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