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 ReservedHeapSpace; 55 class SoftRefPolicy; 56 class Thread; 57 class ThreadClosure; 58 class VirtualSpaceSummary; 59 class WorkGang; 60 class nmethod; 61 62 class GCMessage : public FormatBuffer<1024> { 63 public: 64 bool is_before; 65 66 public: 67 GCMessage() {} 68 }; 69 70 class CollectedHeap; 71 72 class GCHeapLog : public EventLogBase<GCMessage> { 73 private: 74 void log_heap(CollectedHeap* heap, bool before); 75 76 public: 77 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {} 78 79 void log_heap_before(CollectedHeap* heap) { 80 log_heap(heap, true); 81 } 82 void log_heap_after(CollectedHeap* heap) { 83 log_heap(heap, false); 84 } 85 }; 86 87 // 88 // CollectedHeap 89 // GenCollectedHeap 90 // SerialHeap 91 // CMSHeap 92 // G1CollectedHeap 93 // ParallelScavengeHeap 94 // ShenandoahHeap 95 // ZCollectedHeap 96 // 97 class CollectedHeap : public CHeapObj<mtInternal> { 98 friend class VMStructs; 99 friend class JVMCIVMStructs; 100 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 101 friend class MemAllocator; 102 103 private: 104 GCHeapLog* _gc_heap_log; 105 106 protected: 107 // Not used by all GCs 108 MemRegion _reserved; 109 110 bool _is_gc_active; 111 112 // Used for filler objects (static, but initialized in ctor). 113 static size_t _filler_array_max_size; 114 115 unsigned int _total_collections; // ... started 116 unsigned int _total_full_collections; // ... started 117 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 118 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 119 120 // Reason for current garbage collection. Should be set to 121 // a value reflecting no collection between collections. 122 GCCause::Cause _gc_cause; 123 GCCause::Cause _gc_lastcause; 124 PerfStringVariable* _perf_gc_cause; 125 PerfStringVariable* _perf_gc_lastcause; 126 127 // Constructor 128 CollectedHeap(); 129 130 // Create a new tlab. All TLAB allocations must go through this. 131 // To allow more flexible TLAB allocations min_size specifies 132 // the minimum size needed, while requested_size is the requested 133 // size based on ergonomics. The actually allocated size will be 134 // returned in actual_size. 135 virtual HeapWord* allocate_new_tlab(size_t min_size, 136 size_t requested_size, 137 size_t* actual_size); 138 139 // Reinitialize tlabs before resuming mutators. 140 virtual void resize_all_tlabs(); 141 142 // Raw memory allocation facilities 143 // The obj and array allocate methods are covers for these methods. 144 // mem_allocate() should never be 145 // called to allocate TLABs, only individual objects. 146 virtual HeapWord* mem_allocate(size_t size, 147 bool* gc_overhead_limit_was_exceeded) = 0; 148 149 // Filler object utilities. 150 static inline size_t filler_array_hdr_size(); 151 static inline size_t filler_array_min_size(); 152 153 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 154 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 155 156 // Fill with a single array; caller must ensure filler_array_min_size() <= 157 // words <= filler_array_max_size(). 158 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 159 160 // Fill with a single object (either an int array or a java.lang.Object). 161 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 162 163 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 164 165 // Verification functions 166 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 167 PRODUCT_RETURN; 168 debug_only(static void check_for_valid_allocation_state();) 169 170 public: 171 enum Name { 172 None, 173 Serial, 174 Parallel, 175 CMS, 176 G1, 177 Epsilon, 178 Z, 179 Shenandoah 180 }; 181 182 static inline size_t filler_array_max_size() { 183 return _filler_array_max_size; 184 } 185 186 virtual Name kind() const = 0; 187 188 virtual const char* name() const = 0; 189 190 /** 191 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 192 * and JNI_OK on success. 193 */ 194 virtual jint initialize() = 0; 195 196 // In many heaps, there will be a need to perform some initialization activities 197 // after the Universe is fully formed, but before general heap allocation is allowed. 198 // This is the correct place to place such initialization methods. 199 virtual void post_initialize(); 200 201 // Stop any onging concurrent work and prepare for exit. 202 virtual void stop() {} 203 204 // Stop and resume concurrent GC threads interfering with safepoint operations 205 virtual void safepoint_synchronize_begin() {} 206 virtual void safepoint_synchronize_end() {} 207 208 void initialize_reserved_region(const ReservedHeapSpace& rs); 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" iff "p" points into the committed areas of the heap. 230 // This method can be expensive so avoid using it in performance critical 231 // code. 232 virtual bool is_in(const void* p) const = 0; 233 234 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 235 236 // This function verifies that "addr" is a valid oop location, w.r.t. heap 237 // datastructures such as bitmaps and virtual memory address. It does *not* 238 // check if the location is within committed heap memory. 239 virtual void check_oop_location(void* addr) const; 240 241 virtual uint32_t hash_oop(oop obj) const; 242 243 void set_gc_cause(GCCause::Cause v) { 244 if (UsePerfData) { 245 _gc_lastcause = _gc_cause; 246 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 247 _perf_gc_cause->set_value(GCCause::to_string(v)); 248 } 249 _gc_cause = v; 250 } 251 GCCause::Cause gc_cause() { return _gc_cause; } 252 253 oop obj_allocate(Klass* klass, int size, TRAPS); 254 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS); 255 oop class_allocate(Klass* klass, int size, TRAPS); 256 257 // Utilities for turning raw memory into filler objects. 258 // 259 // min_fill_size() is the smallest region that can be filled. 260 // fill_with_objects() can fill arbitrary-sized regions of the heap using 261 // multiple objects. fill_with_object() is for regions known to be smaller 262 // than the largest array of integers; it uses a single object to fill the 263 // region and has slightly less overhead. 264 static size_t min_fill_size() { 265 return size_t(align_object_size(oopDesc::header_size())); 266 } 267 268 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 269 270 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 271 static void fill_with_object(MemRegion region, bool zap = true) { 272 fill_with_object(region.start(), region.word_size(), zap); 273 } 274 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 275 fill_with_object(start, pointer_delta(end, start), zap); 276 } 277 278 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap); 279 virtual size_t min_dummy_object_size() const; 280 size_t tlab_alloc_reserve() const; 281 282 // Return the address "addr" aligned by "alignment_in_bytes" if such 283 // an address is below "end". Return NULL otherwise. 284 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 285 HeapWord* end, 286 unsigned short alignment_in_bytes); 287 288 // Some heaps may offer a contiguous region for shared non-blocking 289 // allocation, via inlined code (by exporting the address of the top and 290 // end fields defining the extent of the contiguous allocation region.) 291 292 // This function returns "true" iff the heap supports this kind of 293 // allocation. (Default is "no".) 294 virtual bool supports_inline_contig_alloc() const { 295 return false; 296 } 297 // These functions return the addresses of the fields that define the 298 // boundaries of the contiguous allocation area. (These fields should be 299 // physically near to one another.) 300 virtual HeapWord* volatile* top_addr() const { 301 guarantee(false, "inline contiguous allocation not supported"); 302 return NULL; 303 } 304 virtual HeapWord** end_addr() const { 305 guarantee(false, "inline contiguous allocation not supported"); 306 return NULL; 307 } 308 309 // Some heaps may be in an unparseable state at certain times between 310 // collections. This may be necessary for efficient implementation of 311 // certain allocation-related activities. Calling this function before 312 // attempting to parse a heap ensures that the heap is in a parsable 313 // state (provided other concurrent activity does not introduce 314 // unparsability). It is normally expected, therefore, that this 315 // method is invoked with the world stopped. 316 // NOTE: if you override this method, make sure you call 317 // super::ensure_parsability so that the non-generational 318 // part of the work gets done. See implementation of 319 // CollectedHeap::ensure_parsability and, for instance, 320 // that of GenCollectedHeap::ensure_parsability(). 321 // The argument "retire_tlabs" controls whether existing TLABs 322 // are merely filled or also retired, thus preventing further 323 // allocation from them and necessitating allocation of new TLABs. 324 virtual void ensure_parsability(bool retire_tlabs); 325 326 // Section on thread-local allocation buffers (TLABs) 327 // If the heap supports thread-local allocation buffers, it should override 328 // the following methods: 329 // Returns "true" iff the heap supports thread-local allocation buffers. 330 // The default is "no". 331 virtual bool supports_tlab_allocation() const = 0; 332 333 // The amount of space available for thread-local allocation buffers. 334 virtual size_t tlab_capacity(Thread *thr) const = 0; 335 336 // The amount of used space for thread-local allocation buffers for the given thread. 337 virtual size_t tlab_used(Thread *thr) const = 0; 338 339 virtual size_t max_tlab_size() const; 340 341 // An estimate of the maximum allocation that could be performed 342 // for thread-local allocation buffers without triggering any 343 // collection or expansion activity. 344 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 345 guarantee(false, "thread-local allocation buffers not supported"); 346 return 0; 347 } 348 349 // Perform a collection of the heap; intended for use in implementing 350 // "System.gc". This probably implies as full a collection as the 351 // "CollectedHeap" supports. 352 virtual void collect(GCCause::Cause cause) = 0; 353 354 // Perform a full collection 355 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 356 357 // This interface assumes that it's being called by the 358 // vm thread. It collects the heap assuming that the 359 // heap lock is already held and that we are executing in 360 // the context of the vm thread. 361 virtual void collect_as_vm_thread(GCCause::Cause cause); 362 363 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 364 size_t size, 365 Metaspace::MetadataType mdtype); 366 367 // Returns "true" iff there is a stop-world GC in progress. (I assume 368 // that it should answer "false" for the concurrent part of a concurrent 369 // collector -- dld). 370 bool is_gc_active() const { return _is_gc_active; } 371 372 // Total number of GC collections (started) 373 unsigned int total_collections() const { return _total_collections; } 374 unsigned int total_full_collections() const { return _total_full_collections;} 375 376 // Increment total number of GC collections (started) 377 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 378 void increment_total_collections(bool full = false) { 379 _total_collections++; 380 if (full) { 381 increment_total_full_collections(); 382 } 383 } 384 385 void increment_total_full_collections() { _total_full_collections++; } 386 387 // Return the SoftRefPolicy for the heap; 388 virtual SoftRefPolicy* soft_ref_policy() = 0; 389 390 virtual MemoryUsage memory_usage(); 391 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0; 392 virtual GrowableArray<MemoryPool*> memory_pools() = 0; 393 394 // Iterate over all objects, calling "cl.do_object" on each. 395 virtual void object_iterate(ObjectClosure* cl) = 0; 396 397 // Similar to object_iterate() except iterates only 398 // over live objects. 399 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 400 401 // Returns the longest time (in ms) that has elapsed since the last 402 // time that any part of the heap was examined by a garbage collection. 403 virtual jlong millis_since_last_gc() = 0; 404 405 // Perform any cleanup actions necessary before allowing a verification. 406 virtual void prepare_for_verify() = 0; 407 408 // Generate any dumps preceding or following a full gc 409 private: 410 void full_gc_dump(GCTimer* timer, bool before); 411 412 virtual void initialize_serviceability() = 0; 413 414 public: 415 void pre_full_gc_dump(GCTimer* timer); 416 void post_full_gc_dump(GCTimer* timer); 417 418 virtual VirtualSpaceSummary create_heap_space_summary(); 419 GCHeapSummary create_heap_summary(); 420 421 MetaspaceSummary create_metaspace_summary(); 422 423 // Print heap information on the given outputStream. 424 virtual void print_on(outputStream* st) const = 0; 425 // The default behavior is to call print_on() on tty. 426 virtual void print() const; 427 428 // Print more detailed heap information on the given 429 // outputStream. The default behavior is to call print_on(). It is 430 // up to each subclass to override it and add any additional output 431 // it needs. 432 virtual void print_extended_on(outputStream* st) const { 433 print_on(st); 434 } 435 436 virtual void print_on_error(outputStream* st) const; 437 438 // Used to print information about locations in the hs_err file. 439 virtual bool print_location(outputStream* st, void* addr) const = 0; 440 441 // Print all GC threads (other than the VM thread) 442 // used by this heap. 443 virtual void print_gc_threads_on(outputStream* st) const = 0; 444 // The default behavior is to call print_gc_threads_on() on tty. 445 void print_gc_threads() { 446 print_gc_threads_on(tty); 447 } 448 // Iterator for all GC threads (other than VM thread) 449 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 450 451 // Print any relevant tracing info that flags imply. 452 // Default implementation does nothing. 453 virtual void print_tracing_info() const = 0; 454 455 void print_heap_before_gc(); 456 void print_heap_after_gc(); 457 458 // Registering and unregistering an nmethod (compiled code) with the heap. 459 virtual void register_nmethod(nmethod* nm) = 0; 460 virtual void unregister_nmethod(nmethod* nm) = 0; 461 // Callback for when nmethod is about to be deleted. 462 virtual void flush_nmethod(nmethod* nm) = 0; 463 virtual void verify_nmethod(nmethod* nm) = 0; 464 465 void trace_heap_before_gc(const GCTracer* gc_tracer); 466 void trace_heap_after_gc(const GCTracer* gc_tracer); 467 468 // Heap verification 469 virtual void verify(VerifyOption option) = 0; 470 471 // Return true if concurrent phase control (via 472 // request_concurrent_phase_control) is supported by this collector. 473 // The default implementation returns false. 474 virtual bool supports_concurrent_phase_control() const; 475 476 // Request the collector enter the indicated concurrent phase, and 477 // wait until it does so. Supports WhiteBox testing. Only one 478 // request may be active at a time. Phases are designated by name; 479 // the set of names and their meaning is GC-specific. Once the 480 // requested phase has been reached, the collector will attempt to 481 // avoid transitioning to a new phase until a new request is made. 482 // [Note: A collector might not be able to remain in a given phase. 483 // For example, a full collection might cancel an in-progress 484 // concurrent collection.] 485 // 486 // Returns true when the phase is reached. Returns false for an 487 // unknown phase. The default implementation returns false. 488 virtual bool request_concurrent_phase(const char* phase); 489 490 // Provides a thread pool to SafepointSynchronize to use 491 // for parallel safepoint cleanup. 492 // GCs that use a GC worker thread pool may want to share 493 // it for use during safepoint cleanup. This is only possible 494 // if the GC can pause and resume concurrent work (e.g. G1 495 // concurrent marking) for an intermittent non-GC safepoint. 496 // If this method returns NULL, SafepointSynchronize will 497 // perform cleanup tasks serially in the VMThread. 498 virtual WorkGang* get_safepoint_workers() { return NULL; } 499 500 // Support for object pinning. This is used by JNI Get*Critical() 501 // and Release*Critical() family of functions. If supported, the GC 502 // must guarantee that pinned objects never move. 503 virtual bool supports_object_pinning() const; 504 virtual oop pin_object(JavaThread* thread, oop obj); 505 virtual void unpin_object(JavaThread* thread, oop obj); 506 507 // Deduplicate the string, iff the GC supports string deduplication. 508 virtual void deduplicate_string(oop str); 509 510 virtual bool is_oop(oop object) const; 511 512 virtual size_t obj_size(oop obj) const; 513 514 // Non product verification and debugging. 515 #ifndef PRODUCT 516 // Support for PromotionFailureALot. Return true if it's time to cause a 517 // promotion failure. The no-argument version uses 518 // this->_promotion_failure_alot_count as the counter. 519 bool promotion_should_fail(volatile size_t* count); 520 bool promotion_should_fail(); 521 522 // Reset the PromotionFailureALot counters. Should be called at the end of a 523 // GC in which promotion failure occurred. 524 void reset_promotion_should_fail(volatile size_t* count); 525 void reset_promotion_should_fail(); 526 #endif // #ifndef PRODUCT 527 }; 528 529 // Class to set and reset the GC cause for a CollectedHeap. 530 531 class GCCauseSetter : StackObj { 532 CollectedHeap* _heap; 533 GCCause::Cause _previous_cause; 534 public: 535 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 536 _heap = heap; 537 _previous_cause = _heap->gc_cause(); 538 _heap->set_gc_cause(cause); 539 } 540 541 ~GCCauseSetter() { 542 _heap->set_gc_cause(_previous_cause); 543 } 544 }; 545 546 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP