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
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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,
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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 WorkerTask;
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 WorkerThreads;
63 class nmethod;
64
65 class ParallelObjectIteratorImpl : public CHeapObj<mtGC> {
66 public:
67 virtual ~ParallelObjectIteratorImpl() {}
68 virtual void object_iterate(ObjectClosure* cl, uint worker_id) = 0;
69 };
70
71 // User facing parallel object iterator. This is a StackObj, which ensures that
72 // the _impl is allocated and deleted in the scope of this object. This ensures
73 // the life cycle of the implementation is as required by ThreadsListHandle,
74 // which is sometimes used by the root iterators.
75 class ParallelObjectIterator : public StackObj {
76 ParallelObjectIteratorImpl* _impl;
77
78 public:
79 ParallelObjectIterator(uint thread_num);
80 ~ParallelObjectIterator();
81 void object_iterate(ObjectClosure* cl, uint worker_id);
82 };
83
84 //
85 // CollectedHeap
86 // GenCollectedHeap
87 // SerialHeap
88 // G1CollectedHeap
89 // ParallelScavengeHeap
90 // ShenandoahHeap
91 // ZCollectedHeap
92 //
93 class CollectedHeap : public CHeapObj<mtGC> {
94 friend class VMStructs;
95 friend class JVMCIVMStructs;
96 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
97 friend class MemAllocator;
98 friend class ParallelObjectIterator;
99
100 private:
101 GCHeapLog* _gc_heap_log;
102
103 // Historic gc information
104 size_t _capacity_at_last_gc;
105 size_t _used_at_last_gc;
106
107 protected:
108 // Not used by all GCs
109 MemRegion _reserved;
110
111 bool _is_gc_active;
112
113 // Used for filler objects (static, but initialized in ctor).
114 static size_t _filler_array_max_size;
115
116 // Last time the whole heap has been examined in support of RMI
117 // MaxObjectInspectionAge.
118 // This timestamp must be monotonically non-decreasing to avoid
119 // time-warp warnings.
120 jlong _last_whole_heap_examined_time_ns;
121
122 unsigned int _total_collections; // ... started
123 unsigned int _total_full_collections; // ... started
124 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
125 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
126
127 // Reason for current garbage collection. Should be set to
128 // a value reflecting no collection between collections.
129 GCCause::Cause _gc_cause;
130 GCCause::Cause _gc_lastcause;
131 PerfStringVariable* _perf_gc_cause;
132 PerfStringVariable* _perf_gc_lastcause;
133
134 // Constructor
135 CollectedHeap();
136
137 // Create a new tlab. All TLAB allocations must go through this.
138 // To allow more flexible TLAB allocations min_size specifies
139 // the minimum size needed, while requested_size is the requested
140 // size based on ergonomics. The actually allocated size will be
141 // returned in actual_size.
142 virtual HeapWord* allocate_new_tlab(size_t min_size,
143 size_t requested_size,
144 size_t* actual_size);
145
146 // Reinitialize tlabs before resuming mutators.
147 virtual void resize_all_tlabs();
148
149 // Raw memory allocation facilities
150 // The obj and array allocate methods are covers for these methods.
151 // mem_allocate() should never be
152 // called to allocate TLABs, only individual objects.
153 virtual HeapWord* mem_allocate(size_t size,
154 bool* gc_overhead_limit_was_exceeded) = 0;
155
156 // Filler object utilities.
157 static inline size_t filler_array_hdr_size();
158 static inline size_t filler_array_min_size();
159
160 static inline void zap_filler_array_with(HeapWord* start, size_t words, juint value);
161 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
162 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
163
164 // Fill with a single array; caller must ensure filler_array_min_size() <=
165 // words <= filler_array_max_size().
166 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
167
168 // Fill with a single object (either an int array or a java.lang.Object).
169 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
170
171 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
172
173 // Verification functions
174 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
175 PRODUCT_RETURN;
176 debug_only(static void check_for_valid_allocation_state();)
177
178 public:
179 enum Name {
180 None,
181 Serial,
182 Parallel,
183 G1,
184 Epsilon,
185 Z,
186 Shenandoah
187 };
188
189 protected:
190 // Get a pointer to the derived heap object. Used to implement
191 // derived class heap() functions rather than being called directly.
192 template<typename T>
193 static T* named_heap(Name kind) {
194 CollectedHeap* heap = Universe::heap();
195 assert(heap != NULL, "Uninitialized heap");
196 assert(kind == heap->kind(), "Heap kind %u should be %u",
197 static_cast<uint>(heap->kind()), static_cast<uint>(kind));
198 return static_cast<T*>(heap);
199 }
200
201 public:
202
203 static inline size_t filler_array_max_size() {
204 return _filler_array_max_size;
205 }
206
207 virtual Name kind() const = 0;
208
209 virtual const char* name() const = 0;
210
211 /**
212 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
213 * and JNI_OK on success.
214 */
215 virtual jint initialize() = 0;
216
217 // In many heaps, there will be a need to perform some initialization activities
218 // after the Universe is fully formed, but before general heap allocation is allowed.
219 // This is the correct place to place such initialization methods.
220 virtual void post_initialize();
221
222 // Stop any onging concurrent work and prepare for exit.
223 virtual void stop() {}
224
225 // Stop and resume concurrent GC threads interfering with safepoint operations
226 virtual void safepoint_synchronize_begin() {}
227 virtual void safepoint_synchronize_end() {}
228
229 void initialize_reserved_region(const ReservedHeapSpace& rs);
230
231 virtual size_t capacity() const = 0;
232 virtual size_t used() const = 0;
233
234 // Returns unused capacity.
235 virtual size_t unused() const;
236
237 // Historic gc information
238 size_t free_at_last_gc() const { return _capacity_at_last_gc - _used_at_last_gc; }
239 size_t used_at_last_gc() const { return _used_at_last_gc; }
240 void update_capacity_and_used_at_gc();
241
242 // Return "true" if the part of the heap that allocates Java
243 // objects has reached the maximal committed limit that it can
244 // reach, without a garbage collection.
245 virtual bool is_maximal_no_gc() const = 0;
246
247 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
248 // memory that the vm could make available for storing 'normal' java objects.
249 // This is based on the reserved address space, but should not include space
250 // that the vm uses internally for bookkeeping or temporary storage
251 // (e.g., in the case of the young gen, one of the survivor
252 // spaces).
253 virtual size_t max_capacity() const = 0;
254
255 // Returns "TRUE" iff "p" points into the committed areas of the heap.
256 // This method can be expensive so avoid using it in performance critical
257 // code.
258 virtual bool is_in(const void* p) const = 0;
259
260 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
261
262 virtual uint32_t hash_oop(oop obj) const;
263
264 void set_gc_cause(GCCause::Cause v);
265 GCCause::Cause gc_cause() { return _gc_cause; }
266
267 oop obj_allocate(Klass* klass, size_t size, TRAPS);
268 oop obj_buffer_allocate(Klass* klass, size_t size, TRAPS); // doesn't clear memory
269 virtual oop array_allocate(Klass* klass, size_t size, int length, bool do_zero, TRAPS);
270 oop class_allocate(Klass* klass, size_t size, TRAPS);
271
272 // Utilities for turning raw memory into filler objects.
273 //
274 // min_fill_size() is the smallest region that can be filled.
275 // fill_with_objects() can fill arbitrary-sized regions of the heap using
276 // multiple objects. fill_with_object() is for regions known to be smaller
277 // than the largest array of integers; it uses a single object to fill the
278 // region and has slightly less overhead.
279 static size_t min_fill_size() {
280 return size_t(align_object_size(oopDesc::header_size()));
281 }
282
283 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
284
285 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
286 static void fill_with_object(MemRegion region, bool zap = true) {
287 fill_with_object(region.start(), region.word_size(), zap);
288 }
289 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
290 fill_with_object(start, pointer_delta(end, start), zap);
291 }
292
293 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
294 static constexpr size_t min_dummy_object_size() {
295 return oopDesc::header_size();
296 }
297
298 size_t tlab_alloc_reserve() const;
299
300 // Some heaps may offer a contiguous region for shared non-blocking
301 // allocation, via inlined code (by exporting the address of the top and
302 // end fields defining the extent of the contiguous allocation region.)
303
304 // This function returns "true" iff the heap supports this kind of
305 // allocation. (Default is "no".)
306 virtual bool supports_inline_contig_alloc() const {
307 return false;
308 }
309 // These functions return the addresses of the fields that define the
310 // boundaries of the contiguous allocation area. (These fields should be
311 // physically near to one another.)
312 virtual HeapWord* volatile* top_addr() const {
313 guarantee(false, "inline contiguous allocation not supported");
314 return NULL;
315 }
316 virtual HeapWord** end_addr() const {
317 guarantee(false, "inline contiguous allocation not supported");
318 return NULL;
319 }
320
321 // Some heaps may be in an unparseable state at certain times between
322 // collections. This may be necessary for efficient implementation of
323 // certain allocation-related activities. Calling this function before
324 // attempting to parse a heap ensures that the heap is in a parsable
325 // state (provided other concurrent activity does not introduce
326 // unparsability). It is normally expected, therefore, that this
327 // method is invoked with the world stopped.
328 // NOTE: if you override this method, make sure you call
329 // super::ensure_parsability so that the non-generational
330 // part of the work gets done. See implementation of
331 // CollectedHeap::ensure_parsability and, for instance,
332 // that of GenCollectedHeap::ensure_parsability().
333 // The argument "retire_tlabs" controls whether existing TLABs
334 // are merely filled or also retired, thus preventing further
335 // allocation from them and necessitating allocation of new TLABs.
336 virtual void ensure_parsability(bool retire_tlabs);
337
338 // The amount of space available for thread-local allocation buffers.
339 virtual size_t tlab_capacity(Thread *thr) const = 0;
340
341 // The amount of used space for thread-local allocation buffers for the given thread.
342 virtual size_t tlab_used(Thread *thr) const = 0;
343
344 virtual size_t max_tlab_size() const;
345
346 // An estimate of the maximum allocation that could be performed
347 // for thread-local allocation buffers without triggering any
348 // collection or expansion activity.
349 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
350 guarantee(false, "thread-local allocation buffers not supported");
351 return 0;
352 }
353
354 // If a GC uses a stack watermark barrier, the stack processing is lazy, concurrent,
355 // incremental and cooperative. In order for that to work well, mechanisms that stop
356 // another thread might want to ensure its roots are in a sane state.
357 virtual bool uses_stack_watermark_barrier() const { return false; }
358
359 // Perform a collection of the heap; intended for use in implementing
360 // "System.gc". This probably implies as full a collection as the
361 // "CollectedHeap" supports.
362 virtual void collect(GCCause::Cause cause) = 0;
363
364 // Perform a full collection
365 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
366
367 // This interface assumes that it's being called by the
368 // vm thread. It collects the heap assuming that the
369 // heap lock is already held and that we are executing in
370 // the context of the vm thread.
371 virtual void collect_as_vm_thread(GCCause::Cause cause);
372
373 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
374 size_t size,
375 Metaspace::MetadataType mdtype);
376
377 // Returns "true" iff there is a stop-world GC in progress. (I assume
378 // that it should answer "false" for the concurrent part of a concurrent
379 // collector -- dld).
380 bool is_gc_active() const { return _is_gc_active; }
381
382 // Total number of GC collections (started)
383 unsigned int total_collections() const { return _total_collections; }
384 unsigned int total_full_collections() const { return _total_full_collections;}
385
386 // Increment total number of GC collections (started)
387 void increment_total_collections(bool full = false) {
388 _total_collections++;
389 if (full) {
390 increment_total_full_collections();
391 }
392 }
393
394 void increment_total_full_collections() { _total_full_collections++; }
395
396 // Return the SoftRefPolicy for the heap;
397 virtual SoftRefPolicy* soft_ref_policy() = 0;
398
399 virtual MemoryUsage memory_usage();
400 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
401 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
402
403 // Iterate over all objects, calling "cl.do_object" on each.
404 virtual void object_iterate(ObjectClosure* cl) = 0;
405
406 protected:
407 virtual ParallelObjectIteratorImpl* parallel_object_iterator(uint thread_num) {
408 return NULL;
409 }
410
411 public:
412 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
413 virtual void keep_alive(oop obj) {}
414
415 // Perform any cleanup actions necessary before allowing a verification.
416 virtual void prepare_for_verify() = 0;
417
418 // Returns the longest time (in ms) that has elapsed since the last
419 // time that the whole heap has been examined by a garbage collection.
420 jlong millis_since_last_whole_heap_examined();
421 // GC should call this when the next whole heap analysis has completed to
422 // satisfy above requirement.
423 void record_whole_heap_examined_timestamp();
424
425 private:
426 // Generate any dumps preceding or following a full gc
427 void full_gc_dump(GCTimer* timer, bool before);
428
429 virtual void initialize_serviceability() = 0;
430
431 public:
432 void pre_full_gc_dump(GCTimer* timer);
433 void post_full_gc_dump(GCTimer* timer);
434
435 virtual VirtualSpaceSummary create_heap_space_summary();
436 GCHeapSummary create_heap_summary();
437
438 MetaspaceSummary create_metaspace_summary();
439
440 // Print heap information on the given outputStream.
441 virtual void print_on(outputStream* st) const = 0;
442 // The default behavior is to call print_on() on tty.
443 virtual void print() const;
444
445 // Print more detailed heap information on the given
446 // outputStream. The default behavior is to call print_on(). It is
447 // up to each subclass to override it and add any additional output
448 // it needs.
449 virtual void print_extended_on(outputStream* st) const {
450 print_on(st);
451 }
452
453 virtual void print_on_error(outputStream* st) const;
454
455 // Used to print information about locations in the hs_err file.
456 virtual bool print_location(outputStream* st, void* addr) const = 0;
457
458 // Iterator for all GC threads (other than VM thread)
459 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
460
461 // Print any relevant tracing info that flags imply.
462 // Default implementation does nothing.
463 virtual void print_tracing_info() const = 0;
464
465 void print_heap_before_gc();
466 void print_heap_after_gc();
467
468 // Registering and unregistering an nmethod (compiled code) with the heap.
469 virtual void register_nmethod(nmethod* nm) = 0;
470 virtual void unregister_nmethod(nmethod* nm) = 0;
471 // Callback for when nmethod is about to be deleted.
472 virtual void flush_nmethod(nmethod* nm) = 0;
473 virtual void verify_nmethod(nmethod* nm) = 0;
474
475 void trace_heap_before_gc(const GCTracer* gc_tracer);
476 void trace_heap_after_gc(const GCTracer* gc_tracer);
477
478 // Heap verification
479 virtual void verify(VerifyOption option) = 0;
480
481 // Return true if concurrent gc control via WhiteBox is supported by
482 // this collector. The default implementation returns false.
483 virtual bool supports_concurrent_gc_breakpoints() const;
484
485 // Workers used in non-GC safepoints for parallel safepoint cleanup. If this
486 // method returns NULL, cleanup tasks are done serially in the VMThread. See
487 // `SafepointSynchronize::do_cleanup_tasks` for details.
488 // GCs using a GC worker thread pool inside GC safepoints may opt to share
489 // that pool with non-GC safepoints, avoiding creating extraneous threads.
490 // Such sharing is safe, because GC safepoints and non-GC safepoints never
491 // overlap. For example, `G1CollectedHeap::workers()` (for GC safepoints) and
492 // `G1CollectedHeap::safepoint_workers()` (for non-GC safepoints) return the
493 // same thread-pool.
494 virtual WorkerThreads* safepoint_workers() { return NULL; }
495
496 // Support for object pinning. This is used by JNI Get*Critical()
497 // and Release*Critical() family of functions. If supported, the GC
498 // must guarantee that pinned objects never move.
499 virtual bool supports_object_pinning() const;
500 virtual oop pin_object(JavaThread* thread, oop obj);
501 virtual void unpin_object(JavaThread* thread, oop obj);
502
503 // Is the given object inside a CDS archive area?
504 virtual bool is_archived_object(oop object) const;
505
506 // Support for loading objects from CDS archive into the heap
507 // (usually as a snapshot of the old generation).
508 virtual bool can_load_archived_objects() const { return false; }
509 virtual HeapWord* allocate_loaded_archive_space(size_t size) { return NULL; }
510 virtual void complete_loaded_archive_space(MemRegion archive_space) { }
511
512 virtual bool is_oop(oop object) const;
513 // Non product verification and debugging.
514 #ifndef PRODUCT
515 // Support for PromotionFailureALot. Return true if it's time to cause a
516 // promotion failure. The no-argument version uses
517 // this->_promotion_failure_alot_count as the counter.
518 bool promotion_should_fail(volatile size_t* count);
519 bool promotion_should_fail();
520
521 // Reset the PromotionFailureALot counters. Should be called at the end of a
522 // GC in which promotion failure occurred.
523 void reset_promotion_should_fail(volatile size_t* count);
524 void reset_promotion_should_fail();
525 #endif // #ifndef PRODUCT
526 };
527
528 // Class to set and reset the GC cause for a CollectedHeap.
529
530 class GCCauseSetter : StackObj {
531 CollectedHeap* _heap;
532 GCCause::Cause _previous_cause;
533 public:
534 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
535 _heap = heap;
536 _previous_cause = _heap->gc_cause();
537 _heap->set_gc_cause(cause);
538 }
539
540 ~GCCauseSetter() {
541 _heap->set_gc_cause(_previous_cause);
542 }
543 };
544
545 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP