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 "gc/shared/verifyOption.hpp" 31 #include "memory/allocation.hpp" 32 #include "runtime/handles.hpp" 33 #include "runtime/perfData.hpp" 34 #include "runtime/safepoint.hpp" 35 #include "services/memoryUsage.hpp" 36 #include "utilities/debug.hpp" 37 #include "utilities/events.hpp" 38 #include "utilities/formatBuffer.hpp" 39 #include "utilities/growableArray.hpp" 40 41 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 42 // is an abstract class: there may be many different kinds of heaps. This 43 // class defines the functions that a heap must implement, and contains 44 // infrastructure common to all heaps. 45 46 class AdaptiveSizePolicy; 47 class BarrierSet; 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", "gc") {} 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 // Returns unused capacity. 214 virtual size_t unused() const; 215 216 // Return "true" if the part of the heap that allocates Java 217 // objects has reached the maximal committed limit that it can 218 // reach, without a garbage collection. 219 virtual bool is_maximal_no_gc() const = 0; 220 221 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 222 // memory that the vm could make available for storing 'normal' java objects. 223 // This is based on the reserved address space, but should not include space 224 // that the vm uses internally for bookkeeping or temporary storage 225 // (e.g., in the case of the young gen, one of the survivor 226 // spaces). 227 virtual size_t max_capacity() const = 0; 228 229 // Returns "TRUE" if "p" points into the reserved area of the heap. 230 bool is_in_reserved(const void* p) const { 231 return _reserved.contains(p); 232 } 233 234 bool is_in_reserved_or_null(const void* p) const { 235 return p == NULL || is_in_reserved(p); 236 } 237 238 // Returns "TRUE" iff "p" points into the committed areas of the heap. 239 // This method can be expensive so avoid using it in performance critical 240 // code. 241 virtual bool is_in(const void* p) const = 0; 242 243 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 244 245 virtual uint32_t hash_oop(oop obj) const; 246 247 void set_gc_cause(GCCause::Cause v) { 248 if (UsePerfData) { 249 _gc_lastcause = _gc_cause; 250 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 251 _perf_gc_cause->set_value(GCCause::to_string(v)); 252 } 253 _gc_cause = v; 254 } 255 GCCause::Cause gc_cause() { return _gc_cause; } 256 257 virtual oop obj_allocate(Klass* klass, int size, TRAPS); 258 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS); 259 virtual oop class_allocate(Klass* klass, int size, TRAPS); 260 261 // Utilities for turning raw memory into filler objects. 262 // 263 // min_fill_size() is the smallest region that can be filled. 264 // fill_with_objects() can fill arbitrary-sized regions of the heap using 265 // multiple objects. fill_with_object() is for regions known to be smaller 266 // than the largest array of integers; it uses a single object to fill the 267 // region and has slightly less overhead. 268 static size_t min_fill_size() { 269 return size_t(align_object_size(oopDesc::header_size())); 270 } 271 272 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 273 274 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 275 static void fill_with_object(MemRegion region, bool zap = true) { 276 fill_with_object(region.start(), region.word_size(), zap); 277 } 278 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 279 fill_with_object(start, pointer_delta(end, start), zap); 280 } 281 282 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap); 283 virtual size_t min_dummy_object_size() const; 284 size_t tlab_alloc_reserve() const; 285 286 // Return the address "addr" aligned by "alignment_in_bytes" if such 287 // an address is below "end". Return NULL otherwise. 288 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 289 HeapWord* end, 290 unsigned short alignment_in_bytes); 291 292 // Some heaps may offer a contiguous region for shared non-blocking 293 // allocation, via inlined code (by exporting the address of the top and 294 // end fields defining the extent of the contiguous allocation region.) 295 296 // This function returns "true" iff the heap supports this kind of 297 // allocation. (Default is "no".) 298 virtual bool supports_inline_contig_alloc() const { 299 return false; 300 } 301 // These functions return the addresses of the fields that define the 302 // boundaries of the contiguous allocation area. (These fields should be 303 // physically near to one another.) 304 virtual HeapWord* volatile* top_addr() const { 305 guarantee(false, "inline contiguous allocation not supported"); 306 return NULL; 307 } 308 virtual HeapWord** end_addr() const { 309 guarantee(false, "inline contiguous allocation not supported"); 310 return NULL; 311 } 312 313 // Some heaps may be in an unparseable state at certain times between 314 // collections. This may be necessary for efficient implementation of 315 // certain allocation-related activities. Calling this function before 316 // attempting to parse a heap ensures that the heap is in a parsable 317 // state (provided other concurrent activity does not introduce 318 // unparsability). It is normally expected, therefore, that this 319 // method is invoked with the world stopped. 320 // NOTE: if you override this method, make sure you call 321 // super::ensure_parsability so that the non-generational 322 // part of the work gets done. See implementation of 323 // CollectedHeap::ensure_parsability and, for instance, 324 // that of GenCollectedHeap::ensure_parsability(). 325 // The argument "retire_tlabs" controls whether existing TLABs 326 // are merely filled or also retired, thus preventing further 327 // allocation from them and necessitating allocation of new TLABs. 328 virtual void ensure_parsability(bool retire_tlabs); 329 330 // Section on thread-local allocation buffers (TLABs) 331 // If the heap supports thread-local allocation buffers, it should override 332 // the following methods: 333 // Returns "true" iff the heap supports thread-local allocation buffers. 334 // The default is "no". 335 virtual bool supports_tlab_allocation() const = 0; 336 337 // The amount of space available for thread-local allocation buffers. 338 virtual size_t tlab_capacity(Thread *thr) const = 0; 339 340 // The amount of used space for thread-local allocation buffers for the given thread. 341 virtual size_t tlab_used(Thread *thr) const = 0; 342 343 virtual size_t max_tlab_size() const; 344 345 // An estimate of the maximum allocation that could be performed 346 // for thread-local allocation buffers without triggering any 347 // collection or expansion activity. 348 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 349 guarantee(false, "thread-local allocation buffers not supported"); 350 return 0; 351 } 352 353 // Perform a collection of the heap; intended for use in implementing 354 // "System.gc". This probably implies as full a collection as the 355 // "CollectedHeap" supports. 356 virtual void collect(GCCause::Cause cause) = 0; 357 358 // Perform a full collection 359 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 360 361 // This interface assumes that it's being called by the 362 // vm thread. It collects the heap assuming that the 363 // heap lock is already held and that we are executing in 364 // the context of the vm thread. 365 virtual void collect_as_vm_thread(GCCause::Cause cause); 366 367 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 368 size_t size, 369 Metaspace::MetadataType mdtype); 370 371 // Returns "true" iff there is a stop-world GC in progress. (I assume 372 // that it should answer "false" for the concurrent part of a concurrent 373 // collector -- dld). 374 bool is_gc_active() const { return _is_gc_active; } 375 376 // Total number of GC collections (started) 377 unsigned int total_collections() const { return _total_collections; } 378 unsigned int total_full_collections() const { return _total_full_collections;} 379 380 // Increment total number of GC collections (started) 381 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 382 void increment_total_collections(bool full = false) { 383 _total_collections++; 384 if (full) { 385 increment_total_full_collections(); 386 } 387 } 388 389 void increment_total_full_collections() { _total_full_collections++; } 390 391 // Return the SoftRefPolicy for the heap; 392 virtual SoftRefPolicy* soft_ref_policy() = 0; 393 394 virtual MemoryUsage memory_usage(); 395 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 396 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 397 398 // Iterate over all objects, calling "cl.do_object" on each. 399 virtual void object_iterate(ObjectClosure* cl) = 0; 400 401 // Similar to object_iterate() except iterates only 402 // over live objects. 403 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 404 405 // NOTE! There is no requirement that a collector implement these 406 // functions. 407 // 408 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 409 // each address in the (reserved) heap is a member of exactly 410 // one block. The defining characteristic of a block is that it is 411 // possible to find its size, and thus to progress forward to the next 412 // block. (Blocks may be of different sizes.) Thus, blocks may 413 // represent Java objects, or they might be free blocks in a 414 // free-list-based heap (or subheap), as long as the two kinds are 415 // distinguishable and the size of each is determinable. 416 417 // Returns the address of the start of the "block" that contains the 418 // address "addr". We say "blocks" instead of "object" since some heaps 419 // may not pack objects densely; a chunk may either be an object or a 420 // non-object. 421 virtual HeapWord* block_start(const void* addr) const = 0; 422 423 // Requires "addr" to be the start of a block, and returns "TRUE" iff 424 // the block is an object. 425 virtual bool block_is_obj(const HeapWord* addr) const = 0; 426 427 // Returns the longest time (in ms) that has elapsed since the last 428 // time that any part of the heap was examined by a garbage collection. 429 virtual jlong millis_since_last_gc() = 0; 430 431 // Perform any cleanup actions necessary before allowing a verification. 432 virtual void prepare_for_verify() = 0; 433 434 // Generate any dumps preceding or following a full gc 435 private: 436 void full_gc_dump(GCTimer* timer, bool before); 437 438 virtual void initialize_serviceability() = 0; 439 440 public: 441 void pre_full_gc_dump(GCTimer* timer); 442 void post_full_gc_dump(GCTimer* timer); 443 444 virtual VirtualSpaceSummary create_heap_space_summary(); 445 GCHeapSummary create_heap_summary(); 446 447 MetaspaceSummary create_metaspace_summary(); 448 449 // Print heap information on the given outputStream. 450 virtual void print_on(outputStream* st) const = 0; 451 // The default behavior is to call print_on() on tty. 452 virtual void print() const; 453 454 // Print more detailed heap information on the given 455 // outputStream. The default behavior is to call print_on(). It is 456 // up to each subclass to override it and add any additional output 457 // it needs. 458 virtual void print_extended_on(outputStream* st) const { 459 print_on(st); 460 } 461 462 virtual void print_on_error(outputStream* st) const; 463 464 // Print all GC threads (other than the VM thread) 465 // used by this heap. 466 virtual void print_gc_threads_on(outputStream* st) const = 0; 467 // The default behavior is to call print_gc_threads_on() on tty. 468 void print_gc_threads() { 469 print_gc_threads_on(tty); 470 } 471 // Iterator for all GC threads (other than VM thread) 472 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 473 474 // Print any relevant tracing info that flags imply. 475 // Default implementation does nothing. 476 virtual void print_tracing_info() const = 0; 477 478 void print_heap_before_gc(); 479 void print_heap_after_gc(); 480 481 // Registering and unregistering an nmethod (compiled code) with the heap. 482 virtual void register_nmethod(nmethod* nm) = 0; 483 virtual void unregister_nmethod(nmethod* nm) = 0; 484 // Callback for when nmethod is about to be deleted. 485 virtual void flush_nmethod(nmethod* nm) = 0; 486 virtual void verify_nmethod(nmethod* nm) = 0; 487 488 void trace_heap_before_gc(const GCTracer* gc_tracer); 489 void trace_heap_after_gc(const GCTracer* gc_tracer); 490 491 // Heap verification 492 virtual void verify(VerifyOption option) = 0; 493 494 // Return true if concurrent phase control (via 495 // request_concurrent_phase_control) is supported by this collector. 496 // The default implementation returns false. 497 virtual bool supports_concurrent_phase_control() const; 498 499 // Request the collector enter the indicated concurrent phase, and 500 // wait until it does so. Supports WhiteBox testing. Only one 501 // request may be active at a time. Phases are designated by name; 502 // the set of names and their meaning is GC-specific. Once the 503 // requested phase has been reached, the collector will attempt to 504 // avoid transitioning to a new phase until a new request is made. 505 // [Note: A collector might not be able to remain in a given phase. 506 // For example, a full collection might cancel an in-progress 507 // concurrent collection.] 508 // 509 // Returns true when the phase is reached. Returns false for an 510 // unknown phase. The default implementation returns false. 511 virtual bool request_concurrent_phase(const char* phase); 512 513 // Provides a thread pool to SafepointSynchronize to use 514 // for parallel safepoint cleanup. 515 // GCs that use a GC worker thread pool may want to share 516 // it for use during safepoint cleanup. This is only possible 517 // if the GC can pause and resume concurrent work (e.g. G1 518 // concurrent marking) for an intermittent non-GC safepoint. 519 // If this method returns NULL, SafepointSynchronize will 520 // perform cleanup tasks serially in the VMThread. 521 virtual WorkGang* get_safepoint_workers() { return NULL; } 522 523 // Support for object pinning. This is used by JNI Get*Critical() 524 // and Release*Critical() family of functions. If supported, the GC 525 // must guarantee that pinned objects never move. 526 virtual bool supports_object_pinning() const; 527 virtual oop pin_object(JavaThread* thread, oop obj); 528 virtual void unpin_object(JavaThread* thread, oop obj); 529 530 // Deduplicate the string, iff the GC supports string deduplication. 531 virtual void deduplicate_string(oop str); 532 533 virtual bool is_oop(oop object) const; 534 535 virtual size_t obj_size(oop obj) const; 536 537 // Non product verification and debugging. 538 #ifndef PRODUCT 539 // Support for PromotionFailureALot. Return true if it's time to cause a 540 // promotion failure. The no-argument version uses 541 // this->_promotion_failure_alot_count as the counter. 542 bool promotion_should_fail(volatile size_t* count); 543 bool promotion_should_fail(); 544 545 // Reset the PromotionFailureALot counters. Should be called at the end of a 546 // GC in which promotion failure occurred. 547 void reset_promotion_should_fail(volatile size_t* count); 548 void reset_promotion_should_fail(); 549 #endif // #ifndef PRODUCT 550 }; 551 552 // Class to set and reset the GC cause for a CollectedHeap. 553 554 class GCCauseSetter : StackObj { 555 CollectedHeap* _heap; 556 GCCause::Cause _previous_cause; 557 public: 558 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 559 _heap = heap; 560 _previous_cause = _heap->gc_cause(); 561 _heap->set_gc_cause(cause); 562 } 563 564 ~GCCauseSetter() { 565 _heap->set_gc_cause(_previous_cause); 566 } 567 }; 568 569 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP