1 /* 2 * Copyright (c) 2001, 2022, 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 "memory/metaspace.hpp" 33 #include "memory/universe.hpp" 34 #include "runtime/handles.hpp" 35 #include "runtime/perfDataTypes.hpp" 36 #include "runtime/safepoint.hpp" 37 #include "services/memoryUsage.hpp" 38 #include "utilities/debug.hpp" 39 #include "utilities/formatBuffer.hpp" 40 #include "utilities/growableArray.hpp" 41 42 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 43 // is an abstract class: there may be many different kinds of heaps. This 44 // class defines the functions that a heap must implement, and contains 45 // infrastructure common to all heaps. 46 47 class AbstractGangTask; 48 class AdaptiveSizePolicy; 49 class BarrierSet; 50 class GCHeapLog; 51 class GCHeapSummary; 52 class GCTimer; 53 class GCTracer; 54 class GCMemoryManager; 55 class MemoryPool; 56 class MetaspaceSummary; 57 class ReservedHeapSpace; 58 class SoftRefPolicy; 59 class Thread; 60 class ThreadClosure; 61 class VirtualSpaceSummary; 62 class WorkGang; 63 class nmethod; 64 65 class ParallelObjectIterator : public CHeapObj<mtGC> { 66 public: 67 virtual void object_iterate(ObjectClosure* cl, uint worker_id) = 0; 68 virtual ~ParallelObjectIterator() {} 69 }; 70 71 // 72 // CollectedHeap 73 // GenCollectedHeap 74 // SerialHeap 75 // G1CollectedHeap 76 // ParallelScavengeHeap 77 // ShenandoahHeap 78 // ZCollectedHeap 79 // 80 class CollectedHeap : public CHeapObj<mtGC> { 81 friend class VMStructs; 82 friend class JVMCIVMStructs; 83 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 84 friend class MemAllocator; 85 86 private: 87 GCHeapLog* _gc_heap_log; 88 89 // Historic gc information 90 size_t _capacity_at_last_gc; 91 size_t _used_at_last_gc; 92 93 protected: 94 // Not used by all GCs 95 MemRegion _reserved; 96 97 bool _is_gc_active; 98 99 // Used for filler objects (static, but initialized in ctor). 100 static size_t _filler_array_max_size; 101 102 // Last time the whole heap has been examined in support of RMI 103 // MaxObjectInspectionAge. 104 // This timestamp must be monotonically non-decreasing to avoid 105 // time-warp warnings. 106 jlong _last_whole_heap_examined_time_ns; 107 108 unsigned int _total_collections; // ... started 109 unsigned int _total_full_collections; // ... started 110 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 111 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 112 113 // Reason for current garbage collection. Should be set to 114 // a value reflecting no collection between collections. 115 GCCause::Cause _gc_cause; 116 GCCause::Cause _gc_lastcause; 117 PerfStringVariable* _perf_gc_cause; 118 PerfStringVariable* _perf_gc_lastcause; 119 120 // Constructor 121 CollectedHeap(); 122 123 // Create a new tlab. All TLAB allocations must go through this. 124 // To allow more flexible TLAB allocations min_size specifies 125 // the minimum size needed, while requested_size is the requested 126 // size based on ergonomics. The actually allocated size will be 127 // returned in actual_size. 128 virtual HeapWord* allocate_new_tlab(size_t min_size, 129 size_t requested_size, 130 size_t* actual_size); 131 132 // Reinitialize tlabs before resuming mutators. 133 virtual void resize_all_tlabs(); 134 135 // Raw memory allocation facilities 136 // The obj and array allocate methods are covers for these methods. 137 // mem_allocate() should never be 138 // called to allocate TLABs, only individual objects. 139 virtual HeapWord* mem_allocate(size_t size, 140 bool* gc_overhead_limit_was_exceeded) = 0; 141 142 // Filler object utilities. 143 static inline size_t filler_array_hdr_size(); 144 static inline size_t filler_array_min_size(); 145 146 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 147 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 148 149 // Fill with a single array; caller must ensure filler_array_min_size() <= 150 // words <= filler_array_max_size(). 151 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 152 153 // Fill with a single object (either an int array or a java.lang.Object). 154 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 155 156 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 157 158 // Verification functions 159 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 160 PRODUCT_RETURN; 161 debug_only(static void check_for_valid_allocation_state();) 162 163 public: 164 enum Name { 165 None, 166 Serial, 167 Parallel, 168 G1, 169 Epsilon, 170 Z, 171 Shenandoah 172 }; 173 174 protected: 175 // Get a pointer to the derived heap object. Used to implement 176 // derived class heap() functions rather than being called directly. 177 template<typename T> 178 static T* named_heap(Name kind) { 179 CollectedHeap* heap = Universe::heap(); 180 assert(heap != NULL, "Uninitialized heap"); 181 assert(kind == heap->kind(), "Heap kind %u should be %u", 182 static_cast<uint>(heap->kind()), static_cast<uint>(kind)); 183 return static_cast<T*>(heap); 184 } 185 186 public: 187 188 static inline size_t filler_array_max_size() { 189 return _filler_array_max_size; 190 } 191 192 virtual Name kind() const = 0; 193 194 virtual const char* name() const = 0; 195 196 /** 197 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 198 * and JNI_OK on success. 199 */ 200 virtual jint initialize() = 0; 201 202 // In many heaps, there will be a need to perform some initialization activities 203 // after the Universe is fully formed, but before general heap allocation is allowed. 204 // This is the correct place to place such initialization methods. 205 virtual void post_initialize(); 206 207 // Stop any onging concurrent work and prepare for exit. 208 virtual void stop() {} 209 210 // Stop and resume concurrent GC threads interfering with safepoint operations 211 virtual void safepoint_synchronize_begin() {} 212 virtual void safepoint_synchronize_end() {} 213 214 void initialize_reserved_region(const ReservedHeapSpace& rs); 215 216 virtual size_t capacity() const = 0; 217 virtual size_t used() const = 0; 218 219 // Returns unused capacity. 220 virtual size_t unused() const; 221 222 // Historic gc information 223 size_t free_at_last_gc() const { return _capacity_at_last_gc - _used_at_last_gc; } 224 size_t used_at_last_gc() const { return _used_at_last_gc; } 225 void update_capacity_and_used_at_gc(); 226 227 // Return "true" if the part of the heap that allocates Java 228 // objects has reached the maximal committed limit that it can 229 // reach, without a garbage collection. 230 virtual bool is_maximal_no_gc() const = 0; 231 232 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 233 // memory that the vm could make available for storing 'normal' java objects. 234 // This is based on the reserved address space, but should not include space 235 // that the vm uses internally for bookkeeping or temporary storage 236 // (e.g., in the case of the young gen, one of the survivor 237 // spaces). 238 virtual size_t max_capacity() const = 0; 239 240 // Returns "TRUE" iff "p" points into the committed areas of the heap. 241 // This method can be expensive so avoid using it in performance critical 242 // code. 243 virtual bool is_in(const void* p) const = 0; 244 245 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 246 247 virtual uint32_t hash_oop(oop obj) const; 248 249 void set_gc_cause(GCCause::Cause v); 250 GCCause::Cause gc_cause() { return _gc_cause; } 251 252 oop obj_allocate(Klass* klass, int size, TRAPS); 253 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS); 254 oop class_allocate(Klass* klass, int size, TRAPS); 255 256 // Utilities for turning raw memory into filler objects. 257 // 258 // min_fill_size() is the smallest region that can be filled. 259 // fill_with_objects() can fill arbitrary-sized regions of the heap using 260 // multiple objects. fill_with_object() is for regions known to be smaller 261 // than the largest array of integers; it uses a single object to fill the 262 // region and has slightly less overhead. 263 static size_t min_fill_size() { 264 return size_t(align_object_size(oopDesc::header_size())); 265 } 266 267 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 268 269 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 270 static void fill_with_object(MemRegion region, bool zap = true) { 271 fill_with_object(region.start(), region.word_size(), zap); 272 } 273 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 274 fill_with_object(start, pointer_delta(end, start), zap); 275 } 276 277 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap); 278 virtual size_t min_dummy_object_size() const; 279 size_t tlab_alloc_reserve() const; 280 281 // Some heaps may offer a contiguous region for shared non-blocking 282 // allocation, via inlined code (by exporting the address of the top and 283 // end fields defining the extent of the contiguous allocation region.) 284 285 // This function returns "true" iff the heap supports this kind of 286 // allocation. (Default is "no".) 287 virtual bool supports_inline_contig_alloc() const { 288 return false; 289 } 290 // These functions return the addresses of the fields that define the 291 // boundaries of the contiguous allocation area. (These fields should be 292 // physically near to one another.) 293 virtual HeapWord* volatile* top_addr() const { 294 guarantee(false, "inline contiguous allocation not supported"); 295 return NULL; 296 } 297 virtual HeapWord** end_addr() const { 298 guarantee(false, "inline contiguous allocation not supported"); 299 return NULL; 300 } 301 302 // Some heaps may be in an unparseable state at certain times between 303 // collections. This may be necessary for efficient implementation of 304 // certain allocation-related activities. Calling this function before 305 // attempting to parse a heap ensures that the heap is in a parsable 306 // state (provided other concurrent activity does not introduce 307 // unparsability). It is normally expected, therefore, that this 308 // method is invoked with the world stopped. 309 // NOTE: if you override this method, make sure you call 310 // super::ensure_parsability so that the non-generational 311 // part of the work gets done. See implementation of 312 // CollectedHeap::ensure_parsability and, for instance, 313 // that of GenCollectedHeap::ensure_parsability(). 314 // The argument "retire_tlabs" controls whether existing TLABs 315 // are merely filled or also retired, thus preventing further 316 // allocation from them and necessitating allocation of new TLABs. 317 virtual void ensure_parsability(bool retire_tlabs); 318 319 // The amount of space available for thread-local allocation buffers. 320 virtual size_t tlab_capacity(Thread *thr) const = 0; 321 322 // The amount of used space for thread-local allocation buffers for the given thread. 323 virtual size_t tlab_used(Thread *thr) const = 0; 324 325 virtual size_t max_tlab_size() const; 326 327 // An estimate of the maximum allocation that could be performed 328 // for thread-local allocation buffers without triggering any 329 // collection or expansion activity. 330 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 331 guarantee(false, "thread-local allocation buffers not supported"); 332 return 0; 333 } 334 335 // If a GC uses a stack watermark barrier, the stack processing is lazy, concurrent, 336 // incremental and cooperative. In order for that to work well, mechanisms that stop 337 // another thread might want to ensure its roots are in a sane state. 338 virtual bool uses_stack_watermark_barrier() const { return false; } 339 340 // Perform a collection of the heap; intended for use in implementing 341 // "System.gc". This probably implies as full a collection as the 342 // "CollectedHeap" supports. 343 virtual void collect(GCCause::Cause cause) = 0; 344 345 // Perform a full collection 346 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 347 348 // This interface assumes that it's being called by the 349 // vm thread. It collects the heap assuming that the 350 // heap lock is already held and that we are executing in 351 // the context of the vm thread. 352 virtual void collect_as_vm_thread(GCCause::Cause cause); 353 354 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 355 size_t size, 356 Metaspace::MetadataType mdtype); 357 358 // Returns "true" iff there is a stop-world GC in progress. (I assume 359 // that it should answer "false" for the concurrent part of a concurrent 360 // collector -- dld). 361 bool is_gc_active() const { return _is_gc_active; } 362 363 // Total number of GC collections (started) 364 unsigned int total_collections() const { return _total_collections; } 365 unsigned int total_full_collections() const { return _total_full_collections;} 366 367 // Increment total number of GC collections (started) 368 void increment_total_collections(bool full = false) { 369 _total_collections++; 370 if (full) { 371 increment_total_full_collections(); 372 } 373 } 374 375 void increment_total_full_collections() { _total_full_collections++; } 376 377 // Return the SoftRefPolicy for the heap; 378 virtual SoftRefPolicy* soft_ref_policy() = 0; 379 380 virtual MemoryUsage memory_usage(); 381 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 382 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 383 384 // Iterate over all objects, calling "cl.do_object" on each. 385 virtual void object_iterate(ObjectClosure* cl) = 0; 386 387 virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num) { 388 return NULL; 389 } 390 391 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 392 virtual void keep_alive(oop obj) {} 393 394 // Perform any cleanup actions necessary before allowing a verification. 395 virtual void prepare_for_verify() = 0; 396 397 // Returns the longest time (in ms) that has elapsed since the last 398 // time that the whole heap has been examined by a garbage collection. 399 jlong millis_since_last_whole_heap_examined(); 400 // GC should call this when the next whole heap analysis has completed to 401 // satisfy above requirement. 402 void record_whole_heap_examined_timestamp(); 403 404 private: 405 // Generate any dumps preceding or following a full gc 406 void full_gc_dump(GCTimer* timer, bool before); 407 408 virtual void initialize_serviceability() = 0; 409 410 public: 411 void pre_full_gc_dump(GCTimer* timer); 412 void post_full_gc_dump(GCTimer* timer); 413 414 virtual VirtualSpaceSummary create_heap_space_summary(); 415 GCHeapSummary create_heap_summary(); 416 417 MetaspaceSummary create_metaspace_summary(); 418 419 // Print heap information on the given outputStream. 420 virtual void print_on(outputStream* st) const = 0; 421 // The default behavior is to call print_on() on tty. 422 virtual void print() const; 423 424 // Print more detailed heap information on the given 425 // outputStream. The default behavior is to call print_on(). It is 426 // up to each subclass to override it and add any additional output 427 // it needs. 428 virtual void print_extended_on(outputStream* st) const { 429 print_on(st); 430 } 431 432 virtual void print_on_error(outputStream* st) const; 433 434 // Used to print information about locations in the hs_err file. 435 virtual bool print_location(outputStream* st, void* addr) const = 0; 436 437 // Iterator for all GC threads (other than VM thread) 438 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 439 440 // Print any relevant tracing info that flags imply. 441 // Default implementation does nothing. 442 virtual void print_tracing_info() const = 0; 443 444 void print_heap_before_gc(); 445 void print_heap_after_gc(); 446 447 // Registering and unregistering an nmethod (compiled code) with the heap. 448 virtual void register_nmethod(nmethod* nm) = 0; 449 virtual void unregister_nmethod(nmethod* nm) = 0; 450 // Callback for when nmethod is about to be deleted. 451 virtual void flush_nmethod(nmethod* nm) = 0; 452 virtual void verify_nmethod(nmethod* nm) = 0; 453 454 void trace_heap_before_gc(const GCTracer* gc_tracer); 455 void trace_heap_after_gc(const GCTracer* gc_tracer); 456 457 // Heap verification 458 virtual void verify(VerifyOption option) = 0; 459 460 // Return true if concurrent gc control via WhiteBox is supported by 461 // this collector. The default implementation returns false. 462 virtual bool supports_concurrent_gc_breakpoints() const; 463 464 // Provides a thread pool to SafepointSynchronize to use 465 // for parallel safepoint cleanup. 466 // GCs that use a GC worker thread pool may want to share 467 // it for use during safepoint cleanup. This is only possible 468 // if the GC can pause and resume concurrent work (e.g. G1 469 // concurrent marking) for an intermittent non-GC safepoint. 470 // If this method returns NULL, SafepointSynchronize will 471 // perform cleanup tasks serially in the VMThread. 472 virtual WorkGang* safepoint_workers() { return NULL; } 473 474 // Support for object pinning. This is used by JNI Get*Critical() 475 // and Release*Critical() family of functions. If supported, the GC 476 // must guarantee that pinned objects never move. 477 virtual bool supports_object_pinning() const; 478 virtual oop pin_object(JavaThread* thread, oop obj); 479 virtual void unpin_object(JavaThread* thread, oop obj); 480 481 // Is the given object inside a CDS archive area? 482 virtual bool is_archived_object(oop object) const; 483 484 virtual bool is_oop(oop object) const; 485 // Non product verification and debugging. 486 #ifndef PRODUCT 487 // Support for PromotionFailureALot. Return true if it's time to cause a 488 // promotion failure. The no-argument version uses 489 // this->_promotion_failure_alot_count as the counter. 490 bool promotion_should_fail(volatile size_t* count); 491 bool promotion_should_fail(); 492 493 // Reset the PromotionFailureALot counters. Should be called at the end of a 494 // GC in which promotion failure occurred. 495 void reset_promotion_should_fail(volatile size_t* count); 496 void reset_promotion_should_fail(); 497 #endif // #ifndef PRODUCT 498 }; 499 500 // Class to set and reset the GC cause for a CollectedHeap. 501 502 class GCCauseSetter : StackObj { 503 CollectedHeap* _heap; 504 GCCause::Cause _previous_cause; 505 public: 506 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 507 _heap = heap; 508 _previous_cause = _heap->gc_cause(); 509 _heap->set_gc_cause(cause); 510 } 511 512 ~GCCauseSetter() { 513 _heap->set_gc_cause(_previous_cause); 514 } 515 }; 516 517 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP