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.
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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
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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/universe.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 AdaptiveSizePolicy;
48 class BarrierSet;
49 class GCHeapSummary;
50 class GCTimer;
51 class GCTracer;
52 class GCMemoryManager;
53 class MemoryPool;
54 class MetaspaceSummary;
55 class ReservedHeapSpace;
56 class SoftRefPolicy;
57 class Thread;
58 class ThreadClosure;
59 class VirtualSpaceSummary;
60 class WorkGang;
61 class nmethod;
62
63 class GCMessage : public FormatBuffer<1024> {
64 public:
65 bool is_before;
66
67 public:
68 GCMessage() {}
69 };
70
71 class CollectedHeap;
72
73 class GCHeapLog : public EventLogBase<GCMessage> {
74 private:
75 void log_heap(CollectedHeap* heap, bool before);
76
77 public:
78 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
79
80 void log_heap_before(CollectedHeap* heap) {
81 log_heap(heap, true);
82 }
83 void log_heap_after(CollectedHeap* heap) {
84 log_heap(heap, false);
85 }
86 };
87
88 //
89 // CollectedHeap
90 // GenCollectedHeap
91 // SerialHeap
92 // G1CollectedHeap
93 // ParallelScavengeHeap
94 // ShenandoahHeap
95 // ZCollectedHeap
96 //
97 class CollectedHeap : public CHeapObj<mtInternal> {
98 friend class VMStructs;
99 friend class JVMCIVMStructs;
100 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
101 friend class MemAllocator;
102
103 private:
104 GCHeapLog* _gc_heap_log;
105
106 protected:
107 // Not used by all GCs
108 MemRegion _reserved;
109
110 bool _is_gc_active;
111
112 // Used for filler objects (static, but initialized in ctor).
113 static size_t _filler_array_max_size;
114
115 // Last time the whole heap has been examined in support of RMI
116 // MaxObjectInspectionAge in ns.
117 jlong _last_whole_heap_examined_time_ns;
118
119 unsigned int _total_collections; // ... started
120 unsigned int _total_full_collections; // ... started
121 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
122 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
123
124 // Reason for current garbage collection. Should be set to
125 // a value reflecting no collection between collections.
126 GCCause::Cause _gc_cause;
127 GCCause::Cause _gc_lastcause;
128 PerfStringVariable* _perf_gc_cause;
129 PerfStringVariable* _perf_gc_lastcause;
130
131 // Constructor
132 CollectedHeap();
133
134 // Create a new tlab. All TLAB allocations must go through this.
135 // To allow more flexible TLAB allocations min_size specifies
136 // the minimum size needed, while requested_size is the requested
137 // size based on ergonomics. The actually allocated size will be
138 // returned in actual_size.
139 virtual HeapWord* allocate_new_tlab(size_t min_size,
140 size_t requested_size,
141 size_t* actual_size);
142
143 // Reinitialize tlabs before resuming mutators.
144 virtual void resize_all_tlabs();
145
146 // Raw memory allocation facilities
147 // The obj and array allocate methods are covers for these methods.
148 // mem_allocate() should never be
149 // called to allocate TLABs, only individual objects.
150 virtual HeapWord* mem_allocate(size_t size,
151 bool* gc_overhead_limit_was_exceeded) = 0;
152
153 // Filler object utilities.
154 static inline size_t filler_array_hdr_size();
155 static inline size_t filler_array_min_size();
156
157 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
158 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
159
160 // Fill with a single array; caller must ensure filler_array_min_size() <=
161 // words <= filler_array_max_size().
162 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
163
164 // Fill with a single object (either an int array or a java.lang.Object).
165 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
166
167 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
168
169 // Verification functions
170 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
171 PRODUCT_RETURN;
172 debug_only(static void check_for_valid_allocation_state();)
173
174 public:
175 enum Name {
176 None,
177 Serial,
178 Parallel,
179 G1,
180 Epsilon,
181 Z,
182 Shenandoah
183 };
184
185 protected:
186 // Get a pointer to the derived heap object. Used to implement
187 // derived class heap() functions rather than being called directly.
188 template<typename T>
189 static T* named_heap(Name kind) {
190 CollectedHeap* heap = Universe::heap();
191 assert(heap != NULL, "Uninitialized heap");
192 assert(kind == heap->kind(), "Heap kind %u should be %u",
193 static_cast<uint>(heap->kind()), static_cast<uint>(kind));
194 return static_cast<T*>(heap);
195 }
196
197 public:
198
199 static inline size_t filler_array_max_size() {
200 return _filler_array_max_size;
201 }
202
203 virtual Name kind() const = 0;
204
205 virtual const char* name() const = 0;
206
207 /**
208 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
209 * and JNI_OK on success.
210 */
211 virtual jint initialize() = 0;
212
213 // In many heaps, there will be a need to perform some initialization activities
214 // after the Universe is fully formed, but before general heap allocation is allowed.
215 // This is the correct place to place such initialization methods.
216 virtual void post_initialize();
217
218 // Stop any onging concurrent work and prepare for exit.
219 virtual void stop() {}
220
221 // Stop and resume concurrent GC threads interfering with safepoint operations
222 virtual void safepoint_synchronize_begin() {}
223 virtual void safepoint_synchronize_end() {}
224
225 void initialize_reserved_region(const ReservedHeapSpace& rs);
226
227 virtual size_t capacity() const = 0;
228 virtual size_t used() const = 0;
229
230 // Returns unused capacity.
231 virtual size_t unused() const;
232
233 // Return "true" if the part of the heap that allocates Java
234 // objects has reached the maximal committed limit that it can
235 // reach, without a garbage collection.
236 virtual bool is_maximal_no_gc() const = 0;
237
238 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
239 // memory that the vm could make available for storing 'normal' java objects.
240 // This is based on the reserved address space, but should not include space
241 // that the vm uses internally for bookkeeping or temporary storage
242 // (e.g., in the case of the young gen, one of the survivor
243 // spaces).
244 virtual size_t max_capacity() const = 0;
245
246 // Returns "TRUE" iff "p" points into the committed areas of the heap.
247 // This method can be expensive so avoid using it in performance critical
248 // code.
249 virtual bool is_in(const void* p) const = 0;
250
251 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
252
253 virtual uint32_t hash_oop(oop obj) const;
254
255 void set_gc_cause(GCCause::Cause v) {
256 if (UsePerfData) {
257 _gc_lastcause = _gc_cause;
258 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
259 _perf_gc_cause->set_value(GCCause::to_string(v));
260 }
261 _gc_cause = v;
262 }
263 GCCause::Cause gc_cause() { return _gc_cause; }
264
265 oop obj_allocate(Klass* klass, int size, TRAPS);
266 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
267 oop class_allocate(Klass* klass, int size, TRAPS);
268
269 // Utilities for turning raw memory into filler objects.
270 //
271 // min_fill_size() is the smallest region that can be filled.
272 // fill_with_objects() can fill arbitrary-sized regions of the heap using
273 // multiple objects. fill_with_object() is for regions known to be smaller
274 // than the largest array of integers; it uses a single object to fill the
275 // region and has slightly less overhead.
276 static size_t min_fill_size() {
277 return size_t(align_object_size(oopDesc::header_size()));
278 }
279
280 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
281
282 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
283 static void fill_with_object(MemRegion region, bool zap = true) {
284 fill_with_object(region.start(), region.word_size(), zap);
285 }
286 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
287 fill_with_object(start, pointer_delta(end, start), zap);
288 }
289
290 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
291 virtual size_t min_dummy_object_size() const;
292 size_t tlab_alloc_reserve() const;
293
294 // Return the address "addr" aligned by "alignment_in_bytes" if such
295 // an address is below "end". Return NULL otherwise.
296 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
297 HeapWord* end,
298 unsigned short alignment_in_bytes);
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 // Section on thread-local allocation buffers (TLABs)
339 // If the heap supports thread-local allocation buffers, it should override
340 // the following methods:
341 // Returns "true" iff the heap supports thread-local allocation buffers.
342 // The default is "no".
343 virtual bool supports_tlab_allocation() const = 0;
344
345 // The amount of space available for thread-local allocation buffers.
346 virtual size_t tlab_capacity(Thread *thr) const = 0;
347
348 // The amount of used space for thread-local allocation buffers for the given thread.
349 virtual size_t tlab_used(Thread *thr) const = 0;
350
351 virtual size_t max_tlab_size() const;
352
353 // An estimate of the maximum allocation that could be performed
354 // for thread-local allocation buffers without triggering any
355 // collection or expansion activity.
356 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
357 guarantee(false, "thread-local allocation buffers not supported");
358 return 0;
359 }
360
361 // Perform a collection of the heap; intended for use in implementing
362 // "System.gc". This probably implies as full a collection as the
363 // "CollectedHeap" supports.
364 virtual void collect(GCCause::Cause cause) = 0;
365
366 // Perform a full collection
367 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
368
369 // This interface assumes that it's being called by the
370 // vm thread. It collects the heap assuming that the
371 // heap lock is already held and that we are executing in
372 // the context of the vm thread.
373 virtual void collect_as_vm_thread(GCCause::Cause cause);
374
375 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
376 size_t size,
377 Metaspace::MetadataType mdtype);
378
379 // Returns "true" iff there is a stop-world GC in progress. (I assume
380 // that it should answer "false" for the concurrent part of a concurrent
381 // collector -- dld).
382 bool is_gc_active() const { return _is_gc_active; }
383
384 // Total number of GC collections (started)
385 unsigned int total_collections() const { return _total_collections; }
386 unsigned int total_full_collections() const { return _total_full_collections;}
387
388 // Increment total number of GC collections (started)
389 void increment_total_collections(bool full = false) {
390 _total_collections++;
391 if (full) {
392 increment_total_full_collections();
393 }
394 }
395
396 void increment_total_full_collections() { _total_full_collections++; }
397
398 // Return the SoftRefPolicy for the heap;
399 virtual SoftRefPolicy* soft_ref_policy() = 0;
400
401 virtual MemoryUsage memory_usage();
402 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
403 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
404
405 // Iterate over all objects, calling "cl.do_object" on each.
406 virtual void object_iterate(ObjectClosure* cl) = 0;
407
408 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
409 virtual void keep_alive(oop obj) {}
410
411 // Perform any cleanup actions necessary before allowing a verification.
412 virtual void prepare_for_verify() = 0;
413
414 // Returns the longest time (in ms) that has elapsed since the last
415 // time that any part of the heap was examined by a garbage collection.
416 jlong millis_since_last_whole_heap_examined();
417 // GC should call this when the next whole heap analysis has completed to
418 // satisfy above requirement.
419 void next_whole_heap_examined();
420
421 private:
422 // Generate any dumps preceding or following a full gc
423 void full_gc_dump(GCTimer* timer, bool before);
424
425 virtual void initialize_serviceability() = 0;
426
427 public:
428 void pre_full_gc_dump(GCTimer* timer);
429 void post_full_gc_dump(GCTimer* timer);
430
431 virtual VirtualSpaceSummary create_heap_space_summary();
432 GCHeapSummary create_heap_summary();
433
434 MetaspaceSummary create_metaspace_summary();
435
436 // Print heap information on the given outputStream.
437 virtual void print_on(outputStream* st) const = 0;
438 // The default behavior is to call print_on() on tty.
439 virtual void print() const;
440
441 // Print more detailed heap information on the given
442 // outputStream. The default behavior is to call print_on(). It is
443 // up to each subclass to override it and add any additional output
444 // it needs.
445 virtual void print_extended_on(outputStream* st) const {
446 print_on(st);
447 }
448
449 virtual void print_on_error(outputStream* st) const;
450
451 // Used to print information about locations in the hs_err file.
452 virtual bool print_location(outputStream* st, void* addr) const = 0;
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 gc control via WhiteBox is supported by
478 // this collector. The default implementation returns false.
479 virtual bool supports_concurrent_gc_breakpoints() const;
480
481 // Provides a thread pool to SafepointSynchronize to use
482 // for parallel safepoint cleanup.
483 // GCs that use a GC worker thread pool may want to share
484 // it for use during safepoint cleanup. This is only possible
485 // if the GC can pause and resume concurrent work (e.g. G1
486 // concurrent marking) for an intermittent non-GC safepoint.
487 // If this method returns NULL, SafepointSynchronize will
488 // perform cleanup tasks serially in the VMThread.
489 virtual WorkGang* get_safepoint_workers() { return NULL; }
490
491 // Support for object pinning. This is used by JNI Get*Critical()
492 // and Release*Critical() family of functions. If supported, the GC
493 // must guarantee that pinned objects never move.
494 virtual bool supports_object_pinning() const;
495 virtual oop pin_object(JavaThread* thread, oop obj);
496 virtual void unpin_object(JavaThread* thread, oop obj);
497
498 // Deduplicate the string, iff the GC supports string deduplication.
499 virtual void deduplicate_string(oop str);
500
501 virtual bool is_oop(oop object) const;
502
503 // Non product verification and debugging.
504 #ifndef PRODUCT
505 // Support for PromotionFailureALot. Return true if it's time to cause a
506 // promotion failure. The no-argument version uses
507 // this->_promotion_failure_alot_count as the counter.
508 bool promotion_should_fail(volatile size_t* count);
509 bool promotion_should_fail();
510
511 // Reset the PromotionFailureALot counters. Should be called at the end of a
512 // GC in which promotion failure occurred.
513 void reset_promotion_should_fail(volatile size_t* count);
514 void reset_promotion_should_fail();
515 #endif // #ifndef PRODUCT
516 };
517
518 // Class to set and reset the GC cause for a CollectedHeap.
519
520 class GCCauseSetter : StackObj {
521 CollectedHeap* _heap;
522 GCCause::Cause _previous_cause;
523 public:
524 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
525 _heap = heap;
526 _previous_cause = _heap->gc_cause();
527 _heap->set_gc_cause(cause);
528 }
529
530 ~GCCauseSetter() {
531 _heap->set_gc_cause(_previous_cause);
532 }
533 };
534
535 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP