 Universe::oops_do(roots); 140 ReferenceProcessor::oops_do(roots); 141 // Consider perm-gen discovered lists to be strong. 142 perm_gen()->ref_processor()->weak_oops_do(roots); 143 } 144 // Global (strong) JNI handles 145 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do)) 146 JNIHandles::oops_do(roots); 147 // All threads execute this; the individual threads are task groups. 148 if (ParallelGCThreads > 0) { 149 Threads::possibly_parallel_oops_do(roots, code_roots); 150 } else { 151 Threads::oops_do(roots, code_roots); 152 } 153 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do)) 154 ObjectSynchronizer::oops_do(roots); 155 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do)) 156 FlatProfiler::oops_do(roots); 157 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do)) 158 Management::oops_do(roots); 159 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do)) 160 JvmtiExport::oops_do(roots); 161 162 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) { 163 if (so & SO_AllClasses) { 164 SystemDictionary::oops_do(roots); 165 } else 166 if (so & SO_SystemClasses) { 167 SystemDictionary::always_strong_oops_do(roots); 168 } 169 } 170 171 if (!_process_strong_tasks->is_task_claimed(SH_PS_SymbolTable_oops_do)) { 172 if (so & SO_Symbols) { 173 SymbolTable::oops_do(roots); 174 } 175 // Verify if the symbol table contents are in the perm gen 176 NOT_PRODUCT(SymbolTable::oops_do(&assert_is_perm_closure)); 177 } 178 179 if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) { 180 if (so & SO_Strings) { 181 StringTable::oops_do(roots); 182 } 183 // Verify if the string table contents are in the perm gen 184 NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure)); 185 } 186 187 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) { 188 if (so & SO_CodeCache) { 189 // (Currently, CMSCollector uses this to do intermediate-strength collections.) 190 assert(collecting_perm_gen, "scanning all of code cache"); 191 assert(code_roots != NULL, "must supply closure for code cache"); 192 if (code_roots != NULL) { 193 CodeCache::blobs_do(code_roots); 194 } 195 } else if (so & (SO_SystemClasses|SO_AllClasses)) { 196 if (!collecting_perm_gen) { 197 // If we are collecting from class statics, but we are not going to 198 // visit all of the CodeCache, collect from the non-perm roots if any. 199 // This makes the code cache function temporarily as a source of strong 200 // roots for oops, until the next major collection. 201 // 202 // If collecting_perm_gen is true, we require that this phase will call 203 // CodeCache::do_unloading. This will kill off nmethods with expired 204 // weak references, such as stale invokedynamic targets. 205 CodeCache::scavenge_root_nmethods_do(code_roots); 206 } 207 } 208 // Verify if the code cache contents are in the perm gen 209 NOT_PRODUCT(CodeBlobToOopClosure assert_code_is_perm(&assert_is_perm_closure, /*do_marking=*/ false)); 210 NOT_PRODUCT(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_perm)); 211 } 212 213 // Roots that should point only into permanent generation. 214 { 215 OopClosure* blk = NULL; 216 if (collecting_perm_gen) { 217 blk = roots; 218 } else { 219 debug_only(blk = &assert_is_perm_closure); 220 } 221 if (blk != NULL) { 222 if (!_process_strong_tasks->is_task_claimed(SH_PS_vmSymbols_oops_do)) 223 vmSymbols::oops_do(blk); 224 } 225 } 226 227 if (!collecting_perm_gen) { 228 // All threads perform this; coordination is handled internally. 229 230 rem_set()->younger_refs_iterate(perm_gen(), perm_blk); 231 } 232 _process_strong_tasks->all_tasks_completed(); 233 } 234 235 class AlwaysTrueClosure: public BoolObjectClosure { 236 public: 237 void do_object(oop p) { ShouldNotReachHere(); } 238 bool do_object_b(oop p) { return true; } 239 }; 240 static AlwaysTrueClosure always_true; 241 242 class SkipAdjustingSharedStrings: public OopClosure { 243 OopClosure* _clo; 244 public: 245 SkipAdjustingSharedStrings(OopClosure* clo) : _clo(clo) {} 246 247 virtual void do_oop(oop* p) { 248 oop o = (*p); 249 if (!o->is_shared_readwrite()) { 250 _clo->do_oop(p); 251 } 252 } 253 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 254 }; 255 256 // Unmarked shared Strings in the StringTable (which got there due to 257 // being in the constant pools of as-yet unloaded shared classes) were 258 // not marked and therefore did not have their mark words preserved. 259 // These entries are also deliberately not purged from the string 260 // table during unloading of unmarked strings. If an identity hash 261 // code was computed for any of these objects, it will not have been 262 // cleared to zero during the forwarding process or by the 263 // RecursiveAdjustSharedObjectClosure, and will be confused by the 264 // adjusting process as a forwarding pointer. We need to skip 265 // forwarding StringTable entries which contain unmarked shared 266 // Strings. Actually, since shared strings won't be moving, we can 267 // just skip adjusting any shared entries in the string table. 268 269 void SharedHeap::process_weak_roots(OopClosure* root_closure, 270 CodeBlobClosure* code_roots, 271 OopClosure* non_root_closure) { 272 // Global (weak) JNI handles 273 JNIHandles::weak_oops_do(&always_true, root_closure); 274 275 CodeCache::blobs_do(code_roots); 276 SymbolTable::oops_do(root_closure); 277 if (UseSharedSpaces && !DumpSharedSpaces) { 278 SkipAdjustingSharedStrings skip_closure(root_closure); 279 StringTable::oops_do(&skip_closure); 280 } else { 281 StringTable::oops_do(root_closure); 282 } 283 } 284 285 void SharedHeap::set_barrier_set(BarrierSet* bs) { 286 _barrier_set = bs; 287 // Cached barrier set for fast access in oops 288 oopDesc::set_bs(bs); 289 } 290 291 void SharedHeap::post_initialize() { 292 ref_processing_init(); 293 } 294 295 void SharedHeap::ref_processing_init() { 296 perm_gen()->ref_processor_init(); 297 } 298 299 // Some utilities. 300 void SharedHeap::print_size_transition(outputStream* out, 301 size_t bytes_before, 302 size_t bytes_after, 303 size_t capacity) { 304 out->print(" %d%s->%d%s(%d%s)", 305 byte_size_in_proper_unit(bytes_before), 306 proper_unit_for_byte_size(bytes_before), 307 byte_size_in_proper_unit(bytes_after), 308 proper_unit_for_byte_size(bytes_after), 309 byte_size_in_proper_unit(capacity), 310 proper_unit_for_byte_size(capacity)); 311 }