1 /* 2 * Copyright (c) 2001, 2011, 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_INTERFACE_COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP 27 28 #include "gc_interface/gcCause.hpp" 29 #include "memory/allocation.hpp" 30 #include "memory/barrierSet.hpp" 31 #include "runtime/handles.hpp" 32 #include "runtime/perfData.hpp" 33 #include "runtime/safepoint.hpp" 34 35 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 36 // is an abstract class: there may be many different kinds of heaps. This 37 // class defines the functions that a heap must implement, and contains 38 // infrastructure common to all heaps. 39 40 class BarrierSet; 41 class ThreadClosure; 42 class AdaptiveSizePolicy; 43 class Thread; 44 class CollectorPolicy; 45 46 // 47 // CollectedHeap 48 // SharedHeap 49 // GenCollectedHeap 50 // G1CollectedHeap 51 // ParallelScavengeHeap 52 // 53 class CollectedHeap : public CHeapObj { 54 friend class VMStructs; 55 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 56 friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe 57 58 #ifdef ASSERT 59 static int _fire_out_of_memory_count; 60 #endif 61 62 // Used for filler objects (static, but initialized in ctor). 63 static size_t _filler_array_max_size; 64 65 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used 66 bool _defer_initial_card_mark; 67 68 protected: 69 MemRegion _reserved; 70 BarrierSet* _barrier_set; 71 bool _is_gc_active; 72 int _n_par_threads; 73 74 unsigned int _total_collections; // ... started 75 unsigned int _total_full_collections; // ... started 76 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 77 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 78 79 // Reason for current garbage collection. Should be set to 80 // a value reflecting no collection between collections. 81 GCCause::Cause _gc_cause; 82 GCCause::Cause _gc_lastcause; 83 PerfStringVariable* _perf_gc_cause; 84 PerfStringVariable* _perf_gc_lastcause; 85 86 // Constructor 87 CollectedHeap(); 88 89 // Do common initializations that must follow instance construction, 90 // for example, those needing virtual calls. 91 // This code could perhaps be moved into initialize() but would 92 // be slightly more awkward because we want the latter to be a 93 // pure virtual. 94 void pre_initialize(); 95 96 // Create a new tlab. All TLAB allocations must go through this. 97 virtual HeapWord* allocate_new_tlab(size_t size); 98 99 // Accumulate statistics on all tlabs. 100 virtual void accumulate_statistics_all_tlabs(); 101 102 // Reinitialize tlabs before resuming mutators. 103 virtual void resize_all_tlabs(); 104 105 protected: 106 // Allocate from the current thread's TLAB, with broken-out slow path. 107 inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size); 108 static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size); 109 110 // Allocate an uninitialized block of the given size, or returns NULL if 111 // this is impossible. 112 inline static HeapWord* common_mem_allocate_noinit(size_t size, TRAPS); 113 114 // Like allocate_init, but the block returned by a successful allocation 115 // is guaranteed initialized to zeros. 116 inline static HeapWord* common_mem_allocate_init(size_t size, TRAPS); 117 118 // Same as common_mem version, except memory is allocated in the permanent area 119 // If there is no permanent area, revert to common_mem_allocate_noinit 120 inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS); 121 122 // Same as common_mem version, except memory is allocated in the permanent area 123 // If there is no permanent area, revert to common_mem_allocate_init 124 inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS); 125 126 // Helper functions for (VM) allocation. 127 inline static void post_allocation_setup_common(KlassHandle klass, 128 HeapWord* obj, size_t size); 129 inline static void post_allocation_setup_no_klass_install(KlassHandle klass, 130 HeapWord* objPtr, 131 size_t size); 132 133 inline static void post_allocation_setup_obj(KlassHandle klass, 134 HeapWord* obj, size_t size); 135 136 inline static void post_allocation_setup_array(KlassHandle klass, 137 HeapWord* obj, size_t size, 138 int length); 139 140 // Clears an allocated object. 141 inline static void init_obj(HeapWord* obj, size_t size); 142 143 // Filler object utilities. 144 static inline size_t filler_array_hdr_size(); 145 static inline size_t filler_array_min_size(); 146 static inline size_t filler_array_max_size(); 147 148 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 149 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 150 151 // Fill with a single array; caller must ensure filler_array_min_size() <= 152 // words <= filler_array_max_size(). 153 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 154 155 // Fill with a single object (either an int array or a java.lang.Object). 156 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 157 158 // Verification functions 159 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size) 160 PRODUCT_RETURN; 161 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 162 PRODUCT_RETURN; 163 debug_only(static void check_for_valid_allocation_state();) 164 165 public: 166 enum Name { 167 Abstract, 168 SharedHeap, 169 GenCollectedHeap, 170 ParallelScavengeHeap, 171 G1CollectedHeap 172 }; 173 174 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; } 175 176 /** 177 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 178 * and JNI_OK on success. 179 */ 180 virtual jint initialize() = 0; 181 182 // In many heaps, there will be a need to perform some initialization activities 183 // after the Universe is fully formed, but before general heap allocation is allowed. 184 // This is the correct place to place such initialization methods. 185 virtual void post_initialize() = 0; 186 187 MemRegion reserved_region() const { return _reserved; } 188 address base() const { return (address)reserved_region().start(); } 189 190 // Future cleanup here. The following functions should specify bytes or 191 // heapwords as part of their signature. 192 virtual size_t capacity() const = 0; 193 virtual size_t used() const = 0; 194 195 // Return "true" if the part of the heap that allocates Java 196 // objects has reached the maximal committed limit that it can 197 // reach, without a garbage collection. 198 virtual bool is_maximal_no_gc() const = 0; 199 200 virtual size_t permanent_capacity() const = 0; 201 virtual size_t permanent_used() const = 0; 202 203 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 204 // memory that the vm could make available for storing 'normal' java objects. 205 // This is based on the reserved address space, but should not include space 206 // that the vm uses internally for bookkeeping or temporary storage (e.g., 207 // perm gen space or, in the case of the young gen, one of the survivor 208 // spaces). 209 virtual size_t max_capacity() const = 0; 210 211 // Returns "TRUE" if "p" points into the reserved area of the heap. 212 bool is_in_reserved(const void* p) const { 213 return _reserved.contains(p); 214 } 215 216 bool is_in_reserved_or_null(const void* p) const { 217 return p == NULL || is_in_reserved(p); 218 } 219 220 // Returns "TRUE" if "p" points to the head of an allocated object in the 221 // heap. Since this method can be expensive in general, we restrict its 222 // use to assertion checking only. 223 virtual bool is_in(const void* p) const = 0; 224 225 bool is_in_or_null(const void* p) const { 226 return p == NULL || is_in(p); 227 } 228 229 // Let's define some terms: a "closed" subset of a heap is one that 230 // 231 // 1) contains all currently-allocated objects, and 232 // 233 // 2) is closed under reference: no object in the closed subset 234 // references one outside the closed subset. 235 // 236 // Membership in a heap's closed subset is useful for assertions. 237 // Clearly, the entire heap is a closed subset, so the default 238 // implementation is to use "is_in_reserved". But this may not be too 239 // liberal to perform useful checking. Also, the "is_in" predicate 240 // defines a closed subset, but may be too expensive, since "is_in" 241 // verifies that its argument points to an object head. The 242 // "closed_subset" method allows a heap to define an intermediate 243 // predicate, allowing more precise checking than "is_in_reserved" at 244 // lower cost than "is_in." 245 246 // One important case is a heap composed of disjoint contiguous spaces, 247 // such as the Garbage-First collector. Such heaps have a convenient 248 // closed subset consisting of the allocated portions of those 249 // contiguous spaces. 250 251 // Return "TRUE" iff the given pointer points into the heap's defined 252 // closed subset (which defaults to the entire heap). 253 virtual bool is_in_closed_subset(const void* p) const { 254 return is_in_reserved(p); 255 } 256 257 bool is_in_closed_subset_or_null(const void* p) const { 258 return p == NULL || is_in_closed_subset(p); 259 } 260 261 // XXX is_permanent() and is_in_permanent() should be better named 262 // to distinguish one from the other. 263 264 // Returns "TRUE" if "p" is allocated as "permanent" data. 265 // If the heap does not use "permanent" data, returns the same 266 // value is_in_reserved() would return. 267 // NOTE: this actually returns true if "p" is in reserved space 268 // for the space not that it is actually allocated (i.e. in committed 269 // space). If you need the more conservative answer use is_permanent(). 270 virtual bool is_in_permanent(const void *p) const = 0; 271 272 273 #ifdef ASSERT 274 // Returns true if "p" is in the part of the 275 // heap being collected. 276 virtual bool is_in_partial_collection(const void *p) = 0; 277 #endif 278 279 bool is_in_permanent_or_null(const void *p) const { 280 return p == NULL || is_in_permanent(p); 281 } 282 283 // Returns "TRUE" if "p" is in the committed area of "permanent" data. 284 // If the heap does not use "permanent" data, returns the same 285 // value is_in() would return. 286 virtual bool is_permanent(const void *p) const = 0; 287 288 bool is_permanent_or_null(const void *p) const { 289 return p == NULL || is_permanent(p); 290 } 291 292 // An object is scavengable if its location may move during a scavenge. 293 // (A scavenge is a GC which is not a full GC.) 294 virtual bool is_scavengable(const void *p) = 0; 295 296 // Returns "TRUE" if "p" is a method oop in the 297 // current heap, with high probability. This predicate 298 // is not stable, in general. 299 bool is_valid_method(oop p) const; 300 301 void set_gc_cause(GCCause::Cause v) { 302 if (UsePerfData) { 303 _gc_lastcause = _gc_cause; 304 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 305 _perf_gc_cause->set_value(GCCause::to_string(v)); 306 } 307 _gc_cause = v; 308 } 309 GCCause::Cause gc_cause() { return _gc_cause; } 310 311 // Number of threads currently working on GC tasks. 312 int n_par_threads() { return _n_par_threads; } 313 314 // May be overridden to set additional parallelism. 315 virtual void set_par_threads(int t) { _n_par_threads = t; }; 316 317 // Preload classes into the shared portion of the heap, and then dump 318 // that data to a file so that it can be loaded directly by another 319 // VM (then terminate). 320 virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); } 321 322 // General obj/array allocation facilities. 323 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS); 324 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS); 325 inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS); 326 327 // Special obj/array allocation facilities. 328 // Some heaps may want to manage "permanent" data uniquely. These default 329 // to the general routines if the heap does not support such handling. 330 inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS); 331 // permanent_obj_allocate_no_klass_install() does not do the installation of 332 // the klass pointer in the newly created object (as permanent_obj_allocate() 333 // above does). This allows for a delay in the installation of the klass 334 // pointer that is needed during the create of klassKlass's. The 335 // method post_allocation_install_obj_klass() is used to install the 336 // klass pointer. 337 inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass, 338 int size, 339 TRAPS); 340 inline static void post_allocation_install_obj_klass(KlassHandle klass, 341 oop obj, 342 int size); 343 inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS); 344 345 // Raw memory allocation facilities 346 // The obj and array allocate methods are covers for these methods. 347 // The permanent allocation method should default to mem_allocate if 348 // permanent memory isn't supported. mem_allocate() should never be 349 // called to allocate TLABs, only individual objects. 350 virtual HeapWord* mem_allocate(size_t size, 351 bool* gc_overhead_limit_was_exceeded) = 0; 352 virtual HeapWord* permanent_mem_allocate(size_t size) = 0; 353 354 // Utilities for turning raw memory into filler objects. 355 // 356 // min_fill_size() is the smallest region that can be filled. 357 // fill_with_objects() can fill arbitrary-sized regions of the heap using 358 // multiple objects. fill_with_object() is for regions known to be smaller 359 // than the largest array of integers; it uses a single object to fill the 360 // region and has slightly less overhead. 361 static size_t min_fill_size() { 362 return size_t(align_object_size(oopDesc::header_size())); 363 } 364 365 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 366 367 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 368 static void fill_with_object(MemRegion region, bool zap = true) { 369 fill_with_object(region.start(), region.word_size(), zap); 370 } 371 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 372 fill_with_object(start, pointer_delta(end, start), zap); 373 } 374 375 // Some heaps may offer a contiguous region for shared non-blocking 376 // allocation, via inlined code (by exporting the address of the top and 377 // end fields defining the extent of the contiguous allocation region.) 378 379 // This function returns "true" iff the heap supports this kind of 380 // allocation. (Default is "no".) 381 virtual bool supports_inline_contig_alloc() const { 382 return false; 383 } 384 // These functions return the addresses of the fields that define the 385 // boundaries of the contiguous allocation area. (These fields should be 386 // physically near to one another.) 387 virtual HeapWord** top_addr() const { 388 guarantee(false, "inline contiguous allocation not supported"); 389 return NULL; 390 } 391 virtual HeapWord** end_addr() const { 392 guarantee(false, "inline contiguous allocation not supported"); 393 return NULL; 394 } 395 396 // Some heaps may be in an unparseable state at certain times between 397 // collections. This may be necessary for efficient implementation of 398 // certain allocation-related activities. Calling this function before 399 // attempting to parse a heap ensures that the heap is in a parsable 400 // state (provided other concurrent activity does not introduce 401 // unparsability). It is normally expected, therefore, that this 402 // method is invoked with the world stopped. 403 // NOTE: if you override this method, make sure you call 404 // super::ensure_parsability so that the non-generational 405 // part of the work gets done. See implementation of 406 // CollectedHeap::ensure_parsability and, for instance, 407 // that of GenCollectedHeap::ensure_parsability(). 408 // The argument "retire_tlabs" controls whether existing TLABs 409 // are merely filled or also retired, thus preventing further 410 // allocation from them and necessitating allocation of new TLABs. 411 virtual void ensure_parsability(bool retire_tlabs); 412 413 // Return an estimate of the maximum allocation that could be performed 414 // without triggering any collection or expansion activity. In a 415 // generational collector, for example, this is probably the largest 416 // allocation that could be supported (without expansion) in the youngest 417 // generation. It is "unsafe" because no locks are taken; the result 418 // should be treated as an approximation, not a guarantee, for use in 419 // heuristic resizing decisions. 420 virtual size_t unsafe_max_alloc() = 0; 421 422 // Section on thread-local allocation buffers (TLABs) 423 // If the heap supports thread-local allocation buffers, it should override 424 // the following methods: 425 // Returns "true" iff the heap supports thread-local allocation buffers. 426 // The default is "no". 427 virtual bool supports_tlab_allocation() const { 428 return false; 429 } 430 // The amount of space available for thread-local allocation buffers. 431 virtual size_t tlab_capacity(Thread *thr) const { 432 guarantee(false, "thread-local allocation buffers not supported"); 433 return 0; 434 } 435 // An estimate of the maximum allocation that could be performed 436 // for thread-local allocation buffers without triggering any 437 // collection or expansion activity. 438 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 439 guarantee(false, "thread-local allocation buffers not supported"); 440 return 0; 441 } 442 443 // Can a compiler initialize a new object without store barriers? 444 // This permission only extends from the creation of a new object 445 // via a TLAB up to the first subsequent safepoint. If such permission 446 // is granted for this heap type, the compiler promises to call 447 // defer_store_barrier() below on any slow path allocation of 448 // a new object for which such initializing store barriers will 449 // have been elided. 450 virtual bool can_elide_tlab_store_barriers() const = 0; 451 452 // If a compiler is eliding store barriers for TLAB-allocated objects, 453 // there is probably a corresponding slow path which can produce 454 // an object allocated anywhere. The compiler's runtime support 455 // promises to call this function on such a slow-path-allocated 456 // object before performing initializations that have elided 457 // store barriers. Returns new_obj, or maybe a safer copy thereof. 458 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj); 459 460 // Answers whether an initializing store to a new object currently 461 // allocated at the given address doesn't need a store 462 // barrier. Returns "true" if it doesn't need an initializing 463 // store barrier; answers "false" if it does. 464 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0; 465 466 // If a compiler is eliding store barriers for TLAB-allocated objects, 467 // we will be informed of a slow-path allocation by a call 468 // to new_store_pre_barrier() above. Such a call precedes the 469 // initialization of the object itself, and no post-store-barriers will 470 // be issued. Some heap types require that the barrier strictly follows 471 // the initializing stores. (This is currently implemented by deferring the 472 // barrier until the next slow-path allocation or gc-related safepoint.) 473 // This interface answers whether a particular heap type needs the card 474 // mark to be thus strictly sequenced after the stores. 475 virtual bool card_mark_must_follow_store() const = 0; 476 477 // If the CollectedHeap was asked to defer a store barrier above, 478 // this informs it to flush such a deferred store barrier to the 479 // remembered set. 480 virtual void flush_deferred_store_barrier(JavaThread* thread); 481 482 // Can a compiler elide a store barrier when it writes 483 // a permanent oop into the heap? Applies when the compiler 484 // is storing x to the heap, where x->is_perm() is true. 485 virtual bool can_elide_permanent_oop_store_barriers() const = 0; 486 487 // Does this heap support heap inspection (+PrintClassHistogram?) 488 virtual bool supports_heap_inspection() const = 0; 489 490 // Perform a collection of the heap; intended for use in implementing 491 // "System.gc". This probably implies as full a collection as the 492 // "CollectedHeap" supports. 493 virtual void collect(GCCause::Cause cause) = 0; 494 495 // This interface assumes that it's being called by the 496 // vm thread. It collects the heap assuming that the 497 // heap lock is already held and that we are executing in 498 // the context of the vm thread. 499 virtual void collect_as_vm_thread(GCCause::Cause cause) = 0; 500 501 // Returns the barrier set for this heap 502 BarrierSet* barrier_set() { return _barrier_set; } 503 504 // Returns "true" iff there is a stop-world GC in progress. (I assume 505 // that it should answer "false" for the concurrent part of a concurrent 506 // collector -- dld). 507 bool is_gc_active() const { return _is_gc_active; } 508 509 // Total number of GC collections (started) 510 unsigned int total_collections() const { return _total_collections; } 511 unsigned int total_full_collections() const { return _total_full_collections;} 512 513 // Increment total number of GC collections (started) 514 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 515 void increment_total_collections(bool full = false) { 516 _total_collections++; 517 if (full) { 518 increment_total_full_collections(); 519 } 520 } 521 522 void increment_total_full_collections() { _total_full_collections++; } 523 524 // Return the AdaptiveSizePolicy for the heap. 525 virtual AdaptiveSizePolicy* size_policy() = 0; 526 527 // Return the CollectorPolicy for the heap 528 virtual CollectorPolicy* collector_policy() const = 0; 529 530 // Iterate over all the ref-containing fields of all objects, calling 531 // "cl.do_oop" on each. This includes objects in permanent memory. 532 virtual void oop_iterate(OopClosure* cl) = 0; 533 534 // Iterate over all objects, calling "cl.do_object" on each. 535 // This includes objects in permanent memory. 536 virtual void object_iterate(ObjectClosure* cl) = 0; 537 538 // Similar to object_iterate() except iterates only 539 // over live objects. 540 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 541 542 // Behaves the same as oop_iterate, except only traverses 543 // interior pointers contained in permanent memory. If there 544 // is no permanent memory, does nothing. 545 virtual void permanent_oop_iterate(OopClosure* cl) = 0; 546 547 // Behaves the same as object_iterate, except only traverses 548 // object contained in permanent memory. If there is no 549 // permanent memory, does nothing. 550 virtual void permanent_object_iterate(ObjectClosure* cl) = 0; 551 552 // NOTE! There is no requirement that a collector implement these 553 // functions. 554 // 555 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 556 // each address in the (reserved) heap is a member of exactly 557 // one block. The defining characteristic of a block is that it is 558 // possible to find its size, and thus to progress forward to the next 559 // block. (Blocks may be of different sizes.) Thus, blocks may 560 // represent Java objects, or they might be free blocks in a 561 // free-list-based heap (or subheap), as long as the two kinds are 562 // distinguishable and the size of each is determinable. 563 564 // Returns the address of the start of the "block" that contains the 565 // address "addr". We say "blocks" instead of "object" since some heaps 566 // may not pack objects densely; a chunk may either be an object or a 567 // non-object. 568 virtual HeapWord* block_start(const void* addr) const = 0; 569 570 // Requires "addr" to be the start of a chunk, and returns its size. 571 // "addr + size" is required to be the start of a new chunk, or the end 572 // of the active area of the heap. 573 virtual size_t block_size(const HeapWord* addr) const = 0; 574 575 // Requires "addr" to be the start of a block, and returns "TRUE" iff 576 // the block is an object. 577 virtual bool block_is_obj(const HeapWord* addr) const = 0; 578 579 // Returns the longest time (in ms) that has elapsed since the last 580 // time that any part of the heap was examined by a garbage collection. 581 virtual jlong millis_since_last_gc() = 0; 582 583 // Perform any cleanup actions necessary before allowing a verification. 584 virtual void prepare_for_verify() = 0; 585 586 // Generate any dumps preceding or following a full gc 587 void pre_full_gc_dump(); 588 void post_full_gc_dump(); 589 590 virtual void print() const = 0; 591 virtual void print_on(outputStream* st) const = 0; 592 593 // Print all GC threads (other than the VM thread) 594 // used by this heap. 595 virtual void print_gc_threads_on(outputStream* st) const = 0; 596 void print_gc_threads() { print_gc_threads_on(tty); } 597 // Iterator for all GC threads (other than VM thread) 598 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 599 600 // Print any relevant tracing info that flags imply. 601 // Default implementation does nothing. 602 virtual void print_tracing_info() const = 0; 603 604 // Heap verification 605 virtual void verify(bool allow_dirty, bool silent, VerifyOption option) = 0; 606 607 // Non product verification and debugging. 608 #ifndef PRODUCT 609 // Support for PromotionFailureALot. Return true if it's time to cause a 610 // promotion failure. The no-argument version uses 611 // this->_promotion_failure_alot_count as the counter. 612 inline bool promotion_should_fail(volatile size_t* count); 613 inline bool promotion_should_fail(); 614 615 // Reset the PromotionFailureALot counters. Should be called at the end of a 616 // GC in which promotion failure ocurred. 617 inline void reset_promotion_should_fail(volatile size_t* count); 618 inline void reset_promotion_should_fail(); 619 #endif // #ifndef PRODUCT 620 621 #ifdef ASSERT 622 static int fired_fake_oom() { 623 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); 624 } 625 #endif 626 627 public: 628 // This is a convenience method that is used in cases where 629 // the actual number of GC worker threads is not pertinent but 630 // only whether there more than 0. Use of this method helps 631 // reduce the occurrence of ParallelGCThreads to uses where the 632 // actual number may be germane. 633 static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; } 634 }; 635 636 // Class to set and reset the GC cause for a CollectedHeap. 637 638 class GCCauseSetter : StackObj { 639 CollectedHeap* _heap; 640 GCCause::Cause _previous_cause; 641 public: 642 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 643 assert(SafepointSynchronize::is_at_safepoint(), 644 "This method manipulates heap state without locking"); 645 _heap = heap; 646 _previous_cause = _heap->gc_cause(); 647 _heap->set_gc_cause(cause); 648 } 649 650 ~GCCauseSetter() { 651 assert(SafepointSynchronize::is_at_safepoint(), 652 "This method manipulates heap state without locking"); 653 _heap->set_gc_cause(_previous_cause); 654 } 655 }; 656 657 #endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP