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/metaspace.hpp"
33 #include "memory/universe.hpp"
34 #include "runtime/handles.hpp"
35 #include "runtime/perfData.hpp"
36 #include "runtime/safepoint.hpp"
37 #include "services/memoryUsage.hpp"
38 #include "utilities/debug.hpp"
39 #include "utilities/events.hpp"
40 #include "utilities/formatBuffer.hpp"
41 #include "utilities/growableArray.hpp"
42
43 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
44 // is an abstract class: there may be many different kinds of heaps. This
45 // class defines the functions that a heap must implement, and contains
46 // infrastructure common to all heaps.
47
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 // 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 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
161 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
162
163 // Fill with a single array; caller must ensure filler_array_min_size() <=
164 // words <= filler_array_max_size().
165 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
166
167 // Fill with a single object (either an int array or a java.lang.Object).
168 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
169
170 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
171
172 // Verification functions
173 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
174 PRODUCT_RETURN;
175 debug_only(static void check_for_valid_allocation_state();)
176
177 public:
178 enum Name {
179 None,
180 Serial,
181 Parallel,
182 G1,
183 Epsilon,
184 Z,
185 Shenandoah
186 };
187
188 protected:
189 // Get a pointer to the derived heap object. Used to implement
190 // derived class heap() functions rather than being called directly.
191 template<typename T>
192 static T* named_heap(Name kind) {
193 CollectedHeap* heap = Universe::heap();
194 assert(heap != NULL, "Uninitialized heap");
195 assert(kind == heap->kind(), "Heap kind %u should be %u",
196 static_cast<uint>(heap->kind()), static_cast<uint>(kind));
197 return static_cast<T*>(heap);
198 }
199
200 public:
201
202 static inline size_t filler_array_max_size() {
203 return _filler_array_max_size;
204 }
205
206 virtual Name kind() const = 0;
207
208 virtual const char* name() const = 0;
209
210 /**
211 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
212 * and JNI_OK on success.
213 */
214 virtual jint initialize() = 0;
215
216 // In many heaps, there will be a need to perform some initialization activities
217 // after the Universe is fully formed, but before general heap allocation is allowed.
218 // This is the correct place to place such initialization methods.
219 virtual void post_initialize();
220
221 // Stop any onging concurrent work and prepare for exit.
222 virtual void stop() {}
223
224 // Stop and resume concurrent GC threads interfering with safepoint operations
225 virtual void safepoint_synchronize_begin() {}
226 virtual void safepoint_synchronize_end() {}
227
228 void initialize_reserved_region(const ReservedHeapSpace& rs);
229
230 virtual size_t capacity() const = 0;
231 virtual size_t used() const = 0;
232
233 // Returns unused capacity.
234 virtual size_t unused() const;
235
236 // Return "true" if the part of the heap that allocates Java
237 // objects has reached the maximal committed limit that it can
238 // reach, without a garbage collection.
239 virtual bool is_maximal_no_gc() const = 0;
240
241 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
242 // memory that the vm could make available for storing 'normal' java objects.
243 // This is based on the reserved address space, but should not include space
244 // that the vm uses internally for bookkeeping or temporary storage
245 // (e.g., in the case of the young gen, one of the survivor
246 // spaces).
247 virtual size_t max_capacity() const = 0;
248
249 // Returns "TRUE" iff "p" points into the committed areas of the heap.
250 // This method can be expensive so avoid using it in performance critical
251 // code.
252 virtual bool is_in(const void* p) const = 0;
253
254 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
255
256 virtual uint32_t hash_oop(oop obj) const;
257
258 void set_gc_cause(GCCause::Cause v) {
259 if (UsePerfData) {
260 _gc_lastcause = _gc_cause;
261 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
262 _perf_gc_cause->set_value(GCCause::to_string(v));
263 }
264 _gc_cause = v;
265 }
266 GCCause::Cause gc_cause() { return _gc_cause; }
267
268 oop obj_allocate(Klass* klass, int size, TRAPS);
269 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
270 oop class_allocate(Klass* klass, int 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 virtual size_t min_dummy_object_size() const;
295 size_t tlab_alloc_reserve() const;
296
297 // Return the address "addr" aligned by "alignment_in_bytes" if such
298 // an address is below "end". Return NULL otherwise.
299 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
300 HeapWord* end,
301 unsigned short alignment_in_bytes);
302
303 // Some heaps may offer a contiguous region for shared non-blocking
304 // allocation, via inlined code (by exporting the address of the top and
305 // end fields defining the extent of the contiguous allocation region.)
306
307 // This function returns "true" iff the heap supports this kind of
308 // allocation. (Default is "no".)
309 virtual bool supports_inline_contig_alloc() const {
310 return false;
311 }
312 // These functions return the addresses of the fields that define the
313 // boundaries of the contiguous allocation area. (These fields should be
314 // physically near to one another.)
315 virtual HeapWord* volatile* top_addr() const {
316 guarantee(false, "inline contiguous allocation not supported");
317 return NULL;
318 }
319 virtual HeapWord** end_addr() const {
320 guarantee(false, "inline contiguous allocation not supported");
321 return NULL;
322 }
323
324 // Some heaps may be in an unparseable state at certain times between
325 // collections. This may be necessary for efficient implementation of
326 // certain allocation-related activities. Calling this function before
327 // attempting to parse a heap ensures that the heap is in a parsable
328 // state (provided other concurrent activity does not introduce
329 // unparsability). It is normally expected, therefore, that this
330 // method is invoked with the world stopped.
331 // NOTE: if you override this method, make sure you call
332 // super::ensure_parsability so that the non-generational
333 // part of the work gets done. See implementation of
334 // CollectedHeap::ensure_parsability and, for instance,
335 // that of GenCollectedHeap::ensure_parsability().
336 // The argument "retire_tlabs" controls whether existing TLABs
337 // are merely filled or also retired, thus preventing further
338 // allocation from them and necessitating allocation of new TLABs.
339 virtual void ensure_parsability(bool retire_tlabs);
340
341 // Section on thread-local allocation buffers (TLABs)
342 // If the heap supports thread-local allocation buffers, it should override
343 // the following methods:
344 // Returns "true" iff the heap supports thread-local allocation buffers.
345 // The default is "no".
346 virtual bool supports_tlab_allocation() const = 0;
347
348 // The amount of space available for thread-local allocation buffers.
349 virtual size_t tlab_capacity(Thread *thr) const = 0;
350
351 // The amount of used space for thread-local allocation buffers for the given thread.
352 virtual size_t tlab_used(Thread *thr) const = 0;
353
354 virtual size_t max_tlab_size() const;
355
356 // An estimate of the maximum allocation that could be performed
357 // for thread-local allocation buffers without triggering any
358 // collection or expansion activity.
359 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
360 guarantee(false, "thread-local allocation buffers not supported");
361 return 0;
362 }
363
364 // Perform a collection of the heap; intended for use in implementing
365 // "System.gc". This probably implies as full a collection as the
366 // "CollectedHeap" supports.
367 virtual void collect(GCCause::Cause cause) = 0;
368
369 // Perform a full collection
370 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
371
372 // This interface assumes that it's being called by the
373 // vm thread. It collects the heap assuming that the
374 // heap lock is already held and that we are executing in
375 // the context of the vm thread.
376 virtual void collect_as_vm_thread(GCCause::Cause cause);
377
378 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
379 size_t size,
380 Metaspace::MetadataType mdtype);
381
382 // Returns "true" iff there is a stop-world GC in progress. (I assume
383 // that it should answer "false" for the concurrent part of a concurrent
384 // collector -- dld).
385 bool is_gc_active() const { return _is_gc_active; }
386
387 // Total number of GC collections (started)
388 unsigned int total_collections() const { return _total_collections; }
389 unsigned int total_full_collections() const { return _total_full_collections;}
390
391 // Increment total number of GC collections (started)
392 void increment_total_collections(bool full = false) {
393 _total_collections++;
394 if (full) {
395 increment_total_full_collections();
396 }
397 }
398
399 void increment_total_full_collections() { _total_full_collections++; }
400
401 // Return the SoftRefPolicy for the heap;
402 virtual SoftRefPolicy* soft_ref_policy() = 0;
403
404 virtual MemoryUsage memory_usage();
405 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
406 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
407
408 // Iterate over all objects, calling "cl.do_object" on each.
409 virtual void object_iterate(ObjectClosure* cl) = 0;
410
411 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
412 virtual void keep_alive(oop obj) {}
413
414 // Perform any cleanup actions necessary before allowing a verification.
415 virtual void prepare_for_verify() = 0;
416
417 // Returns the longest time (in ms) that has elapsed since the last
418 // time that the whole heap has been examined by a garbage collection.
419 jlong millis_since_last_whole_heap_examined();
420 // GC should call this when the next whole heap analysis has completed to
421 // satisfy above requirement.
422 void record_whole_heap_examined_timestamp();
423
424 private:
425 // Generate any dumps preceding or following a full gc
426 void full_gc_dump(GCTimer* timer, bool before);
427
428 virtual void initialize_serviceability() = 0;
429
430 public:
431 void pre_full_gc_dump(GCTimer* timer);
432 void post_full_gc_dump(GCTimer* timer);
433
434 virtual VirtualSpaceSummary create_heap_space_summary();
435 GCHeapSummary create_heap_summary();
436
437 MetaspaceSummary create_metaspace_summary();
438
439 // Print heap information on the given outputStream.
440 virtual void print_on(outputStream* st) const = 0;
441 // The default behavior is to call print_on() on tty.
442 virtual void print() const;
443
444 // Print more detailed heap information on the given
445 // outputStream. The default behavior is to call print_on(). It is
446 // up to each subclass to override it and add any additional output
447 // it needs.
448 virtual void print_extended_on(outputStream* st) const {
449 print_on(st);
450 }
451
452 virtual void print_on_error(outputStream* st) const;
453
454 // Used to print information about locations in the hs_err file.
455 virtual bool print_location(outputStream* st, void* addr) const = 0;
456
457 // Iterator for all GC threads (other than VM thread)
458 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
459
460 // Print any relevant tracing info that flags imply.
461 // Default implementation does nothing.
462 virtual void print_tracing_info() const = 0;
463
464 void print_heap_before_gc();
465 void print_heap_after_gc();
466
467 // Registering and unregistering an nmethod (compiled code) with the heap.
468 virtual void register_nmethod(nmethod* nm) = 0;
469 virtual void unregister_nmethod(nmethod* nm) = 0;
470 // Callback for when nmethod is about to be deleted.
471 virtual void flush_nmethod(nmethod* nm) = 0;
472 virtual void verify_nmethod(nmethod* nm) = 0;
473
474 void trace_heap_before_gc(const GCTracer* gc_tracer);
475 void trace_heap_after_gc(const GCTracer* gc_tracer);
476
477 // Heap verification
478 virtual void verify(VerifyOption option) = 0;
479
480 // Return true if concurrent gc control via WhiteBox is supported by
481 // this collector. The default implementation returns false.
482 virtual bool supports_concurrent_gc_breakpoints() const;
483
484 // Provides a thread pool to SafepointSynchronize to use
485 // for parallel safepoint cleanup.
486 // GCs that use a GC worker thread pool may want to share
487 // it for use during safepoint cleanup. This is only possible
488 // if the GC can pause and resume concurrent work (e.g. G1
489 // concurrent marking) for an intermittent non-GC safepoint.
490 // If this method returns NULL, SafepointSynchronize will
491 // perform cleanup tasks serially in the VMThread.
492 virtual WorkGang* get_safepoint_workers() { return NULL; }
493
494 // Support for object pinning. This is used by JNI Get*Critical()
495 // and Release*Critical() family of functions. If supported, the GC
496 // must guarantee that pinned objects never move.
497 virtual bool supports_object_pinning() const;
498 virtual oop pin_object(JavaThread* thread, oop obj);
499 virtual void unpin_object(JavaThread* thread, oop obj);
500
501 // Deduplicate the string, iff the GC supports string deduplication.
502 virtual void deduplicate_string(oop str);
503
504 virtual bool is_oop(oop object) const;
505
506 // Non product verification and debugging.
507 #ifndef PRODUCT
508 // Support for PromotionFailureALot. Return true if it's time to cause a
509 // promotion failure. The no-argument version uses
510 // this->_promotion_failure_alot_count as the counter.
511 bool promotion_should_fail(volatile size_t* count);
512 bool promotion_should_fail();
513
514 // Reset the PromotionFailureALot counters. Should be called at the end of a
515 // GC in which promotion failure occurred.
516 void reset_promotion_should_fail(volatile size_t* count);
517 void reset_promotion_should_fail();
518 #endif // #ifndef PRODUCT
519 };
520
521 // Class to set and reset the GC cause for a CollectedHeap.
522
523 class GCCauseSetter : StackObj {
524 CollectedHeap* _heap;
525 GCCause::Cause _previous_cause;
526 public:
527 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
528 _heap = heap;
529 _previous_cause = _heap->gc_cause();
530 _heap->set_gc_cause(cause);
531 }
532
533 ~GCCauseSetter() {
534 _heap->set_gc_cause(_previous_cause);
535 }
536 };
537
538 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP