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/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 unsigned int _total_collections; // ... started
116 unsigned int _total_full_collections; // ... started
117 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
118 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
119
120 // Reason for current garbage collection. Should be set to
121 // a value reflecting no collection between collections.
122 GCCause::Cause _gc_cause;
123 GCCause::Cause _gc_lastcause;
124 PerfStringVariable* _perf_gc_cause;
125 PerfStringVariable* _perf_gc_lastcause;
126
127 // Constructor
128 CollectedHeap();
129
130 // Create a new tlab. All TLAB allocations must go through this.
131 // To allow more flexible TLAB allocations min_size specifies
132 // the minimum size needed, while requested_size is the requested
133 // size based on ergonomics. The actually allocated size will be
134 // returned in actual_size.
135 virtual HeapWord* allocate_new_tlab(size_t min_size,
136 size_t requested_size,
137 size_t* actual_size);
138
139 // Reinitialize tlabs before resuming mutators.
140 virtual void resize_all_tlabs();
141
142 // Raw memory allocation facilities
143 // The obj and array allocate methods are covers for these methods.
144 // mem_allocate() should never be
145 // called to allocate TLABs, only individual objects.
146 virtual HeapWord* mem_allocate(size_t size,
147 bool* gc_overhead_limit_was_exceeded) = 0;
148
149 // Filler object utilities.
150 static inline size_t filler_array_hdr_size();
151 static inline size_t filler_array_min_size();
152
153 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
154 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
155
156 // Fill with a single array; caller must ensure filler_array_min_size() <=
157 // words <= filler_array_max_size().
158 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
159
160 // Fill with a single object (either an int array or a java.lang.Object).
161 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
162
163 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
164
165 // Verification functions
166 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
167 PRODUCT_RETURN;
168 debug_only(static void check_for_valid_allocation_state();)
169
170 public:
171 enum Name {
172 None,
173 Serial,
174 Parallel,
175 G1,
176 Epsilon,
177 Z,
178 Shenandoah
179 };
180
181 protected:
182 // Get a pointer to the derived heap object. Used to implement
183 // derived class heap() functions rather than being called directly.
184 template<typename T>
185 static T* named_heap(Name kind) {
186 CollectedHeap* heap = Universe::heap();
187 assert(heap != NULL, "Uninitialized heap");
188 assert(kind == heap->kind(), "Heap kind %u should be %u",
189 static_cast<uint>(heap->kind()), static_cast<uint>(kind));
190 return static_cast<T*>(heap);
191 }
192
193 public:
194
195 static inline size_t filler_array_max_size() {
196 return _filler_array_max_size;
197 }
198
199 virtual Name kind() const = 0;
200
201 virtual const char* name() const = 0;
202
203 /**
204 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
205 * and JNI_OK on success.
206 */
207 virtual jint initialize() = 0;
208
209 // In many heaps, there will be a need to perform some initialization activities
210 // after the Universe is fully formed, but before general heap allocation is allowed.
211 // This is the correct place to place such initialization methods.
212 virtual void post_initialize();
213
214 // Stop any onging concurrent work and prepare for exit.
215 virtual void stop() {}
216
217 // Stop and resume concurrent GC threads interfering with safepoint operations
218 virtual void safepoint_synchronize_begin() {}
219 virtual void safepoint_synchronize_end() {}
220
221 void initialize_reserved_region(const ReservedHeapSpace& rs);
222
223 virtual size_t capacity() const = 0;
224 virtual size_t used() const = 0;
225
226 // Returns unused capacity.
227 virtual size_t unused() const;
228
229 // Return "true" if the part of the heap that allocates Java
230 // objects has reached the maximal committed limit that it can
231 // reach, without a garbage collection.
232 virtual bool is_maximal_no_gc() const = 0;
233
234 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
235 // memory that the vm could make available for storing 'normal' java objects.
236 // This is based on the reserved address space, but should not include space
237 // that the vm uses internally for bookkeeping or temporary storage
238 // (e.g., in the case of the young gen, one of the survivor
239 // spaces).
240 virtual size_t max_capacity() const = 0;
241
242 // Returns "TRUE" iff "p" points into the committed areas of the heap.
243 // This method can be expensive so avoid using it in performance critical
244 // code.
245 virtual bool is_in(const void* p) const = 0;
246
247 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
248
249 virtual uint32_t hash_oop(oop obj) const;
250
251 void set_gc_cause(GCCause::Cause v) {
252 if (UsePerfData) {
253 _gc_lastcause = _gc_cause;
254 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
255 _perf_gc_cause->set_value(GCCause::to_string(v));
256 }
257 _gc_cause = v;
258 }
259 GCCause::Cause gc_cause() { return _gc_cause; }
260
261 oop obj_allocate(Klass* klass, int size, TRAPS);
262 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
263 oop class_allocate(Klass* klass, int size, TRAPS);
264
265 // Utilities for turning raw memory into filler objects.
266 //
267 // min_fill_size() is the smallest region that can be filled.
268 // fill_with_objects() can fill arbitrary-sized regions of the heap using
269 // multiple objects. fill_with_object() is for regions known to be smaller
270 // than the largest array of integers; it uses a single object to fill the
271 // region and has slightly less overhead.
272 static size_t min_fill_size() {
273 return size_t(align_object_size(oopDesc::header_size()));
274 }
275
276 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
277
278 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
279 static void fill_with_object(MemRegion region, bool zap = true) {
280 fill_with_object(region.start(), region.word_size(), zap);
281 }
282 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
283 fill_with_object(start, pointer_delta(end, start), zap);
284 }
285
286 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
287 virtual size_t min_dummy_object_size() const;
288 size_t tlab_alloc_reserve() const;
289
290 // Return the address "addr" aligned by "alignment_in_bytes" if such
291 // an address is below "end". Return NULL otherwise.
292 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
293 HeapWord* end,
294 unsigned short alignment_in_bytes);
295
296 // Some heaps may offer a contiguous region for shared non-blocking
297 // allocation, via inlined code (by exporting the address of the top and
298 // end fields defining the extent of the contiguous allocation region.)
299
300 // This function returns "true" iff the heap supports this kind of
301 // allocation. (Default is "no".)
302 virtual bool supports_inline_contig_alloc() const {
303 return false;
304 }
305 // These functions return the addresses of the fields that define the
306 // boundaries of the contiguous allocation area. (These fields should be
307 // physically near to one another.)
308 virtual HeapWord* volatile* top_addr() const {
309 guarantee(false, "inline contiguous allocation not supported");
310 return NULL;
311 }
312 virtual HeapWord** end_addr() const {
313 guarantee(false, "inline contiguous allocation not supported");
314 return NULL;
315 }
316
317 // Some heaps may be in an unparseable state at certain times between
318 // collections. This may be necessary for efficient implementation of
319 // certain allocation-related activities. Calling this function before
320 // attempting to parse a heap ensures that the heap is in a parsable
321 // state (provided other concurrent activity does not introduce
322 // unparsability). It is normally expected, therefore, that this
323 // method is invoked with the world stopped.
324 // NOTE: if you override this method, make sure you call
325 // super::ensure_parsability so that the non-generational
326 // part of the work gets done. See implementation of
327 // CollectedHeap::ensure_parsability and, for instance,
328 // that of GenCollectedHeap::ensure_parsability().
329 // The argument "retire_tlabs" controls whether existing TLABs
330 // are merely filled or also retired, thus preventing further
331 // allocation from them and necessitating allocation of new TLABs.
332 virtual void ensure_parsability(bool retire_tlabs);
333
334 // Section on thread-local allocation buffers (TLABs)
335 // If the heap supports thread-local allocation buffers, it should override
336 // the following methods:
337 // Returns "true" iff the heap supports thread-local allocation buffers.
338 // The default is "no".
339 virtual bool supports_tlab_allocation() const = 0;
340
341 // The amount of space available for thread-local allocation buffers.
342 virtual size_t tlab_capacity(Thread *thr) const = 0;
343
344 // The amount of used space for thread-local allocation buffers for the given thread.
345 virtual size_t tlab_used(Thread *thr) const = 0;
346
347 virtual size_t max_tlab_size() const;
348
349 // An estimate of the maximum allocation that could be performed
350 // for thread-local allocation buffers without triggering any
351 // collection or expansion activity.
352 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
353 guarantee(false, "thread-local allocation buffers not supported");
354 return 0;
355 }
356
357 // Perform a collection of the heap; intended for use in implementing
358 // "System.gc". This probably implies as full a collection as the
359 // "CollectedHeap" supports.
360 virtual void collect(GCCause::Cause cause) = 0;
361
362 // Perform a full collection
363 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
364
365 // This interface assumes that it's being called by the
366 // vm thread. It collects the heap assuming that the
367 // heap lock is already held and that we are executing in
368 // the context of the vm thread.
369 virtual void collect_as_vm_thread(GCCause::Cause cause);
370
371 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
372 size_t size,
373 Metaspace::MetadataType mdtype);
374
375 // Returns "true" iff there is a stop-world GC in progress. (I assume
376 // that it should answer "false" for the concurrent part of a concurrent
377 // collector -- dld).
378 bool is_gc_active() const { return _is_gc_active; }
379
380 // Total number of GC collections (started)
381 unsigned int total_collections() const { return _total_collections; }
382 unsigned int total_full_collections() const { return _total_full_collections;}
383
384 // Increment total number of GC collections (started)
385 void increment_total_collections(bool full = false) {
386 _total_collections++;
387 if (full) {
388 increment_total_full_collections();
389 }
390 }
391
392 void increment_total_full_collections() { _total_full_collections++; }
393
394 // Return the SoftRefPolicy for the heap;
395 virtual SoftRefPolicy* soft_ref_policy() = 0;
396
397 virtual MemoryUsage memory_usage();
398 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
399 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
400
401 // Iterate over all objects, calling "cl.do_object" on each.
402 virtual void object_iterate(ObjectClosure* cl) = 0;
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 // Iterator for all GC threads (other than VM thread)
448 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
449
450 // Print any relevant tracing info that flags imply.
451 // Default implementation does nothing.
452 virtual void print_tracing_info() const = 0;
453
454 void print_heap_before_gc();
455 void print_heap_after_gc();
456
457 // Registering and unregistering an nmethod (compiled code) with the heap.
458 virtual void register_nmethod(nmethod* nm) = 0;
459 virtual void unregister_nmethod(nmethod* nm) = 0;
460 // Callback for when nmethod is about to be deleted.
461 virtual void flush_nmethod(nmethod* nm) = 0;
462 virtual void verify_nmethod(nmethod* nm) = 0;
463
464 void trace_heap_before_gc(const GCTracer* gc_tracer);
465 void trace_heap_after_gc(const GCTracer* gc_tracer);
466
467 // Heap verification
468 virtual void verify(VerifyOption option) = 0;
469
470 // Return true if concurrent gc control via WhiteBox is supported by
471 // this collector. The default implementation returns false.
472 virtual bool supports_concurrent_gc_breakpoints() const;
473
474 // Provides a thread pool to SafepointSynchronize to use
475 // for parallel safepoint cleanup.
476 // GCs that use a GC worker thread pool may want to share
477 // it for use during safepoint cleanup. This is only possible
478 // if the GC can pause and resume concurrent work (e.g. G1
479 // concurrent marking) for an intermittent non-GC safepoint.
480 // If this method returns NULL, SafepointSynchronize will
481 // perform cleanup tasks serially in the VMThread.
482 virtual WorkGang* get_safepoint_workers() { return NULL; }
483
484 // Support for object pinning. This is used by JNI Get*Critical()
485 // and Release*Critical() family of functions. If supported, the GC
486 // must guarantee that pinned objects never move.
487 virtual bool supports_object_pinning() const;
488 virtual oop pin_object(JavaThread* thread, oop obj);
489 virtual void unpin_object(JavaThread* thread, oop obj);
490
491 // Deduplicate the string, iff the GC supports string deduplication.
492 virtual void deduplicate_string(oop str);
493
494 virtual bool is_oop(oop object) const;
495
496 // Non product verification and debugging.
497 #ifndef PRODUCT
498 // Support for PromotionFailureALot. Return true if it's time to cause a
499 // promotion failure. The no-argument version uses
500 // this->_promotion_failure_alot_count as the counter.
501 bool promotion_should_fail(volatile size_t* count);
502 bool promotion_should_fail();
503
504 // Reset the PromotionFailureALot counters. Should be called at the end of a
505 // GC in which promotion failure occurred.
506 void reset_promotion_should_fail(volatile size_t* count);
507 void reset_promotion_should_fail();
508 #endif // #ifndef PRODUCT
509 };
510
511 // Class to set and reset the GC cause for a CollectedHeap.
512
513 class GCCauseSetter : StackObj {
514 CollectedHeap* _heap;
515 GCCause::Cause _previous_cause;
516 public:
517 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
518 _heap = heap;
519 _previous_cause = _heap->gc_cause();
520 _heap->set_gc_cause(cause);
521 }
522
523 ~GCCauseSetter() {
524 _heap->set_gc_cause(_previous_cause);
525 }
526 };
527
528 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP