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.
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 "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/formatBuffer.hpp"
38 #include "utilities/growableArray.hpp"
39
40 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
41 // is an abstract class: there may be many different kinds of heaps. This
42 // class defines the functions that a heap must implement, and contains
43 // infrastructure common to all heaps.
44
45 class AdaptiveSizePolicy;
46 class BarrierSet;
47 class GCHeapSummary;
48 class GCTimer;
49 class GCTracer;
50 class GCMemoryManager;
51 class MemoryPool;
52 class MetaspaceSummary;
53 class ReservedHeapSpace;
54 class SoftRefPolicy;
55 class Thread;
56 class ThreadClosure;
57 class VirtualSpaceSummary;
58 class WorkGang;
59 class nmethod;
60
61 class GCMessage : public FormatBuffer<1024> {
62 public:
63 bool is_before;
64
65 public:
66 GCMessage() {}
67 };
68
69 class CollectedHeap;
70 class GCHeapLog;
71
72 //
73 // CollectedHeap
74 // GenCollectedHeap
75 // SerialHeap
76 // CMSHeap
77 // G1CollectedHeap
78 // ParallelScavengeHeap
79 // ShenandoahHeap
80 // ZCollectedHeap
81 //
82 class CollectedHeap : public CHeapObj<mtInternal> {
83 friend class VMStructs;
84 friend class JVMCIVMStructs;
85 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
86 friend class MemAllocator;
87
88 private:
89 GCHeapLog* _gc_heap_log;
90
91 protected:
92 // Not used by all GCs
93 MemRegion _reserved;
94
95 bool _is_gc_active;
96
97 // Used for filler objects (static, but initialized in ctor).
98 static size_t _filler_array_max_size;
99
100 unsigned int _total_collections; // ... started
101 unsigned int _total_full_collections; // ... started
102 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
103 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
104
105 // Reason for current garbage collection. Should be set to
106 // a value reflecting no collection between collections.
107 GCCause::Cause _gc_cause;
108 GCCause::Cause _gc_lastcause;
109 PerfStringVariable* _perf_gc_cause;
110 PerfStringVariable* _perf_gc_lastcause;
111
112 // Constructor
113 CollectedHeap();
114
115 // Create a new tlab. All TLAB allocations must go through this.
116 // To allow more flexible TLAB allocations min_size specifies
117 // the minimum size needed, while requested_size is the requested
118 // size based on ergonomics. The actually allocated size will be
119 // returned in actual_size.
120 virtual HeapWord* allocate_new_tlab(size_t min_size,
121 size_t requested_size,
122 size_t* actual_size);
123
124 // Reinitialize tlabs before resuming mutators.
125 virtual void resize_all_tlabs();
126
127 // Raw memory allocation facilities
128 // The obj and array allocate methods are covers for these methods.
129 // mem_allocate() should never be
130 // called to allocate TLABs, only individual objects.
131 virtual HeapWord* mem_allocate(size_t size,
132 bool* gc_overhead_limit_was_exceeded) = 0;
133
134 // Filler object utilities.
135 static inline size_t filler_array_hdr_size();
136 static inline size_t filler_array_min_size();
137
138 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
139 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
140
141 // Fill with a single array; caller must ensure filler_array_min_size() <=
142 // words <= filler_array_max_size().
143 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
144
145 // Fill with a single object (either an int array or a java.lang.Object).
146 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
147
148 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
149
150 // Verification functions
151 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
152 PRODUCT_RETURN;
153 debug_only(static void check_for_valid_allocation_state();)
154
155 public:
156 enum Name {
157 None,
158 Serial,
159 Parallel,
160 CMS,
161 G1,
162 Epsilon,
163 Z,
164 Shenandoah
165 };
166
167 static inline size_t filler_array_max_size() {
168 return _filler_array_max_size;
169 }
170
171 virtual Name kind() const = 0;
172
173 virtual const char* name() const = 0;
174
175 /**
176 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
177 * and JNI_OK on success.
178 */
179 virtual jint initialize() = 0;
180
181 // In many heaps, there will be a need to perform some initialization activities
182 // after the Universe is fully formed, but before general heap allocation is allowed.
183 // This is the correct place to place such initialization methods.
184 virtual void post_initialize();
185
186 // Stop any onging concurrent work and prepare for exit.
187 virtual void stop() {}
188
189 // Stop and resume concurrent GC threads interfering with safepoint operations
190 virtual void safepoint_synchronize_begin() {}
191 virtual void safepoint_synchronize_end() {}
192
193 void initialize_reserved_region(const ReservedHeapSpace& rs);
194
195 virtual size_t capacity() const = 0;
196 virtual size_t used() const = 0;
197
198 // Returns unused capacity.
199 virtual size_t unused() const;
200
201 // Return "true" if the part of the heap that allocates Java
202 // objects has reached the maximal committed limit that it can
203 // reach, without a garbage collection.
204 virtual bool is_maximal_no_gc() const = 0;
205
206 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
207 // memory that the vm could make available for storing 'normal' java objects.
208 // This is based on the reserved address space, but should not include space
209 // that the vm uses internally for bookkeeping or temporary storage
210 // (e.g., in the case of the young gen, one of the survivor
211 // spaces).
212 virtual size_t max_capacity() const = 0;
213
214 // Returns "TRUE" iff "p" points into the committed areas of the heap.
215 // This method can be expensive so avoid using it in performance critical
216 // code.
217 virtual bool is_in(const void* p) const = 0;
218
219 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
220
221 virtual uint32_t hash_oop(oop obj) const;
222
223 void set_gc_cause(GCCause::Cause v) {
224 if (UsePerfData) {
225 _gc_lastcause = _gc_cause;
226 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
227 _perf_gc_cause->set_value(GCCause::to_string(v));
228 }
229 _gc_cause = v;
230 }
231 GCCause::Cause gc_cause() { return _gc_cause; }
232
233 oop obj_allocate(Klass* klass, int size, TRAPS);
234 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
235 oop class_allocate(Klass* klass, int size, TRAPS);
236
237 // Utilities for turning raw memory into filler objects.
238 //
239 // min_fill_size() is the smallest region that can be filled.
240 // fill_with_objects() can fill arbitrary-sized regions of the heap using
241 // multiple objects. fill_with_object() is for regions known to be smaller
242 // than the largest array of integers; it uses a single object to fill the
243 // region and has slightly less overhead.
244 static size_t min_fill_size() {
245 return size_t(align_object_size(oopDesc::header_size()));
246 }
247
248 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
249
250 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
251 static void fill_with_object(MemRegion region, bool zap = true) {
252 fill_with_object(region.start(), region.word_size(), zap);
253 }
254 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
255 fill_with_object(start, pointer_delta(end, start), zap);
256 }
257
258 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
259 virtual size_t min_dummy_object_size() const;
260 size_t tlab_alloc_reserve() const;
261
262 // Return the address "addr" aligned by "alignment_in_bytes" if such
263 // an address is below "end". Return NULL otherwise.
264 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
265 HeapWord* end,
266 unsigned short alignment_in_bytes);
267
268 // Some heaps may offer a contiguous region for shared non-blocking
269 // allocation, via inlined code (by exporting the address of the top and
270 // end fields defining the extent of the contiguous allocation region.)
271
272 // This function returns "true" iff the heap supports this kind of
273 // allocation. (Default is "no".)
274 virtual bool supports_inline_contig_alloc() const {
275 return false;
276 }
277 // These functions return the addresses of the fields that define the
278 // boundaries of the contiguous allocation area. (These fields should be
279 // physically near to one another.)
280 virtual HeapWord* volatile* top_addr() const {
281 guarantee(false, "inline contiguous allocation not supported");
282 return NULL;
283 }
284 virtual HeapWord** end_addr() const {
285 guarantee(false, "inline contiguous allocation not supported");
286 return NULL;
287 }
288
289 // Some heaps may be in an unparseable state at certain times between
290 // collections. This may be necessary for efficient implementation of
291 // certain allocation-related activities. Calling this function before
292 // attempting to parse a heap ensures that the heap is in a parsable
293 // state (provided other concurrent activity does not introduce
294 // unparsability). It is normally expected, therefore, that this
295 // method is invoked with the world stopped.
296 // NOTE: if you override this method, make sure you call
297 // super::ensure_parsability so that the non-generational
298 // part of the work gets done. See implementation of
299 // CollectedHeap::ensure_parsability and, for instance,
300 // that of GenCollectedHeap::ensure_parsability().
301 // The argument "retire_tlabs" controls whether existing TLABs
302 // are merely filled or also retired, thus preventing further
303 // allocation from them and necessitating allocation of new TLABs.
304 virtual void ensure_parsability(bool retire_tlabs);
305
306 // Section on thread-local allocation buffers (TLABs)
307 // If the heap supports thread-local allocation buffers, it should override
308 // the following methods:
309 // Returns "true" iff the heap supports thread-local allocation buffers.
310 // The default is "no".
311 virtual bool supports_tlab_allocation() const = 0;
312
313 // The amount of space available for thread-local allocation buffers.
314 virtual size_t tlab_capacity(Thread *thr) const = 0;
315
316 // The amount of used space for thread-local allocation buffers for the given thread.
317 virtual size_t tlab_used(Thread *thr) const = 0;
318
319 virtual size_t max_tlab_size() const;
320
321 // An estimate of the maximum allocation that could be performed
322 // for thread-local allocation buffers without triggering any
323 // collection or expansion activity.
324 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
325 guarantee(false, "thread-local allocation buffers not supported");
326 return 0;
327 }
328
329 // Perform a collection of the heap; intended for use in implementing
330 // "System.gc". This probably implies as full a collection as the
331 // "CollectedHeap" supports.
332 virtual void collect(GCCause::Cause cause) = 0;
333
334 // Perform a full collection
335 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
336
337 // This interface assumes that it's being called by the
338 // vm thread. It collects the heap assuming that the
339 // heap lock is already held and that we are executing in
340 // the context of the vm thread.
341 virtual void collect_as_vm_thread(GCCause::Cause cause);
342
343 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
344 size_t size,
345 Metaspace::MetadataType mdtype);
346
347 // Returns "true" iff there is a stop-world GC in progress. (I assume
348 // that it should answer "false" for the concurrent part of a concurrent
349 // collector -- dld).
350 bool is_gc_active() const { return _is_gc_active; }
351
352 // Total number of GC collections (started)
353 unsigned int total_collections() const { return _total_collections; }
354 unsigned int total_full_collections() const { return _total_full_collections;}
355
356 // Increment total number of GC collections (started)
357 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
358 void increment_total_collections(bool full = false) {
359 _total_collections++;
360 if (full) {
361 increment_total_full_collections();
362 }
363 }
364
365 void increment_total_full_collections() { _total_full_collections++; }
366
367 // Return the SoftRefPolicy for the heap;
368 virtual SoftRefPolicy* soft_ref_policy() = 0;
369
370 virtual MemoryUsage memory_usage();
371 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
372 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
373
374 // Iterate over all objects, calling "cl.do_object" on each.
375 virtual void object_iterate(ObjectClosure* cl) = 0;
376
377 // Similar to object_iterate() except iterates only
378 // over live objects.
379 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
380
381 // Returns the longest time (in ms) that has elapsed since the last
382 // time that any part of the heap was examined by a garbage collection.
383 virtual jlong millis_since_last_gc() = 0;
384
385 // Perform any cleanup actions necessary before allowing a verification.
386 virtual void prepare_for_verify() = 0;
387
388 // Generate any dumps preceding or following a full gc
389 private:
390 void full_gc_dump(GCTimer* timer, bool before);
391
392 virtual void initialize_serviceability() = 0;
393
394 public:
395 void pre_full_gc_dump(GCTimer* timer);
396 void post_full_gc_dump(GCTimer* timer);
397
398 virtual VirtualSpaceSummary create_heap_space_summary();
399 GCHeapSummary create_heap_summary();
400
401 MetaspaceSummary create_metaspace_summary();
402
403 // Print heap information on the given outputStream.
404 virtual void print_on(outputStream* st) const = 0;
405 // The default behavior is to call print_on() on tty.
406 virtual void print() const;
407
408 // Print more detailed heap information on the given
409 // outputStream. The default behavior is to call print_on(). It is
410 // up to each subclass to override it and add any additional output
411 // it needs.
412 virtual void print_extended_on(outputStream* st) const {
413 print_on(st);
414 }
415
416 virtual void print_on_error(outputStream* st) const;
417
418 // Used to print information about locations in the hs_err file.
419 virtual bool print_location(outputStream* st, void* addr) const = 0;
420
421 // Print all GC threads (other than the VM thread)
422 // used by this heap.
423 virtual void print_gc_threads_on(outputStream* st) const = 0;
424 // The default behavior is to call print_gc_threads_on() on tty.
425 void print_gc_threads() {
426 print_gc_threads_on(tty);
427 }
428 // Iterator for all GC threads (other than VM thread)
429 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
430
431 // Print any relevant tracing info that flags imply.
432 // Default implementation does nothing.
433 virtual void print_tracing_info() const = 0;
434
435 void print_heap_before_gc();
436 void print_heap_after_gc();
437
438 // Registering and unregistering an nmethod (compiled code) with the heap.
439 virtual void register_nmethod(nmethod* nm) = 0;
440 virtual void unregister_nmethod(nmethod* nm) = 0;
441 // Callback for when nmethod is about to be deleted.
442 virtual void flush_nmethod(nmethod* nm) = 0;
443 virtual void verify_nmethod(nmethod* nm) = 0;
444
445 void trace_heap_before_gc(const GCTracer* gc_tracer);
446 void trace_heap_after_gc(const GCTracer* gc_tracer);
447
448 // Heap verification
449 virtual void verify(VerifyOption option) = 0;
450
451 // Return true if concurrent phase control (via
452 // request_concurrent_phase_control) is supported by this collector.
453 // The default implementation returns false.
454 virtual bool supports_concurrent_phase_control() const;
455
456 // Request the collector enter the indicated concurrent phase, and
457 // wait until it does so. Supports WhiteBox testing. Only one
458 // request may be active at a time. Phases are designated by name;
459 // the set of names and their meaning is GC-specific. Once the
460 // requested phase has been reached, the collector will attempt to
461 // avoid transitioning to a new phase until a new request is made.
462 // [Note: A collector might not be able to remain in a given phase.
463 // For example, a full collection might cancel an in-progress
464 // concurrent collection.]
465 //
466 // Returns true when the phase is reached. Returns false for an
467 // unknown phase. The default implementation returns false.
468 virtual bool request_concurrent_phase(const char* phase);
469
470 // Provides a thread pool to SafepointSynchronize to use
471 // for parallel safepoint cleanup.
472 // GCs that use a GC worker thread pool may want to share
473 // it for use during safepoint cleanup. This is only possible
474 // if the GC can pause and resume concurrent work (e.g. G1
475 // concurrent marking) for an intermittent non-GC safepoint.
476 // If this method returns NULL, SafepointSynchronize will
477 // perform cleanup tasks serially in the VMThread.
478 virtual WorkGang* get_safepoint_workers() { return NULL; }
479
480 // Support for object pinning. This is used by JNI Get*Critical()
481 // and Release*Critical() family of functions. If supported, the GC
482 // must guarantee that pinned objects never move.
483 virtual bool supports_object_pinning() const;
484 virtual oop pin_object(JavaThread* thread, oop obj);
485 virtual void unpin_object(JavaThread* thread, oop obj);
486
487 // Deduplicate the string, iff the GC supports string deduplication.
488 virtual void deduplicate_string(oop str);
489
490 virtual bool is_oop(oop object) const;
491
492 virtual size_t obj_size(oop obj) const;
493
494 // Non product verification and debugging.
495 #ifndef PRODUCT
496 // Support for PromotionFailureALot. Return true if it's time to cause a
497 // promotion failure. The no-argument version uses
498 // this->_promotion_failure_alot_count as the counter.
499 bool promotion_should_fail(volatile size_t* count);
500 bool promotion_should_fail();
501
502 // Reset the PromotionFailureALot counters. Should be called at the end of a
503 // GC in which promotion failure occurred.
504 void reset_promotion_should_fail(volatile size_t* count);
505 void reset_promotion_should_fail();
506 #endif // #ifndef PRODUCT
507 };
508
509 // Class to set and reset the GC cause for a CollectedHeap.
510
511 class GCCauseSetter : StackObj {
512 CollectedHeap* _heap;
513 GCCause::Cause _previous_cause;
514 public:
515 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
516 _heap = heap;
517 _previous_cause = _heap->gc_cause();
518 _heap->set_gc_cause(cause);
519 }
520
521 ~GCCauseSetter() {
522 _heap->set_gc_cause(_previous_cause);
523 }
524 };
525
526 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP