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 class ParallelObjectIterator : public CHeapObj<mtGC> {
90 public:
91 virtual void object_iterate(ObjectClosure* cl, uint worker_id) = 0;
92 };
93
94 //
95 // CollectedHeap
96 // GenCollectedHeap
97 // SerialHeap
98 // G1CollectedHeap
99 // ParallelScavengeHeap
100 // ShenandoahHeap
101 // ZCollectedHeap
102 //
103 class CollectedHeap : public CHeapObj<mtInternal> {
104 friend class VMStructs;
105 friend class JVMCIVMStructs;
106 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
107 friend class MemAllocator;
108
109 private:
110 GCHeapLog* _gc_heap_log;
111
112 protected:
113 // Not used by all GCs
114 MemRegion _reserved;
115
116 bool _is_gc_active;
117
118 // Used for filler objects (static, but initialized in ctor).
119 static size_t _filler_array_max_size;
120
121 unsigned int _total_collections; // ... started
122 unsigned int _total_full_collections; // ... started
123 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
124 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
125
126 // Reason for current garbage collection. Should be set to
127 // a value reflecting no collection between collections.
128 GCCause::Cause _gc_cause;
129 GCCause::Cause _gc_lastcause;
130 PerfStringVariable* _perf_gc_cause;
131 PerfStringVariable* _perf_gc_lastcause;
132
133 // Constructor
134 CollectedHeap();
135
136 // Create a new tlab. All TLAB allocations must go through this.
137 // To allow more flexible TLAB allocations min_size specifies
138 // the minimum size needed, while requested_size is the requested
139 // size based on ergonomics. The actually allocated size will be
140 // returned in actual_size.
141 virtual HeapWord* allocate_new_tlab(size_t min_size,
142 size_t requested_size,
143 size_t* actual_size);
144
145 // Reinitialize tlabs before resuming mutators.
146 virtual void resize_all_tlabs();
147
148 // Raw memory allocation facilities
149 // The obj and array allocate methods are covers for these methods.
150 // mem_allocate() should never be
151 // called to allocate TLABs, only individual objects.
152 virtual HeapWord* mem_allocate(size_t size,
153 bool* gc_overhead_limit_was_exceeded) = 0;
154
155 // Filler object utilities.
156 static inline size_t filler_array_hdr_size();
157 static inline size_t filler_array_min_size();
158
159 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
160 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
161
162 // Fill with a single array; caller must ensure filler_array_min_size() <=
163 // words <= filler_array_max_size().
164 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
165
166 // Fill with a single object (either an int array or a java.lang.Object).
167 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
168
169 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
170
171 // Verification functions
172 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
173 PRODUCT_RETURN;
174 debug_only(static void check_for_valid_allocation_state();)
175
176 public:
177 enum Name {
178 None,
179 Serial,
180 Parallel,
181 G1,
182 Epsilon,
183 Z,
184 Shenandoah
185 };
186
187 static inline size_t filler_array_max_size() {
188 return _filler_array_max_size;
189 }
190
191 virtual Name kind() const = 0;
192
193 virtual const char* name() const = 0;
194
195 /**
196 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
197 * and JNI_OK on success.
198 */
199 virtual jint initialize() = 0;
200
201 // In many heaps, there will be a need to perform some initialization activities
202 // after the Universe is fully formed, but before general heap allocation is allowed.
203 // This is the correct place to place such initialization methods.
204 virtual void post_initialize();
205
206 // Stop any onging concurrent work and prepare for exit.
207 virtual void stop() {}
208
209 // Stop and resume concurrent GC threads interfering with safepoint operations
210 virtual void safepoint_synchronize_begin() {}
211 virtual void safepoint_synchronize_end() {}
212
213 void initialize_reserved_region(const ReservedHeapSpace& rs);
214
215 virtual size_t capacity() const = 0;
216 virtual size_t used() const = 0;
217
218 // Returns unused capacity.
219 virtual size_t unused() const;
220
221 // Return "true" if the part of the heap that allocates Java
222 // objects has reached the maximal committed limit that it can
223 // reach, without a garbage collection.
224 virtual bool is_maximal_no_gc() const = 0;
225
226 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
227 // memory that the vm could make available for storing 'normal' java objects.
228 // This is based on the reserved address space, but should not include space
229 // that the vm uses internally for bookkeeping or temporary storage
230 // (e.g., in the case of the young gen, one of the survivor
231 // spaces).
232 virtual size_t max_capacity() const = 0;
233
234 // Returns "TRUE" iff "p" points into the committed areas of the heap.
235 // This method can be expensive so avoid using it in performance critical
236 // code.
237 virtual bool is_in(const void* p) const = 0;
238
239 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
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 void increment_total_collections(bool full = false) {
378 _total_collections++;
379 if (full) {
380 increment_total_full_collections();
381 }
382 }
383
384 void increment_total_full_collections() { _total_full_collections++; }
385
386 // Return the SoftRefPolicy for the heap;
387 virtual SoftRefPolicy* soft_ref_policy() = 0;
388
389 virtual MemoryUsage memory_usage();
390 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
391 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
392
393 // Iterate over all objects, calling "cl.do_object" on each.
394 virtual void object_iterate(ObjectClosure* cl) = 0;
395
396 virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num) {
397 return NULL;
398 }
399
400 // Run given task, parallelly if possible.
401 virtual Tickspan run_task(AbstractGangTask* task) = 0;
402
403 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
404 virtual void keep_alive(oop obj) {}
405
406 // Returns the longest time (in ms) that has elapsed since the last
407 // time that any part of the heap was examined by a garbage collection.
408 virtual jlong millis_since_last_gc() = 0;
409
410 // Perform any cleanup actions necessary before allowing a verification.
411 virtual void prepare_for_verify() = 0;
412
413 // Generate any dumps preceding or following a full gc
414 private:
415 void full_gc_dump(GCTimer* timer, bool before);
416
417 virtual void initialize_serviceability() = 0;
418
419 public:
420 void pre_full_gc_dump(GCTimer* timer);
421 void post_full_gc_dump(GCTimer* timer);
422
423 virtual VirtualSpaceSummary create_heap_space_summary();
424 GCHeapSummary create_heap_summary();
425
426 MetaspaceSummary create_metaspace_summary();
427
428 // Print heap information on the given outputStream.
429 virtual void print_on(outputStream* st) const = 0;
430 // The default behavior is to call print_on() on tty.
431 virtual void print() const;
432
433 // Print more detailed heap information on the given
434 // outputStream. The default behavior is to call print_on(). It is
435 // up to each subclass to override it and add any additional output
436 // it needs.
437 virtual void print_extended_on(outputStream* st) const {
438 print_on(st);
439 }
440
441 virtual void print_on_error(outputStream* st) const;
442
443 // Used to print information about locations in the hs_err file.
444 virtual bool print_location(outputStream* st, void* addr) const = 0;
445
446 // Print all GC threads (other than the VM thread)
447 // used by this heap.
448 virtual void print_gc_threads_on(outputStream* st) const = 0;
449 // The default behavior is to call print_gc_threads_on() on tty.
450 void print_gc_threads() {
451 print_gc_threads_on(tty);
452 }
453 // Iterator for all GC threads (other than VM thread)
454 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
455
456 // Print any relevant tracing info that flags imply.
457 // Default implementation does nothing.
458 virtual void print_tracing_info() const = 0;
459
460 void print_heap_before_gc();
461 void print_heap_after_gc();
462
463 // Registering and unregistering an nmethod (compiled code) with the heap.
464 virtual void register_nmethod(nmethod* nm) = 0;
465 virtual void unregister_nmethod(nmethod* nm) = 0;
466 // Callback for when nmethod is about to be deleted.
467 virtual void flush_nmethod(nmethod* nm) = 0;
468 virtual void verify_nmethod(nmethod* nm) = 0;
469
470 void trace_heap_before_gc(const GCTracer* gc_tracer);
471 void trace_heap_after_gc(const GCTracer* gc_tracer);
472
473 // Heap verification
474 virtual void verify(VerifyOption option) = 0;
475
476 // Return true if concurrent gc control via WhiteBox is supported by
477 // this collector. The default implementation returns false.
478 virtual bool supports_concurrent_gc_breakpoints() const;
479
480 // Provides a thread pool to SafepointSynchronize to use
481 // for parallel safepoint cleanup.
482 // GCs that use a GC worker thread pool may want to share
483 // it for use during safepoint cleanup. This is only possible
484 // if the GC can pause and resume concurrent work (e.g. G1
485 // concurrent marking) for an intermittent non-GC safepoint.
486 // If this method returns NULL, SafepointSynchronize will
487 // perform cleanup tasks serially in the VMThread.
488 virtual WorkGang* get_safepoint_workers() { return NULL; }
489
490 // Support for object pinning. This is used by JNI Get*Critical()
491 // and Release*Critical() family of functions. If supported, the GC
492 // must guarantee that pinned objects never move.
493 virtual bool supports_object_pinning() const;
494 virtual oop pin_object(JavaThread* thread, oop obj);
495 virtual void unpin_object(JavaThread* thread, oop obj);
496
497 // Deduplicate the string, iff the GC supports string deduplication.
498 virtual void deduplicate_string(oop str);
499
500 virtual bool is_oop(oop object) const;
501
502 virtual size_t obj_size(oop obj) const;
503
504 // Non product verification and debugging.
505 #ifndef PRODUCT
506 // Support for PromotionFailureALot. Return true if it's time to cause a
507 // promotion failure. The no-argument version uses
508 // this->_promotion_failure_alot_count as the counter.
509 bool promotion_should_fail(volatile size_t* count);
510 bool promotion_should_fail();
511
512 // Reset the PromotionFailureALot counters. Should be called at the end of a
513 // GC in which promotion failure occurred.
514 void reset_promotion_should_fail(volatile size_t* count);
515 void reset_promotion_should_fail();
516 #endif // #ifndef PRODUCT
517 };
518
519 // Class to set and reset the GC cause for a CollectedHeap.
520
521 class GCCauseSetter : StackObj {
522 CollectedHeap* _heap;
523 GCCause::Cause _previous_cause;
524 public:
525 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
526 _heap = heap;
527 _previous_cause = _heap->gc_cause();
528 _heap->set_gc_cause(cause);
529 }
530
531 ~GCCauseSetter() {
532 _heap->set_gc_cause(_previous_cause);
533 }
534 };
535
536 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP