1 /*
2 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "memory/allocation.hpp"
26 #include "memory/universe.hpp"
27
28 #include "gc/shared/gcArguments.hpp"
29 #include "gc/shared/gcTimer.hpp"
30 #include "gc/shared/gcTraceTime.inline.hpp"
31 #include "gc/shared/memAllocator.hpp"
32 #include "gc/shared/plab.hpp"
33
34 #include "gc/shenandoah/shenandoahAllocTracker.hpp"
35 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
36 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
37 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
38 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
39 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
40 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
41 #include "gc/shenandoah/shenandoahControlThread.hpp"
42 #include "gc/shenandoah/shenandoahFreeSet.hpp"
43 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
44 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
45 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
46 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
47 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
48 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
49 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
50 #include "gc/shenandoah/shenandoahMetrics.hpp"
51 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
52 #include "gc/shenandoah/shenandoahNormalMode.hpp"
53 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
54 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
55 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
56 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
57 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
58 #include "gc/shenandoah/shenandoahStringDedup.hpp"
59 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
60 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
61 #include "gc/shenandoah/shenandoahUtils.hpp"
62 #include "gc/shenandoah/shenandoahVerifier.hpp"
63 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
64 #include "gc/shenandoah/shenandoahVMOperations.hpp"
65 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
66 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
67 #if INCLUDE_JFR
68 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
69 #endif
70
71 #include "memory/metaspace.hpp"
72 #include "oops/compressedOops.inline.hpp"
73 #include "runtime/globals.hpp"
74 #include "runtime/interfaceSupport.inline.hpp"
75 #include "runtime/safepointMechanism.hpp"
76 #include "runtime/vmThread.hpp"
77 #include "services/mallocTracker.hpp"
78
79 #ifdef ASSERT
80 template <class T>
81 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
82 T o = RawAccess<>::oop_load(p);
83 if (! CompressedOops::is_null(o)) {
84 oop obj = CompressedOops::decode_not_null(o);
85 shenandoah_assert_not_forwarded(p, obj);
86 }
87 }
88
89 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
90 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
91 #endif
92
93 class ShenandoahPretouchHeapTask : public AbstractGangTask {
94 private:
95 ShenandoahRegionIterator _regions;
96 const size_t _page_size;
97 public:
98 ShenandoahPretouchHeapTask(size_t page_size) :
99 AbstractGangTask("Shenandoah Pretouch Heap"),
100 _page_size(page_size) {}
101
102 virtual void work(uint worker_id) {
103 ShenandoahHeapRegion* r = _regions.next();
104 while (r != NULL) {
105 os::pretouch_memory(r->bottom(), r->end(), _page_size);
106 r = _regions.next();
107 }
108 }
109 };
110
111 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
112 private:
113 ShenandoahRegionIterator _regions;
114 char* _bitmap_base;
115 const size_t _bitmap_size;
116 const size_t _page_size;
117 public:
118 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
119 AbstractGangTask("Shenandoah Pretouch Bitmap"),
120 _bitmap_base(bitmap_base),
121 _bitmap_size(bitmap_size),
122 _page_size(page_size) {}
123
124 virtual void work(uint worker_id) {
125 ShenandoahHeapRegion* r = _regions.next();
126 while (r != NULL) {
127 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
128 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
129 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
130
131 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
132
133 r = _regions.next();
134 }
135 }
136 };
137
138 jint ShenandoahHeap::initialize() {
139 initialize_heuristics();
140
141 //
142 // Figure out heap sizing
143 //
144
145 size_t init_byte_size = InitialHeapSize;
146 size_t min_byte_size = MinHeapSize;
147 size_t max_byte_size = MaxHeapSize;
148 size_t heap_alignment = HeapAlignment;
149
150 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
151
152 if (ShenandoahAlwaysPreTouch) {
153 // Enabled pre-touch means the entire heap is committed right away.
154 init_byte_size = max_byte_size;
155 }
156
157 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
158 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
159
160 _num_regions = ShenandoahHeapRegion::region_count();
161
162 size_t num_committed_regions = init_byte_size / reg_size_bytes;
163 num_committed_regions = MIN2(num_committed_regions, _num_regions);
164 assert(num_committed_regions <= _num_regions, "sanity");
165 _initial_size = num_committed_regions * reg_size_bytes;
166
167 size_t num_min_regions = min_byte_size / reg_size_bytes;
168 num_min_regions = MIN2(num_min_regions, _num_regions);
169 assert(num_min_regions <= _num_regions, "sanity");
170 _minimum_size = num_min_regions * reg_size_bytes;
171
172 _committed = _initial_size;
173
174 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
175 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
176
177 //
178 // Reserve and commit memory for heap
179 //
180
181 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
182 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*) (heap_rs.base() + heap_rs.size()));
183 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
184 _heap_region_special = heap_rs.special();
185
186 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
187 "Misaligned heap: " PTR_FORMAT, p2i(base()));
188
189 #if SHENANDOAH_OPTIMIZED_OBJTASK
190 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
191 // Fail if we ever attempt to address more than we can.
192 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
193 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
194 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
195 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
196 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
197 vm_exit_during_initialization("Fatal Error", buf);
198 }
199 #endif
200
201 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
202 if (!_heap_region_special) {
203 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
204 "Cannot commit heap memory");
205 }
206
207 //
208 // Reserve and commit memory for bitmap(s)
209 //
210
211 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
212 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
213
214 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
215
216 guarantee(bitmap_bytes_per_region != 0,
217 "Bitmap bytes per region should not be zero");
218 guarantee(is_power_of_2(bitmap_bytes_per_region),
219 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
220
221 if (bitmap_page_size > bitmap_bytes_per_region) {
222 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
223 _bitmap_bytes_per_slice = bitmap_page_size;
224 } else {
225 _bitmap_regions_per_slice = 1;
226 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
227 }
228
229 guarantee(_bitmap_regions_per_slice >= 1,
230 "Should have at least one region per slice: " SIZE_FORMAT,
231 _bitmap_regions_per_slice);
232
233 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
234 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
235 _bitmap_bytes_per_slice, bitmap_page_size);
236
237 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
238 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
239 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
240 _bitmap_region_special = bitmap.special();
241
242 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
243 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
244 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
245 if (!_bitmap_region_special) {
246 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
247 "Cannot commit bitmap memory");
248 }
249
250 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
251
252 if (ShenandoahVerify) {
253 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
254 if (!verify_bitmap.special()) {
255 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
256 "Cannot commit verification bitmap memory");
257 }
258 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
259 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
260 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
261 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
262 }
263
264 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
265 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
266 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
267 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
268 _aux_bitmap_region_special = aux_bitmap.special();
269 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
270
271 //
272 // Create regions and region sets
273 //
274
275 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
276 _free_set = new ShenandoahFreeSet(this, _num_regions);
277 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
278
279 {
280 ShenandoahHeapLocker locker(lock());
281
282 size_t size_words = ShenandoahHeapRegion::region_size_words();
283
284 for (size_t i = 0; i < _num_regions; i++) {
285 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
286 bool is_committed = i < num_committed_regions;
287 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
288
289 _marking_context->initialize_top_at_mark_start(r);
290 _regions[i] = r;
291 assert(!collection_set()->is_in(i), "New region should not be in collection set");
292 }
293
294 // Initialize to complete
295 _marking_context->mark_complete();
296
297 _free_set->rebuild();
298 }
299
300 if (ShenandoahAlwaysPreTouch) {
301 assert(!AlwaysPreTouch, "Should have been overridden");
302
303 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
304 // before initialize() below zeroes it with initializing thread. For any given region,
305 // we touch the region and the corresponding bitmaps from the same thread.
306 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
307
308 size_t pretouch_heap_page_size = heap_page_size;
309 size_t pretouch_bitmap_page_size = bitmap_page_size;
310
311 #ifdef LINUX
312 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
313 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
314 // them into huge one. Therefore, we need to pretouch with smaller pages.
315 if (UseTransparentHugePages) {
316 pretouch_heap_page_size = (size_t)os::vm_page_size();
317 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
318 }
319 #endif
320
321 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
322 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
323
324 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
325 _num_regions, pretouch_bitmap_page_size);
326 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
327 _workers->run_task(&bcl);
328
329 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
330 _num_regions, pretouch_heap_page_size);
331 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
332 _workers->run_task(&hcl);
333 }
334
335 //
336 // Initialize the rest of GC subsystems
337 //
338
339 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
340 for (uint worker = 0; worker < _max_workers; worker++) {
341 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
342 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
343 }
344
345 // The call below uses stuff (the SATB* things) that are in G1, but probably
346 // belong into a shared location.
347 ShenandoahBarrierSet::satb_mark_queue_set().initialize(this,
348 20 /* G1SATBProcessCompletedThreshold */,
349 60 /* G1SATBBufferEnqueueingThresholdPercent */);
350
351 _monitoring_support = new ShenandoahMonitoringSupport(this);
352 _phase_timings = new ShenandoahPhaseTimings();
353 ShenandoahStringDedup::initialize();
354 ShenandoahCodeRoots::initialize();
355
356 if (ShenandoahAllocationTrace) {
357 _alloc_tracker = new ShenandoahAllocTracker();
358 }
359
360 if (ShenandoahPacing) {
361 _pacer = new ShenandoahPacer(this);
362 _pacer->setup_for_idle();
363 } else {
364 _pacer = NULL;
365 }
366
367 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
368 new ShenandoahTraversalGC(this, _num_regions) :
369 NULL;
370
371 _control_thread = new ShenandoahControlThread();
372
373 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
374 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
375 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
376 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
377 );
378
379 log_info(gc, init)("Safepointing mechanism: %s",
380 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
381 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
382
383 return JNI_OK;
384 }
385
386 void ShenandoahHeap::initialize_heuristics() {
387 if (ShenandoahGCMode != NULL) {
388 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
389 _gc_mode = new ShenandoahTraversalMode();
390 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
391 _gc_mode = new ShenandoahNormalMode();
392 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
393 _gc_mode = new ShenandoahPassiveMode();
394 } else {
395 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
396 }
397 } else {
398 ShouldNotReachHere();
399 }
400 _gc_mode->initialize_flags();
401 _heuristics = _gc_mode->initialize_heuristics();
402
403 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
404 vm_exit_during_initialization(
405 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
406 _heuristics->name()));
407 }
408 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
409 vm_exit_during_initialization(
410 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
411 _heuristics->name()));
412 }
413 log_info(gc, init)("Shenandoah heuristics: %s",
414 _heuristics->name());
415 }
416
417 #ifdef _MSC_VER
418 #pragma warning( push )
419 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
420 #endif
421
422 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
423 CollectedHeap(),
424 _initial_size(0),
425 _used(0),
426 _committed(0),
427 _bytes_allocated_since_gc_start(0),
428 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
429 _workers(NULL),
430 _safepoint_workers(NULL),
431 _heap_region_special(false),
432 _num_regions(0),
433 _regions(NULL),
434 _update_refs_iterator(this),
435 _control_thread(NULL),
436 _shenandoah_policy(policy),
437 _heuristics(NULL),
438 _free_set(NULL),
439 _scm(new ShenandoahConcurrentMark()),
440 _traversal_gc(NULL),
441 _full_gc(new ShenandoahMarkCompact()),
442 _pacer(NULL),
443 _verifier(NULL),
444 _alloc_tracker(NULL),
445 _phase_timings(NULL),
446 _monitoring_support(NULL),
447 _memory_pool(NULL),
448 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
449 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
450 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
451 _soft_ref_policy(),
452 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
453 _ref_processor(NULL),
454 _marking_context(NULL),
455 _bitmap_size(0),
456 _bitmap_regions_per_slice(0),
457 _bitmap_bytes_per_slice(0),
458 _bitmap_region_special(false),
459 _aux_bitmap_region_special(false),
460 _liveness_cache(NULL),
461 _collection_set(NULL)
462 {
463 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
464 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
465
466 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
467
468 _max_workers = MAX2(_max_workers, 1U);
469 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
470 /* are_GC_task_threads */ true,
471 /* are_ConcurrentGC_threads */ true);
472 if (_workers == NULL) {
473 vm_exit_during_initialization("Failed necessary allocation.");
474 } else {
475 _workers->initialize_workers();
476 }
477
478 if (ShenandoahParallelSafepointThreads > 1) {
479 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
480 ShenandoahParallelSafepointThreads,
481 /* are_GC_task_threads */ false,
482 /* are_ConcurrentGC_threads */ false);
483 _safepoint_workers->initialize_workers();
484 }
485 }
486
487 #ifdef _MSC_VER
488 #pragma warning( pop )
489 #endif
490
491 class ShenandoahResetBitmapTask : public AbstractGangTask {
492 private:
493 ShenandoahRegionIterator _regions;
494
495 public:
496 ShenandoahResetBitmapTask() :
497 AbstractGangTask("Parallel Reset Bitmap Task") {}
498
499 void work(uint worker_id) {
500 ShenandoahHeapRegion* region = _regions.next();
501 ShenandoahHeap* heap = ShenandoahHeap::heap();
502 ShenandoahMarkingContext* const ctx = heap->marking_context();
503 while (region != NULL) {
504 if (heap->is_bitmap_slice_committed(region)) {
505 ctx->clear_bitmap(region);
506 }
507 region = _regions.next();
508 }
509 }
510 };
511
512 void ShenandoahHeap::reset_mark_bitmap() {
513 assert_gc_workers(_workers->active_workers());
514 mark_incomplete_marking_context();
515
516 ShenandoahResetBitmapTask task;
517 _workers->run_task(&task);
518 }
519
520 void ShenandoahHeap::print_on(outputStream* st) const {
521 st->print_cr("Shenandoah Heap");
522 st->print_cr(" " SIZE_FORMAT "K total, " SIZE_FORMAT "K committed, " SIZE_FORMAT "K used",
523 max_capacity() / K, committed() / K, used() / K);
524 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"K regions",
525 num_regions(), ShenandoahHeapRegion::region_size_bytes() / K);
526
527 st->print("Status: ");
528 if (has_forwarded_objects()) st->print("has forwarded objects, ");
529 if (is_concurrent_mark_in_progress()) st->print("marking, ");
530 if (is_evacuation_in_progress()) st->print("evacuating, ");
531 if (is_update_refs_in_progress()) st->print("updating refs, ");
532 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
533 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
534 if (is_full_gc_in_progress()) st->print("full gc, ");
535 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
536
537 if (cancelled_gc()) {
538 st->print("cancelled");
539 } else {
540 st->print("not cancelled");
541 }
542 st->cr();
543
544 st->print_cr("Reserved region:");
545 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
546 p2i(reserved_region().start()),
547 p2i(reserved_region().end()));
548
549 ShenandoahCollectionSet* cset = collection_set();
550 st->print_cr("Collection set:");
551 if (cset != NULL) {
552 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
553 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
554 } else {
555 st->print_cr(" (NULL)");
556 }
557
558 st->cr();
559 MetaspaceUtils::print_on(st);
560
561 if (Verbose) {
562 print_heap_regions_on(st);
563 }
564 }
565
566 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
567 public:
568 void do_thread(Thread* thread) {
569 assert(thread != NULL, "Sanity");
570 assert(thread->is_Worker_thread(), "Only worker thread expected");
571 ShenandoahThreadLocalData::initialize_gclab(thread);
572 }
573 };
574
575 void ShenandoahHeap::post_initialize() {
576 CollectedHeap::post_initialize();
577 MutexLocker ml(Threads_lock);
578
579 ShenandoahInitWorkerGCLABClosure init_gclabs;
580 _workers->threads_do(&init_gclabs);
581
582 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
583 // Now, we will let WorkGang to initialize gclab when new worker is created.
584 _workers->set_initialize_gclab();
585
586 _scm->initialize(_max_workers);
587 _full_gc->initialize(_gc_timer);
588
589 ref_processing_init();
590
591 _heuristics->initialize();
592
593 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
594 }
595
596 size_t ShenandoahHeap::used() const {
597 return OrderAccess::load_acquire(&_used);
598 }
599
600 size_t ShenandoahHeap::committed() const {
601 OrderAccess::acquire();
602 return _committed;
603 }
604
605 void ShenandoahHeap::increase_committed(size_t bytes) {
606 assert_heaplock_or_safepoint();
607 _committed += bytes;
608 }
609
610 void ShenandoahHeap::decrease_committed(size_t bytes) {
611 assert_heaplock_or_safepoint();
612 _committed -= bytes;
613 }
614
615 void ShenandoahHeap::increase_used(size_t bytes) {
616 Atomic::add(bytes, &_used);
617 }
618
619 void ShenandoahHeap::set_used(size_t bytes) {
620 OrderAccess::release_store_fence(&_used, bytes);
621 }
622
623 void ShenandoahHeap::decrease_used(size_t bytes) {
624 assert(used() >= bytes, "never decrease heap size by more than we've left");
625 Atomic::sub(bytes, &_used);
626 }
627
628 void ShenandoahHeap::increase_allocated(size_t bytes) {
629 Atomic::add(bytes, &_bytes_allocated_since_gc_start);
630 }
631
632 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
633 size_t bytes = words * HeapWordSize;
634 if (!waste) {
635 increase_used(bytes);
636 }
637 increase_allocated(bytes);
638 if (ShenandoahPacing) {
639 control_thread()->pacing_notify_alloc(words);
640 if (waste) {
641 pacer()->claim_for_alloc(words, true);
642 }
643 }
644 }
645
646 size_t ShenandoahHeap::capacity() const {
647 return committed();
648 }
649
650 size_t ShenandoahHeap::max_capacity() const {
651 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
652 }
653
654 size_t ShenandoahHeap::min_capacity() const {
655 return _minimum_size;
656 }
657
658 size_t ShenandoahHeap::initial_capacity() const {
659 return _initial_size;
660 }
661
662 bool ShenandoahHeap::is_in(const void* p) const {
663 HeapWord* heap_base = (HeapWord*) base();
664 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
665 return p >= heap_base && p < last_region_end;
666 }
667
668 void ShenandoahHeap::op_uncommit(double shrink_before) {
669 assert (ShenandoahUncommit, "should be enabled");
670
671 // Application allocates from the beginning of the heap, and GC allocates at
672 // the end of it. It is more efficient to uncommit from the end, so that applications
673 // could enjoy the near committed regions. GC allocations are much less frequent,
674 // and therefore can accept the committing costs.
675
676 size_t count = 0;
677 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
678 ShenandoahHeapRegion* r = get_region(i - 1);
679 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
680 ShenandoahHeapLocker locker(lock());
681 if (r->is_empty_committed()) {
682 // Do not uncommit below minimal capacity
683 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
684 break;
685 }
686
687 r->make_uncommitted();
688 count++;
689 }
690 }
691 SpinPause(); // allow allocators to take the lock
692 }
693
694 if (count > 0) {
695 control_thread()->notify_heap_changed();
696 }
697 }
698
699 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
700 // New object should fit the GCLAB size
701 size_t min_size = MAX2(size, PLAB::min_size());
702
703 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
704 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
705 new_size = MIN2(new_size, PLAB::max_size());
706 new_size = MAX2(new_size, PLAB::min_size());
707
708 // Record new heuristic value even if we take any shortcut. This captures
709 // the case when moderately-sized objects always take a shortcut. At some point,
710 // heuristics should catch up with them.
711 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
712
713 if (new_size < size) {
714 // New size still does not fit the object. Fall back to shared allocation.
715 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
716 return NULL;
717 }
718
719 // Retire current GCLAB, and allocate a new one.
720 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
721 gclab->retire();
722
723 size_t actual_size = 0;
724 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
725 if (gclab_buf == NULL) {
726 return NULL;
727 }
728
729 assert (size <= actual_size, "allocation should fit");
730
731 if (ZeroTLAB) {
732 // ..and clear it.
733 Copy::zero_to_words(gclab_buf, actual_size);
734 } else {
735 // ...and zap just allocated object.
736 #ifdef ASSERT
737 // Skip mangling the space corresponding to the object header to
738 // ensure that the returned space is not considered parsable by
739 // any concurrent GC thread.
740 size_t hdr_size = oopDesc::header_size();
741 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
742 #endif // ASSERT
743 }
744 gclab->set_buf(gclab_buf, actual_size);
745 return gclab->allocate(size);
746 }
747
748 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
749 size_t requested_size,
750 size_t* actual_size) {
751 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
752 HeapWord* res = allocate_memory(req);
753 if (res != NULL) {
754 *actual_size = req.actual_size();
755 } else {
756 *actual_size = 0;
757 }
758 return res;
759 }
760
761 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
762 size_t word_size,
763 size_t* actual_size) {
764 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
765 HeapWord* res = allocate_memory(req);
766 if (res != NULL) {
767 *actual_size = req.actual_size();
768 } else {
769 *actual_size = 0;
770 }
771 return res;
772 }
773
774 ShenandoahHeap* ShenandoahHeap::heap() {
775 CollectedHeap* heap = Universe::heap();
776 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
777 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
778 return (ShenandoahHeap*) heap;
779 }
780
781 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
782 CollectedHeap* heap = Universe::heap();
783 return (ShenandoahHeap*) heap;
784 }
785
786 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
787 ShenandoahAllocTrace trace_alloc(req.size(), req.type());
788
789 intptr_t pacer_epoch = 0;
790 bool in_new_region = false;
791 HeapWord* result = NULL;
792
793 if (req.is_mutator_alloc()) {
794 if (ShenandoahPacing) {
795 pacer()->pace_for_alloc(req.size());
796 pacer_epoch = pacer()->epoch();
797 }
798
799 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
800 result = allocate_memory_under_lock(req, in_new_region);
801 }
802
803 // Allocation failed, block until control thread reacted, then retry allocation.
804 //
805 // It might happen that one of the threads requesting allocation would unblock
806 // way later after GC happened, only to fail the second allocation, because
807 // other threads have already depleted the free storage. In this case, a better
808 // strategy is to try again, as long as GC makes progress.
809 //
810 // Then, we need to make sure the allocation was retried after at least one
811 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
812
813 size_t tries = 0;
814
815 while (result == NULL && _progress_last_gc.is_set()) {
816 tries++;
817 control_thread()->handle_alloc_failure(req.size());
818 result = allocate_memory_under_lock(req, in_new_region);
819 }
820
821 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
822 tries++;
823 control_thread()->handle_alloc_failure(req.size());
824 result = allocate_memory_under_lock(req, in_new_region);
825 }
826
827 } else {
828 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
829 result = allocate_memory_under_lock(req, in_new_region);
830 // Do not call handle_alloc_failure() here, because we cannot block.
831 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
832 }
833
834 if (in_new_region) {
835 control_thread()->notify_heap_changed();
836 }
837
838 if (result != NULL) {
839 size_t requested = req.size();
840 size_t actual = req.actual_size();
841
842 assert (req.is_lab_alloc() || (requested == actual),
843 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
844 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
845
846 if (req.is_mutator_alloc()) {
847 notify_mutator_alloc_words(actual, false);
848
849 // If we requested more than we were granted, give the rest back to pacer.
850 // This only matters if we are in the same pacing epoch: do not try to unpace
851 // over the budget for the other phase.
852 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
853 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
854 }
855 } else {
856 increase_used(actual*HeapWordSize);
857 }
858 }
859
860 return result;
861 }
862
863 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
864 ShenandoahHeapLocker locker(lock());
865 return _free_set->allocate(req, in_new_region);
866 }
867
868 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
869 bool* gc_overhead_limit_was_exceeded) {
870 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
871 return allocate_memory(req);
872 }
873
874 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
875 size_t size,
876 Metaspace::MetadataType mdtype) {
877 MetaWord* result;
878
879 // Inform metaspace OOM to GC heuristics if class unloading is possible.
880 if (heuristics()->can_unload_classes()) {
881 ShenandoahHeuristics* h = heuristics();
882 h->record_metaspace_oom();
883 }
884
885 // Expand and retry allocation
886 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
887 if (result != NULL) {
888 return result;
889 }
890
891 // Start full GC
892 collect(GCCause::_metadata_GC_clear_soft_refs);
893
894 // Retry allocation
895 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
896 if (result != NULL) {
897 return result;
898 }
899
900 // Expand and retry allocation
901 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
902 if (result != NULL) {
903 return result;
904 }
905
906 // Out of memory
907 return NULL;
908 }
909
910 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
911 private:
912 ShenandoahHeap* const _heap;
913 Thread* const _thread;
914 public:
915 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
916 _heap(heap), _thread(Thread::current()) {}
917
918 void do_object(oop p) {
919 shenandoah_assert_marked(NULL, p);
920 if (!p->is_forwarded()) {
921 _heap->evacuate_object(p, _thread);
922 }
923 }
924 };
925
926 class ShenandoahEvacuationTask : public AbstractGangTask {
927 private:
928 ShenandoahHeap* const _sh;
929 ShenandoahCollectionSet* const _cs;
930 bool _concurrent;
931 public:
932 ShenandoahEvacuationTask(ShenandoahHeap* sh,
933 ShenandoahCollectionSet* cs,
934 bool concurrent) :
935 AbstractGangTask("Parallel Evacuation Task"),
936 _sh(sh),
937 _cs(cs),
938 _concurrent(concurrent)
939 {}
940
941 void work(uint worker_id) {
942 if (_concurrent) {
943 ShenandoahConcurrentWorkerSession worker_session(worker_id);
944 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
945 ShenandoahEvacOOMScope oom_evac_scope;
946 do_work();
947 } else {
948 ShenandoahParallelWorkerSession worker_session(worker_id);
949 ShenandoahEvacOOMScope oom_evac_scope;
950 do_work();
951 }
952 }
953
954 private:
955 void do_work() {
956 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
957 ShenandoahHeapRegion* r;
958 while ((r =_cs->claim_next()) != NULL) {
959 assert(r->has_live(), "all-garbage regions are reclaimed early");
960 _sh->marked_object_iterate(r, &cl);
961
962 if (ShenandoahPacing) {
963 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
964 }
965
966 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
967 break;
968 }
969 }
970 }
971 };
972
973 void ShenandoahHeap::trash_cset_regions() {
974 ShenandoahHeapLocker locker(lock());
975
976 ShenandoahCollectionSet* set = collection_set();
977 ShenandoahHeapRegion* r;
978 set->clear_current_index();
979 while ((r = set->next()) != NULL) {
980 r->make_trash();
981 }
982 collection_set()->clear();
983 }
984
985 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
986 st->print_cr("Heap Regions:");
987 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
988 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
989 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
990 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
991
992 for (size_t i = 0; i < num_regions(); i++) {
993 get_region(i)->print_on(st);
994 }
995 }
996
997 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
998 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
999
1000 oop humongous_obj = oop(start->bottom());
1001 size_t size = humongous_obj->size();
1002 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1003 size_t index = start->region_number() + required_regions - 1;
1004
1005 assert(!start->has_live(), "liveness must be zero");
1006
1007 for(size_t i = 0; i < required_regions; i++) {
1008 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1009 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1010 ShenandoahHeapRegion* region = get_region(index --);
1011
1012 assert(region->is_humongous(), "expect correct humongous start or continuation");
1013 assert(!region->is_cset(), "Humongous region should not be in collection set");
1014
1015 region->make_trash_immediate();
1016 }
1017 }
1018
1019 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1020 public:
1021 void do_thread(Thread* thread) {
1022 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1023 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1024 gclab->retire();
1025 }
1026 };
1027
1028 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1029 if (UseTLAB) {
1030 CollectedHeap::ensure_parsability(retire_tlabs);
1031 }
1032 ShenandoahRetireGCLABClosure cl;
1033 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1034 cl.do_thread(t);
1035 }
1036 workers()->threads_do(&cl);
1037 }
1038
1039 void ShenandoahHeap::resize_tlabs() {
1040 CollectedHeap::resize_all_tlabs();
1041 }
1042
1043 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1044 private:
1045 ShenandoahRootEvacuator* _rp;
1046
1047 public:
1048 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1049 AbstractGangTask("Shenandoah evacuate and update roots"),
1050 _rp(rp) {}
1051
1052 void work(uint worker_id) {
1053 ShenandoahParallelWorkerSession worker_session(worker_id);
1054 ShenandoahEvacOOMScope oom_evac_scope;
1055 ShenandoahEvacuateUpdateRootsClosure cl;
1056 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1057 _rp->roots_do(worker_id, &cl);
1058 }
1059 };
1060
1061 void ShenandoahHeap::evacuate_and_update_roots() {
1062 #if COMPILER2_OR_JVMCI
1063 DerivedPointerTable::clear();
1064 #endif
1065 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1066 {
1067 // Include concurrent roots if current cycle can not process those roots concurrently
1068 ShenandoahRootEvacuator rp(workers()->active_workers(),
1069 ShenandoahPhaseTimings::init_evac,
1070 !ShenandoahConcurrentRoots::should_do_concurrent_roots());
1071 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1072 workers()->run_task(&roots_task);
1073 }
1074
1075 #if COMPILER2_OR_JVMCI
1076 DerivedPointerTable::update_pointers();
1077 #endif
1078 }
1079
1080 // Returns size in bytes
1081 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1082 if (ShenandoahElasticTLAB) {
1083 // With Elastic TLABs, return the max allowed size, and let the allocation path
1084 // figure out the safe size for current allocation.
1085 return ShenandoahHeapRegion::max_tlab_size_bytes();
1086 } else {
1087 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1088 }
1089 }
1090
1091 size_t ShenandoahHeap::max_tlab_size() const {
1092 // Returns size in words
1093 return ShenandoahHeapRegion::max_tlab_size_words();
1094 }
1095
1096 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1097 public:
1098 void do_thread(Thread* thread) {
1099 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1100 gclab->retire();
1101 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1102 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1103 }
1104 }
1105 };
1106
1107 void ShenandoahHeap::retire_and_reset_gclabs() {
1108 ShenandoahRetireAndResetGCLABClosure cl;
1109 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1110 cl.do_thread(t);
1111 }
1112 workers()->threads_do(&cl);
1113 }
1114
1115 void ShenandoahHeap::collect(GCCause::Cause cause) {
1116 control_thread()->request_gc(cause);
1117 }
1118
1119 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1120 //assert(false, "Shouldn't need to do full collections");
1121 }
1122
1123 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1124 Space* sp = heap_region_containing(addr);
1125 if (sp != NULL) {
1126 return sp->block_start(addr);
1127 }
1128 return NULL;
1129 }
1130
1131 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1132 Space* sp = heap_region_containing(addr);
1133 return sp->block_is_obj(addr);
1134 }
1135
1136 jlong ShenandoahHeap::millis_since_last_gc() {
1137 double v = heuristics()->time_since_last_gc() * 1000;
1138 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1139 return (jlong)v;
1140 }
1141
1142 void ShenandoahHeap::prepare_for_verify() {
1143 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1144 make_parsable(false);
1145 }
1146 }
1147
1148 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1149 workers()->print_worker_threads_on(st);
1150 if (ShenandoahStringDedup::is_enabled()) {
1151 ShenandoahStringDedup::print_worker_threads_on(st);
1152 }
1153 }
1154
1155 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1156 workers()->threads_do(tcl);
1157 if (_safepoint_workers != NULL) {
1158 _safepoint_workers->threads_do(tcl);
1159 }
1160 if (ShenandoahStringDedup::is_enabled()) {
1161 ShenandoahStringDedup::threads_do(tcl);
1162 }
1163 }
1164
1165 void ShenandoahHeap::print_tracing_info() const {
1166 LogTarget(Info, gc, stats) lt;
1167 if (lt.is_enabled()) {
1168 ResourceMark rm;
1169 LogStream ls(lt);
1170
1171 phase_timings()->print_on(&ls);
1172
1173 ls.cr();
1174 ls.cr();
1175
1176 shenandoah_policy()->print_gc_stats(&ls);
1177
1178 ls.cr();
1179 ls.cr();
1180
1181 if (ShenandoahPacing) {
1182 pacer()->print_on(&ls);
1183 }
1184
1185 ls.cr();
1186 ls.cr();
1187
1188 if (ShenandoahAllocationTrace) {
1189 assert(alloc_tracker() != NULL, "Must be");
1190 alloc_tracker()->print_on(&ls);
1191 } else {
1192 ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1193 }
1194 }
1195 }
1196
1197 void ShenandoahHeap::verify(VerifyOption vo) {
1198 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1199 if (ShenandoahVerify) {
1200 verifier()->verify_generic(vo);
1201 } else {
1202 // TODO: Consider allocating verification bitmaps on demand,
1203 // and turn this on unconditionally.
1204 }
1205 }
1206 }
1207 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1208 return _free_set->capacity();
1209 }
1210
1211 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1212 private:
1213 MarkBitMap* _bitmap;
1214 Stack<oop,mtGC>* _oop_stack;
1215
1216 template <class T>
1217 void do_oop_work(T* p) {
1218 T o = RawAccess<>::oop_load(p);
1219 if (!CompressedOops::is_null(o)) {
1220 oop obj = CompressedOops::decode_not_null(o);
1221 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1222 assert(oopDesc::is_oop(obj), "must be a valid oop");
1223 if (!_bitmap->is_marked((HeapWord*) obj)) {
1224 _bitmap->mark((HeapWord*) obj);
1225 _oop_stack->push(obj);
1226 }
1227 }
1228 }
1229 public:
1230 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1231 _bitmap(bitmap), _oop_stack(oop_stack) {}
1232 void do_oop(oop* p) { do_oop_work(p); }
1233 void do_oop(narrowOop* p) { do_oop_work(p); }
1234 };
1235
1236 /*
1237 * This is public API, used in preparation of object_iterate().
1238 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1239 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1240 * control, we call SH::make_tlabs_parsable().
1241 */
1242 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1243 // No-op.
1244 }
1245
1246 /*
1247 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1248 *
1249 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1250 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1251 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1252 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1253 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1254 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1255 * wiped the bitmap in preparation for next marking).
1256 *
1257 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1258 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1259 * is allowed to report dead objects, but is not required to do so.
1260 */
1261 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1262 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1263 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1264 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1265 return;
1266 }
1267
1268 // Reset bitmap
1269 _aux_bit_map.clear();
1270
1271 Stack<oop,mtGC> oop_stack;
1272
1273 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1274 ShenandoahHeapIterationRootScanner rp;
1275 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1276
1277 if (unload_classes()) {
1278 rp.strong_roots_do(&oops);
1279 } else {
1280 rp.roots_do(&oops);
1281 }
1282
1283 // Work through the oop stack to traverse heap.
1284 while (! oop_stack.is_empty()) {
1285 oop obj = oop_stack.pop();
1286 assert(oopDesc::is_oop(obj), "must be a valid oop");
1287 cl->do_object(obj);
1288 obj->oop_iterate(&oops);
1289 }
1290
1291 assert(oop_stack.is_empty(), "should be empty");
1292
1293 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1294 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1295 }
1296 }
1297
1298 void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) {
1299 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1300 object_iterate(cl);
1301 }
1302
1303 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1304 for (size_t i = 0; i < num_regions(); i++) {
1305 ShenandoahHeapRegion* current = get_region(i);
1306 blk->heap_region_do(current);
1307 }
1308 }
1309
1310 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1311 private:
1312 ShenandoahHeap* const _heap;
1313 ShenandoahHeapRegionClosure* const _blk;
1314
1315 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1316 volatile size_t _index;
1317 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1318
1319 public:
1320 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1321 AbstractGangTask("Parallel Region Task"),
1322 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1323
1324 void work(uint worker_id) {
1325 size_t stride = ShenandoahParallelRegionStride;
1326
1327 size_t max = _heap->num_regions();
1328 while (_index < max) {
1329 size_t cur = Atomic::add(stride, &_index) - stride;
1330 size_t start = cur;
1331 size_t end = MIN2(cur + stride, max);
1332 if (start >= max) break;
1333
1334 for (size_t i = cur; i < end; i++) {
1335 ShenandoahHeapRegion* current = _heap->get_region(i);
1336 _blk->heap_region_do(current);
1337 }
1338 }
1339 }
1340 };
1341
1342 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1343 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1344 if (num_regions() > ShenandoahParallelRegionStride) {
1345 ShenandoahParallelHeapRegionTask task(blk);
1346 workers()->run_task(&task);
1347 } else {
1348 heap_region_iterate(blk);
1349 }
1350 }
1351
1352 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1353 private:
1354 ShenandoahMarkingContext* const _ctx;
1355 public:
1356 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1357
1358 void heap_region_do(ShenandoahHeapRegion* r) {
1359 if (r->is_active()) {
1360 r->clear_live_data();
1361 _ctx->capture_top_at_mark_start(r);
1362 } else {
1363 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1364 assert(_ctx->top_at_mark_start(r) == r->top(),
1365 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1366 }
1367 }
1368
1369 bool is_thread_safe() { return true; }
1370 };
1371
1372 void ShenandoahHeap::op_init_mark() {
1373 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1374 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1375
1376 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1377 assert(!marking_context()->is_complete(), "should not be complete");
1378
1379 if (ShenandoahVerify) {
1380 verifier()->verify_before_concmark();
1381 }
1382
1383 if (VerifyBeforeGC) {
1384 Universe::verify();
1385 }
1386
1387 set_concurrent_mark_in_progress(true);
1388 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1389 {
1390 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1391 make_parsable(true);
1392 }
1393
1394 {
1395 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1396 ShenandoahClearLivenessClosure clc;
1397 parallel_heap_region_iterate(&clc);
1398 }
1399
1400 // Make above changes visible to worker threads
1401 OrderAccess::fence();
1402
1403 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1404
1405 if (UseTLAB) {
1406 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1407 resize_tlabs();
1408 }
1409
1410 if (ShenandoahPacing) {
1411 pacer()->setup_for_mark();
1412 }
1413 }
1414
1415 void ShenandoahHeap::op_mark() {
1416 concurrent_mark()->mark_from_roots();
1417 }
1418
1419 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1420 private:
1421 ShenandoahMarkingContext* const _ctx;
1422 public:
1423 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1424
1425 void heap_region_do(ShenandoahHeapRegion* r) {
1426 if (r->is_active()) {
1427 HeapWord *tams = _ctx->top_at_mark_start(r);
1428 HeapWord *top = r->top();
1429 if (top > tams) {
1430 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1431 }
1432 } else {
1433 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1434 assert(_ctx->top_at_mark_start(r) == r->top(),
1435 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1436 }
1437 }
1438
1439 bool is_thread_safe() { return true; }
1440 };
1441
1442 void ShenandoahHeap::op_final_mark() {
1443 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1444
1445 // It is critical that we
1446 // evacuate roots right after finishing marking, so that we don't
1447 // get unmarked objects in the roots.
1448
1449 if (!cancelled_gc()) {
1450 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1451
1452 if (has_forwarded_objects()) {
1453 // Degen may be caused by failed evacuation of roots
1454 if (is_degenerated_gc_in_progress()) {
1455 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
1456 } else {
1457 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots);
1458 }
1459 }
1460
1461 if (ShenandoahVerify) {
1462 verifier()->verify_roots_no_forwarded();
1463 }
1464
1465 stop_concurrent_marking();
1466
1467 {
1468 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1469
1470 // All allocations past TAMS are implicitly live, adjust the region data.
1471 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1472 ShenandoahCompleteLivenessClosure cl;
1473 parallel_heap_region_iterate(&cl);
1474 }
1475
1476 {
1477 ShenandoahGCPhase prepare_evac(ShenandoahPhaseTimings::prepare_evac);
1478
1479 make_parsable(true);
1480
1481 trash_cset_regions();
1482
1483 {
1484 ShenandoahHeapLocker locker(lock());
1485 _collection_set->clear();
1486 _free_set->clear();
1487
1488 heuristics()->choose_collection_set(_collection_set);
1489
1490 _free_set->rebuild();
1491 }
1492 }
1493
1494 // If collection set has candidates, start evacuation.
1495 // Otherwise, bypass the rest of the cycle.
1496 if (!collection_set()->is_empty()) {
1497 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1498
1499 if (ShenandoahVerify) {
1500 verifier()->verify_before_evacuation();
1501 }
1502
1503 set_evacuation_in_progress(true);
1504 // From here on, we need to update references.
1505 set_has_forwarded_objects(true);
1506
1507 if (!is_degenerated_gc_in_progress()) {
1508 evacuate_and_update_roots();
1509 }
1510
1511 if (ShenandoahPacing) {
1512 pacer()->setup_for_evac();
1513 }
1514
1515 if (ShenandoahVerify) {
1516 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1517 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1518 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1519 verifier()->verify_roots_no_forwarded_except(types);
1520 } else {
1521 verifier()->verify_roots_no_forwarded();
1522 }
1523 verifier()->verify_during_evacuation();
1524 }
1525 } else {
1526 if (ShenandoahVerify) {
1527 verifier()->verify_after_concmark();
1528 }
1529
1530 if (VerifyAfterGC) {
1531 Universe::verify();
1532 }
1533 }
1534
1535 } else {
1536 concurrent_mark()->cancel();
1537 stop_concurrent_marking();
1538
1539 if (process_references()) {
1540 // Abandon reference processing right away: pre-cleaning must have failed.
1541 ReferenceProcessor *rp = ref_processor();
1542 rp->disable_discovery();
1543 rp->abandon_partial_discovery();
1544 rp->verify_no_references_recorded();
1545 }
1546 }
1547 }
1548
1549 void ShenandoahHeap::op_final_evac() {
1550 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1551
1552 set_evacuation_in_progress(false);
1553
1554 retire_and_reset_gclabs();
1555
1556 if (ShenandoahVerify) {
1557 verifier()->verify_after_evacuation();
1558 }
1559
1560 if (VerifyAfterGC) {
1561 Universe::verify();
1562 }
1563 }
1564
1565 void ShenandoahHeap::op_conc_evac() {
1566 ShenandoahEvacuationTask task(this, _collection_set, true);
1567 workers()->run_task(&task);
1568 }
1569
1570 void ShenandoahHeap::op_stw_evac() {
1571 ShenandoahEvacuationTask task(this, _collection_set, false);
1572 workers()->run_task(&task);
1573 }
1574
1575 void ShenandoahHeap::op_updaterefs() {
1576 update_heap_references(true);
1577 }
1578
1579 void ShenandoahHeap::op_cleanup() {
1580 free_set()->recycle_trash();
1581 }
1582
1583 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1584 private:
1585 ShenandoahJNIHandleRoots<true /*concurrent*/> _jni_roots;
1586 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1587 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1588
1589 public:
1590 ShenandoahConcurrentRootsEvacUpdateTask() :
1591 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task") {
1592 }
1593
1594 void work(uint worker_id) {
1595 ShenandoahEvacOOMScope oom;
1596 ShenandoahEvacuateUpdateRootsClosure cl;
1597 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1598
1599 _jni_roots.oops_do<ShenandoahEvacuateUpdateRootsClosure>(&cl);
1600 _cld_roots.cld_do(&clds);
1601 _weak_roots.oops_do<ShenandoahEvacuateUpdateRootsClosure>(&cl);
1602 }
1603 };
1604
1605 void ShenandoahHeap::op_roots() {
1606 if (is_evacuation_in_progress() &&
1607 ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1608 ShenandoahConcurrentRootsEvacUpdateTask task;
1609 workers()->run_task(&task);
1610 }
1611 }
1612
1613 void ShenandoahHeap::op_reset() {
1614 reset_mark_bitmap();
1615 }
1616
1617 void ShenandoahHeap::op_preclean() {
1618 concurrent_mark()->preclean_weak_refs();
1619 }
1620
1621 void ShenandoahHeap::op_init_traversal() {
1622 traversal_gc()->init_traversal_collection();
1623 }
1624
1625 void ShenandoahHeap::op_traversal() {
1626 traversal_gc()->concurrent_traversal_collection();
1627 }
1628
1629 void ShenandoahHeap::op_final_traversal() {
1630 traversal_gc()->final_traversal_collection();
1631 }
1632
1633 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1634 ShenandoahMetricsSnapshot metrics;
1635 metrics.snap_before();
1636
1637 full_gc()->do_it(cause);
1638 if (UseTLAB) {
1639 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1640 resize_all_tlabs();
1641 }
1642
1643 metrics.snap_after();
1644
1645 if (metrics.is_good_progress()) {
1646 _progress_last_gc.set();
1647 } else {
1648 // Nothing to do. Tell the allocation path that we have failed to make
1649 // progress, and it can finally fail.
1650 _progress_last_gc.unset();
1651 }
1652 }
1653
1654 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1655 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1656 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1657 // some phase, we have to upgrade the Degenerate GC to Full GC.
1658
1659 clear_cancelled_gc();
1660
1661 ShenandoahMetricsSnapshot metrics;
1662 metrics.snap_before();
1663
1664 switch (point) {
1665 case _degenerated_traversal:
1666 {
1667 // Drop the collection set. Note: this leaves some already forwarded objects
1668 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1669 // workarounds in ShenandoahTraversalHeuristics.
1670
1671 ShenandoahHeapLocker locker(lock());
1672 collection_set()->clear_current_index();
1673 for (size_t i = 0; i < collection_set()->count(); i++) {
1674 ShenandoahHeapRegion* r = collection_set()->next();
1675 r->make_regular_bypass();
1676 }
1677 collection_set()->clear();
1678 }
1679 op_final_traversal();
1680 op_cleanup();
1681 return;
1682
1683 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1684 // but enters it at different points, depending on which concurrent phase had
1685 // degenerated.
1686
1687 case _degenerated_outside_cycle:
1688 // We have degenerated from outside the cycle, which means something is bad with
1689 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1690 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1691 // we can do the most aggressive degen cycle, which includes processing references and
1692 // class unloading, unless those features are explicitly disabled.
1693 //
1694 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1695 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1696 set_process_references(heuristics()->can_process_references());
1697 set_unload_classes(heuristics()->can_unload_classes());
1698
1699 if (is_traversal_mode()) {
1700 // Not possible to degenerate from here, upgrade to Full GC right away.
1701 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1702 op_degenerated_fail();
1703 return;
1704 }
1705
1706 op_reset();
1707
1708 op_init_mark();
1709 if (cancelled_gc()) {
1710 op_degenerated_fail();
1711 return;
1712 }
1713
1714 case _degenerated_mark:
1715 op_final_mark();
1716 if (cancelled_gc()) {
1717 op_degenerated_fail();
1718 return;
1719 }
1720
1721 op_cleanup();
1722
1723 case _degenerated_evac:
1724 // If heuristics thinks we should do the cycle, this flag would be set,
1725 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1726 if (is_evacuation_in_progress()) {
1727
1728 // Degeneration under oom-evac protocol might have left some objects in
1729 // collection set un-evacuated. Restart evacuation from the beginning to
1730 // capture all objects. For all the objects that are already evacuated,
1731 // it would be a simple check, which is supposed to be fast. This is also
1732 // safe to do even without degeneration, as CSet iterator is at beginning
1733 // in preparation for evacuation anyway.
1734 //
1735 // Before doing that, we need to make sure we never had any cset-pinned
1736 // regions. This may happen if allocation failure happened when evacuating
1737 // the about-to-be-pinned object, oom-evac protocol left the object in
1738 // the collection set, and then the pin reached the cset region. If we continue
1739 // the cycle here, we would trash the cset and alive objects in it. To avoid
1740 // it, we fail degeneration right away and slide into Full GC to recover.
1741
1742 {
1743 collection_set()->clear_current_index();
1744
1745 ShenandoahHeapRegion* r;
1746 while ((r = collection_set()->next()) != NULL) {
1747 if (r->is_pinned()) {
1748 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1749 op_degenerated_fail();
1750 return;
1751 }
1752 }
1753
1754 collection_set()->clear_current_index();
1755 }
1756
1757 op_stw_evac();
1758 if (cancelled_gc()) {
1759 op_degenerated_fail();
1760 return;
1761 }
1762 }
1763
1764 // If heuristics thinks we should do the cycle, this flag would be set,
1765 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1766 if (has_forwarded_objects()) {
1767 op_init_updaterefs();
1768 if (cancelled_gc()) {
1769 op_degenerated_fail();
1770 return;
1771 }
1772 }
1773
1774 case _degenerated_updaterefs:
1775 if (has_forwarded_objects()) {
1776 op_final_updaterefs();
1777 if (cancelled_gc()) {
1778 op_degenerated_fail();
1779 return;
1780 }
1781 }
1782
1783 op_cleanup();
1784 break;
1785
1786 default:
1787 ShouldNotReachHere();
1788 }
1789
1790 if (ShenandoahVerify) {
1791 verifier()->verify_after_degenerated();
1792 }
1793
1794 if (VerifyAfterGC) {
1795 Universe::verify();
1796 }
1797
1798 metrics.snap_after();
1799
1800 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1801 // because that probably means the heap is overloaded and/or fragmented.
1802 if (!metrics.is_good_progress()) {
1803 _progress_last_gc.unset();
1804 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1805 op_degenerated_futile();
1806 } else {
1807 _progress_last_gc.set();
1808 }
1809 }
1810
1811 void ShenandoahHeap::op_degenerated_fail() {
1812 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1813 shenandoah_policy()->record_degenerated_upgrade_to_full();
1814 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1815 }
1816
1817 void ShenandoahHeap::op_degenerated_futile() {
1818 shenandoah_policy()->record_degenerated_upgrade_to_full();
1819 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1820 }
1821
1822 void ShenandoahHeap::stop_concurrent_marking() {
1823 assert(is_concurrent_mark_in_progress(), "How else could we get here?");
1824 set_concurrent_mark_in_progress(false);
1825 if (!cancelled_gc()) {
1826 // If we needed to update refs, and concurrent marking has been cancelled,
1827 // we need to finish updating references.
1828 set_has_forwarded_objects(false);
1829 mark_complete_marking_context();
1830 }
1831 }
1832
1833 void ShenandoahHeap::force_satb_flush_all_threads() {
1834 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
1835 // No need to flush SATBs
1836 return;
1837 }
1838
1839 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1840 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
1841 }
1842 // The threads are not "acquiring" their thread-local data, but it does not
1843 // hurt to "release" the updates here anyway.
1844 OrderAccess::fence();
1845 }
1846
1847 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1848 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1849 ShenandoahThreadLocalData::set_gc_state(t, state);
1850 }
1851 }
1852
1853 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1854 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1855 _gc_state.set_cond(mask, value);
1856 set_gc_state_all_threads(_gc_state.raw_value());
1857 }
1858
1859 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1860 if (has_forwarded_objects()) {
1861 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
1862 } else {
1863 set_gc_state_mask(MARKING, in_progress);
1864 }
1865 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1866 }
1867
1868 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
1869 set_gc_state_mask(TRAVERSAL | HAS_FORWARDED | UPDATEREFS, in_progress);
1870 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1871 }
1872
1873 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1874 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1875 set_gc_state_mask(EVACUATION, in_progress);
1876 }
1877
1878 void ShenandoahHeap::ref_processing_init() {
1879 assert(_max_workers > 0, "Sanity");
1880
1881 _ref_processor =
1882 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
1883 ParallelRefProcEnabled, // MT processing
1884 _max_workers, // Degree of MT processing
1885 true, // MT discovery
1886 _max_workers, // Degree of MT discovery
1887 false, // Reference discovery is not atomic
1888 NULL, // No closure, should be installed before use
1889 true); // Scale worker threads
1890
1891 shenandoah_assert_rp_isalive_not_installed();
1892 }
1893
1894 GCTracer* ShenandoahHeap::tracer() {
1895 return shenandoah_policy()->tracer();
1896 }
1897
1898 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1899 return _free_set->used();
1900 }
1901
1902 bool ShenandoahHeap::try_cancel_gc() {
1903 while (true) {
1904 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1905 if (prev == CANCELLABLE) return true;
1906 else if (prev == CANCELLED) return false;
1907 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1908 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1909 {
1910 // We need to provide a safepoint here, otherwise we might
1911 // spin forever if a SP is pending.
1912 ThreadBlockInVM sp(JavaThread::current());
1913 SpinPause();
1914 }
1915 }
1916 }
1917
1918 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1919 if (try_cancel_gc()) {
1920 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1921 log_info(gc)("%s", msg.buffer());
1922 Events::log(Thread::current(), "%s", msg.buffer());
1923 }
1924 }
1925
1926 uint ShenandoahHeap::max_workers() {
1927 return _max_workers;
1928 }
1929
1930 void ShenandoahHeap::stop() {
1931 // The shutdown sequence should be able to terminate when GC is running.
1932
1933 // Step 0. Notify policy to disable event recording.
1934 _shenandoah_policy->record_shutdown();
1935
1936 // Step 1. Notify control thread that we are in shutdown.
1937 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1938 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1939 control_thread()->prepare_for_graceful_shutdown();
1940
1941 // Step 2. Notify GC workers that we are cancelling GC.
1942 cancel_gc(GCCause::_shenandoah_stop_vm);
1943
1944 // Step 3. Wait until GC worker exits normally.
1945 control_thread()->stop();
1946
1947 // Step 4. Stop String Dedup thread if it is active
1948 if (ShenandoahStringDedup::is_enabled()) {
1949 ShenandoahStringDedup::stop();
1950 }
1951 }
1952
1953 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1954 if (!unload_classes()) return;
1955 bool purged_class;
1956
1957 // Unload classes and purge SystemDictionary.
1958 {
1959 ShenandoahGCPhase phase(full_gc ?
1960 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1961 ShenandoahPhaseTimings::purge_class_unload);
1962 purged_class = SystemDictionary::do_unloading(gc_timer());
1963 }
1964
1965 {
1966 ShenandoahGCPhase phase(full_gc ?
1967 ShenandoahPhaseTimings::full_gc_purge_par :
1968 ShenandoahPhaseTimings::purge_par);
1969 ShenandoahIsAliveSelector is_alive;
1970 uint num_workers = _workers->active_workers();
1971 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
1972 _workers->run_task(&unlink_task);
1973 }
1974
1975 {
1976 ShenandoahGCPhase phase(full_gc ?
1977 ShenandoahPhaseTimings::full_gc_purge_cldg :
1978 ShenandoahPhaseTimings::purge_cldg);
1979 ClassLoaderDataGraph::purge();
1980 }
1981 // Resize and verify metaspace
1982 MetaspaceGC::compute_new_size();
1983 MetaspaceUtils::verify_metrics();
1984 }
1985
1986 // Process leftover weak oops: update them, if needed or assert they do not
1987 // need updating otherwise.
1988 // Weak processor API requires us to visit the oops, even if we are not doing
1989 // anything to them.
1990 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1991 ShenandoahGCPhase root_phase(full_gc ?
1992 ShenandoahPhaseTimings::full_gc_purge :
1993 ShenandoahPhaseTimings::purge);
1994 uint num_workers = _workers->active_workers();
1995 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1996 ShenandoahPhaseTimings::full_gc_purge_par :
1997 ShenandoahPhaseTimings::purge_par;
1998 // Cleanup weak roots
1999 ShenandoahGCPhase phase(timing_phase);
2000 if (has_forwarded_objects()) {
2001 ShenandoahForwardedIsAliveClosure is_alive;
2002 ShenandoahUpdateRefsClosure keep_alive;
2003 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2004 cleaning_task(&is_alive, &keep_alive, num_workers);
2005 _workers->run_task(&cleaning_task);
2006 } else {
2007 ShenandoahIsAliveClosure is_alive;
2008 #ifdef ASSERT
2009 ShenandoahAssertNotForwardedClosure verify_cl;
2010 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2011 cleaning_task(&is_alive, &verify_cl, num_workers);
2012 #else
2013 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2014 cleaning_task(&is_alive, &do_nothing_cl, num_workers);
2015 #endif
2016 _workers->run_task(&cleaning_task);
2017 }
2018 }
2019
2020 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2021 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2022 stw_process_weak_roots(full_gc);
2023 stw_unload_classes(full_gc);
2024 }
2025
2026 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2027 set_gc_state_mask(HAS_FORWARDED, cond);
2028 }
2029
2030 void ShenandoahHeap::set_process_references(bool pr) {
2031 _process_references.set_cond(pr);
2032 }
2033
2034 void ShenandoahHeap::set_unload_classes(bool uc) {
2035 _unload_classes.set_cond(uc);
2036 }
2037
2038 bool ShenandoahHeap::process_references() const {
2039 return _process_references.is_set();
2040 }
2041
2042 bool ShenandoahHeap::unload_classes() const {
2043 return _unload_classes.is_set();
2044 }
2045
2046 address ShenandoahHeap::in_cset_fast_test_addr() {
2047 ShenandoahHeap* heap = ShenandoahHeap::heap();
2048 assert(heap->collection_set() != NULL, "Sanity");
2049 return (address) heap->collection_set()->biased_map_address();
2050 }
2051
2052 address ShenandoahHeap::cancelled_gc_addr() {
2053 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2054 }
2055
2056 address ShenandoahHeap::gc_state_addr() {
2057 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2058 }
2059
2060 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2061 return OrderAccess::load_acquire(&_bytes_allocated_since_gc_start);
2062 }
2063
2064 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2065 OrderAccess::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2066 }
2067
2068 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2069 _degenerated_gc_in_progress.set_cond(in_progress);
2070 }
2071
2072 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2073 _full_gc_in_progress.set_cond(in_progress);
2074 }
2075
2076 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2077 assert (is_full_gc_in_progress(), "should be");
2078 _full_gc_move_in_progress.set_cond(in_progress);
2079 }
2080
2081 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2082 set_gc_state_mask(UPDATEREFS, in_progress);
2083 }
2084
2085 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2086 ShenandoahCodeRoots::add_nmethod(nm);
2087 }
2088
2089 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2090 ShenandoahCodeRoots::remove_nmethod(nm);
2091 }
2092
2093 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2094 ShenandoahHeapLocker locker(lock());
2095 heap_region_containing(o)->make_pinned();
2096 return o;
2097 }
2098
2099 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2100 ShenandoahHeapLocker locker(lock());
2101 heap_region_containing(o)->make_unpinned();
2102 }
2103
2104 GCTimer* ShenandoahHeap::gc_timer() const {
2105 return _gc_timer;
2106 }
2107
2108 #ifdef ASSERT
2109 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2110 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2111
2112 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2113 if (UseDynamicNumberOfGCThreads ||
2114 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2115 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2116 } else {
2117 // Use ParallelGCThreads inside safepoints
2118 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2119 }
2120 } else {
2121 if (UseDynamicNumberOfGCThreads ||
2122 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2123 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2124 } else {
2125 // Use ConcGCThreads outside safepoints
2126 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2127 }
2128 }
2129 }
2130 #endif
2131
2132 ShenandoahVerifier* ShenandoahHeap::verifier() {
2133 guarantee(ShenandoahVerify, "Should be enabled");
2134 assert (_verifier != NULL, "sanity");
2135 return _verifier;
2136 }
2137
2138 template<class T>
2139 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2140 private:
2141 T cl;
2142 ShenandoahHeap* _heap;
2143 ShenandoahRegionIterator* _regions;
2144 bool _concurrent;
2145 public:
2146 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2147 AbstractGangTask("Concurrent Update References Task"),
2148 cl(T()),
2149 _heap(ShenandoahHeap::heap()),
2150 _regions(regions),
2151 _concurrent(concurrent) {
2152 }
2153
2154 void work(uint worker_id) {
2155 if (_concurrent) {
2156 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2157 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2158 do_work();
2159 } else {
2160 ShenandoahParallelWorkerSession worker_session(worker_id);
2161 do_work();
2162 }
2163 }
2164
2165 private:
2166 void do_work() {
2167 ShenandoahHeapRegion* r = _regions->next();
2168 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2169 while (r != NULL) {
2170 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
2171 assert (top_at_start_ur >= r->bottom(), "sanity");
2172 if (r->is_active() && !r->is_cset()) {
2173 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
2174 }
2175 if (ShenandoahPacing) {
2176 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
2177 }
2178 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2179 return;
2180 }
2181 r = _regions->next();
2182 }
2183 }
2184 };
2185
2186 void ShenandoahHeap::update_heap_references(bool concurrent) {
2187 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2188 workers()->run_task(&task);
2189 }
2190
2191 void ShenandoahHeap::op_init_updaterefs() {
2192 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2193
2194 set_evacuation_in_progress(false);
2195
2196 retire_and_reset_gclabs();
2197
2198 if (ShenandoahVerify) {
2199 if (!is_degenerated_gc_in_progress()) {
2200 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2201 }
2202 verifier()->verify_before_updaterefs();
2203 }
2204
2205 set_update_refs_in_progress(true);
2206 make_parsable(true);
2207 for (uint i = 0; i < num_regions(); i++) {
2208 ShenandoahHeapRegion* r = get_region(i);
2209 r->set_concurrent_iteration_safe_limit(r->top());
2210 }
2211
2212 // Reset iterator.
2213 _update_refs_iterator.reset();
2214
2215 if (ShenandoahPacing) {
2216 pacer()->setup_for_updaterefs();
2217 }
2218 }
2219
2220 void ShenandoahHeap::op_final_updaterefs() {
2221 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2222
2223 // Check if there is left-over work, and finish it
2224 if (_update_refs_iterator.has_next()) {
2225 ShenandoahGCPhase final_work(ShenandoahPhaseTimings::final_update_refs_finish_work);
2226
2227 // Finish updating references where we left off.
2228 clear_cancelled_gc();
2229 update_heap_references(false);
2230 }
2231
2232 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2233 // everything. On degenerated paths, cancelled gc would not be set anyway.
2234 if (cancelled_gc()) {
2235 clear_cancelled_gc();
2236 }
2237 assert(!cancelled_gc(), "Should have been done right before");
2238
2239 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2240 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2241 }
2242
2243 if (is_degenerated_gc_in_progress()) {
2244 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2245 } else {
2246 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2247 }
2248
2249 // Has to be done before cset is clear
2250 if (ShenandoahVerify) {
2251 verifier()->verify_roots_in_to_space();
2252 }
2253
2254 ShenandoahGCPhase final_update_refs(ShenandoahPhaseTimings::final_update_refs_recycle);
2255
2256 trash_cset_regions();
2257 set_has_forwarded_objects(false);
2258 set_update_refs_in_progress(false);
2259
2260 if (ShenandoahVerify) {
2261 verifier()->verify_after_updaterefs();
2262 }
2263
2264 if (VerifyAfterGC) {
2265 Universe::verify();
2266 }
2267
2268 {
2269 ShenandoahHeapLocker locker(lock());
2270 _free_set->rebuild();
2271 }
2272 }
2273
2274 #ifdef ASSERT
2275 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2276 _lock.assert_owned_by_current_thread();
2277 }
2278
2279 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2280 _lock.assert_not_owned_by_current_thread();
2281 }
2282
2283 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2284 _lock.assert_owned_by_current_thread_or_safepoint();
2285 }
2286 #endif
2287
2288 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2289 print_on(st);
2290 print_heap_regions_on(st);
2291 }
2292
2293 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2294 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2295
2296 size_t regions_from = _bitmap_regions_per_slice * slice;
2297 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2298 for (size_t g = regions_from; g < regions_to; g++) {
2299 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2300 if (skip_self && g == r->region_number()) continue;
2301 if (get_region(g)->is_committed()) {
2302 return true;
2303 }
2304 }
2305 return false;
2306 }
2307
2308 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2309 assert_heaplock_owned_by_current_thread();
2310
2311 // Bitmaps in special regions do not need commits
2312 if (_bitmap_region_special) {
2313 return true;
2314 }
2315
2316 if (is_bitmap_slice_committed(r, true)) {
2317 // Some other region from the group is already committed, meaning the bitmap
2318 // slice is already committed, we exit right away.
2319 return true;
2320 }
2321
2322 // Commit the bitmap slice:
2323 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2324 size_t off = _bitmap_bytes_per_slice * slice;
2325 size_t len = _bitmap_bytes_per_slice;
2326 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2327 return false;
2328 }
2329 return true;
2330 }
2331
2332 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2333 assert_heaplock_owned_by_current_thread();
2334
2335 // Bitmaps in special regions do not need uncommits
2336 if (_bitmap_region_special) {
2337 return true;
2338 }
2339
2340 if (is_bitmap_slice_committed(r, true)) {
2341 // Some other region from the group is still committed, meaning the bitmap
2342 // slice is should stay committed, exit right away.
2343 return true;
2344 }
2345
2346 // Uncommit the bitmap slice:
2347 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2348 size_t off = _bitmap_bytes_per_slice * slice;
2349 size_t len = _bitmap_bytes_per_slice;
2350 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2351 return false;
2352 }
2353 return true;
2354 }
2355
2356 void ShenandoahHeap::safepoint_synchronize_begin() {
2357 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2358 SuspendibleThreadSet::synchronize();
2359 }
2360 }
2361
2362 void ShenandoahHeap::safepoint_synchronize_end() {
2363 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2364 SuspendibleThreadSet::desynchronize();
2365 }
2366 }
2367
2368 void ShenandoahHeap::vmop_entry_init_mark() {
2369 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2370 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2371 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2372
2373 try_inject_alloc_failure();
2374 VM_ShenandoahInitMark op;
2375 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2376 }
2377
2378 void ShenandoahHeap::vmop_entry_final_mark() {
2379 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2380 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2381 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2382
2383 try_inject_alloc_failure();
2384 VM_ShenandoahFinalMarkStartEvac op;
2385 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2386 }
2387
2388 void ShenandoahHeap::vmop_entry_final_evac() {
2389 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2390 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2391 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2392
2393 VM_ShenandoahFinalEvac op;
2394 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2395 }
2396
2397 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2398 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2399 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2400 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2401
2402 try_inject_alloc_failure();
2403 VM_ShenandoahInitUpdateRefs op;
2404 VMThread::execute(&op);
2405 }
2406
2407 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2408 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2409 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2410 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2411
2412 try_inject_alloc_failure();
2413 VM_ShenandoahFinalUpdateRefs op;
2414 VMThread::execute(&op);
2415 }
2416
2417 void ShenandoahHeap::vmop_entry_init_traversal() {
2418 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2419 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2420 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2421
2422 try_inject_alloc_failure();
2423 VM_ShenandoahInitTraversalGC op;
2424 VMThread::execute(&op);
2425 }
2426
2427 void ShenandoahHeap::vmop_entry_final_traversal() {
2428 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2429 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2430 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2431
2432 try_inject_alloc_failure();
2433 VM_ShenandoahFinalTraversalGC op;
2434 VMThread::execute(&op);
2435 }
2436
2437 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2438 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2439 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2440 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2441
2442 try_inject_alloc_failure();
2443 VM_ShenandoahFullGC op(cause);
2444 VMThread::execute(&op);
2445 }
2446
2447 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2448 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2449 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2450 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2451
2452 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2453 VMThread::execute(°enerated_gc);
2454 }
2455
2456 void ShenandoahHeap::entry_init_mark() {
2457 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2458 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2459 const char* msg = init_mark_event_message();
2460 GCTraceTime(Info, gc) time(msg, gc_timer());
2461 EventMark em("%s", msg);
2462
2463 ShenandoahWorkerScope scope(workers(),
2464 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2465 "init marking");
2466
2467 op_init_mark();
2468 }
2469
2470 void ShenandoahHeap::entry_final_mark() {
2471 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2472 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2473 const char* msg = final_mark_event_message();
2474 GCTraceTime(Info, gc) time(msg, gc_timer());
2475 EventMark em("%s", msg);
2476
2477 ShenandoahWorkerScope scope(workers(),
2478 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2479 "final marking");
2480
2481 op_final_mark();
2482 }
2483
2484 void ShenandoahHeap::entry_final_evac() {
2485 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2486 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2487 static const char* msg = "Pause Final Evac";
2488 GCTraceTime(Info, gc) time(msg, gc_timer());
2489 EventMark em("%s", msg);
2490
2491 op_final_evac();
2492 }
2493
2494 void ShenandoahHeap::entry_init_updaterefs() {
2495 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2496 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2497
2498 static const char* msg = "Pause Init Update Refs";
2499 GCTraceTime(Info, gc) time(msg, gc_timer());
2500 EventMark em("%s", msg);
2501
2502 // No workers used in this phase, no setup required
2503
2504 op_init_updaterefs();
2505 }
2506
2507 void ShenandoahHeap::entry_final_updaterefs() {
2508 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2509 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2510
2511 static const char* msg = "Pause Final Update Refs";
2512 GCTraceTime(Info, gc) time(msg, gc_timer());
2513 EventMark em("%s", msg);
2514
2515 ShenandoahWorkerScope scope(workers(),
2516 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2517 "final reference update");
2518
2519 op_final_updaterefs();
2520 }
2521
2522 void ShenandoahHeap::entry_init_traversal() {
2523 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2524 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2525
2526 static const char* msg = "Pause Init Traversal";
2527 GCTraceTime(Info, gc) time(msg, gc_timer());
2528 EventMark em("%s", msg);
2529
2530 ShenandoahWorkerScope scope(workers(),
2531 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2532 "init traversal");
2533
2534 op_init_traversal();
2535 }
2536
2537 void ShenandoahHeap::entry_final_traversal() {
2538 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2539 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2540
2541 static const char* msg = "Pause Final Traversal";
2542 GCTraceTime(Info, gc) time(msg, gc_timer());
2543 EventMark em("%s", msg);
2544
2545 ShenandoahWorkerScope scope(workers(),
2546 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2547 "final traversal");
2548
2549 op_final_traversal();
2550 }
2551
2552 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2553 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2554 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2555
2556 static const char* msg = "Pause Full";
2557 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2558 EventMark em("%s", msg);
2559
2560 ShenandoahWorkerScope scope(workers(),
2561 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2562 "full gc");
2563
2564 op_full(cause);
2565 }
2566
2567 void ShenandoahHeap::entry_degenerated(int point) {
2568 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2569 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2570
2571 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2572 const char* msg = degen_event_message(dpoint);
2573 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2574 EventMark em("%s", msg);
2575
2576 ShenandoahWorkerScope scope(workers(),
2577 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2578 "stw degenerated gc");
2579
2580 set_degenerated_gc_in_progress(true);
2581 op_degenerated(dpoint);
2582 set_degenerated_gc_in_progress(false);
2583 }
2584
2585 void ShenandoahHeap::entry_mark() {
2586 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2587
2588 const char* msg = conc_mark_event_message();
2589 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2590 EventMark em("%s", msg);
2591
2592 ShenandoahWorkerScope scope(workers(),
2593 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2594 "concurrent marking");
2595
2596 try_inject_alloc_failure();
2597 op_mark();
2598 }
2599
2600 void ShenandoahHeap::entry_evac() {
2601 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2602 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2603
2604 static const char* msg = "Concurrent evacuation";
2605 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2606 EventMark em("%s", msg);
2607
2608 ShenandoahWorkerScope scope(workers(),
2609 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2610 "concurrent evacuation");
2611
2612 try_inject_alloc_failure();
2613 op_conc_evac();
2614 }
2615
2616 void ShenandoahHeap::entry_updaterefs() {
2617 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2618
2619 static const char* msg = "Concurrent update references";
2620 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2621 EventMark em("%s", msg);
2622
2623 ShenandoahWorkerScope scope(workers(),
2624 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2625 "concurrent reference update");
2626
2627 try_inject_alloc_failure();
2628 op_updaterefs();
2629 }
2630
2631 void ShenandoahHeap::entry_roots() {
2632 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2633
2634 static const char* msg = "Concurrent roots processing";
2635 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2636 EventMark em("%s", msg);
2637
2638 ShenandoahWorkerScope scope(workers(),
2639 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2640 "concurrent root processing");
2641
2642 try_inject_alloc_failure();
2643 op_roots();
2644 }
2645
2646 void ShenandoahHeap::entry_cleanup() {
2647 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2648
2649 static const char* msg = "Concurrent cleanup";
2650 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2651 EventMark em("%s", msg);
2652
2653 // This phase does not use workers, no need for setup
2654
2655 try_inject_alloc_failure();
2656 op_cleanup();
2657 }
2658
2659 void ShenandoahHeap::entry_reset() {
2660 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2661
2662 static const char* msg = "Concurrent reset";
2663 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2664 EventMark em("%s", msg);
2665
2666 ShenandoahWorkerScope scope(workers(),
2667 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2668 "concurrent reset");
2669
2670 try_inject_alloc_failure();
2671 op_reset();
2672 }
2673
2674 void ShenandoahHeap::entry_preclean() {
2675 if (ShenandoahPreclean && process_references()) {
2676 static const char* msg = "Concurrent precleaning";
2677 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2678 EventMark em("%s", msg);
2679
2680 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2681
2682 ShenandoahWorkerScope scope(workers(),
2683 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2684 "concurrent preclean",
2685 /* check_workers = */ false);
2686
2687 try_inject_alloc_failure();
2688 op_preclean();
2689 }
2690 }
2691
2692 void ShenandoahHeap::entry_traversal() {
2693 static const char* msg = "Concurrent traversal";
2694 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2695 EventMark em("%s", msg);
2696
2697 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2698
2699 ShenandoahWorkerScope scope(workers(),
2700 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2701 "concurrent traversal");
2702
2703 try_inject_alloc_failure();
2704 op_traversal();
2705 }
2706
2707 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2708 static const char *msg = "Concurrent uncommit";
2709 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2710 EventMark em("%s", msg);
2711
2712 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2713
2714 op_uncommit(shrink_before);
2715 }
2716
2717 void ShenandoahHeap::try_inject_alloc_failure() {
2718 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2719 _inject_alloc_failure.set();
2720 os::naked_short_sleep(1);
2721 if (cancelled_gc()) {
2722 log_info(gc)("Allocation failure was successfully injected");
2723 }
2724 }
2725 }
2726
2727 bool ShenandoahHeap::should_inject_alloc_failure() {
2728 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2729 }
2730
2731 void ShenandoahHeap::initialize_serviceability() {
2732 _memory_pool = new ShenandoahMemoryPool(this);
2733 _cycle_memory_manager.add_pool(_memory_pool);
2734 _stw_memory_manager.add_pool(_memory_pool);
2735 }
2736
2737 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2738 GrowableArray<GCMemoryManager*> memory_managers(2);
2739 memory_managers.append(&_cycle_memory_manager);
2740 memory_managers.append(&_stw_memory_manager);
2741 return memory_managers;
2742 }
2743
2744 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2745 GrowableArray<MemoryPool*> memory_pools(1);
2746 memory_pools.append(_memory_pool);
2747 return memory_pools;
2748 }
2749
2750 MemoryUsage ShenandoahHeap::memory_usage() {
2751 return _memory_pool->get_memory_usage();
2752 }
2753
2754 void ShenandoahHeap::enter_evacuation() {
2755 _oom_evac_handler.enter_evacuation();
2756 }
2757
2758 void ShenandoahHeap::leave_evacuation() {
2759 _oom_evac_handler.leave_evacuation();
2760 }
2761
2762 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2763 _heap(ShenandoahHeap::heap()),
2764 _index(0) {}
2765
2766 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2767 _heap(heap),
2768 _index(0) {}
2769
2770 void ShenandoahRegionIterator::reset() {
2771 _index = 0;
2772 }
2773
2774 bool ShenandoahRegionIterator::has_next() const {
2775 return _index < _heap->num_regions();
2776 }
2777
2778 char ShenandoahHeap::gc_state() const {
2779 return _gc_state.raw_value();
2780 }
2781
2782 void ShenandoahHeap::deduplicate_string(oop str) {
2783 assert(java_lang_String::is_instance(str), "invariant");
2784
2785 if (ShenandoahStringDedup::is_enabled()) {
2786 ShenandoahStringDedup::deduplicate(str);
2787 }
2788 }
2789
2790 const char* ShenandoahHeap::init_mark_event_message() const {
2791 bool update_refs = has_forwarded_objects();
2792 bool proc_refs = process_references();
2793 bool unload_cls = unload_classes();
2794
2795 if (update_refs && proc_refs && unload_cls) {
2796 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
2797 } else if (update_refs && proc_refs) {
2798 return "Pause Init Mark (update refs) (process weakrefs)";
2799 } else if (update_refs && unload_cls) {
2800 return "Pause Init Mark (update refs) (unload classes)";
2801 } else if (proc_refs && unload_cls) {
2802 return "Pause Init Mark (process weakrefs) (unload classes)";
2803 } else if (update_refs) {
2804 return "Pause Init Mark (update refs)";
2805 } else if (proc_refs) {
2806 return "Pause Init Mark (process weakrefs)";
2807 } else if (unload_cls) {
2808 return "Pause Init Mark (unload classes)";
2809 } else {
2810 return "Pause Init Mark";
2811 }
2812 }
2813
2814 const char* ShenandoahHeap::final_mark_event_message() const {
2815 bool update_refs = has_forwarded_objects();
2816 bool proc_refs = process_references();
2817 bool unload_cls = unload_classes();
2818
2819 if (update_refs && proc_refs && unload_cls) {
2820 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
2821 } else if (update_refs && proc_refs) {
2822 return "Pause Final Mark (update refs) (process weakrefs)";
2823 } else if (update_refs && unload_cls) {
2824 return "Pause Final Mark (update refs) (unload classes)";
2825 } else if (proc_refs && unload_cls) {
2826 return "Pause Final Mark (process weakrefs) (unload classes)";
2827 } else if (update_refs) {
2828 return "Pause Final Mark (update refs)";
2829 } else if (proc_refs) {
2830 return "Pause Final Mark (process weakrefs)";
2831 } else if (unload_cls) {
2832 return "Pause Final Mark (unload classes)";
2833 } else {
2834 return "Pause Final Mark";
2835 }
2836 }
2837
2838 const char* ShenandoahHeap::conc_mark_event_message() const {
2839 bool update_refs = has_forwarded_objects();
2840 bool proc_refs = process_references();
2841 bool unload_cls = unload_classes();
2842
2843 if (update_refs && proc_refs && unload_cls) {
2844 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
2845 } else if (update_refs && proc_refs) {
2846 return "Concurrent marking (update refs) (process weakrefs)";
2847 } else if (update_refs && unload_cls) {
2848 return "Concurrent marking (update refs) (unload classes)";
2849 } else if (proc_refs && unload_cls) {
2850 return "Concurrent marking (process weakrefs) (unload classes)";
2851 } else if (update_refs) {
2852 return "Concurrent marking (update refs)";
2853 } else if (proc_refs) {
2854 return "Concurrent marking (process weakrefs)";
2855 } else if (unload_cls) {
2856 return "Concurrent marking (unload classes)";
2857 } else {
2858 return "Concurrent marking";
2859 }
2860 }
2861
2862 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
2863 switch (point) {
2864 case _degenerated_unset:
2865 return "Pause Degenerated GC (<UNSET>)";
2866 case _degenerated_traversal:
2867 return "Pause Degenerated GC (Traversal)";
2868 case _degenerated_outside_cycle:
2869 return "Pause Degenerated GC (Outside of Cycle)";
2870 case _degenerated_mark:
2871 return "Pause Degenerated GC (Mark)";
2872 case _degenerated_evac:
2873 return "Pause Degenerated GC (Evacuation)";
2874 case _degenerated_updaterefs:
2875 return "Pause Degenerated GC (Update Refs)";
2876 default:
2877 ShouldNotReachHere();
2878 return "ERROR";
2879 }
2880 }
2881
2882 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2883 #ifdef ASSERT
2884 assert(_liveness_cache != NULL, "sanity");
2885 assert(worker_id < _max_workers, "sanity");
2886 for (uint i = 0; i < num_regions(); i++) {
2887 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2888 }
2889 #endif
2890 return _liveness_cache[worker_id];
2891 }
2892
2893 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2894 assert(worker_id < _max_workers, "sanity");
2895 assert(_liveness_cache != NULL, "sanity");
2896 jushort* ld = _liveness_cache[worker_id];
2897 for (uint i = 0; i < num_regions(); i++) {
2898 ShenandoahHeapRegion* r = get_region(i);
2899 jushort live = ld[i];
2900 if (live > 0) {
2901 r->increase_live_data_gc_words(live);
2902 ld[i] = 0;
2903 }
2904 }
2905 }