1 /*
2 * Copyright (c) 2001, 2020, 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.
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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/heapInspection.hpp"
33 #include "runtime/handles.hpp"
34 #include "runtime/perfData.hpp"
35 #include "runtime/safepoint.hpp"
36 #include "services/memoryUsage.hpp"
37 #include "utilities/debug.hpp"
38 #include "utilities/events.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 GCHeapSummary;
51 class GCTimer;
52 class GCTracer;
53 class GCMemoryManager;
54 class MemoryPool;
55 class MetaspaceSummary;
56 class ReservedHeapSpace;
57 class SoftRefPolicy;
58 class Thread;
59 class ThreadClosure;
60 class VirtualSpaceSummary;
61 class WorkGang;
62 class nmethod;
63
64 class GCMessage : public FormatBuffer<1024> {
65 public:
66 bool is_before;
67
68 public:
69 GCMessage() {}
70 };
71
72 class CollectedHeap;
73
74 class GCHeapLog : public EventLogBase<GCMessage> {
75 private:
76 void log_heap(CollectedHeap* heap, bool before);
77
78 public:
79 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
80
81 void log_heap_before(CollectedHeap* heap) {
82 log_heap(heap, true);
83 }
84 void log_heap_after(CollectedHeap* heap) {
85 log_heap(heap, false);
86 }
87 };
88
89 //
90 // CollectedHeap
91 // GenCollectedHeap
92 // SerialHeap
93 // G1CollectedHeap
94 // ParallelScavengeHeap
95 // ShenandoahHeap
96 // ZCollectedHeap
97 //
98 class CollectedHeap : public CHeapObj<mtInternal> {
99 friend class VMStructs;
100 friend class JVMCIVMStructs;
101 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
102 friend class MemAllocator;
103
104 private:
105 GCHeapLog* _gc_heap_log;
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 unsigned int _total_collections; // ... started
117 unsigned int _total_full_collections; // ... started
118 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
119 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
120
121 // Reason for current garbage collection. Should be set to
122 // a value reflecting no collection between collections.
123 GCCause::Cause _gc_cause;
124 GCCause::Cause _gc_lastcause;
125 PerfStringVariable* _perf_gc_cause;
126 PerfStringVariable* _perf_gc_lastcause;
127
128 // Constructor
129 CollectedHeap();
130
131 // Create a new tlab. All TLAB allocations must go through this.
132 // To allow more flexible TLAB allocations min_size specifies
133 // the minimum size needed, while requested_size is the requested
134 // size based on ergonomics. The actually allocated size will be
135 // returned in actual_size.
136 virtual HeapWord* allocate_new_tlab(size_t min_size,
137 size_t requested_size,
138 size_t* actual_size);
139
140 // Reinitialize tlabs before resuming mutators.
141 virtual void resize_all_tlabs();
142
143 // Raw memory allocation facilities
144 // The obj and array allocate methods are covers for these methods.
145 // mem_allocate() should never be
146 // called to allocate TLABs, only individual objects.
147 virtual HeapWord* mem_allocate(size_t size,
148 bool* gc_overhead_limit_was_exceeded) = 0;
149
150 // Filler object utilities.
151 static inline size_t filler_array_hdr_size();
152 static inline size_t filler_array_min_size();
153
154 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
155 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
156
157 // Fill with a single array; caller must ensure filler_array_min_size() <=
158 // words <= filler_array_max_size().
159 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
160
161 // Fill with a single object (either an int array or a java.lang.Object).
162 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
163
164 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
165
166 // Verification functions
167 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
168 PRODUCT_RETURN;
169 debug_only(static void check_for_valid_allocation_state();)
170
171 public:
172 enum Name {
173 None,
174 Serial,
175 Parallel,
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 virtual uint32_t hash_oop(oop obj) const;
237
238 void set_gc_cause(GCCause::Cause v) {
239 if (UsePerfData) {
240 _gc_lastcause = _gc_cause;
241 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
242 _perf_gc_cause->set_value(GCCause::to_string(v));
243 }
244 _gc_cause = v;
245 }
246 GCCause::Cause gc_cause() { return _gc_cause; }
247
248 oop obj_allocate(Klass* klass, int size, TRAPS);
249 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
250 oop class_allocate(Klass* klass, int size, TRAPS);
251
252 // Utilities for turning raw memory into filler objects.
253 //
254 // min_fill_size() is the smallest region that can be filled.
255 // fill_with_objects() can fill arbitrary-sized regions of the heap using
256 // multiple objects. fill_with_object() is for regions known to be smaller
257 // than the largest array of integers; it uses a single object to fill the
258 // region and has slightly less overhead.
259 static size_t min_fill_size() {
260 return size_t(align_object_size(oopDesc::header_size()));
261 }
262
263 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
264
265 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
266 static void fill_with_object(MemRegion region, bool zap = true) {
267 fill_with_object(region.start(), region.word_size(), zap);
268 }
269 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
270 fill_with_object(start, pointer_delta(end, start), zap);
271 }
272
273 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
274 virtual size_t min_dummy_object_size() const;
275 size_t tlab_alloc_reserve() const;
276
277 // Return the address "addr" aligned by "alignment_in_bytes" if such
278 // an address is below "end". Return NULL otherwise.
279 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
280 HeapWord* end,
281 unsigned short alignment_in_bytes);
282
283 // Some heaps may offer a contiguous region for shared non-blocking
284 // allocation, via inlined code (by exporting the address of the top and
285 // end fields defining the extent of the contiguous allocation region.)
286
287 // This function returns "true" iff the heap supports this kind of
288 // allocation. (Default is "no".)
289 virtual bool supports_inline_contig_alloc() const {
290 return false;
291 }
292 // These functions return the addresses of the fields that define the
293 // boundaries of the contiguous allocation area. (These fields should be
294 // physically near to one another.)
295 virtual HeapWord* volatile* top_addr() const {
296 guarantee(false, "inline contiguous allocation not supported");
297 return NULL;
298 }
299 virtual HeapWord** end_addr() const {
300 guarantee(false, "inline contiguous allocation not supported");
301 return NULL;
302 }
303
304 // Some heaps may be in an unparseable state at certain times between
305 // collections. This may be necessary for efficient implementation of
306 // certain allocation-related activities. Calling this function before
307 // attempting to parse a heap ensures that the heap is in a parsable
308 // state (provided other concurrent activity does not introduce
309 // unparsability). It is normally expected, therefore, that this
310 // method is invoked with the world stopped.
311 // NOTE: if you override this method, make sure you call
312 // super::ensure_parsability so that the non-generational
313 // part of the work gets done. See implementation of
314 // CollectedHeap::ensure_parsability and, for instance,
315 // that of GenCollectedHeap::ensure_parsability().
316 // The argument "retire_tlabs" controls whether existing TLABs
317 // are merely filled or also retired, thus preventing further
318 // allocation from them and necessitating allocation of new TLABs.
319 virtual void ensure_parsability(bool retire_tlabs);
320
321 // Section on thread-local allocation buffers (TLABs)
322 // If the heap supports thread-local allocation buffers, it should override
323 // the following methods:
324 // Returns "true" iff the heap supports thread-local allocation buffers.
325 // The default is "no".
326 virtual bool supports_tlab_allocation() const = 0;
327
328 // The amount of space available for thread-local allocation buffers.
329 virtual size_t tlab_capacity(Thread *thr) const = 0;
330
331 // The amount of used space for thread-local allocation buffers for the given thread.
332 virtual size_t tlab_used(Thread *thr) const = 0;
333
334 virtual size_t max_tlab_size() const;
335
336 // An estimate of the maximum allocation that could be performed
337 // for thread-local allocation buffers without triggering any
338 // collection or expansion activity.
339 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
340 guarantee(false, "thread-local allocation buffers not supported");
341 return 0;
342 }
343
344 // Perform a collection of the heap; intended for use in implementing
345 // "System.gc". This probably implies as full a collection as the
346 // "CollectedHeap" supports.
347 virtual void collect(GCCause::Cause cause) = 0;
348
349 // Perform a full collection
350 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
351
352 // This interface assumes that it's being called by the
353 // vm thread. It collects the heap assuming that the
354 // heap lock is already held and that we are executing in
355 // the context of the vm thread.
356 virtual void collect_as_vm_thread(GCCause::Cause cause);
357
358 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
359 size_t size,
360 Metaspace::MetadataType mdtype);
361
362 // Returns "true" iff there is a stop-world GC in progress. (I assume
363 // that it should answer "false" for the concurrent part of a concurrent
364 // collector -- dld).
365 bool is_gc_active() const { return _is_gc_active; }
366
367 // Total number of GC collections (started)
368 unsigned int total_collections() const { return _total_collections; }
369 unsigned int total_full_collections() const { return _total_full_collections;}
370
371 // Increment total number of GC collections (started)
372 void increment_total_collections(bool full = false) {
373 _total_collections++;
374 if (full) {
375 increment_total_full_collections();
376 }
377 }
378
379 void increment_total_full_collections() { _total_full_collections++; }
380
381 // Return the SoftRefPolicy for the heap;
382 virtual SoftRefPolicy* soft_ref_policy() = 0;
383
384 virtual MemoryUsage memory_usage();
385 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
386 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
387
388 // Iterate over all objects, calling "cl.do_object" on each.
389 virtual void object_iterate(ObjectClosure* cl) = 0;
390
391 // Run parallel heap inspection, return false as not supported by heap.
392 virtual bool run_par_heap_inspect_task(KlassInfoTable* cit,
393 BoolObjectClosure* filter,
394 size_t* missed_count,
395 size_t thread_num) {
396 return false;
397 }
398
399 // Parallel iterate over all objects, reture false if heap not support.
400 virtual bool object_iterate_try_parallel(AbstractGangTask *task, size_t thread_num) {
401 return false;
402 }
403
404 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
405 virtual void keep_alive(oop obj) {}
406
407 // Returns the longest time (in ms) that has elapsed since the last
408 // time that any part of the heap was examined by a garbage collection.
409 virtual jlong millis_since_last_gc() = 0;
410
411 // Perform any cleanup actions necessary before allowing a verification.
412 virtual void prepare_for_verify() = 0;
413
414 // Generate any dumps preceding or following a full gc
415 private:
416 void full_gc_dump(GCTimer* timer, bool before);
417
418 virtual void initialize_serviceability() = 0;
419
420 public:
421 void pre_full_gc_dump(GCTimer* timer);
422 void post_full_gc_dump(GCTimer* timer);
423
424 virtual VirtualSpaceSummary create_heap_space_summary();
425 GCHeapSummary create_heap_summary();
426
427 MetaspaceSummary create_metaspace_summary();
428
429 // Print heap information on the given outputStream.
430 virtual void print_on(outputStream* st) const = 0;
431 // The default behavior is to call print_on() on tty.
432 virtual void print() const;
433
434 // Print more detailed heap information on the given
435 // outputStream. The default behavior is to call print_on(). It is
436 // up to each subclass to override it and add any additional output
437 // it needs.
438 virtual void print_extended_on(outputStream* st) const {
439 print_on(st);
440 }
441
442 virtual void print_on_error(outputStream* st) const;
443
444 // Used to print information about locations in the hs_err file.
445 virtual bool print_location(outputStream* st, void* addr) const = 0;
446
447 // Print all GC threads (other than the VM thread)
448 // used by this heap.
449 virtual void print_gc_threads_on(outputStream* st) const = 0;
450 // The default behavior is to call print_gc_threads_on() on tty.
451 void print_gc_threads() {
452 print_gc_threads_on(tty);
453 }
454 // Iterator for all GC threads (other than VM thread)
455 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
456
457 // Print any relevant tracing info that flags imply.
458 // Default implementation does nothing.
459 virtual void print_tracing_info() const = 0;
460
461 void print_heap_before_gc();
462 void print_heap_after_gc();
463
464 // Registering and unregistering an nmethod (compiled code) with the heap.
465 virtual void register_nmethod(nmethod* nm) = 0;
466 virtual void unregister_nmethod(nmethod* nm) = 0;
467 // Callback for when nmethod is about to be deleted.
468 virtual void flush_nmethod(nmethod* nm) = 0;
469 virtual void verify_nmethod(nmethod* nm) = 0;
470
471 void trace_heap_before_gc(const GCTracer* gc_tracer);
472 void trace_heap_after_gc(const GCTracer* gc_tracer);
473
474 // Heap verification
475 virtual void verify(VerifyOption option) = 0;
476
477 // Return true if concurrent phase control (via
478 // request_concurrent_phase_control) is supported by this collector.
479 // The default implementation returns false.
480 virtual bool supports_concurrent_phase_control() const;
481
482 // Request the collector enter the indicated concurrent phase, and
483 // wait until it does so. Supports WhiteBox testing. Only one
484 // request may be active at a time. Phases are designated by name;
485 // the set of names and their meaning is GC-specific. Once the
486 // requested phase has been reached, the collector will attempt to
487 // avoid transitioning to a new phase until a new request is made.
488 // [Note: A collector might not be able to remain in a given phase.
489 // For example, a full collection might cancel an in-progress
490 // concurrent collection.]
491 //
492 // Returns true when the phase is reached. Returns false for an
493 // unknown phase. The default implementation returns false.
494 virtual bool request_concurrent_phase(const char* phase);
495
496 // Provides a thread pool to SafepointSynchronize to use
497 // for parallel safepoint cleanup.
498 // GCs that use a GC worker thread pool may want to share
499 // it for use during safepoint cleanup. This is only possible
500 // if the GC can pause and resume concurrent work (e.g. G1
501 // concurrent marking) for an intermittent non-GC safepoint.
502 // If this method returns NULL, SafepointSynchronize will
503 // perform cleanup tasks serially in the VMThread.
504 virtual WorkGang* get_safepoint_workers() { return NULL; }
505
506 // Support for object pinning. This is used by JNI Get*Critical()
507 // and Release*Critical() family of functions. If supported, the GC
508 // must guarantee that pinned objects never move.
509 virtual bool supports_object_pinning() const;
510 virtual oop pin_object(JavaThread* thread, oop obj);
511 virtual void unpin_object(JavaThread* thread, oop obj);
512
513 // Deduplicate the string, iff the GC supports string deduplication.
514 virtual void deduplicate_string(oop str);
515
516 virtual bool is_oop(oop object) const;
517
518 virtual size_t obj_size(oop obj) const;
519
520 // Non product verification and debugging.
521 #ifndef PRODUCT
522 // Support for PromotionFailureALot. Return true if it's time to cause a
523 // promotion failure. The no-argument version uses
524 // this->_promotion_failure_alot_count as the counter.
525 bool promotion_should_fail(volatile size_t* count);
526 bool promotion_should_fail();
527
528 // Reset the PromotionFailureALot counters. Should be called at the end of a
529 // GC in which promotion failure occurred.
530 void reset_promotion_should_fail(volatile size_t* count);
531 void reset_promotion_should_fail();
532 #endif // #ifndef PRODUCT
533 };
534
535 // Class to set and reset the GC cause for a CollectedHeap.
536
537 class GCCauseSetter : StackObj {
538 CollectedHeap* _heap;
539 GCCause::Cause _previous_cause;
540 public:
541 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
542 _heap = heap;
543 _previous_cause = _heap->gc_cause();
544 _heap->set_gc_cause(cause);
545 }
546
547 ~GCCauseSetter() {
548 _heap->set_gc_cause(_previous_cause);
549 }
550 };
551
552 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP