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 *
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 "runtime/handles.hpp"
33 #include "runtime/perfData.hpp"
34 #include "runtime/safepoint.hpp"
35 #include "services/memoryUsage.hpp"
36 #include "utilities/debug.hpp"
37 #include "utilities/events.hpp"
38 #include "utilities/formatBuffer.hpp"
39 #include "utilities/growableArray.hpp"
40
41 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
42 // is an abstract class: there may be many different kinds of heaps. This
43 // class defines the functions that a heap must implement, and contains
44 // infrastructure common to all heaps.
45
46 class AdaptiveSizePolicy;
47 class BarrierSet;
48 class GCHeapSummary;
49 class GCTimer;
50 class GCTracer;
51 class GCMemoryManager;
52 class MemoryPool;
53 class MetaspaceSummary;
54 class ReservedHeapSpace;
55 class SoftRefPolicy;
56 class Thread;
57 class ThreadClosure;
58 class VirtualSpaceSummary;
59 class WorkGang;
60 class nmethod;
61
62 class GCMessage : public FormatBuffer<1024> {
63 public:
64 bool is_before;
65
66 public:
67 GCMessage() {}
68 };
69
70 class CollectedHeap;
71
72 class GCHeapLog : public EventLogBase<GCMessage> {
73 private:
74 void log_heap(CollectedHeap* heap, bool before);
75
76 public:
77 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
78
79 void log_heap_before(CollectedHeap* heap) {
80 log_heap(heap, true);
81 }
82 void log_heap_after(CollectedHeap* heap) {
83 log_heap(heap, false);
84 }
85 };
86
87 //
88 // CollectedHeap
89 // GenCollectedHeap
90 // SerialHeap
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 protected:
106 // Not used by all GCs
107 MemRegion _reserved;
108
109 bool _is_gc_active;
110
111 // Used for filler objects (static, but initialized in ctor).
112 static size_t _filler_array_max_size;
113
114 unsigned int _total_collections; // ... started
115 unsigned int _total_full_collections; // ... started
116 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
117 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
118
119 // Reason for current garbage collection. Should be set to
120 // a value reflecting no collection between collections.
121 GCCause::Cause _gc_cause;
122 GCCause::Cause _gc_lastcause;
123 PerfStringVariable* _perf_gc_cause;
124 PerfStringVariable* _perf_gc_lastcause;
125
126 // Constructor
127 CollectedHeap();
128
129 // Create a new tlab. All TLAB allocations must go through this.
130 // To allow more flexible TLAB allocations min_size specifies
131 // the minimum size needed, while requested_size is the requested
132 // size based on ergonomics. The actually allocated size will be
133 // returned in actual_size.
134 virtual HeapWord* allocate_new_tlab(size_t min_size,
135 size_t requested_size,
136 size_t* actual_size);
137
138 // Reinitialize tlabs before resuming mutators.
139 virtual void resize_all_tlabs();
140
141 // Raw memory allocation facilities
142 // The obj and array allocate methods are covers for these methods.
143 // mem_allocate() should never be
144 // called to allocate TLABs, only individual objects.
145 virtual HeapWord* mem_allocate(size_t size,
146 bool* gc_overhead_limit_was_exceeded) = 0;
147
148 // Filler object utilities.
149 static inline size_t filler_array_hdr_size();
150 static inline size_t filler_array_min_size();
151
152 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
153 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
154
155 // Fill with a single array; caller must ensure filler_array_min_size() <=
156 // words <= filler_array_max_size().
157 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
158
159 // Fill with a single object (either an int array or a java.lang.Object).
160 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
161
162 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
163
164 // Verification functions
165 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
166 PRODUCT_RETURN;
167 debug_only(static void check_for_valid_allocation_state();)
168
169 public:
170 enum Name {
171 None,
172 Serial,
173 Parallel,
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 // TODO(tsan): _reserved MemRegion is not available to all collectors.
207 // Should we support collectors without _reserved MemRegion? See 8224815.
208 TSAN_ONLY(MemRegion reserved_region() const { return _reserved; })
209
210 void initialize_reserved_region(const ReservedHeapSpace& rs);
211
212 virtual size_t capacity() const = 0;
213 virtual size_t used() const = 0;
214
215 // Returns unused capacity.
216 virtual size_t unused() const;
217
218 // Return "true" if the part of the heap that allocates Java
219 // objects has reached the maximal committed limit that it can
220 // reach, without a garbage collection.
221 virtual bool is_maximal_no_gc() const = 0;
222
223 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
224 // memory that the vm could make available for storing 'normal' java objects.
225 // This is based on the reserved address space, but should not include space
226 // that the vm uses internally for bookkeeping or temporary storage
227 // (e.g., in the case of the young gen, one of the survivor
228 // spaces).
229 virtual size_t max_capacity() const = 0;
230
231 // Returns "TRUE" iff "p" points into the committed areas of the heap.
232 // This method can be expensive so avoid using it in performance critical
233 // code.
234 virtual bool is_in(const void* p) const = 0;
235
236 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
237
238 virtual uint32_t hash_oop(oop obj) const;
239
240 void set_gc_cause(GCCause::Cause v) {
241 if (UsePerfData) {
242 _gc_lastcause = _gc_cause;
243 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
244 _perf_gc_cause->set_value(GCCause::to_string(v));
245 }
246 _gc_cause = v;
247 }
248 GCCause::Cause gc_cause() { return _gc_cause; }
249
250 oop obj_allocate(Klass* klass, int size, TRAPS);
251 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
252 oop class_allocate(Klass* klass, int size, TRAPS);
253
254 // Utilities for turning raw memory into filler objects.
255 //
256 // min_fill_size() is the smallest region that can be filled.
257 // fill_with_objects() can fill arbitrary-sized regions of the heap using
258 // multiple objects. fill_with_object() is for regions known to be smaller
259 // than the largest array of integers; it uses a single object to fill the
260 // region and has slightly less overhead.
261 static size_t min_fill_size() {
262 return size_t(align_object_size(oopDesc::header_size()));
263 }
264
265 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
266
267 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
268 static void fill_with_object(MemRegion region, bool zap = true) {
269 fill_with_object(region.start(), region.word_size(), zap);
270 }
271 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
272 fill_with_object(start, pointer_delta(end, start), zap);
273 }
274
275 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
276 virtual size_t min_dummy_object_size() const;
277 size_t tlab_alloc_reserve() const;
278
279 // Return the address "addr" aligned by "alignment_in_bytes" if such
280 // an address is below "end". Return NULL otherwise.
281 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
282 HeapWord* end,
283 unsigned short alignment_in_bytes);
284
285 // Some heaps may offer a contiguous region for shared non-blocking
286 // allocation, via inlined code (by exporting the address of the top and
287 // end fields defining the extent of the contiguous allocation region.)
288
289 // This function returns "true" iff the heap supports this kind of
290 // allocation. (Default is "no".)
291 virtual bool supports_inline_contig_alloc() const {
292 return false;
293 }
294 // These functions return the addresses of the fields that define the
295 // boundaries of the contiguous allocation area. (These fields should be
296 // physically near to one another.)
297 virtual HeapWord* volatile* top_addr() const {
298 guarantee(false, "inline contiguous allocation not supported");
299 return NULL;
300 }
301 virtual HeapWord** end_addr() const {
302 guarantee(false, "inline contiguous allocation not supported");
303 return NULL;
304 }
305
306 // Some heaps may be in an unparseable state at certain times between
307 // collections. This may be necessary for efficient implementation of
308 // certain allocation-related activities. Calling this function before
309 // attempting to parse a heap ensures that the heap is in a parsable
310 // state (provided other concurrent activity does not introduce
311 // unparsability). It is normally expected, therefore, that this
312 // method is invoked with the world stopped.
313 // NOTE: if you override this method, make sure you call
314 // super::ensure_parsability so that the non-generational
315 // part of the work gets done. See implementation of
316 // CollectedHeap::ensure_parsability and, for instance,
317 // that of GenCollectedHeap::ensure_parsability().
318 // The argument "retire_tlabs" controls whether existing TLABs
319 // are merely filled or also retired, thus preventing further
320 // allocation from them and necessitating allocation of new TLABs.
321 virtual void ensure_parsability(bool retire_tlabs);
322
323 // Section on thread-local allocation buffers (TLABs)
324 // If the heap supports thread-local allocation buffers, it should override
325 // the following methods:
326 // Returns "true" iff the heap supports thread-local allocation buffers.
327 // The default is "no".
328 virtual bool supports_tlab_allocation() const = 0;
329
330 // The amount of space available for thread-local allocation buffers.
331 virtual size_t tlab_capacity(Thread *thr) const = 0;
332
333 // The amount of used space for thread-local allocation buffers for the given thread.
334 virtual size_t tlab_used(Thread *thr) const = 0;
335
336 virtual size_t max_tlab_size() const;
337
338 // An estimate of the maximum allocation that could be performed
339 // for thread-local allocation buffers without triggering any
340 // collection or expansion activity.
341 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
342 guarantee(false, "thread-local allocation buffers not supported");
343 return 0;
344 }
345
346 // Perform a collection of the heap; intended for use in implementing
347 // "System.gc". This probably implies as full a collection as the
348 // "CollectedHeap" supports.
349 virtual void collect(GCCause::Cause cause) = 0;
350
351 // Perform a full collection
352 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
353
354 // This interface assumes that it's being called by the
355 // vm thread. It collects the heap assuming that the
356 // heap lock is already held and that we are executing in
357 // the context of the vm thread.
358 virtual void collect_as_vm_thread(GCCause::Cause cause);
359
360 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
361 size_t size,
362 Metaspace::MetadataType mdtype);
363
364 // Returns "true" iff there is a stop-world GC in progress. (I assume
365 // that it should answer "false" for the concurrent part of a concurrent
366 // collector -- dld).
367 bool is_gc_active() const { return _is_gc_active; }
368
369 // Total number of GC collections (started)
370 unsigned int total_collections() const { return _total_collections; }
371 unsigned int total_full_collections() const { return _total_full_collections;}
372
373 // Increment total number of GC collections (started)
374 void increment_total_collections(bool full = false) {
375 _total_collections++;
376 if (full) {
377 increment_total_full_collections();
378 }
379 }
380
381 void increment_total_full_collections() { _total_full_collections++; }
382
383 // Return the SoftRefPolicy for the heap;
384 virtual SoftRefPolicy* soft_ref_policy() = 0;
385
386 virtual MemoryUsage memory_usage();
387 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
388 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
389
390 // Iterate over all objects, calling "cl.do_object" on each.
391 virtual void object_iterate(ObjectClosure* cl) = 0;
392
393 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
394 virtual void keep_alive(oop obj) {}
395
396 // Returns the longest time (in ms) that has elapsed since the last
397 // time that any part of the heap was examined by a garbage collection.
398 virtual jlong millis_since_last_gc() = 0;
399
400 // Perform any cleanup actions necessary before allowing a verification.
401 virtual void prepare_for_verify() = 0;
402
403 // Generate any dumps preceding or following a full gc
404 private:
405 void full_gc_dump(GCTimer* timer, bool before);
406
407 virtual void initialize_serviceability() = 0;
408
409 public:
410 void pre_full_gc_dump(GCTimer* timer);
411 void post_full_gc_dump(GCTimer* timer);
412
413 virtual VirtualSpaceSummary create_heap_space_summary();
414 GCHeapSummary create_heap_summary();
415
416 MetaspaceSummary create_metaspace_summary();
417
418 // Print heap information on the given outputStream.
419 virtual void print_on(outputStream* st) const = 0;
420 // The default behavior is to call print_on() on tty.
421 virtual void print() const;
422
423 // Print more detailed heap information on the given
424 // outputStream. The default behavior is to call print_on(). It is
425 // up to each subclass to override it and add any additional output
426 // it needs.
427 virtual void print_extended_on(outputStream* st) const {
428 print_on(st);
429 }
430
431 virtual void print_on_error(outputStream* st) const;
432
433 // Used to print information about locations in the hs_err file.
434 virtual bool print_location(outputStream* st, void* addr) const = 0;
435
436 // Print all GC threads (other than the VM thread)
437 // used by this heap.
438 virtual void print_gc_threads_on(outputStream* st) const = 0;
439 // The default behavior is to call print_gc_threads_on() on tty.
440 void print_gc_threads() {
441 print_gc_threads_on(tty);
442 }
443 // Iterator for all GC threads (other than VM thread)
444 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
445
446 // Print any relevant tracing info that flags imply.
447 // Default implementation does nothing.
448 virtual void print_tracing_info() const = 0;
449
450 void print_heap_before_gc();
451 void print_heap_after_gc();
452
453 // Registering and unregistering an nmethod (compiled code) with the heap.
454 virtual void register_nmethod(nmethod* nm) = 0;
455 virtual void unregister_nmethod(nmethod* nm) = 0;
456 // Callback for when nmethod is about to be deleted.
457 virtual void flush_nmethod(nmethod* nm) = 0;
458 virtual void verify_nmethod(nmethod* nm) = 0;
459
460 void trace_heap_before_gc(const GCTracer* gc_tracer);
461 void trace_heap_after_gc(const GCTracer* gc_tracer);
462
463 // Heap verification
464 virtual void verify(VerifyOption option) = 0;
465
466 // Return true if concurrent phase control (via
467 // request_concurrent_phase_control) is supported by this collector.
468 // The default implementation returns false.
469 virtual bool supports_concurrent_phase_control() const;
470
471 // Request the collector enter the indicated concurrent phase, and
472 // wait until it does so. Supports WhiteBox testing. Only one
473 // request may be active at a time. Phases are designated by name;
474 // the set of names and their meaning is GC-specific. Once the
475 // requested phase has been reached, the collector will attempt to
476 // avoid transitioning to a new phase until a new request is made.
477 // [Note: A collector might not be able to remain in a given phase.
478 // For example, a full collection might cancel an in-progress
479 // concurrent collection.]
480 //
481 // Returns true when the phase is reached. Returns false for an
482 // unknown phase. The default implementation returns false.
483 virtual bool request_concurrent_phase(const char* phase);
484
485 // Provides a thread pool to SafepointSynchronize to use
486 // for parallel safepoint cleanup.
487 // GCs that use a GC worker thread pool may want to share
488 // it for use during safepoint cleanup. This is only possible
489 // if the GC can pause and resume concurrent work (e.g. G1
490 // concurrent marking) for an intermittent non-GC safepoint.
491 // If this method returns NULL, SafepointSynchronize will
492 // perform cleanup tasks serially in the VMThread.
493 virtual WorkGang* get_safepoint_workers() { return NULL; }
494
495 // Support for object pinning. This is used by JNI Get*Critical()
496 // and Release*Critical() family of functions. If supported, the GC
497 // must guarantee that pinned objects never move.
498 virtual bool supports_object_pinning() const;
499 virtual oop pin_object(JavaThread* thread, oop obj);
500 virtual void unpin_object(JavaThread* thread, oop obj);
501
502 // Deduplicate the string, iff the GC supports string deduplication.
503 virtual void deduplicate_string(oop str);
504
505 virtual bool is_oop(oop object) const;
506
507 virtual size_t obj_size(oop obj) const;
508
509 // Non product verification and debugging.
510 #ifndef PRODUCT
511 // Support for PromotionFailureALot. Return true if it's time to cause a
512 // promotion failure. The no-argument version uses
513 // this->_promotion_failure_alot_count as the counter.
514 bool promotion_should_fail(volatile size_t* count);
515 bool promotion_should_fail();
516
517 // Reset the PromotionFailureALot counters. Should be called at the end of a
518 // GC in which promotion failure occurred.
519 void reset_promotion_should_fail(volatile size_t* count);
520 void reset_promotion_should_fail();
521 #endif // #ifndef PRODUCT
522 };
523
524 // Class to set and reset the GC cause for a CollectedHeap.
525
526 class GCCauseSetter : StackObj {
527 CollectedHeap* _heap;
528 GCCause::Cause _previous_cause;
529 public:
530 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
531 _heap = heap;
532 _previous_cause = _heap->gc_cause();
533 _heap->set_gc_cause(cause);
534 }
535
536 ~GCCauseSetter() {
537 _heap->set_gc_cause(_previous_cause);
538 }
539 };
540
541 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP