1 /* 2 * Copyright (c) 2000, 2018, 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 #ifndef SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP 27 28 #include "gc/shared/collectedHeap.hpp" 29 #include "gc/shared/collectorPolicy.hpp" 30 #include "gc/shared/generation.hpp" 31 #include "gc/shared/softRefGenPolicy.hpp" 32 33 class AdaptiveSizePolicy; 34 class GCPolicyCounters; 35 class GenerationSpec; 36 class StrongRootsScope; 37 class SubTasksDone; 38 class WorkGang; 39 40 // A "GenCollectedHeap" is a CollectedHeap that uses generational 41 // collection. It has two generations, young and old. 42 class GenCollectedHeap : public CollectedHeap { 43 friend class GenCollectorPolicy; 44 friend class Generation; 45 friend class DefNewGeneration; 46 friend class TenuredGeneration; 47 friend class ConcurrentMarkSweepGeneration; 48 friend class CMSCollector; 49 friend class GenMarkSweep; 50 friend class VM_GenCollectForAllocation; 51 friend class VM_GenCollectFull; 52 friend class VM_GenCollectFullConcurrent; 53 friend class VM_GC_HeapInspection; 54 friend class VM_HeapDumper; 55 friend class HeapInspection; 56 friend class GCCauseSetter; 57 friend class VMStructs; 58 public: 59 friend class VM_PopulateDumpSharedSpace; 60 61 enum GenerationType { 62 YoungGen, 63 OldGen 64 }; 65 66 private: 67 Generation* _young_gen; 68 Generation* _old_gen; 69 70 GenerationSpec* _young_gen_spec; 71 GenerationSpec* _old_gen_spec; 72 73 // The singleton CardTable Remembered Set. 74 CardTableRS* _rem_set; 75 76 // The generational collector policy. 77 GenCollectorPolicy* _gen_policy; 78 79 SoftRefGenPolicy _soft_ref_gen_policy; 80 81 // The sizing of the heap is controlled by a sizing policy. 82 AdaptiveSizePolicy* _size_policy; 83 84 GCPolicyCounters* _gc_policy_counters; 85 86 // Indicates that the most recent previous incremental collection failed. 87 // The flag is cleared when an action is taken that might clear the 88 // condition that caused that incremental collection to fail. 89 bool _incremental_collection_failed; 90 91 // In support of ExplicitGCInvokesConcurrent functionality 92 unsigned int _full_collections_completed; 93 94 // Collects the given generation. 95 void collect_generation(Generation* gen, bool full, size_t size, bool is_tlab, 96 bool run_verification, bool clear_soft_refs, 97 bool restore_marks_for_biased_locking); 98 99 // Reserve aligned space for the heap as needed by the contained generations. 100 char* allocate(size_t alignment, ReservedSpace* heap_rs); 101 102 // Initialize ("weak") refs processing support 103 void ref_processing_init(); 104 105 protected: 106 107 // The set of potentially parallel tasks in root scanning. 108 enum GCH_strong_roots_tasks { 109 GCH_PS_Universe_oops_do, 110 GCH_PS_JNIHandles_oops_do, 111 GCH_PS_ObjectSynchronizer_oops_do, 112 GCH_PS_FlatProfiler_oops_do, 113 GCH_PS_Management_oops_do, 114 GCH_PS_SystemDictionary_oops_do, 115 GCH_PS_ClassLoaderDataGraph_oops_do, 116 GCH_PS_jvmti_oops_do, 117 GCH_PS_CodeCache_oops_do, 118 GCH_PS_aot_oops_do, 119 GCH_PS_younger_gens, 120 // Leave this one last. 121 GCH_PS_NumElements 122 }; 123 124 // Data structure for claiming the (potentially) parallel tasks in 125 // (gen-specific) roots processing. 126 SubTasksDone* _process_strong_tasks; 127 128 GCMemoryManager* _young_manager; 129 GCMemoryManager* _old_manager; 130 131 // Helper functions for allocation 132 HeapWord* attempt_allocation(size_t size, 133 bool is_tlab, 134 bool first_only); 135 136 // Helper function for two callbacks below. 137 // Considers collection of the first max_level+1 generations. 138 void do_collection(bool full, 139 bool clear_all_soft_refs, 140 size_t size, 141 bool is_tlab, 142 GenerationType max_generation); 143 144 // Callback from VM_GenCollectForAllocation operation. 145 // This function does everything necessary/possible to satisfy an 146 // allocation request that failed in the youngest generation that should 147 // have handled it (including collection, expansion, etc.) 148 HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab); 149 150 // Callback from VM_GenCollectFull operation. 151 // Perform a full collection of the first max_level+1 generations. 152 virtual void do_full_collection(bool clear_all_soft_refs); 153 void do_full_collection(bool clear_all_soft_refs, GenerationType max_generation); 154 155 // Does the "cause" of GC indicate that 156 // we absolutely __must__ clear soft refs? 157 bool must_clear_all_soft_refs(); 158 159 GenCollectedHeap(GenCollectorPolicy *policy, 160 Generation::Name young, 161 Generation::Name old, 162 const char* policy_counters_name); 163 164 virtual void check_gen_kinds() = 0; 165 166 public: 167 168 // Returns JNI_OK on success 169 virtual jint initialize(); 170 171 void initialize_size_policy(size_t init_eden_size, 172 size_t init_promo_size, 173 size_t init_survivor_size); 174 175 // Does operations required after initialization has been done. 176 void post_initialize(); 177 178 Generation* young_gen() const { return _young_gen; } 179 Generation* old_gen() const { return _old_gen; } 180 181 bool is_young_gen(const Generation* gen) const { return gen == _young_gen; } 182 bool is_old_gen(const Generation* gen) const { return gen == _old_gen; } 183 184 GenerationSpec* young_gen_spec() const; 185 GenerationSpec* old_gen_spec() const; 186 187 // The generational collector policy. 188 GenCollectorPolicy* gen_policy() const { return _gen_policy; } 189 190 virtual CollectorPolicy* collector_policy() const { return gen_policy(); } 191 192 virtual SoftRefPolicy* soft_ref_policy() { return &_soft_ref_gen_policy; } 193 194 // Adaptive size policy 195 virtual AdaptiveSizePolicy* size_policy() { 196 return _size_policy; 197 } 198 199 // Performance Counter support 200 GCPolicyCounters* counters() { return _gc_policy_counters; } 201 202 // Return the (conservative) maximum heap alignment 203 static size_t conservative_max_heap_alignment() { 204 return Generation::GenGrain; 205 } 206 207 size_t capacity() const; 208 size_t used() const; 209 210 // Save the "used_region" for both generations. 211 void save_used_regions(); 212 213 size_t max_capacity() const; 214 215 HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded); 216 217 // We may support a shared contiguous allocation area, if the youngest 218 // generation does. 219 bool supports_inline_contig_alloc() const; 220 HeapWord* volatile* top_addr() const; 221 HeapWord** end_addr() const; 222 223 // Perform a full collection of the heap; intended for use in implementing 224 // "System.gc". This implies as full a collection as the CollectedHeap 225 // supports. Caller does not hold the Heap_lock on entry. 226 virtual void collect(GCCause::Cause cause); 227 228 // The same as above but assume that the caller holds the Heap_lock. 229 void collect_locked(GCCause::Cause cause); 230 231 // Perform a full collection of generations up to and including max_generation. 232 // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry. 233 void collect(GCCause::Cause cause, GenerationType max_generation); 234 235 // Returns "TRUE" iff "p" points into the committed areas of the heap. 236 // The methods is_in(), is_in_closed_subset() and is_in_youngest() may 237 // be expensive to compute in general, so, to prevent 238 // their inadvertent use in product jvm's, we restrict their use to 239 // assertion checking or verification only. 240 bool is_in(const void* p) const; 241 242 // Returns true if the reference is to an object in the reserved space 243 // for the young generation. 244 // Assumes the the young gen address range is less than that of the old gen. 245 bool is_in_young(oop p); 246 247 #ifdef ASSERT 248 bool is_in_partial_collection(const void* p); 249 #endif 250 251 virtual bool is_scavengable(oop obj) { 252 return is_in_young(obj); 253 } 254 255 // Optimized nmethod scanning support routines 256 virtual void register_nmethod(nmethod* nm); 257 virtual void verify_nmethod(nmethod* nmethod); 258 259 // Iteration functions. 260 void oop_iterate_no_header(OopClosure* cl); 261 void oop_iterate(ExtendedOopClosure* cl); 262 void object_iterate(ObjectClosure* cl); 263 void safe_object_iterate(ObjectClosure* cl); 264 Space* space_containing(const void* addr) const; 265 266 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 267 // each address in the (reserved) heap is a member of exactly 268 // one block. The defining characteristic of a block is that it is 269 // possible to find its size, and thus to progress forward to the next 270 // block. (Blocks may be of different sizes.) Thus, blocks may 271 // represent Java objects, or they might be free blocks in a 272 // free-list-based heap (or subheap), as long as the two kinds are 273 // distinguishable and the size of each is determinable. 274 275 // Returns the address of the start of the "block" that contains the 276 // address "addr". We say "blocks" instead of "object" since some heaps 277 // may not pack objects densely; a chunk may either be an object or a 278 // non-object. 279 virtual HeapWord* block_start(const void* addr) const; 280 281 // Requires "addr" to be the start of a chunk, and returns its size. 282 // "addr + size" is required to be the start of a new chunk, or the end 283 // of the active area of the heap. Assumes (and verifies in non-product 284 // builds) that addr is in the allocated part of the heap and is 285 // the start of a chunk. 286 virtual size_t block_size(const HeapWord* addr) const; 287 288 // Requires "addr" to be the start of a block, and returns "TRUE" iff 289 // the block is an object. Assumes (and verifies in non-product 290 // builds) that addr is in the allocated part of the heap and is 291 // the start of a chunk. 292 virtual bool block_is_obj(const HeapWord* addr) const; 293 294 // Section on TLAB's. 295 virtual bool supports_tlab_allocation() const; 296 virtual size_t tlab_capacity(Thread* thr) const; 297 virtual size_t tlab_used(Thread* thr) const; 298 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 299 virtual HeapWord* allocate_new_tlab(size_t size); 300 301 // The "requestor" generation is performing some garbage collection 302 // action for which it would be useful to have scratch space. The 303 // requestor promises to allocate no more than "max_alloc_words" in any 304 // older generation (via promotion say.) Any blocks of space that can 305 // be provided are returned as a list of ScratchBlocks, sorted by 306 // decreasing size. 307 ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words); 308 // Allow each generation to reset any scratch space that it has 309 // contributed as it needs. 310 void release_scratch(); 311 312 // Ensure parsability: override 313 virtual void ensure_parsability(bool retire_tlabs); 314 315 // Time in ms since the longest time a collector ran in 316 // in any generation. 317 virtual jlong millis_since_last_gc(); 318 319 // Total number of full collections completed. 320 unsigned int total_full_collections_completed() { 321 assert(_full_collections_completed <= _total_full_collections, 322 "Can't complete more collections than were started"); 323 return _full_collections_completed; 324 } 325 326 // Update above counter, as appropriate, at the end of a stop-world GC cycle 327 unsigned int update_full_collections_completed(); 328 // Update above counter, as appropriate, at the end of a concurrent GC cycle 329 unsigned int update_full_collections_completed(unsigned int count); 330 331 // Update "time of last gc" for all generations to "now". 332 void update_time_of_last_gc(jlong now) { 333 _young_gen->update_time_of_last_gc(now); 334 _old_gen->update_time_of_last_gc(now); 335 } 336 337 // Update the gc statistics for each generation. 338 void update_gc_stats(Generation* current_generation, bool full) { 339 _old_gen->update_gc_stats(current_generation, full); 340 } 341 342 bool no_gc_in_progress() { return !is_gc_active(); } 343 344 // Override. 345 void prepare_for_verify(); 346 347 // Override. 348 void verify(VerifyOption option); 349 350 // Override. 351 virtual void print_on(outputStream* st) const; 352 virtual void print_gc_threads_on(outputStream* st) const; 353 virtual void gc_threads_do(ThreadClosure* tc) const; 354 virtual void print_tracing_info() const; 355 356 void print_heap_change(size_t young_prev_used, size_t old_prev_used) const; 357 358 // The functions below are helper functions that a subclass of 359 // "CollectedHeap" can use in the implementation of its virtual 360 // functions. 361 362 class GenClosure : public StackObj { 363 public: 364 virtual void do_generation(Generation* gen) = 0; 365 }; 366 367 // Apply "cl.do_generation" to all generations in the heap 368 // If "old_to_young" determines the order. 369 void generation_iterate(GenClosure* cl, bool old_to_young); 370 371 // Return "true" if all generations have reached the 372 // maximal committed limit that they can reach, without a garbage 373 // collection. 374 virtual bool is_maximal_no_gc() const; 375 376 // This function returns the CardTableRS object that allows us to scan 377 // generations in a fully generational heap. 378 CardTableRS* rem_set() { return _rem_set; } 379 380 // Convenience function to be used in situations where the heap type can be 381 // asserted to be this type. 382 static GenCollectedHeap* heap(); 383 384 // The ScanningOption determines which of the roots 385 // the closure is applied to: 386 // "SO_None" does none; 387 enum ScanningOption { 388 SO_None = 0x0, 389 SO_AllCodeCache = 0x8, 390 SO_ScavengeCodeCache = 0x10 391 }; 392 393 protected: 394 void process_roots(StrongRootsScope* scope, 395 ScanningOption so, 396 OopClosure* strong_roots, 397 OopClosure* weak_roots, 398 CLDClosure* strong_cld_closure, 399 CLDClosure* weak_cld_closure, 400 CodeBlobToOopClosure* code_roots); 401 402 void process_string_table_roots(StrongRootsScope* scope, 403 OopClosure* root_closure); 404 405 // Accessor for memory state verification support 406 NOT_PRODUCT( 407 virtual size_t skip_header_HeapWords() { return 0; } 408 ) 409 410 virtual void gc_prologue(bool full); 411 virtual void gc_epilogue(bool full); 412 413 public: 414 void young_process_roots(StrongRootsScope* scope, 415 OopsInGenClosure* root_closure, 416 OopsInGenClosure* old_gen_closure, 417 CLDClosure* cld_closure); 418 419 void full_process_roots(StrongRootsScope* scope, 420 bool is_adjust_phase, 421 ScanningOption so, 422 bool only_strong_roots, 423 OopsInGenClosure* root_closure, 424 CLDClosure* cld_closure); 425 426 // Apply "root_closure" to all the weak roots of the system. 427 // These include JNI weak roots, string table, 428 // and referents of reachable weak refs. 429 void gen_process_weak_roots(OopClosure* root_closure); 430 431 // Set the saved marks of generations, if that makes sense. 432 // In particular, if any generation might iterate over the oops 433 // in other generations, it should call this method. 434 void save_marks(); 435 436 // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects 437 // allocated since the last call to save_marks in generations at or above 438 // "level". The "cur" closure is 439 // applied to references in the generation at "level", and the "older" 440 // closure to older generations. 441 #define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix) \ 442 void oop_since_save_marks_iterate(GenerationType start_gen, \ 443 OopClosureType* cur, \ 444 OopClosureType* older); 445 446 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL) 447 448 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL 449 450 // Returns "true" iff no allocations have occurred since the last 451 // call to "save_marks". 452 bool no_allocs_since_save_marks(); 453 454 // Returns true if an incremental collection is likely to fail. 455 // We optionally consult the young gen, if asked to do so; 456 // otherwise we base our answer on whether the previous incremental 457 // collection attempt failed with no corrective action as of yet. 458 bool incremental_collection_will_fail(bool consult_young) { 459 // The first disjunct remembers if an incremental collection failed, even 460 // when we thought (second disjunct) that it would not. 461 return incremental_collection_failed() || 462 (consult_young && !_young_gen->collection_attempt_is_safe()); 463 } 464 465 // If a generation bails out of an incremental collection, 466 // it sets this flag. 467 bool incremental_collection_failed() const { 468 return _incremental_collection_failed; 469 } 470 void set_incremental_collection_failed() { 471 _incremental_collection_failed = true; 472 } 473 void clear_incremental_collection_failed() { 474 _incremental_collection_failed = false; 475 } 476 477 // Promotion of obj into gen failed. Try to promote obj to higher 478 // gens in ascending order; return the new location of obj if successful. 479 // Otherwise, try expand-and-allocate for obj in both the young and old 480 // generation; return the new location of obj if successful. Otherwise, return NULL. 481 oop handle_failed_promotion(Generation* old_gen, 482 oop obj, 483 size_t obj_size); 484 485 486 private: 487 // Return true if an allocation should be attempted in the older generation 488 // if it fails in the younger generation. Return false, otherwise. 489 bool should_try_older_generation_allocation(size_t word_size) const; 490 491 // Try to allocate space by expanding the heap. 492 HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab); 493 494 HeapWord* mem_allocate_work(size_t size, 495 bool is_tlab, 496 bool* gc_overhead_limit_was_exceeded); 497 498 // Override 499 void check_for_non_bad_heap_word_value(HeapWord* addr, 500 size_t size) PRODUCT_RETURN; 501 502 // For use by mark-sweep. As implemented, mark-sweep-compact is global 503 // in an essential way: compaction is performed across generations, by 504 // iterating over spaces. 505 void prepare_for_compaction(); 506 507 // Perform a full collection of the generations up to and including max_generation. 508 // This is the low level interface used by the public versions of 509 // collect() and collect_locked(). Caller holds the Heap_lock on entry. 510 void collect_locked(GCCause::Cause cause, GenerationType max_generation); 511 512 // Save the tops of the spaces in all generations 513 void record_gen_tops_before_GC() PRODUCT_RETURN; 514 }; 515 516 #endif // SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP