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 *
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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.
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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 "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