1 /* 2 * Copyright (c) 2001, 2019, 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_GC_SHARED_COLLECTEDHEAP_HPP 26 #define SHARE_GC_SHARED_COLLECTEDHEAP_HPP 27 28 #include "gc/shared/gcCause.hpp" 29 #include "gc/shared/gcWhen.hpp" 30 #include "memory/allocation.hpp" 31 #include "runtime/handles.hpp" 32 #include "runtime/perfData.hpp" 33 #include "runtime/safepoint.hpp" 34 #include "services/memoryUsage.hpp" 35 #include "utilities/debug.hpp" 36 #include "utilities/events.hpp" 37 #include "utilities/formatBuffer.hpp" 38 #include "utilities/growableArray.hpp" 39 40 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 41 // is an abstract class: there may be many different kinds of heaps. This 42 // class defines the functions that a heap must implement, and contains 43 // infrastructure common to all heaps. 44 45 class AdaptiveSizePolicy; 46 class BarrierSet; 47 class CollectorPolicy; 48 class GCHeapSummary; 49 class GCTimer; 50 class GCTracer; 51 class GCMemoryManager; 52 class MemoryPool; 53 class MetaspaceSummary; 54 class SoftRefPolicy; 55 class Thread; 56 class ThreadClosure; 57 class VirtualSpaceSummary; 58 class WorkGang; 59 class nmethod; 60 61 class GCMessage : public FormatBuffer<1024> { 62 public: 63 bool is_before; 64 65 public: 66 GCMessage() {} 67 }; 68 69 class CollectedHeap; 70 71 class GCHeapLog : public EventLogBase<GCMessage> { 72 private: 73 void log_heap(CollectedHeap* heap, bool before); 74 75 public: 76 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {} 77 78 void log_heap_before(CollectedHeap* heap) { 79 log_heap(heap, true); 80 } 81 void log_heap_after(CollectedHeap* heap) { 82 log_heap(heap, false); 83 } 84 }; 85 86 // 87 // CollectedHeap 88 // GenCollectedHeap 89 // SerialHeap 90 // CMSHeap 91 // G1CollectedHeap 92 // ParallelScavengeHeap 93 // ShenandoahHeap 94 // ZCollectedHeap 95 // 96 class CollectedHeap : public CHeapObj<mtInternal> { 97 friend class VMStructs; 98 friend class JVMCIVMStructs; 99 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 100 friend class MemAllocator; 101 102 private: 103 GCHeapLog* _gc_heap_log; 104 105 MemRegion _reserved; 106 107 protected: 108 bool _is_gc_active; 109 110 // Used for filler objects (static, but initialized in ctor). 111 static size_t _filler_array_max_size; 112 113 unsigned int _total_collections; // ... started 114 unsigned int _total_full_collections; // ... started 115 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 116 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 117 118 // Reason for current garbage collection. Should be set to 119 // a value reflecting no collection between collections. 120 GCCause::Cause _gc_cause; 121 GCCause::Cause _gc_lastcause; 122 PerfStringVariable* _perf_gc_cause; 123 PerfStringVariable* _perf_gc_lastcause; 124 125 // Constructor 126 CollectedHeap(); 127 128 // Create a new tlab. All TLAB allocations must go through this. 129 // To allow more flexible TLAB allocations min_size specifies 130 // the minimum size needed, while requested_size is the requested 131 // size based on ergonomics. The actually allocated size will be 132 // returned in actual_size. 133 virtual HeapWord* allocate_new_tlab(size_t min_size, 134 size_t requested_size, 135 size_t* actual_size); 136 137 // Reinitialize tlabs before resuming mutators. 138 virtual void resize_all_tlabs(); 139 140 // Raw memory allocation facilities 141 // The obj and array allocate methods are covers for these methods. 142 // mem_allocate() should never be 143 // called to allocate TLABs, only individual objects. 144 virtual HeapWord* mem_allocate(size_t size, 145 bool* gc_overhead_limit_was_exceeded) = 0; 146 147 // Filler object utilities. 148 static inline size_t filler_array_hdr_size(); 149 static inline size_t filler_array_min_size(); 150 151 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 152 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 153 154 // Fill with a single array; caller must ensure filler_array_min_size() <= 155 // words <= filler_array_max_size(). 156 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 157 158 // Fill with a single object (either an int array or a java.lang.Object). 159 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 160 161 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 162 163 // Verification functions 164 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 165 PRODUCT_RETURN; 166 debug_only(static void check_for_valid_allocation_state();) 167 168 public: 169 enum Name { 170 None, 171 Serial, 172 Parallel, 173 CMS, 174 G1, 175 Epsilon, 176 Z, 177 Shenandoah 178 }; 179 180 static inline size_t filler_array_max_size() { 181 return _filler_array_max_size; 182 } 183 184 virtual Name kind() const = 0; 185 186 virtual const char* name() const = 0; 187 188 /** 189 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 190 * and JNI_OK on success. 191 */ 192 virtual jint initialize() = 0; 193 194 // In many heaps, there will be a need to perform some initialization activities 195 // after the Universe is fully formed, but before general heap allocation is allowed. 196 // This is the correct place to place such initialization methods. 197 virtual void post_initialize(); 198 199 // Stop any onging concurrent work and prepare for exit. 200 virtual void stop() {} 201 202 // Stop and resume concurrent GC threads interfering with safepoint operations 203 virtual void safepoint_synchronize_begin() {} 204 virtual void safepoint_synchronize_end() {} 205 206 void initialize_reserved_region(HeapWord *start, HeapWord *end); 207 MemRegion reserved_region() const { return _reserved; } 208 address base() const { return (address)reserved_region().start(); } 209 210 virtual size_t capacity() const = 0; 211 virtual size_t used() const = 0; 212 213 // Return "true" if the part of the heap that allocates Java 214 // objects has reached the maximal committed limit that it can 215 // reach, without a garbage collection. 216 virtual bool is_maximal_no_gc() const = 0; 217 218 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 219 // memory that the vm could make available for storing 'normal' java objects. 220 // This is based on the reserved address space, but should not include space 221 // that the vm uses internally for bookkeeping or temporary storage 222 // (e.g., in the case of the young gen, one of the survivor 223 // spaces). 224 virtual size_t max_capacity() const = 0; 225 226 // Returns "TRUE" if "p" points into the reserved area of the heap. 227 bool is_in_reserved(const void* p) const { 228 return _reserved.contains(p); 229 } 230 231 bool is_in_reserved_or_null(const void* p) const { 232 return p == NULL || is_in_reserved(p); 233 } 234 235 // Returns "TRUE" iff "p" points into the committed areas of the heap. 236 // This method can be expensive so avoid using it in performance critical 237 // code. 238 virtual bool is_in(const void* p) const = 0; 239 240 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 241 242 // Let's define some terms: a "closed" subset of a heap is one that 243 // 244 // 1) contains all currently-allocated objects, and 245 // 246 // 2) is closed under reference: no object in the closed subset 247 // references one outside the closed subset. 248 // 249 // Membership in a heap's closed subset is useful for assertions. 250 // Clearly, the entire heap is a closed subset, so the default 251 // implementation is to use "is_in_reserved". But this may not be too 252 // liberal to perform useful checking. Also, the "is_in" predicate 253 // defines a closed subset, but may be too expensive, since "is_in" 254 // verifies that its argument points to an object head. The 255 // "closed_subset" method allows a heap to define an intermediate 256 // predicate, allowing more precise checking than "is_in_reserved" at 257 // lower cost than "is_in." 258 259 // One important case is a heap composed of disjoint contiguous spaces, 260 // such as the Garbage-First collector. Such heaps have a convenient 261 // closed subset consisting of the allocated portions of those 262 // contiguous spaces. 263 264 // Return "TRUE" iff the given pointer points into the heap's defined 265 // closed subset (which defaults to the entire heap). 266 virtual bool is_in_closed_subset(const void* p) const { 267 return is_in_reserved(p); 268 } 269 270 bool is_in_closed_subset_or_null(const void* p) const { 271 return p == NULL || is_in_closed_subset(p); 272 } 273 274 void set_gc_cause(GCCause::Cause v) { 275 if (UsePerfData) { 276 _gc_lastcause = _gc_cause; 277 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 278 _perf_gc_cause->set_value(GCCause::to_string(v)); 279 } 280 _gc_cause = v; 281 } 282 GCCause::Cause gc_cause() { return _gc_cause; } 283 284 virtual oop obj_allocate(Klass* klass, int size, TRAPS); 285 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS); 286 virtual oop class_allocate(Klass* klass, int size, TRAPS); 287 288 // Utilities for turning raw memory into filler objects. 289 // 290 // min_fill_size() is the smallest region that can be filled. 291 // fill_with_objects() can fill arbitrary-sized regions of the heap using 292 // multiple objects. fill_with_object() is for regions known to be smaller 293 // than the largest array of integers; it uses a single object to fill the 294 // region and has slightly less overhead. 295 static size_t min_fill_size() { 296 return size_t(align_object_size(oopDesc::header_size())); 297 } 298 299 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 300 301 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 302 static void fill_with_object(MemRegion region, bool zap = true) { 303 fill_with_object(region.start(), region.word_size(), zap); 304 } 305 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 306 fill_with_object(start, pointer_delta(end, start), zap); 307 } 308 309 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap); 310 virtual size_t min_dummy_object_size() const; 311 size_t tlab_alloc_reserve() const; 312 313 // Return the address "addr" aligned by "alignment_in_bytes" if such 314 // an address is below "end". Return NULL otherwise. 315 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 316 HeapWord* end, 317 unsigned short alignment_in_bytes); 318 319 // Some heaps may offer a contiguous region for shared non-blocking 320 // allocation, via inlined code (by exporting the address of the top and 321 // end fields defining the extent of the contiguous allocation region.) 322 323 // This function returns "true" iff the heap supports this kind of 324 // allocation. (Default is "no".) 325 virtual bool supports_inline_contig_alloc() const { 326 return false; 327 } 328 // These functions return the addresses of the fields that define the 329 // boundaries of the contiguous allocation area. (These fields should be 330 // physically near to one another.) 331 virtual HeapWord* volatile* top_addr() const { 332 guarantee(false, "inline contiguous allocation not supported"); 333 return NULL; 334 } 335 virtual HeapWord** end_addr() const { 336 guarantee(false, "inline contiguous allocation not supported"); 337 return NULL; 338 } 339 340 // Some heaps may be in an unparseable state at certain times between 341 // collections. This may be necessary for efficient implementation of 342 // certain allocation-related activities. Calling this function before 343 // attempting to parse a heap ensures that the heap is in a parsable 344 // state (provided other concurrent activity does not introduce 345 // unparsability). It is normally expected, therefore, that this 346 // method is invoked with the world stopped. 347 // NOTE: if you override this method, make sure you call 348 // super::ensure_parsability so that the non-generational 349 // part of the work gets done. See implementation of 350 // CollectedHeap::ensure_parsability and, for instance, 351 // that of GenCollectedHeap::ensure_parsability(). 352 // The argument "retire_tlabs" controls whether existing TLABs 353 // are merely filled or also retired, thus preventing further 354 // allocation from them and necessitating allocation of new TLABs. 355 virtual void ensure_parsability(bool retire_tlabs); 356 357 // Section on thread-local allocation buffers (TLABs) 358 // If the heap supports thread-local allocation buffers, it should override 359 // the following methods: 360 // Returns "true" iff the heap supports thread-local allocation buffers. 361 // The default is "no". 362 virtual bool supports_tlab_allocation() const = 0; 363 364 // The amount of space available for thread-local allocation buffers. 365 virtual size_t tlab_capacity(Thread *thr) const = 0; 366 367 // The amount of used space for thread-local allocation buffers for the given thread. 368 virtual size_t tlab_used(Thread *thr) const = 0; 369 370 virtual size_t max_tlab_size() const; 371 372 // An estimate of the maximum allocation that could be performed 373 // for thread-local allocation buffers without triggering any 374 // collection or expansion activity. 375 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 376 guarantee(false, "thread-local allocation buffers not supported"); 377 return 0; 378 } 379 380 // Perform a collection of the heap; intended for use in implementing 381 // "System.gc". This probably implies as full a collection as the 382 // "CollectedHeap" supports. 383 virtual void collect(GCCause::Cause cause) = 0; 384 385 // Perform a full collection 386 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 387 388 // This interface assumes that it's being called by the 389 // vm thread. It collects the heap assuming that the 390 // heap lock is already held and that we are executing in 391 // the context of the vm thread. 392 virtual void collect_as_vm_thread(GCCause::Cause cause); 393 394 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 395 size_t size, 396 Metaspace::MetadataType mdtype); 397 398 // Returns "true" iff there is a stop-world GC in progress. (I assume 399 // that it should answer "false" for the concurrent part of a concurrent 400 // collector -- dld). 401 bool is_gc_active() const { return _is_gc_active; } 402 403 // Total number of GC collections (started) 404 unsigned int total_collections() const { return _total_collections; } 405 unsigned int total_full_collections() const { return _total_full_collections;} 406 407 // Increment total number of GC collections (started) 408 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 409 void increment_total_collections(bool full = false) { 410 _total_collections++; 411 if (full) { 412 increment_total_full_collections(); 413 } 414 } 415 416 void increment_total_full_collections() { _total_full_collections++; } 417 418 // Return the CollectorPolicy for the heap 419 virtual CollectorPolicy* collector_policy() const = 0; 420 421 // Return the SoftRefPolicy for the heap; 422 virtual SoftRefPolicy* soft_ref_policy() = 0; 423 424 virtual MemoryUsage memory_usage(); 425 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 426 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 427 428 // Iterate over all objects, calling "cl.do_object" on each. 429 virtual void object_iterate(ObjectClosure* cl) = 0; 430 431 // Similar to object_iterate() except iterates only 432 // over live objects. 433 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 434 435 // NOTE! There is no requirement that a collector implement these 436 // functions. 437 // 438 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 439 // each address in the (reserved) heap is a member of exactly 440 // one block. The defining characteristic of a block is that it is 441 // possible to find its size, and thus to progress forward to the next 442 // block. (Blocks may be of different sizes.) Thus, blocks may 443 // represent Java objects, or they might be free blocks in a 444 // free-list-based heap (or subheap), as long as the two kinds are 445 // distinguishable and the size of each is determinable. 446 447 // Returns the address of the start of the "block" that contains the 448 // address "addr". We say "blocks" instead of "object" since some heaps 449 // may not pack objects densely; a chunk may either be an object or a 450 // non-object. 451 virtual HeapWord* block_start(const void* addr) const = 0; 452 453 // Requires "addr" to be the start of a chunk, and returns its size. 454 // "addr + size" is required to be the start of a new chunk, or the end 455 // of the active area of the heap. 456 virtual size_t block_size(const HeapWord* addr) const = 0; 457 458 // Requires "addr" to be the start of a block, and returns "TRUE" iff 459 // the block is an object. 460 virtual bool block_is_obj(const HeapWord* addr) const = 0; 461 462 // Returns the longest time (in ms) that has elapsed since the last 463 // time that any part of the heap was examined by a garbage collection. 464 virtual jlong millis_since_last_gc() = 0; 465 466 // Perform any cleanup actions necessary before allowing a verification. 467 virtual void prepare_for_verify() = 0; 468 469 // Generate any dumps preceding or following a full gc 470 private: 471 void full_gc_dump(GCTimer* timer, bool before); 472 473 virtual void initialize_serviceability() = 0; 474 475 public: 476 void pre_full_gc_dump(GCTimer* timer); 477 void post_full_gc_dump(GCTimer* timer); 478 479 virtual VirtualSpaceSummary create_heap_space_summary(); 480 GCHeapSummary create_heap_summary(); 481 482 MetaspaceSummary create_metaspace_summary(); 483 484 // Print heap information on the given outputStream. 485 virtual void print_on(outputStream* st) const = 0; 486 // The default behavior is to call print_on() on tty. 487 virtual void print() const { 488 print_on(tty); 489 } 490 // Print more detailed heap information on the given 491 // outputStream. The default behavior is to call print_on(). It is 492 // up to each subclass to override it and add any additional output 493 // it needs. 494 virtual void print_extended_on(outputStream* st) const { 495 print_on(st); 496 } 497 498 virtual void print_on_error(outputStream* st) const; 499 500 // Print all GC threads (other than the VM thread) 501 // used by this heap. 502 virtual void print_gc_threads_on(outputStream* st) const = 0; 503 // The default behavior is to call print_gc_threads_on() on tty. 504 void print_gc_threads() { 505 print_gc_threads_on(tty); 506 } 507 // Iterator for all GC threads (other than VM thread) 508 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 509 510 // Print any relevant tracing info that flags imply. 511 // Default implementation does nothing. 512 virtual void print_tracing_info() const = 0; 513 514 void print_heap_before_gc(); 515 void print_heap_after_gc(); 516 517 // An object is scavengable if its location may move during a scavenge. 518 // (A scavenge is a GC which is not a full GC.) 519 virtual bool is_scavengable(oop obj) = 0; 520 // Registering and unregistering an nmethod (compiled code) with the heap. 521 // Override with specific mechanism for each specialized heap type. 522 virtual void register_nmethod(nmethod* nm) {} 523 virtual void unregister_nmethod(nmethod* nm) {} 524 virtual void flush_nmethod(nmethod* nm) {} 525 virtual void verify_nmethod(nmethod* nmethod) {} 526 527 void trace_heap_before_gc(const GCTracer* gc_tracer); 528 void trace_heap_after_gc(const GCTracer* gc_tracer); 529 530 // Heap verification 531 virtual void verify(VerifyOption option) = 0; 532 533 // Return true if concurrent phase control (via 534 // request_concurrent_phase_control) is supported by this collector. 535 // The default implementation returns false. 536 virtual bool supports_concurrent_phase_control() const; 537 538 // Request the collector enter the indicated concurrent phase, and 539 // wait until it does so. Supports WhiteBox testing. Only one 540 // request may be active at a time. Phases are designated by name; 541 // the set of names and their meaning is GC-specific. Once the 542 // requested phase has been reached, the collector will attempt to 543 // avoid transitioning to a new phase until a new request is made. 544 // [Note: A collector might not be able to remain in a given phase. 545 // For example, a full collection might cancel an in-progress 546 // concurrent collection.] 547 // 548 // Returns true when the phase is reached. Returns false for an 549 // unknown phase. The default implementation returns false. 550 virtual bool request_concurrent_phase(const char* phase); 551 552 // Provides a thread pool to SafepointSynchronize to use 553 // for parallel safepoint cleanup. 554 // GCs that use a GC worker thread pool may want to share 555 // it for use during safepoint cleanup. This is only possible 556 // if the GC can pause and resume concurrent work (e.g. G1 557 // concurrent marking) for an intermittent non-GC safepoint. 558 // If this method returns NULL, SafepointSynchronize will 559 // perform cleanup tasks serially in the VMThread. 560 virtual WorkGang* get_safepoint_workers() { return NULL; } 561 562 // Support for object pinning. This is used by JNI Get*Critical() 563 // and Release*Critical() family of functions. If supported, the GC 564 // must guarantee that pinned objects never move. 565 virtual bool supports_object_pinning() const; 566 virtual oop pin_object(JavaThread* thread, oop obj); 567 virtual void unpin_object(JavaThread* thread, oop obj); 568 569 // Deduplicate the string, iff the GC supports string deduplication. 570 virtual void deduplicate_string(oop str); 571 572 virtual bool is_oop(oop object) const; 573 574 virtual size_t obj_size(oop obj) const; 575 576 // Cells are memory slices allocated by the allocator. Objects are initialized 577 // in cells. The cell itself may have a header, found at a negative offset of 578 // oops. Usually, the size of the cell header is 0, but it may be larger. 579 virtual ptrdiff_t cell_header_size() const { return 0; } 580 581 // Non product verification and debugging. 582 #ifndef PRODUCT 583 // Support for PromotionFailureALot. Return true if it's time to cause a 584 // promotion failure. The no-argument version uses 585 // this->_promotion_failure_alot_count as the counter. 586 bool promotion_should_fail(volatile size_t* count); 587 bool promotion_should_fail(); 588 589 // Reset the PromotionFailureALot counters. Should be called at the end of a 590 // GC in which promotion failure occurred. 591 void reset_promotion_should_fail(volatile size_t* count); 592 void reset_promotion_should_fail(); 593 #endif // #ifndef PRODUCT 594 }; 595 596 // Class to set and reset the GC cause for a CollectedHeap. 597 598 class GCCauseSetter : StackObj { 599 CollectedHeap* _heap; 600 GCCause::Cause _previous_cause; 601 public: 602 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 603 _heap = heap; 604 _previous_cause = _heap->gc_cause(); 605 _heap->set_gc_cause(cause); 606 } 607 608 ~GCCauseSetter() { 609 _heap->set_gc_cause(_previous_cause); 610 } 611 }; 612 613 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP