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_size_policy(size_t init_eden_size, 168 size_t init_promo_size, 169 size_t init_survivor_size); 170 171 // Does operations required after initialization has been done. 172 void post_initialize(); 173 174 Generation* young_gen() const { return _young_gen; } 175 Generation* old_gen() const { return _old_gen; } 176 177 bool is_young_gen(const Generation* gen) const { return gen == _young_gen; } 178 bool is_old_gen(const Generation* gen) const { return gen == _old_gen; } 179 180 GenerationSpec* young_gen_spec() const; 181 GenerationSpec* old_gen_spec() const; 182 183 // The generational collector policy. 184 GenCollectorPolicy* gen_policy() const { return _gen_policy; } 185 186 virtual CollectorPolicy* collector_policy() const { return gen_policy(); } 187 188 virtual SoftRefPolicy* soft_ref_policy() { return &_soft_ref_gen_policy; } 189 190 // Adaptive size policy 191 virtual AdaptiveSizePolicy* size_policy() { 192 return _size_policy; 193 } 194 195 // Return the (conservative) maximum heap alignment 196 static size_t conservative_max_heap_alignment() { 197 return Generation::GenGrain; 198 } 199 200 size_t capacity() const; 201 size_t used() const; 202 203 // Save the "used_region" for both generations. 204 void save_used_regions(); 205 206 size_t max_capacity() const; 207 208 HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded); 209 210 // We may support a shared contiguous allocation area, if the youngest 211 // generation does. 212 bool supports_inline_contig_alloc() const; 213 HeapWord* volatile* top_addr() const; 214 HeapWord** end_addr() const; 215 216 // Perform a full collection of the heap; intended for use in implementing 217 // "System.gc". This implies as full a collection as the CollectedHeap 218 // supports. Caller does not hold the Heap_lock on entry. 219 virtual void collect(GCCause::Cause cause); 220 221 // The same as above but assume that the caller holds the Heap_lock. 222 void collect_locked(GCCause::Cause cause); 223 224 // Perform a full collection of generations up to and including max_generation. 225 // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry. 226 void collect(GCCause::Cause cause, GenerationType max_generation); 227 228 // Returns "TRUE" iff "p" points into the committed areas of the heap. 229 // The methods is_in(), is_in_closed_subset() and is_in_youngest() may 230 // be expensive to compute in general, so, to prevent 231 // their inadvertent use in product jvm's, we restrict their use to 232 // assertion checking or verification only. 233 bool is_in(const void* p) const; 234 235 // Returns true if the reference is to an object in the reserved space 236 // for the young generation. 237 // Assumes the the young gen address range is less than that of the old gen. 238 bool is_in_young(oop p); 239 240 #ifdef ASSERT 241 bool is_in_partial_collection(const void* p); 242 #endif 243 244 virtual bool is_scavengable(oop obj) { 245 return is_in_young(obj); 246 } 247 248 // Optimized nmethod scanning support routines 249 virtual void register_nmethod(nmethod* nm); 250 virtual void verify_nmethod(nmethod* nmethod); 251 252 // Iteration functions. 253 void oop_iterate_no_header(OopClosure* cl); 254 void oop_iterate(ExtendedOopClosure* cl); 255 void object_iterate(ObjectClosure* cl); 256 void safe_object_iterate(ObjectClosure* cl); 257 Space* space_containing(const void* addr) const; 258 259 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 260 // each address in the (reserved) heap is a member of exactly 261 // one block. The defining characteristic of a block is that it is 262 // possible to find its size, and thus to progress forward to the next 263 // block. (Blocks may be of different sizes.) Thus, blocks may 264 // represent Java objects, or they might be free blocks in a 265 // free-list-based heap (or subheap), as long as the two kinds are 266 // distinguishable and the size of each is determinable. 267 268 // Returns the address of the start of the "block" that contains the 269 // address "addr". We say "blocks" instead of "object" since some heaps 270 // may not pack objects densely; a chunk may either be an object or a 271 // non-object. 272 virtual HeapWord* block_start(const void* addr) const; 273 274 // Requires "addr" to be the start of a chunk, and returns its size. 275 // "addr + size" is required to be the start of a new chunk, or the end 276 // of the active area of the heap. Assumes (and verifies in non-product 277 // builds) that addr is in the allocated part of the heap and is 278 // the start of a chunk. 279 virtual size_t block_size(const HeapWord* addr) const; 280 281 // Requires "addr" to be the start of a block, and returns "TRUE" iff 282 // the block is an object. Assumes (and verifies in non-product 283 // builds) that addr is in the allocated part of the heap and is 284 // the start of a chunk. 285 virtual bool block_is_obj(const HeapWord* addr) const; 286 287 // Section on TLAB's. 288 virtual bool supports_tlab_allocation() const; 289 virtual size_t tlab_capacity(Thread* thr) const; 290 virtual size_t tlab_used(Thread* thr) const; 291 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 292 virtual HeapWord* allocate_new_tlab(size_t size); 293 294 // The "requestor" generation is performing some garbage collection 295 // action for which it would be useful to have scratch space. The 296 // requestor promises to allocate no more than "max_alloc_words" in any 297 // older generation (via promotion say.) Any blocks of space that can 298 // be provided are returned as a list of ScratchBlocks, sorted by 299 // decreasing size. 300 ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words); 301 // Allow each generation to reset any scratch space that it has 302 // contributed as it needs. 303 void release_scratch(); 304 305 // Ensure parsability: override 306 virtual void ensure_parsability(bool retire_tlabs); 307 308 // Time in ms since the longest time a collector ran in 309 // in any generation. 310 virtual jlong millis_since_last_gc(); 311 312 // Total number of full collections completed. 313 unsigned int total_full_collections_completed() { 314 assert(_full_collections_completed <= _total_full_collections, 315 "Can't complete more collections than were started"); 316 return _full_collections_completed; 317 } 318 319 // Update above counter, as appropriate, at the end of a stop-world GC cycle 320 unsigned int update_full_collections_completed(); 321 // Update above counter, as appropriate, at the end of a concurrent GC cycle 322 unsigned int update_full_collections_completed(unsigned int count); 323 324 // Update "time of last gc" for all generations to "now". 325 void update_time_of_last_gc(jlong now) { 326 _young_gen->update_time_of_last_gc(now); 327 _old_gen->update_time_of_last_gc(now); 328 } 329 330 // Update the gc statistics for each generation. 331 void update_gc_stats(Generation* current_generation, bool full) { 332 _old_gen->update_gc_stats(current_generation, full); 333 } 334 335 bool no_gc_in_progress() { return !is_gc_active(); } 336 337 // Override. 338 void prepare_for_verify(); 339 340 // Override. 341 void verify(VerifyOption option); 342 343 // Override. 344 virtual void print_on(outputStream* st) const; 345 virtual void print_gc_threads_on(outputStream* st) const; 346 virtual void gc_threads_do(ThreadClosure* tc) const; 347 virtual void print_tracing_info() const; 348 349 void print_heap_change(size_t young_prev_used, size_t old_prev_used) const; 350 351 // The functions below are helper functions that a subclass of 352 // "CollectedHeap" can use in the implementation of its virtual 353 // functions. 354 355 class GenClosure : public StackObj { 356 public: 357 virtual void do_generation(Generation* gen) = 0; 358 }; 359 360 // Apply "cl.do_generation" to all generations in the heap 361 // If "old_to_young" determines the order. 362 void generation_iterate(GenClosure* cl, bool old_to_young); 363 364 // Return "true" if all generations have reached the 365 // maximal committed limit that they can reach, without a garbage 366 // collection. 367 virtual bool is_maximal_no_gc() const; 368 369 // This function returns the CardTableRS object that allows us to scan 370 // generations in a fully generational heap. 371 CardTableRS* rem_set() { return _rem_set; } 372 373 // Convenience function to be used in situations where the heap type can be 374 // asserted to be this type. 375 static GenCollectedHeap* heap(); 376 377 // The ScanningOption determines which of the roots 378 // the closure is applied to: 379 // "SO_None" does none; 380 enum ScanningOption { 381 SO_None = 0x0, 382 SO_AllCodeCache = 0x8, 383 SO_ScavengeCodeCache = 0x10 384 }; 385 386 protected: 387 void process_roots(StrongRootsScope* scope, 388 ScanningOption so, 389 OopClosure* strong_roots, 390 OopClosure* weak_roots, 391 CLDClosure* strong_cld_closure, 392 CLDClosure* weak_cld_closure, 393 CodeBlobToOopClosure* code_roots); 394 395 void process_string_table_roots(StrongRootsScope* scope, 396 OopClosure* root_closure); 397 398 // Accessor for memory state verification support 399 NOT_PRODUCT( 400 virtual size_t skip_header_HeapWords() { return 0; } 401 ) 402 403 virtual void gc_prologue(bool full); 404 virtual void gc_epilogue(bool full); 405 406 public: 407 void young_process_roots(StrongRootsScope* scope, 408 OopsInGenClosure* root_closure, 409 OopsInGenClosure* old_gen_closure, 410 CLDClosure* cld_closure); 411 412 void full_process_roots(StrongRootsScope* scope, 413 bool is_adjust_phase, 414 ScanningOption so, 415 bool only_strong_roots, 416 OopsInGenClosure* root_closure, 417 CLDClosure* cld_closure); 418 419 // Apply "root_closure" to all the weak roots of the system. 420 // These include JNI weak roots, string table, 421 // and referents of reachable weak refs. 422 void gen_process_weak_roots(OopClosure* root_closure); 423 424 // Set the saved marks of generations, if that makes sense. 425 // In particular, if any generation might iterate over the oops 426 // in other generations, it should call this method. 427 void save_marks(); 428 429 // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects 430 // allocated since the last call to save_marks in generations at or above 431 // "level". The "cur" closure is 432 // applied to references in the generation at "level", and the "older" 433 // closure to older generations. 434 #define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix) \ 435 void oop_since_save_marks_iterate(GenerationType start_gen, \ 436 OopClosureType* cur, \ 437 OopClosureType* older); 438 439 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL) 440 441 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL 442 443 // Returns "true" iff no allocations have occurred since the last 444 // call to "save_marks". 445 bool no_allocs_since_save_marks(); 446 447 // Returns true if an incremental collection is likely to fail. 448 // We optionally consult the young gen, if asked to do so; 449 // otherwise we base our answer on whether the previous incremental 450 // collection attempt failed with no corrective action as of yet. 451 bool incremental_collection_will_fail(bool consult_young) { 452 // The first disjunct remembers if an incremental collection failed, even 453 // when we thought (second disjunct) that it would not. 454 return incremental_collection_failed() || 455 (consult_young && !_young_gen->collection_attempt_is_safe()); 456 } 457 458 // If a generation bails out of an incremental collection, 459 // it sets this flag. 460 bool incremental_collection_failed() const { 461 return _incremental_collection_failed; 462 } 463 void set_incremental_collection_failed() { 464 _incremental_collection_failed = true; 465 } 466 void clear_incremental_collection_failed() { 467 _incremental_collection_failed = false; 468 } 469 470 // Promotion of obj into gen failed. Try to promote obj to higher 471 // gens in ascending order; return the new location of obj if successful. 472 // Otherwise, try expand-and-allocate for obj in both the young and old 473 // generation; return the new location of obj if successful. Otherwise, return NULL. 474 oop handle_failed_promotion(Generation* old_gen, 475 oop obj, 476 size_t obj_size); 477 478 479 private: 480 // Return true if an allocation should be attempted in the older generation 481 // if it fails in the younger generation. Return false, otherwise. 482 bool should_try_older_generation_allocation(size_t word_size) const; 483 484 // Try to allocate space by expanding the heap. 485 HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab); 486 487 HeapWord* mem_allocate_work(size_t size, 488 bool is_tlab, 489 bool* gc_overhead_limit_was_exceeded); 490 491 // Override 492 void check_for_non_bad_heap_word_value(HeapWord* addr, 493 size_t size) PRODUCT_RETURN; 494 495 // For use by mark-sweep. As implemented, mark-sweep-compact is global 496 // in an essential way: compaction is performed across generations, by 497 // iterating over spaces. 498 void prepare_for_compaction(); 499 500 // Perform a full collection of the generations up to and including max_generation. 501 // This is the low level interface used by the public versions of 502 // collect() and collect_locked(). Caller holds the Heap_lock on entry. 503 void collect_locked(GCCause::Cause cause, GenerationType max_generation); 504 505 // Save the tops of the spaces in all generations 506 void record_gen_tops_before_GC() PRODUCT_RETURN; 507 }; 508 509 #endif // SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP