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/locationPrinter.inline.hpp"
32 #include "gc/shared/memAllocator.hpp"
33 #include "gc/shared/plab.hpp"
34
35 #include "gc/shenandoah/shenandoahAllocTracker.hpp"
36 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
37 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
38 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
39 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
40 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
42 #include "gc/shenandoah/shenandoahControlThread.hpp"
43 #include "gc/shenandoah/shenandoahFreeSet.hpp"
44 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
45 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
46 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
48 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
49 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
50 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
51 #include "gc/shenandoah/shenandoahMetrics.hpp"
52 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
53 #include "gc/shenandoah/shenandoahNormalMode.hpp"
54 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
55 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
56 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
57 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
58 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
59 #include "gc/shenandoah/shenandoahStringDedup.hpp"
60 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
61 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
62 #include "gc/shenandoah/shenandoahUtils.hpp"
63 #include "gc/shenandoah/shenandoahVerifier.hpp"
64 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
65 #include "gc/shenandoah/shenandoahVMOperations.hpp"
66 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
68 #if INCLUDE_JFR
69 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
70 #endif
71
72 #include "memory/metaspace.hpp"
73 #include "oops/compressedOops.inline.hpp"
74 #include "runtime/globals.hpp"
75 #include "runtime/interfaceSupport.inline.hpp"
76 #include "runtime/safepointMechanism.hpp"
77 #include "runtime/vmThread.hpp"
78 #include "services/mallocTracker.hpp"
79
80 #ifdef ASSERT
81 template <class T>
82 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
83 T o = RawAccess<>::oop_load(p);
84 if (! CompressedOops::is_null(o)) {
85 oop obj = CompressedOops::decode_not_null(o);
86 shenandoah_assert_not_forwarded(p, obj);
87 }
88 }
89
90 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
91 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
92 #endif
93
94 class ShenandoahPretouchHeapTask : public AbstractGangTask {
95 private:
96 ShenandoahRegionIterator _regions;
97 const size_t _page_size;
98 public:
99 ShenandoahPretouchHeapTask(size_t page_size) :
100 AbstractGangTask("Shenandoah Pretouch Heap"),
101 _page_size(page_size) {}
102
103 virtual void work(uint worker_id) {
104 ShenandoahHeapRegion* r = _regions.next();
105 while (r != NULL) {
106 os::pretouch_memory(r->bottom(), r->end(), _page_size);
107 r = _regions.next();
108 }
109 }
110 };
111
112 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
113 private:
114 ShenandoahRegionIterator _regions;
115 char* _bitmap_base;
116 const size_t _bitmap_size;
117 const size_t _page_size;
118 public:
119 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
120 AbstractGangTask("Shenandoah Pretouch Bitmap"),
121 _bitmap_base(bitmap_base),
122 _bitmap_size(bitmap_size),
123 _page_size(page_size) {}
124
125 virtual void work(uint worker_id) {
126 ShenandoahHeapRegion* r = _regions.next();
127 while (r != NULL) {
128 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
129 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
130 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
131
132 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
133
134 r = _regions.next();
135 }
136 }
137 };
138
139 jint ShenandoahHeap::initialize() {
140 initialize_heuristics();
141
142 //
143 // Figure out heap sizing
144 //
145
146 size_t init_byte_size = InitialHeapSize;
147 size_t min_byte_size = MinHeapSize;
148 size_t max_byte_size = MaxHeapSize;
149 size_t heap_alignment = HeapAlignment;
150
151 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
152
153 if (ShenandoahAlwaysPreTouch) {
154 // Enabled pre-touch means the entire heap is committed right away.
155 init_byte_size = max_byte_size;
156 }
157
158 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
159 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
160
161 _num_regions = ShenandoahHeapRegion::region_count();
162
163 size_t num_committed_regions = init_byte_size / reg_size_bytes;
164 num_committed_regions = MIN2(num_committed_regions, _num_regions);
165 assert(num_committed_regions <= _num_regions, "sanity");
166 _initial_size = num_committed_regions * reg_size_bytes;
167
168 size_t num_min_regions = min_byte_size / reg_size_bytes;
169 num_min_regions = MIN2(num_min_regions, _num_regions);
170 assert(num_min_regions <= _num_regions, "sanity");
171 _minimum_size = num_min_regions * reg_size_bytes;
172
173 _committed = _initial_size;
174
175 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
176 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
177
178 //
179 // Reserve and commit memory for heap
180 //
181
182 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
183 initialize_reserved_region(heap_rs);
184 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
185 _heap_region_special = heap_rs.special();
186
187 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
188 "Misaligned heap: " PTR_FORMAT, p2i(base()));
189
190 #if SHENANDOAH_OPTIMIZED_OBJTASK
191 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
192 // Fail if we ever attempt to address more than we can.
193 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
194 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
195 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
196 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
197 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
198 vm_exit_during_initialization("Fatal Error", buf);
199 }
200 #endif
201
202 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
203 if (!_heap_region_special) {
204 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
205 "Cannot commit heap memory");
206 }
207
208 //
209 // Reserve and commit memory for bitmap(s)
210 //
211
212 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
213 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
214
215 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
216
217 guarantee(bitmap_bytes_per_region != 0,
218 "Bitmap bytes per region should not be zero");
219 guarantee(is_power_of_2(bitmap_bytes_per_region),
220 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
221
222 if (bitmap_page_size > bitmap_bytes_per_region) {
223 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
224 _bitmap_bytes_per_slice = bitmap_page_size;
225 } else {
226 _bitmap_regions_per_slice = 1;
227 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
228 }
229
230 guarantee(_bitmap_regions_per_slice >= 1,
231 "Should have at least one region per slice: " SIZE_FORMAT,
232 _bitmap_regions_per_slice);
233
234 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
235 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
236 _bitmap_bytes_per_slice, bitmap_page_size);
237
238 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
239 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
240 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
241 _bitmap_region_special = bitmap.special();
242
243 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
244 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
245 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
246 if (!_bitmap_region_special) {
247 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
248 "Cannot commit bitmap memory");
249 }
250
251 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
252
253 if (ShenandoahVerify) {
254 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
255 if (!verify_bitmap.special()) {
256 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
257 "Cannot commit verification bitmap memory");
258 }
259 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
260 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
261 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
262 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
263 }
264
265 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
266 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
267 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
268 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
269 _aux_bitmap_region_special = aux_bitmap.special();
270 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
271
272 //
273 // Create regions and region sets
274 //
275
276 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
277 _free_set = new ShenandoahFreeSet(this, _num_regions);
278 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
279
280 {
281 ShenandoahHeapLocker locker(lock());
282
283 size_t size_words = ShenandoahHeapRegion::region_size_words();
284
285 for (size_t i = 0; i < _num_regions; i++) {
286 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
287 bool is_committed = i < num_committed_regions;
288 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
289
290 _marking_context->initialize_top_at_mark_start(r);
291 _regions[i] = r;
292 assert(!collection_set()->is_in(i), "New region should not be in collection set");
293 }
294
295 // Initialize to complete
296 _marking_context->mark_complete();
297
298 _free_set->rebuild();
299 }
300
301 if (ShenandoahAlwaysPreTouch) {
302 assert(!AlwaysPreTouch, "Should have been overridden");
303
304 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
305 // before initialize() below zeroes it with initializing thread. For any given region,
306 // we touch the region and the corresponding bitmaps from the same thread.
307 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
308
309 size_t pretouch_heap_page_size = heap_page_size;
310 size_t pretouch_bitmap_page_size = bitmap_page_size;
311
312 #ifdef LINUX
313 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
314 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
315 // them into huge one. Therefore, we need to pretouch with smaller pages.
316 if (UseTransparentHugePages) {
317 pretouch_heap_page_size = (size_t)os::vm_page_size();
318 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
319 }
320 #endif
321
322 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
323 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
324
325 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
326 _num_regions, pretouch_bitmap_page_size);
327 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
328 _workers->run_task(&bcl);
329
330 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
331 _num_regions, pretouch_heap_page_size);
332 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
333 _workers->run_task(&hcl);
334 }
335
336 //
337 // Initialize the rest of GC subsystems
338 //
339
340 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
341 for (uint worker = 0; worker < _max_workers; worker++) {
342 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
343 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
344 }
345
346 // The call below uses stuff (the SATB* things) that are in G1, but probably
347 // belong into a shared location.
348 ShenandoahBarrierSet::satb_mark_queue_set().initialize(this,
349 20 /* G1SATBProcessCompletedThreshold */,
350 60 /* G1SATBBufferEnqueueingThresholdPercent */);
351
352 _monitoring_support = new ShenandoahMonitoringSupport(this);
353 _phase_timings = new ShenandoahPhaseTimings();
354 ShenandoahStringDedup::initialize();
355 ShenandoahCodeRoots::initialize();
356
357 if (ShenandoahAllocationTrace) {
358 _alloc_tracker = new ShenandoahAllocTracker();
359 }
360
361 if (ShenandoahPacing) {
362 _pacer = new ShenandoahPacer(this);
363 _pacer->setup_for_idle();
364 } else {
365 _pacer = NULL;
366 }
367
368 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
369 new ShenandoahTraversalGC(this, _num_regions) :
370 NULL;
371
372 _control_thread = new ShenandoahControlThread();
373
374 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
375 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
376 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
377 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
378 );
379
380 log_info(gc, init)("Safepointing mechanism: %s",
381 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
382 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
383
384 return JNI_OK;
385 }
386
387 void ShenandoahHeap::initialize_heuristics() {
388 if (ShenandoahGCMode != NULL) {
389 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
390 _gc_mode = new ShenandoahTraversalMode();
391 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
392 _gc_mode = new ShenandoahNormalMode();
393 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
394 _gc_mode = new ShenandoahPassiveMode();
395 } else {
396 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
397 }
398 } else {
399 ShouldNotReachHere();
400 }
401 _gc_mode->initialize_flags();
402 _heuristics = _gc_mode->initialize_heuristics();
403
404 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
405 vm_exit_during_initialization(
406 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
407 _heuristics->name()));
408 }
409 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
410 vm_exit_during_initialization(
411 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
412 _heuristics->name()));
413 }
414 log_info(gc, init)("Shenandoah heuristics: %s",
415 _heuristics->name());
416 }
417
418 #ifdef _MSC_VER
419 #pragma warning( push )
420 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
421 #endif
422
423 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
424 CollectedHeap(),
425 _initial_size(0),
426 _used(0),
427 _committed(0),
428 _bytes_allocated_since_gc_start(0),
429 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
430 _workers(NULL),
431 _safepoint_workers(NULL),
432 _heap_region_special(false),
433 _num_regions(0),
434 _regions(NULL),
435 _update_refs_iterator(this),
436 _control_thread(NULL),
437 _shenandoah_policy(policy),
438 _heuristics(NULL),
439 _free_set(NULL),
440 _scm(new ShenandoahConcurrentMark()),
441 _traversal_gc(NULL),
442 _full_gc(new ShenandoahMarkCompact()),
443 _pacer(NULL),
444 _verifier(NULL),
445 _alloc_tracker(NULL),
446 _phase_timings(NULL),
447 _monitoring_support(NULL),
448 _memory_pool(NULL),
449 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
450 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
451 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
452 _soft_ref_policy(),
453 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
454 _ref_processor(NULL),
455 _marking_context(NULL),
456 _bitmap_size(0),
457 _bitmap_regions_per_slice(0),
458 _bitmap_bytes_per_slice(0),
459 _bitmap_region_special(false),
460 _aux_bitmap_region_special(false),
461 _liveness_cache(NULL),
462 _collection_set(NULL)
463 {
464 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
465 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
466
467 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
468
469 _max_workers = MAX2(_max_workers, 1U);
470 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
471 /* are_GC_task_threads */ true,
472 /* are_ConcurrentGC_threads */ true);
473 if (_workers == NULL) {
474 vm_exit_during_initialization("Failed necessary allocation.");
475 } else {
476 _workers->initialize_workers();
477 }
478
479 if (ShenandoahParallelSafepointThreads > 1) {
480 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
481 ShenandoahParallelSafepointThreads,
482 /* are_GC_task_threads */ false,
483 /* are_ConcurrentGC_threads */ false);
484 _safepoint_workers->initialize_workers();
485 }
486 }
487
488 #ifdef _MSC_VER
489 #pragma warning( pop )
490 #endif
491
492 class ShenandoahResetBitmapTask : public AbstractGangTask {
493 private:
494 ShenandoahRegionIterator _regions;
495
496 public:
497 ShenandoahResetBitmapTask() :
498 AbstractGangTask("Parallel Reset Bitmap Task") {}
499
500 void work(uint worker_id) {
501 ShenandoahHeapRegion* region = _regions.next();
502 ShenandoahHeap* heap = ShenandoahHeap::heap();
503 ShenandoahMarkingContext* const ctx = heap->marking_context();
504 while (region != NULL) {
505 if (heap->is_bitmap_slice_committed(region)) {
506 ctx->clear_bitmap(region);
507 }
508 region = _regions.next();
509 }
510 }
511 };
512
513 void ShenandoahHeap::reset_mark_bitmap() {
514 assert_gc_workers(_workers->active_workers());
515 mark_incomplete_marking_context();
516
517 ShenandoahResetBitmapTask task;
518 _workers->run_task(&task);
519 }
520
521 void ShenandoahHeap::print_on(outputStream* st) const {
522 st->print_cr("Shenandoah Heap");
523 st->print_cr(" " SIZE_FORMAT "K total, " SIZE_FORMAT "K committed, " SIZE_FORMAT "K used",
524 max_capacity() / K, committed() / K, used() / K);
525 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"K regions",
526 num_regions(), ShenandoahHeapRegion::region_size_bytes() / K);
527
528 st->print("Status: ");
529 if (has_forwarded_objects()) st->print("has forwarded objects, ");
530 if (is_concurrent_mark_in_progress()) st->print("marking, ");
531 if (is_evacuation_in_progress()) st->print("evacuating, ");
532 if (is_update_refs_in_progress()) st->print("updating refs, ");
533 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
534 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
535 if (is_full_gc_in_progress()) st->print("full gc, ");
536 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
537
538 if (cancelled_gc()) {
539 st->print("cancelled");
540 } else {
541 st->print("not cancelled");
542 }
543 st->cr();
544
545 st->print_cr("Reserved region:");
546 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
547 p2i(reserved_region().start()),
548 p2i(reserved_region().end()));
549
550 ShenandoahCollectionSet* cset = collection_set();
551 st->print_cr("Collection set:");
552 if (cset != NULL) {
553 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
554 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
555 } else {
556 st->print_cr(" (NULL)");
557 }
558
559 st->cr();
560 MetaspaceUtils::print_on(st);
561
562 if (Verbose) {
563 print_heap_regions_on(st);
564 }
565 }
566
567 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
568 public:
569 void do_thread(Thread* thread) {
570 assert(thread != NULL, "Sanity");
571 assert(thread->is_Worker_thread(), "Only worker thread expected");
572 ShenandoahThreadLocalData::initialize_gclab(thread);
573 }
574 };
575
576 void ShenandoahHeap::post_initialize() {
577 CollectedHeap::post_initialize();
578 MutexLocker ml(Threads_lock);
579
580 ShenandoahInitWorkerGCLABClosure init_gclabs;
581 _workers->threads_do(&init_gclabs);
582
583 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
584 // Now, we will let WorkGang to initialize gclab when new worker is created.
585 _workers->set_initialize_gclab();
586
587 _scm->initialize(_max_workers);
588 _full_gc->initialize(_gc_timer);
589
590 ref_processing_init();
591
592 _heuristics->initialize();
593
594 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
595 }
596
597 size_t ShenandoahHeap::used() const {
598 return OrderAccess::load_acquire(&_used);
599 }
600
601 size_t ShenandoahHeap::committed() const {
602 OrderAccess::acquire();
603 return _committed;
604 }
605
606 void ShenandoahHeap::increase_committed(size_t bytes) {
607 assert_heaplock_or_safepoint();
608 _committed += bytes;
609 }
610
611 void ShenandoahHeap::decrease_committed(size_t bytes) {
612 assert_heaplock_or_safepoint();
613 _committed -= bytes;
614 }
615
616 void ShenandoahHeap::increase_used(size_t bytes) {
617 Atomic::add(bytes, &_used);
618 }
619
620 void ShenandoahHeap::set_used(size_t bytes) {
621 OrderAccess::release_store_fence(&_used, bytes);
622 }
623
624 void ShenandoahHeap::decrease_used(size_t bytes) {
625 assert(used() >= bytes, "never decrease heap size by more than we've left");
626 Atomic::sub(bytes, &_used);
627 }
628
629 void ShenandoahHeap::increase_allocated(size_t bytes) {
630 Atomic::add(bytes, &_bytes_allocated_since_gc_start);
631 }
632
633 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
634 size_t bytes = words * HeapWordSize;
635 if (!waste) {
636 increase_used(bytes);
637 }
638 increase_allocated(bytes);
639 if (ShenandoahPacing) {
640 control_thread()->pacing_notify_alloc(words);
641 if (waste) {
642 pacer()->claim_for_alloc(words, true);
643 }
644 }
645 }
646
647 size_t ShenandoahHeap::capacity() const {
648 return committed();
649 }
650
651 size_t ShenandoahHeap::max_capacity() const {
652 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
653 }
654
655 size_t ShenandoahHeap::min_capacity() const {
656 return _minimum_size;
657 }
658
659 size_t ShenandoahHeap::initial_capacity() const {
660 return _initial_size;
661 }
662
663 bool ShenandoahHeap::is_in(const void* p) const {
664 HeapWord* heap_base = (HeapWord*) base();
665 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
666 return p >= heap_base && p < last_region_end;
667 }
668
669 void ShenandoahHeap::op_uncommit(double shrink_before) {
670 assert (ShenandoahUncommit, "should be enabled");
671
672 // Application allocates from the beginning of the heap, and GC allocates at
673 // the end of it. It is more efficient to uncommit from the end, so that applications
674 // could enjoy the near committed regions. GC allocations are much less frequent,
675 // and therefore can accept the committing costs.
676
677 size_t count = 0;
678 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
679 ShenandoahHeapRegion* r = get_region(i - 1);
680 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
681 ShenandoahHeapLocker locker(lock());
682 if (r->is_empty_committed()) {
683 // Do not uncommit below minimal capacity
684 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
685 break;
686 }
687
688 r->make_uncommitted();
689 count++;
690 }
691 }
692 SpinPause(); // allow allocators to take the lock
693 }
694
695 if (count > 0) {
696 control_thread()->notify_heap_changed();
697 }
698 }
699
700 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
701 // New object should fit the GCLAB size
702 size_t min_size = MAX2(size, PLAB::min_size());
703
704 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
705 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
706 new_size = MIN2(new_size, PLAB::max_size());
707 new_size = MAX2(new_size, PLAB::min_size());
708
709 // Record new heuristic value even if we take any shortcut. This captures
710 // the case when moderately-sized objects always take a shortcut. At some point,
711 // heuristics should catch up with them.
712 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
713
714 if (new_size < size) {
715 // New size still does not fit the object. Fall back to shared allocation.
716 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
717 return NULL;
718 }
719
720 // Retire current GCLAB, and allocate a new one.
721 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
722 gclab->retire();
723
724 size_t actual_size = 0;
725 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
726 if (gclab_buf == NULL) {
727 return NULL;
728 }
729
730 assert (size <= actual_size, "allocation should fit");
731
732 if (ZeroTLAB) {
733 // ..and clear it.
734 Copy::zero_to_words(gclab_buf, actual_size);
735 } else {
736 // ...and zap just allocated object.
737 #ifdef ASSERT
738 // Skip mangling the space corresponding to the object header to
739 // ensure that the returned space is not considered parsable by
740 // any concurrent GC thread.
741 size_t hdr_size = oopDesc::header_size();
742 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
743 #endif // ASSERT
744 }
745 gclab->set_buf(gclab_buf, actual_size);
746 return gclab->allocate(size);
747 }
748
749 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
750 size_t requested_size,
751 size_t* actual_size) {
752 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
753 HeapWord* res = allocate_memory(req);
754 if (res != NULL) {
755 *actual_size = req.actual_size();
756 } else {
757 *actual_size = 0;
758 }
759 return res;
760 }
761
762 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
763 size_t word_size,
764 size_t* actual_size) {
765 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
766 HeapWord* res = allocate_memory(req);
767 if (res != NULL) {
768 *actual_size = req.actual_size();
769 } else {
770 *actual_size = 0;
771 }
772 return res;
773 }
774
775 ShenandoahHeap* ShenandoahHeap::heap() {
776 CollectedHeap* heap = Universe::heap();
777 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
778 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
779 return (ShenandoahHeap*) heap;
780 }
781
782 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
783 CollectedHeap* heap = Universe::heap();
784 return (ShenandoahHeap*) heap;
785 }
786
787 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
788 ShenandoahAllocTrace trace_alloc(req.size(), req.type());
789
790 intptr_t pacer_epoch = 0;
791 bool in_new_region = false;
792 HeapWord* result = NULL;
793
794 if (req.is_mutator_alloc()) {
795 if (ShenandoahPacing) {
796 pacer()->pace_for_alloc(req.size());
797 pacer_epoch = pacer()->epoch();
798 }
799
800 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
801 result = allocate_memory_under_lock(req, in_new_region);
802 }
803
804 // Allocation failed, block until control thread reacted, then retry allocation.
805 //
806 // It might happen that one of the threads requesting allocation would unblock
807 // way later after GC happened, only to fail the second allocation, because
808 // other threads have already depleted the free storage. In this case, a better
809 // strategy is to try again, as long as GC makes progress.
810 //
811 // Then, we need to make sure the allocation was retried after at least one
812 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
813
814 size_t tries = 0;
815
816 while (result == NULL && _progress_last_gc.is_set()) {
817 tries++;
818 control_thread()->handle_alloc_failure(req.size());
819 result = allocate_memory_under_lock(req, in_new_region);
820 }
821
822 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
823 tries++;
824 control_thread()->handle_alloc_failure(req.size());
825 result = allocate_memory_under_lock(req, in_new_region);
826 }
827
828 } else {
829 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
830 result = allocate_memory_under_lock(req, in_new_region);
831 // Do not call handle_alloc_failure() here, because we cannot block.
832 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
833 }
834
835 if (in_new_region) {
836 control_thread()->notify_heap_changed();
837 }
838
839 if (result != NULL) {
840 size_t requested = req.size();
841 size_t actual = req.actual_size();
842
843 assert (req.is_lab_alloc() || (requested == actual),
844 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
845 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
846
847 if (req.is_mutator_alloc()) {
848 notify_mutator_alloc_words(actual, false);
849
850 // If we requested more than we were granted, give the rest back to pacer.
851 // This only matters if we are in the same pacing epoch: do not try to unpace
852 // over the budget for the other phase.
853 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
854 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
855 }
856 } else {
857 increase_used(actual*HeapWordSize);
858 }
859 }
860
861 return result;
862 }
863
864 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
865 ShenandoahHeapLocker locker(lock());
866 return _free_set->allocate(req, in_new_region);
867 }
868
869 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
870 bool* gc_overhead_limit_was_exceeded) {
871 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
872 return allocate_memory(req);
873 }
874
875 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
876 size_t size,
877 Metaspace::MetadataType mdtype) {
878 MetaWord* result;
879
880 // Inform metaspace OOM to GC heuristics if class unloading is possible.
881 if (heuristics()->can_unload_classes()) {
882 ShenandoahHeuristics* h = heuristics();
883 h->record_metaspace_oom();
884 }
885
886 // Expand and retry allocation
887 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
888 if (result != NULL) {
889 return result;
890 }
891
892 // Start full GC
893 collect(GCCause::_metadata_GC_clear_soft_refs);
894
895 // Retry allocation
896 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
897 if (result != NULL) {
898 return result;
899 }
900
901 // Expand and retry allocation
902 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
903 if (result != NULL) {
904 return result;
905 }
906
907 // Out of memory
908 return NULL;
909 }
910
911 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
912 private:
913 ShenandoahHeap* const _heap;
914 Thread* const _thread;
915 public:
916 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
917 _heap(heap), _thread(Thread::current()) {}
918
919 void do_object(oop p) {
920 shenandoah_assert_marked(NULL, p);
921 if (!p->is_forwarded()) {
922 _heap->evacuate_object(p, _thread);
923 }
924 }
925 };
926
927 class ShenandoahEvacuationTask : public AbstractGangTask {
928 private:
929 ShenandoahHeap* const _sh;
930 ShenandoahCollectionSet* const _cs;
931 bool _concurrent;
932 public:
933 ShenandoahEvacuationTask(ShenandoahHeap* sh,
934 ShenandoahCollectionSet* cs,
935 bool concurrent) :
936 AbstractGangTask("Parallel Evacuation Task"),
937 _sh(sh),
938 _cs(cs),
939 _concurrent(concurrent)
940 {}
941
942 void work(uint worker_id) {
943 if (_concurrent) {
944 ShenandoahConcurrentWorkerSession worker_session(worker_id);
945 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
946 ShenandoahEvacOOMScope oom_evac_scope;
947 do_work();
948 } else {
949 ShenandoahParallelWorkerSession worker_session(worker_id);
950 ShenandoahEvacOOMScope oom_evac_scope;
951 do_work();
952 }
953 }
954
955 private:
956 void do_work() {
957 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
958 ShenandoahHeapRegion* r;
959 while ((r =_cs->claim_next()) != NULL) {
960 assert(r->has_live(), "all-garbage regions are reclaimed early");
961 _sh->marked_object_iterate(r, &cl);
962
963 if (ShenandoahPacing) {
964 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
965 }
966
967 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
968 break;
969 }
970 }
971 }
972 };
973
974 void ShenandoahHeap::trash_cset_regions() {
975 ShenandoahHeapLocker locker(lock());
976
977 ShenandoahCollectionSet* set = collection_set();
978 ShenandoahHeapRegion* r;
979 set->clear_current_index();
980 while ((r = set->next()) != NULL) {
981 r->make_trash();
982 }
983 collection_set()->clear();
984 }
985
986 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
987 st->print_cr("Heap Regions:");
988 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
989 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
990 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
991 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
992
993 for (size_t i = 0; i < num_regions(); i++) {
994 get_region(i)->print_on(st);
995 }
996 }
997
998 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
999 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1000
1001 oop humongous_obj = oop(start->bottom());
1002 size_t size = humongous_obj->size();
1003 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1004 size_t index = start->region_number() + required_regions - 1;
1005
1006 assert(!start->has_live(), "liveness must be zero");
1007
1008 for(size_t i = 0; i < required_regions; i++) {
1009 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1010 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1011 ShenandoahHeapRegion* region = get_region(index --);
1012
1013 assert(region->is_humongous(), "expect correct humongous start or continuation");
1014 assert(!region->is_cset(), "Humongous region should not be in collection set");
1015
1016 region->make_trash_immediate();
1017 }
1018 }
1019
1020 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1021 public:
1022 void do_thread(Thread* thread) {
1023 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1024 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1025 gclab->retire();
1026 }
1027 };
1028
1029 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1030 if (UseTLAB) {
1031 CollectedHeap::ensure_parsability(retire_tlabs);
1032 }
1033 ShenandoahRetireGCLABClosure cl;
1034 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1035 cl.do_thread(t);
1036 }
1037 workers()->threads_do(&cl);
1038 }
1039
1040 void ShenandoahHeap::resize_tlabs() {
1041 CollectedHeap::resize_all_tlabs();
1042 }
1043
1044 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1045 private:
1046 ShenandoahRootEvacuator* _rp;
1047
1048 public:
1049 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1050 AbstractGangTask("Shenandoah evacuate and update roots"),
1051 _rp(rp) {}
1052
1053 void work(uint worker_id) {
1054 ShenandoahParallelWorkerSession worker_session(worker_id);
1055 ShenandoahEvacOOMScope oom_evac_scope;
1056 ShenandoahEvacuateUpdateRootsClosure cl;
1057 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1058 _rp->roots_do(worker_id, &cl);
1059 }
1060 };
1061
1062 void ShenandoahHeap::evacuate_and_update_roots() {
1063 #if COMPILER2_OR_JVMCI
1064 DerivedPointerTable::clear();
1065 #endif
1066 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1067 {
1068 // Include concurrent roots if current cycle can not process those roots concurrently
1069 ShenandoahRootEvacuator rp(workers()->active_workers(),
1070 ShenandoahPhaseTimings::init_evac,
1071 !ShenandoahConcurrentRoots::should_do_concurrent_roots());
1072 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1073 workers()->run_task(&roots_task);
1074 }
1075
1076 #if COMPILER2_OR_JVMCI
1077 DerivedPointerTable::update_pointers();
1078 #endif
1079 }
1080
1081 // Returns size in bytes
1082 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1083 if (ShenandoahElasticTLAB) {
1084 // With Elastic TLABs, return the max allowed size, and let the allocation path
1085 // figure out the safe size for current allocation.
1086 return ShenandoahHeapRegion::max_tlab_size_bytes();
1087 } else {
1088 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1089 }
1090 }
1091
1092 size_t ShenandoahHeap::max_tlab_size() const {
1093 // Returns size in words
1094 return ShenandoahHeapRegion::max_tlab_size_words();
1095 }
1096
1097 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1098 public:
1099 void do_thread(Thread* thread) {
1100 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1101 gclab->retire();
1102 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1103 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1104 }
1105 }
1106 };
1107
1108 void ShenandoahHeap::retire_and_reset_gclabs() {
1109 ShenandoahRetireAndResetGCLABClosure cl;
1110 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1111 cl.do_thread(t);
1112 }
1113 workers()->threads_do(&cl);
1114 }
1115
1116 void ShenandoahHeap::collect(GCCause::Cause cause) {
1117 control_thread()->request_gc(cause);
1118 }
1119
1120 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1121 //assert(false, "Shouldn't need to do full collections");
1122 }
1123
1124 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1125 Space* sp = heap_region_containing(addr);
1126 if (sp != NULL) {
1127 return sp->block_start(addr);
1128 }
1129 return NULL;
1130 }
1131
1132 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1133 Space* sp = heap_region_containing(addr);
1134 return sp->block_is_obj(addr);
1135 }
1136
1137 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1138 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1139 }
1140
1141 jlong ShenandoahHeap::millis_since_last_gc() {
1142 double v = heuristics()->time_since_last_gc() * 1000;
1143 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1144 return (jlong)v;
1145 }
1146
1147 void ShenandoahHeap::prepare_for_verify() {
1148 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1149 make_parsable(false);
1150 }
1151 }
1152
1153 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1154 workers()->print_worker_threads_on(st);
1155 if (ShenandoahStringDedup::is_enabled()) {
1156 ShenandoahStringDedup::print_worker_threads_on(st);
1157 }
1158 }
1159
1160 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1161 workers()->threads_do(tcl);
1162 if (_safepoint_workers != NULL) {
1163 _safepoint_workers->threads_do(tcl);
1164 }
1165 if (ShenandoahStringDedup::is_enabled()) {
1166 ShenandoahStringDedup::threads_do(tcl);
1167 }
1168 }
1169
1170 void ShenandoahHeap::print_tracing_info() const {
1171 LogTarget(Info, gc, stats) lt;
1172 if (lt.is_enabled()) {
1173 ResourceMark rm;
1174 LogStream ls(lt);
1175
1176 phase_timings()->print_on(&ls);
1177
1178 ls.cr();
1179 ls.cr();
1180
1181 shenandoah_policy()->print_gc_stats(&ls);
1182
1183 ls.cr();
1184 ls.cr();
1185
1186 if (ShenandoahPacing) {
1187 pacer()->print_on(&ls);
1188 }
1189
1190 ls.cr();
1191 ls.cr();
1192
1193 if (ShenandoahAllocationTrace) {
1194 assert(alloc_tracker() != NULL, "Must be");
1195 alloc_tracker()->print_on(&ls);
1196 } else {
1197 ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1198 }
1199 }
1200 }
1201
1202 void ShenandoahHeap::verify(VerifyOption vo) {
1203 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1204 if (ShenandoahVerify) {
1205 verifier()->verify_generic(vo);
1206 } else {
1207 // TODO: Consider allocating verification bitmaps on demand,
1208 // and turn this on unconditionally.
1209 }
1210 }
1211 }
1212 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1213 return _free_set->capacity();
1214 }
1215
1216 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1217 private:
1218 MarkBitMap* _bitmap;
1219 Stack<oop,mtGC>* _oop_stack;
1220
1221 template <class T>
1222 void do_oop_work(T* p) {
1223 T o = RawAccess<>::oop_load(p);
1224 if (!CompressedOops::is_null(o)) {
1225 oop obj = CompressedOops::decode_not_null(o);
1226 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1227 assert(oopDesc::is_oop(obj), "must be a valid oop");
1228 if (!_bitmap->is_marked((HeapWord*) obj)) {
1229 _bitmap->mark((HeapWord*) obj);
1230 _oop_stack->push(obj);
1231 }
1232 }
1233 }
1234 public:
1235 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1236 _bitmap(bitmap), _oop_stack(oop_stack) {}
1237 void do_oop(oop* p) { do_oop_work(p); }
1238 void do_oop(narrowOop* p) { do_oop_work(p); }
1239 };
1240
1241 /*
1242 * This is public API, used in preparation of object_iterate().
1243 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1244 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1245 * control, we call SH::make_tlabs_parsable().
1246 */
1247 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1248 // No-op.
1249 }
1250
1251 /*
1252 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1253 *
1254 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1255 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1256 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1257 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1258 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1259 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1260 * wiped the bitmap in preparation for next marking).
1261 *
1262 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1263 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1264 * is allowed to report dead objects, but is not required to do so.
1265 */
1266 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1267 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1268 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1269 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1270 return;
1271 }
1272
1273 // Reset bitmap
1274 _aux_bit_map.clear();
1275
1276 Stack<oop,mtGC> oop_stack;
1277
1278 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1279 ShenandoahHeapIterationRootScanner rp;
1280 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1281
1282 if (unload_classes()) {
1283 rp.strong_roots_do(&oops);
1284 } else {
1285 rp.roots_do(&oops);
1286 }
1287
1288 // Work through the oop stack to traverse heap.
1289 while (! oop_stack.is_empty()) {
1290 oop obj = oop_stack.pop();
1291 assert(oopDesc::is_oop(obj), "must be a valid oop");
1292 cl->do_object(obj);
1293 obj->oop_iterate(&oops);
1294 }
1295
1296 assert(oop_stack.is_empty(), "should be empty");
1297
1298 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1299 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1300 }
1301 }
1302
1303 void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) {
1304 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1305 object_iterate(cl);
1306 }
1307
1308 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1309 for (size_t i = 0; i < num_regions(); i++) {
1310 ShenandoahHeapRegion* current = get_region(i);
1311 blk->heap_region_do(current);
1312 }
1313 }
1314
1315 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1316 private:
1317 ShenandoahHeap* const _heap;
1318 ShenandoahHeapRegionClosure* const _blk;
1319
1320 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1321 volatile size_t _index;
1322 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1323
1324 public:
1325 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1326 AbstractGangTask("Parallel Region Task"),
1327 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1328
1329 void work(uint worker_id) {
1330 size_t stride = ShenandoahParallelRegionStride;
1331
1332 size_t max = _heap->num_regions();
1333 while (_index < max) {
1334 size_t cur = Atomic::add(stride, &_index) - stride;
1335 size_t start = cur;
1336 size_t end = MIN2(cur + stride, max);
1337 if (start >= max) break;
1338
1339 for (size_t i = cur; i < end; i++) {
1340 ShenandoahHeapRegion* current = _heap->get_region(i);
1341 _blk->heap_region_do(current);
1342 }
1343 }
1344 }
1345 };
1346
1347 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1348 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1349 if (num_regions() > ShenandoahParallelRegionStride) {
1350 ShenandoahParallelHeapRegionTask task(blk);
1351 workers()->run_task(&task);
1352 } else {
1353 heap_region_iterate(blk);
1354 }
1355 }
1356
1357 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1358 private:
1359 ShenandoahMarkingContext* const _ctx;
1360 public:
1361 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1362
1363 void heap_region_do(ShenandoahHeapRegion* r) {
1364 if (r->is_active()) {
1365 r->clear_live_data();
1366 _ctx->capture_top_at_mark_start(r);
1367 } else {
1368 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1369 assert(_ctx->top_at_mark_start(r) == r->top(),
1370 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1371 }
1372 }
1373
1374 bool is_thread_safe() { return true; }
1375 };
1376
1377 void ShenandoahHeap::op_init_mark() {
1378 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1379 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1380
1381 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1382 assert(!marking_context()->is_complete(), "should not be complete");
1383
1384 if (ShenandoahVerify) {
1385 verifier()->verify_before_concmark();
1386 }
1387
1388 if (VerifyBeforeGC) {
1389 Universe::verify();
1390 }
1391
1392 set_concurrent_mark_in_progress(true);
1393 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1394 {
1395 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1396 make_parsable(true);
1397 }
1398
1399 {
1400 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1401 ShenandoahClearLivenessClosure clc;
1402 parallel_heap_region_iterate(&clc);
1403 }
1404
1405 // Make above changes visible to worker threads
1406 OrderAccess::fence();
1407
1408 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1409
1410 if (UseTLAB) {
1411 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1412 resize_tlabs();
1413 }
1414
1415 if (ShenandoahPacing) {
1416 pacer()->setup_for_mark();
1417 }
1418 }
1419
1420 void ShenandoahHeap::op_mark() {
1421 concurrent_mark()->mark_from_roots();
1422 }
1423
1424 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1425 private:
1426 ShenandoahMarkingContext* const _ctx;
1427 public:
1428 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1429
1430 void heap_region_do(ShenandoahHeapRegion* r) {
1431 if (r->is_active()) {
1432 HeapWord *tams = _ctx->top_at_mark_start(r);
1433 HeapWord *top = r->top();
1434 if (top > tams) {
1435 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1436 }
1437 } else {
1438 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1439 assert(_ctx->top_at_mark_start(r) == r->top(),
1440 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1441 }
1442 }
1443
1444 bool is_thread_safe() { return true; }
1445 };
1446
1447 void ShenandoahHeap::op_final_mark() {
1448 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1449
1450 // It is critical that we
1451 // evacuate roots right after finishing marking, so that we don't
1452 // get unmarked objects in the roots.
1453
1454 if (!cancelled_gc()) {
1455 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1456
1457 if (has_forwarded_objects()) {
1458 // Degen may be caused by failed evacuation of roots
1459 if (is_degenerated_gc_in_progress()) {
1460 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
1461 } else {
1462 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots);
1463 }
1464 }
1465
1466 if (ShenandoahVerify) {
1467 verifier()->verify_roots_no_forwarded();
1468 }
1469
1470 stop_concurrent_marking();
1471
1472 {
1473 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1474
1475 // All allocations past TAMS are implicitly live, adjust the region data.
1476 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1477 ShenandoahCompleteLivenessClosure cl;
1478 parallel_heap_region_iterate(&cl);
1479 }
1480
1481 {
1482 ShenandoahGCPhase prepare_evac(ShenandoahPhaseTimings::prepare_evac);
1483
1484 make_parsable(true);
1485
1486 trash_cset_regions();
1487
1488 {
1489 ShenandoahHeapLocker locker(lock());
1490 _collection_set->clear();
1491 _free_set->clear();
1492
1493 heuristics()->choose_collection_set(_collection_set);
1494
1495 _free_set->rebuild();
1496 }
1497 }
1498
1499 // If collection set has candidates, start evacuation.
1500 // Otherwise, bypass the rest of the cycle.
1501 if (!collection_set()->is_empty()) {
1502 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1503
1504 if (ShenandoahVerify) {
1505 verifier()->verify_before_evacuation();
1506 }
1507
1508 set_evacuation_in_progress(true);
1509 // From here on, we need to update references.
1510 set_has_forwarded_objects(true);
1511
1512 if (!is_degenerated_gc_in_progress()) {
1513 evacuate_and_update_roots();
1514 }
1515
1516 if (ShenandoahPacing) {
1517 pacer()->setup_for_evac();
1518 }
1519
1520 if (ShenandoahVerify) {
1521 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1522 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1523 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1524 verifier()->verify_roots_no_forwarded_except(types);
1525 } else {
1526 verifier()->verify_roots_no_forwarded();
1527 }
1528 verifier()->verify_during_evacuation();
1529 }
1530 } else {
1531 if (ShenandoahVerify) {
1532 verifier()->verify_after_concmark();
1533 }
1534
1535 if (VerifyAfterGC) {
1536 Universe::verify();
1537 }
1538 }
1539
1540 } else {
1541 concurrent_mark()->cancel();
1542 stop_concurrent_marking();
1543
1544 if (process_references()) {
1545 // Abandon reference processing right away: pre-cleaning must have failed.
1546 ReferenceProcessor *rp = ref_processor();
1547 rp->disable_discovery();
1548 rp->abandon_partial_discovery();
1549 rp->verify_no_references_recorded();
1550 }
1551 }
1552 }
1553
1554 void ShenandoahHeap::op_final_evac() {
1555 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1556
1557 set_evacuation_in_progress(false);
1558
1559 retire_and_reset_gclabs();
1560
1561 if (ShenandoahVerify) {
1562 verifier()->verify_after_evacuation();
1563 }
1564
1565 if (VerifyAfterGC) {
1566 Universe::verify();
1567 }
1568 }
1569
1570 void ShenandoahHeap::op_conc_evac() {
1571 ShenandoahEvacuationTask task(this, _collection_set, true);
1572 workers()->run_task(&task);
1573 }
1574
1575 void ShenandoahHeap::op_stw_evac() {
1576 ShenandoahEvacuationTask task(this, _collection_set, false);
1577 workers()->run_task(&task);
1578 }
1579
1580 void ShenandoahHeap::op_updaterefs() {
1581 update_heap_references(true);
1582 }
1583
1584 void ShenandoahHeap::op_cleanup() {
1585 free_set()->recycle_trash();
1586 }
1587
1588 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1589 private:
1590 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1591 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1592 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1593
1594 public:
1595 ShenandoahConcurrentRootsEvacUpdateTask() :
1596 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task") {
1597 }
1598
1599 void work(uint worker_id) {
1600 ShenandoahEvacOOMScope oom;
1601 {
1602 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1603 // may race against OopStorage::release() calls.
1604 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1605 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1606 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1607 }
1608
1609 {
1610 ShenandoahEvacuateUpdateRootsClosure cl;
1611 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1612 _cld_roots.cld_do(&clds);
1613 }
1614 }
1615 };
1616
1617 void ShenandoahHeap::op_roots() {
1618 if (is_evacuation_in_progress() &&
1619 ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1620 ShenandoahConcurrentRootsEvacUpdateTask task;
1621 workers()->run_task(&task);
1622 }
1623 }
1624
1625 void ShenandoahHeap::op_reset() {
1626 reset_mark_bitmap();
1627 }
1628
1629 void ShenandoahHeap::op_preclean() {
1630 concurrent_mark()->preclean_weak_refs();
1631 }
1632
1633 void ShenandoahHeap::op_init_traversal() {
1634 traversal_gc()->init_traversal_collection();
1635 }
1636
1637 void ShenandoahHeap::op_traversal() {
1638 traversal_gc()->concurrent_traversal_collection();
1639 }
1640
1641 void ShenandoahHeap::op_final_traversal() {
1642 traversal_gc()->final_traversal_collection();
1643 }
1644
1645 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1646 ShenandoahMetricsSnapshot metrics;
1647 metrics.snap_before();
1648
1649 full_gc()->do_it(cause);
1650 if (UseTLAB) {
1651 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1652 resize_all_tlabs();
1653 }
1654
1655 metrics.snap_after();
1656
1657 if (metrics.is_good_progress()) {
1658 _progress_last_gc.set();
1659 } else {
1660 // Nothing to do. Tell the allocation path that we have failed to make
1661 // progress, and it can finally fail.
1662 _progress_last_gc.unset();
1663 }
1664 }
1665
1666 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1667 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1668 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1669 // some phase, we have to upgrade the Degenerate GC to Full GC.
1670
1671 clear_cancelled_gc();
1672
1673 ShenandoahMetricsSnapshot metrics;
1674 metrics.snap_before();
1675
1676 switch (point) {
1677 case _degenerated_traversal:
1678 {
1679 // Drop the collection set. Note: this leaves some already forwarded objects
1680 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1681 // workarounds in ShenandoahTraversalHeuristics.
1682
1683 ShenandoahHeapLocker locker(lock());
1684 collection_set()->clear_current_index();
1685 for (size_t i = 0; i < collection_set()->count(); i++) {
1686 ShenandoahHeapRegion* r = collection_set()->next();
1687 r->make_regular_bypass();
1688 }
1689 collection_set()->clear();
1690 }
1691 op_final_traversal();
1692 op_cleanup();
1693 return;
1694
1695 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1696 // but enters it at different points, depending on which concurrent phase had
1697 // degenerated.
1698
1699 case _degenerated_outside_cycle:
1700 // We have degenerated from outside the cycle, which means something is bad with
1701 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1702 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1703 // we can do the most aggressive degen cycle, which includes processing references and
1704 // class unloading, unless those features are explicitly disabled.
1705 //
1706 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1707 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1708 set_process_references(heuristics()->can_process_references());
1709 set_unload_classes(heuristics()->can_unload_classes());
1710
1711 if (is_traversal_mode()) {
1712 // Not possible to degenerate from here, upgrade to Full GC right away.
1713 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1714 op_degenerated_fail();
1715 return;
1716 }
1717
1718 op_reset();
1719
1720 op_init_mark();
1721 if (cancelled_gc()) {
1722 op_degenerated_fail();
1723 return;
1724 }
1725
1726 case _degenerated_mark:
1727 op_final_mark();
1728 if (cancelled_gc()) {
1729 op_degenerated_fail();
1730 return;
1731 }
1732
1733 op_cleanup();
1734
1735 case _degenerated_evac:
1736 // If heuristics thinks we should do the cycle, this flag would be set,
1737 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1738 if (is_evacuation_in_progress()) {
1739
1740 // Degeneration under oom-evac protocol might have left some objects in
1741 // collection set un-evacuated. Restart evacuation from the beginning to
1742 // capture all objects. For all the objects that are already evacuated,
1743 // it would be a simple check, which is supposed to be fast. This is also
1744 // safe to do even without degeneration, as CSet iterator is at beginning
1745 // in preparation for evacuation anyway.
1746 //
1747 // Before doing that, we need to make sure we never had any cset-pinned
1748 // regions. This may happen if allocation failure happened when evacuating
1749 // the about-to-be-pinned object, oom-evac protocol left the object in
1750 // the collection set, and then the pin reached the cset region. If we continue
1751 // the cycle here, we would trash the cset and alive objects in it. To avoid
1752 // it, we fail degeneration right away and slide into Full GC to recover.
1753
1754 {
1755 collection_set()->clear_current_index();
1756
1757 ShenandoahHeapRegion* r;
1758 while ((r = collection_set()->next()) != NULL) {
1759 if (r->is_pinned()) {
1760 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1761 op_degenerated_fail();
1762 return;
1763 }
1764 }
1765
1766 collection_set()->clear_current_index();
1767 }
1768
1769 op_stw_evac();
1770 if (cancelled_gc()) {
1771 op_degenerated_fail();
1772 return;
1773 }
1774 }
1775
1776 // If heuristics thinks we should do the cycle, this flag would be set,
1777 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1778 if (has_forwarded_objects()) {
1779 op_init_updaterefs();
1780 if (cancelled_gc()) {
1781 op_degenerated_fail();
1782 return;
1783 }
1784 }
1785
1786 case _degenerated_updaterefs:
1787 if (has_forwarded_objects()) {
1788 op_final_updaterefs();
1789 if (cancelled_gc()) {
1790 op_degenerated_fail();
1791 return;
1792 }
1793 }
1794
1795 op_cleanup();
1796 break;
1797
1798 default:
1799 ShouldNotReachHere();
1800 }
1801
1802 if (ShenandoahVerify) {
1803 verifier()->verify_after_degenerated();
1804 }
1805
1806 if (VerifyAfterGC) {
1807 Universe::verify();
1808 }
1809
1810 metrics.snap_after();
1811
1812 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1813 // because that probably means the heap is overloaded and/or fragmented.
1814 if (!metrics.is_good_progress()) {
1815 _progress_last_gc.unset();
1816 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1817 op_degenerated_futile();
1818 } else {
1819 _progress_last_gc.set();
1820 }
1821 }
1822
1823 void ShenandoahHeap::op_degenerated_fail() {
1824 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1825 shenandoah_policy()->record_degenerated_upgrade_to_full();
1826 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1827 }
1828
1829 void ShenandoahHeap::op_degenerated_futile() {
1830 shenandoah_policy()->record_degenerated_upgrade_to_full();
1831 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1832 }
1833
1834 void ShenandoahHeap::stop_concurrent_marking() {
1835 assert(is_concurrent_mark_in_progress(), "How else could we get here?");
1836 set_concurrent_mark_in_progress(false);
1837 if (!cancelled_gc()) {
1838 // If we needed to update refs, and concurrent marking has been cancelled,
1839 // we need to finish updating references.
1840 set_has_forwarded_objects(false);
1841 mark_complete_marking_context();
1842 }
1843 }
1844
1845 void ShenandoahHeap::force_satb_flush_all_threads() {
1846 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
1847 // No need to flush SATBs
1848 return;
1849 }
1850
1851 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1852 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
1853 }
1854 // The threads are not "acquiring" their thread-local data, but it does not
1855 // hurt to "release" the updates here anyway.
1856 OrderAccess::fence();
1857 }
1858
1859 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1860 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1861 ShenandoahThreadLocalData::set_gc_state(t, state);
1862 }
1863 }
1864
1865 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1866 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1867 _gc_state.set_cond(mask, value);
1868 set_gc_state_all_threads(_gc_state.raw_value());
1869 }
1870
1871 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1872 if (has_forwarded_objects()) {
1873 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
1874 } else {
1875 set_gc_state_mask(MARKING, in_progress);
1876 }
1877 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1878 }
1879
1880 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
1881 set_gc_state_mask(TRAVERSAL | HAS_FORWARDED | UPDATEREFS, in_progress);
1882 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1883 }
1884
1885 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1886 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1887 set_gc_state_mask(EVACUATION, in_progress);
1888 }
1889
1890 void ShenandoahHeap::ref_processing_init() {
1891 assert(_max_workers > 0, "Sanity");
1892
1893 _ref_processor =
1894 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
1895 ParallelRefProcEnabled, // MT processing
1896 _max_workers, // Degree of MT processing
1897 true, // MT discovery
1898 _max_workers, // Degree of MT discovery
1899 false, // Reference discovery is not atomic
1900 NULL, // No closure, should be installed before use
1901 true); // Scale worker threads
1902
1903 shenandoah_assert_rp_isalive_not_installed();
1904 }
1905
1906 GCTracer* ShenandoahHeap::tracer() {
1907 return shenandoah_policy()->tracer();
1908 }
1909
1910 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1911 return _free_set->used();
1912 }
1913
1914 bool ShenandoahHeap::try_cancel_gc() {
1915 while (true) {
1916 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1917 if (prev == CANCELLABLE) return true;
1918 else if (prev == CANCELLED) return false;
1919 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1920 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1921 {
1922 // We need to provide a safepoint here, otherwise we might
1923 // spin forever if a SP is pending.
1924 ThreadBlockInVM sp(JavaThread::current());
1925 SpinPause();
1926 }
1927 }
1928 }
1929
1930 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1931 if (try_cancel_gc()) {
1932 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1933 log_info(gc)("%s", msg.buffer());
1934 Events::log(Thread::current(), "%s", msg.buffer());
1935 }
1936 }
1937
1938 uint ShenandoahHeap::max_workers() {
1939 return _max_workers;
1940 }
1941
1942 void ShenandoahHeap::stop() {
1943 // The shutdown sequence should be able to terminate when GC is running.
1944
1945 // Step 0. Notify policy to disable event recording.
1946 _shenandoah_policy->record_shutdown();
1947
1948 // Step 1. Notify control thread that we are in shutdown.
1949 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1950 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1951 control_thread()->prepare_for_graceful_shutdown();
1952
1953 // Step 2. Notify GC workers that we are cancelling GC.
1954 cancel_gc(GCCause::_shenandoah_stop_vm);
1955
1956 // Step 3. Wait until GC worker exits normally.
1957 control_thread()->stop();
1958
1959 // Step 4. Stop String Dedup thread if it is active
1960 if (ShenandoahStringDedup::is_enabled()) {
1961 ShenandoahStringDedup::stop();
1962 }
1963 }
1964
1965 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1966 if (!unload_classes()) return;
1967 bool purged_class;
1968
1969 // Unload classes and purge SystemDictionary.
1970 {
1971 ShenandoahGCPhase phase(full_gc ?
1972 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1973 ShenandoahPhaseTimings::purge_class_unload);
1974 purged_class = SystemDictionary::do_unloading(gc_timer());
1975 }
1976
1977 {
1978 ShenandoahGCPhase phase(full_gc ?
1979 ShenandoahPhaseTimings::full_gc_purge_par :
1980 ShenandoahPhaseTimings::purge_par);
1981 ShenandoahIsAliveSelector is_alive;
1982 uint num_workers = _workers->active_workers();
1983 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
1984 _workers->run_task(&unlink_task);
1985 }
1986
1987 {
1988 ShenandoahGCPhase phase(full_gc ?
1989 ShenandoahPhaseTimings::full_gc_purge_cldg :
1990 ShenandoahPhaseTimings::purge_cldg);
1991 ClassLoaderDataGraph::purge();
1992 }
1993 // Resize and verify metaspace
1994 MetaspaceGC::compute_new_size();
1995 MetaspaceUtils::verify_metrics();
1996 }
1997
1998 // Process leftover weak oops: update them, if needed or assert they do not
1999 // need updating otherwise.
2000 // Weak processor API requires us to visit the oops, even if we are not doing
2001 // anything to them.
2002 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2003 ShenandoahGCPhase root_phase(full_gc ?
2004 ShenandoahPhaseTimings::full_gc_purge :
2005 ShenandoahPhaseTimings::purge);
2006 uint num_workers = _workers->active_workers();
2007 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2008 ShenandoahPhaseTimings::full_gc_purge_par :
2009 ShenandoahPhaseTimings::purge_par;
2010 // Cleanup weak roots
2011 ShenandoahGCPhase phase(timing_phase);
2012 if (has_forwarded_objects()) {
2013 ShenandoahForwardedIsAliveClosure is_alive;
2014 ShenandoahUpdateRefsClosure keep_alive;
2015 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2016 cleaning_task(&is_alive, &keep_alive, num_workers);
2017 _workers->run_task(&cleaning_task);
2018 } else {
2019 ShenandoahIsAliveClosure is_alive;
2020 #ifdef ASSERT
2021 ShenandoahAssertNotForwardedClosure verify_cl;
2022 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2023 cleaning_task(&is_alive, &verify_cl, num_workers);
2024 #else
2025 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2026 cleaning_task(&is_alive, &do_nothing_cl, num_workers);
2027 #endif
2028 _workers->run_task(&cleaning_task);
2029 }
2030 }
2031
2032 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2033 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2034 stw_process_weak_roots(full_gc);
2035 stw_unload_classes(full_gc);
2036 }
2037
2038 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2039 set_gc_state_mask(HAS_FORWARDED, cond);
2040 }
2041
2042 void ShenandoahHeap::set_process_references(bool pr) {
2043 _process_references.set_cond(pr);
2044 }
2045
2046 void ShenandoahHeap::set_unload_classes(bool uc) {
2047 _unload_classes.set_cond(uc);
2048 }
2049
2050 bool ShenandoahHeap::process_references() const {
2051 return _process_references.is_set();
2052 }
2053
2054 bool ShenandoahHeap::unload_classes() const {
2055 return _unload_classes.is_set();
2056 }
2057
2058 address ShenandoahHeap::in_cset_fast_test_addr() {
2059 ShenandoahHeap* heap = ShenandoahHeap::heap();
2060 assert(heap->collection_set() != NULL, "Sanity");
2061 return (address) heap->collection_set()->biased_map_address();
2062 }
2063
2064 address ShenandoahHeap::cancelled_gc_addr() {
2065 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2066 }
2067
2068 address ShenandoahHeap::gc_state_addr() {
2069 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2070 }
2071
2072 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2073 return OrderAccess::load_acquire(&_bytes_allocated_since_gc_start);
2074 }
2075
2076 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2077 OrderAccess::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2078 }
2079
2080 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2081 _degenerated_gc_in_progress.set_cond(in_progress);
2082 }
2083
2084 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2085 _full_gc_in_progress.set_cond(in_progress);
2086 }
2087
2088 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2089 assert (is_full_gc_in_progress(), "should be");
2090 _full_gc_move_in_progress.set_cond(in_progress);
2091 }
2092
2093 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2094 set_gc_state_mask(UPDATEREFS, in_progress);
2095 }
2096
2097 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2098 ShenandoahCodeRoots::add_nmethod(nm);
2099 }
2100
2101 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2102 ShenandoahCodeRoots::remove_nmethod(nm);
2103 }
2104
2105 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2106 ShenandoahHeapLocker locker(lock());
2107 heap_region_containing(o)->make_pinned();
2108 return o;
2109 }
2110
2111 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2112 ShenandoahHeapLocker locker(lock());
2113 heap_region_containing(o)->make_unpinned();
2114 }
2115
2116 GCTimer* ShenandoahHeap::gc_timer() const {
2117 return _gc_timer;
2118 }
2119
2120 #ifdef ASSERT
2121 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2122 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2123
2124 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2125 if (UseDynamicNumberOfGCThreads ||
2126 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2127 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2128 } else {
2129 // Use ParallelGCThreads inside safepoints
2130 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2131 }
2132 } else {
2133 if (UseDynamicNumberOfGCThreads ||
2134 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2135 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2136 } else {
2137 // Use ConcGCThreads outside safepoints
2138 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2139 }
2140 }
2141 }
2142 #endif
2143
2144 ShenandoahVerifier* ShenandoahHeap::verifier() {
2145 guarantee(ShenandoahVerify, "Should be enabled");
2146 assert (_verifier != NULL, "sanity");
2147 return _verifier;
2148 }
2149
2150 template<class T>
2151 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2152 private:
2153 T cl;
2154 ShenandoahHeap* _heap;
2155 ShenandoahRegionIterator* _regions;
2156 bool _concurrent;
2157 public:
2158 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2159 AbstractGangTask("Concurrent Update References Task"),
2160 cl(T()),
2161 _heap(ShenandoahHeap::heap()),
2162 _regions(regions),
2163 _concurrent(concurrent) {
2164 }
2165
2166 void work(uint worker_id) {
2167 if (_concurrent) {
2168 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2169 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2170 do_work();
2171 } else {
2172 ShenandoahParallelWorkerSession worker_session(worker_id);
2173 do_work();
2174 }
2175 }
2176
2177 private:
2178 void do_work() {
2179 ShenandoahHeapRegion* r = _regions->next();
2180 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2181 while (r != NULL) {
2182 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
2183 assert (top_at_start_ur >= r->bottom(), "sanity");
2184 if (r->is_active() && !r->is_cset()) {
2185 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
2186 }
2187 if (ShenandoahPacing) {
2188 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
2189 }
2190 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2191 return;
2192 }
2193 r = _regions->next();
2194 }
2195 }
2196 };
2197
2198 void ShenandoahHeap::update_heap_references(bool concurrent) {
2199 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2200 workers()->run_task(&task);
2201 }
2202
2203 void ShenandoahHeap::op_init_updaterefs() {
2204 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2205
2206 set_evacuation_in_progress(false);
2207
2208 retire_and_reset_gclabs();
2209
2210 if (ShenandoahVerify) {
2211 if (!is_degenerated_gc_in_progress()) {
2212 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2213 }
2214 verifier()->verify_before_updaterefs();
2215 }
2216
2217 set_update_refs_in_progress(true);
2218 make_parsable(true);
2219 for (uint i = 0; i < num_regions(); i++) {
2220 ShenandoahHeapRegion* r = get_region(i);
2221 r->set_concurrent_iteration_safe_limit(r->top());
2222 }
2223
2224 // Reset iterator.
2225 _update_refs_iterator.reset();
2226
2227 if (ShenandoahPacing) {
2228 pacer()->setup_for_updaterefs();
2229 }
2230 }
2231
2232 void ShenandoahHeap::op_final_updaterefs() {
2233 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2234
2235 // Check if there is left-over work, and finish it
2236 if (_update_refs_iterator.has_next()) {
2237 ShenandoahGCPhase final_work(ShenandoahPhaseTimings::final_update_refs_finish_work);
2238
2239 // Finish updating references where we left off.
2240 clear_cancelled_gc();
2241 update_heap_references(false);
2242 }
2243
2244 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2245 // everything. On degenerated paths, cancelled gc would not be set anyway.
2246 if (cancelled_gc()) {
2247 clear_cancelled_gc();
2248 }
2249 assert(!cancelled_gc(), "Should have been done right before");
2250
2251 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2252 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2253 }
2254
2255 if (is_degenerated_gc_in_progress()) {
2256 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2257 } else {
2258 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2259 }
2260
2261 // Has to be done before cset is clear
2262 if (ShenandoahVerify) {
2263 verifier()->verify_roots_in_to_space();
2264 }
2265
2266 ShenandoahGCPhase final_update_refs(ShenandoahPhaseTimings::final_update_refs_recycle);
2267
2268 trash_cset_regions();
2269 set_has_forwarded_objects(false);
2270 set_update_refs_in_progress(false);
2271
2272 if (ShenandoahVerify) {
2273 verifier()->verify_after_updaterefs();
2274 }
2275
2276 if (VerifyAfterGC) {
2277 Universe::verify();
2278 }
2279
2280 {
2281 ShenandoahHeapLocker locker(lock());
2282 _free_set->rebuild();
2283 }
2284 }
2285
2286 #ifdef ASSERT
2287 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2288 _lock.assert_owned_by_current_thread();
2289 }
2290
2291 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2292 _lock.assert_not_owned_by_current_thread();
2293 }
2294
2295 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2296 _lock.assert_owned_by_current_thread_or_safepoint();
2297 }
2298 #endif
2299
2300 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2301 print_on(st);
2302 print_heap_regions_on(st);
2303 }
2304
2305 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2306 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2307
2308 size_t regions_from = _bitmap_regions_per_slice * slice;
2309 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2310 for (size_t g = regions_from; g < regions_to; g++) {
2311 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2312 if (skip_self && g == r->region_number()) continue;
2313 if (get_region(g)->is_committed()) {
2314 return true;
2315 }
2316 }
2317 return false;
2318 }
2319
2320 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2321 assert_heaplock_owned_by_current_thread();
2322
2323 // Bitmaps in special regions do not need commits
2324 if (_bitmap_region_special) {
2325 return true;
2326 }
2327
2328 if (is_bitmap_slice_committed(r, true)) {
2329 // Some other region from the group is already committed, meaning the bitmap
2330 // slice is already committed, we exit right away.
2331 return true;
2332 }
2333
2334 // Commit the bitmap slice:
2335 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2336 size_t off = _bitmap_bytes_per_slice * slice;
2337 size_t len = _bitmap_bytes_per_slice;
2338 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2339 return false;
2340 }
2341 return true;
2342 }
2343
2344 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2345 assert_heaplock_owned_by_current_thread();
2346
2347 // Bitmaps in special regions do not need uncommits
2348 if (_bitmap_region_special) {
2349 return true;
2350 }
2351
2352 if (is_bitmap_slice_committed(r, true)) {
2353 // Some other region from the group is still committed, meaning the bitmap
2354 // slice is should stay committed, exit right away.
2355 return true;
2356 }
2357
2358 // Uncommit the bitmap slice:
2359 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2360 size_t off = _bitmap_bytes_per_slice * slice;
2361 size_t len = _bitmap_bytes_per_slice;
2362 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2363 return false;
2364 }
2365 return true;
2366 }
2367
2368 void ShenandoahHeap::safepoint_synchronize_begin() {
2369 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2370 SuspendibleThreadSet::synchronize();
2371 }
2372 }
2373
2374 void ShenandoahHeap::safepoint_synchronize_end() {
2375 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2376 SuspendibleThreadSet::desynchronize();
2377 }
2378 }
2379
2380 void ShenandoahHeap::vmop_entry_init_mark() {
2381 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2382 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2383 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2384
2385 try_inject_alloc_failure();
2386 VM_ShenandoahInitMark op;
2387 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2388 }
2389
2390 void ShenandoahHeap::vmop_entry_final_mark() {
2391 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2392 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2393 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2394
2395 try_inject_alloc_failure();
2396 VM_ShenandoahFinalMarkStartEvac op;
2397 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2398 }
2399
2400 void ShenandoahHeap::vmop_entry_final_evac() {
2401 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2402 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2403 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2404
2405 VM_ShenandoahFinalEvac op;
2406 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2407 }
2408
2409 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2410 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2411 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2412 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2413
2414 try_inject_alloc_failure();
2415 VM_ShenandoahInitUpdateRefs op;
2416 VMThread::execute(&op);
2417 }
2418
2419 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2420 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2421 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2422 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2423
2424 try_inject_alloc_failure();
2425 VM_ShenandoahFinalUpdateRefs op;
2426 VMThread::execute(&op);
2427 }
2428
2429 void ShenandoahHeap::vmop_entry_init_traversal() {
2430 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2431 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2432 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2433
2434 try_inject_alloc_failure();
2435 VM_ShenandoahInitTraversalGC op;
2436 VMThread::execute(&op);
2437 }
2438
2439 void ShenandoahHeap::vmop_entry_final_traversal() {
2440 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2441 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2442 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2443
2444 try_inject_alloc_failure();
2445 VM_ShenandoahFinalTraversalGC op;
2446 VMThread::execute(&op);
2447 }
2448
2449 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2450 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2451 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2452 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2453
2454 try_inject_alloc_failure();
2455 VM_ShenandoahFullGC op(cause);
2456 VMThread::execute(&op);
2457 }
2458
2459 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2460 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2461 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2462 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2463
2464 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2465 VMThread::execute(°enerated_gc);
2466 }
2467
2468 void ShenandoahHeap::entry_init_mark() {
2469 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2470 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2471 const char* msg = init_mark_event_message();
2472 GCTraceTime(Info, gc) time(msg, gc_timer());
2473 EventMark em("%s", msg);
2474
2475 ShenandoahWorkerScope scope(workers(),
2476 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2477 "init marking");
2478
2479 op_init_mark();
2480 }
2481
2482 void ShenandoahHeap::entry_final_mark() {
2483 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2484 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2485 const char* msg = final_mark_event_message();
2486 GCTraceTime(Info, gc) time(msg, gc_timer());
2487 EventMark em("%s", msg);
2488
2489 ShenandoahWorkerScope scope(workers(),
2490 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2491 "final marking");
2492
2493 op_final_mark();
2494 }
2495
2496 void ShenandoahHeap::entry_final_evac() {
2497 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2498 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2499 static const char* msg = "Pause Final Evac";
2500 GCTraceTime(Info, gc) time(msg, gc_timer());
2501 EventMark em("%s", msg);
2502
2503 op_final_evac();
2504 }
2505
2506 void ShenandoahHeap::entry_init_updaterefs() {
2507 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2508 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2509
2510 static const char* msg = "Pause Init Update Refs";
2511 GCTraceTime(Info, gc) time(msg, gc_timer());
2512 EventMark em("%s", msg);
2513
2514 // No workers used in this phase, no setup required
2515
2516 op_init_updaterefs();
2517 }
2518
2519 void ShenandoahHeap::entry_final_updaterefs() {
2520 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2521 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2522
2523 static const char* msg = "Pause Final Update Refs";
2524 GCTraceTime(Info, gc) time(msg, gc_timer());
2525 EventMark em("%s", msg);
2526
2527 ShenandoahWorkerScope scope(workers(),
2528 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2529 "final reference update");
2530
2531 op_final_updaterefs();
2532 }
2533
2534 void ShenandoahHeap::entry_init_traversal() {
2535 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2536 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2537
2538 static const char* msg = "Pause Init Traversal";
2539 GCTraceTime(Info, gc) time(msg, gc_timer());
2540 EventMark em("%s", msg);
2541
2542 ShenandoahWorkerScope scope(workers(),
2543 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2544 "init traversal");
2545
2546 op_init_traversal();
2547 }
2548
2549 void ShenandoahHeap::entry_final_traversal() {
2550 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2551 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2552
2553 static const char* msg = "Pause Final Traversal";
2554 GCTraceTime(Info, gc) time(msg, gc_timer());
2555 EventMark em("%s", msg);
2556
2557 ShenandoahWorkerScope scope(workers(),
2558 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2559 "final traversal");
2560
2561 op_final_traversal();
2562 }
2563
2564 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2565 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2566 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2567
2568 static const char* msg = "Pause Full";
2569 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2570 EventMark em("%s", msg);
2571
2572 ShenandoahWorkerScope scope(workers(),
2573 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2574 "full gc");
2575
2576 op_full(cause);
2577 }
2578
2579 void ShenandoahHeap::entry_degenerated(int point) {
2580 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2581 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2582
2583 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2584 const char* msg = degen_event_message(dpoint);
2585 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2586 EventMark em("%s", msg);
2587
2588 ShenandoahWorkerScope scope(workers(),
2589 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2590 "stw degenerated gc");
2591
2592 set_degenerated_gc_in_progress(true);
2593 op_degenerated(dpoint);
2594 set_degenerated_gc_in_progress(false);
2595 }
2596
2597 void ShenandoahHeap::entry_mark() {
2598 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2599
2600 const char* msg = conc_mark_event_message();
2601 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2602 EventMark em("%s", msg);
2603
2604 ShenandoahWorkerScope scope(workers(),
2605 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2606 "concurrent marking");
2607
2608 try_inject_alloc_failure();
2609 op_mark();
2610 }
2611
2612 void ShenandoahHeap::entry_evac() {
2613 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2614 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2615
2616 static const char* msg = "Concurrent evacuation";
2617 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2618 EventMark em("%s", msg);
2619
2620 ShenandoahWorkerScope scope(workers(),
2621 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2622 "concurrent evacuation");
2623
2624 try_inject_alloc_failure();
2625 op_conc_evac();
2626 }
2627
2628 void ShenandoahHeap::entry_updaterefs() {
2629 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2630
2631 static const char* msg = "Concurrent update references";
2632 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2633 EventMark em("%s", msg);
2634
2635 ShenandoahWorkerScope scope(workers(),
2636 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2637 "concurrent reference update");
2638
2639 try_inject_alloc_failure();
2640 op_updaterefs();
2641 }
2642
2643 void ShenandoahHeap::entry_roots() {
2644 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2645
2646 static const char* msg = "Concurrent roots processing";
2647 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2648 EventMark em("%s", msg);
2649
2650 ShenandoahWorkerScope scope(workers(),
2651 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2652 "concurrent root processing");
2653
2654 try_inject_alloc_failure();
2655 op_roots();
2656 }
2657
2658 void ShenandoahHeap::entry_cleanup() {
2659 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2660
2661 static const char* msg = "Concurrent cleanup";
2662 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2663 EventMark em("%s", msg);
2664
2665 // This phase does not use workers, no need for setup
2666
2667 try_inject_alloc_failure();
2668 op_cleanup();
2669 }
2670
2671 void ShenandoahHeap::entry_reset() {
2672 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2673
2674 static const char* msg = "Concurrent reset";
2675 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2676 EventMark em("%s", msg);
2677
2678 ShenandoahWorkerScope scope(workers(),
2679 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2680 "concurrent reset");
2681
2682 try_inject_alloc_failure();
2683 op_reset();
2684 }
2685
2686 void ShenandoahHeap::entry_preclean() {
2687 if (ShenandoahPreclean && process_references()) {
2688 static const char* msg = "Concurrent precleaning";
2689 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2690 EventMark em("%s", msg);
2691
2692 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2693
2694 ShenandoahWorkerScope scope(workers(),
2695 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2696 "concurrent preclean",
2697 /* check_workers = */ false);
2698
2699 try_inject_alloc_failure();
2700 op_preclean();
2701 }
2702 }
2703
2704 void ShenandoahHeap::entry_traversal() {
2705 static const char* msg = "Concurrent traversal";
2706 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2707 EventMark em("%s", msg);
2708
2709 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2710
2711 ShenandoahWorkerScope scope(workers(),
2712 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2713 "concurrent traversal");
2714
2715 try_inject_alloc_failure();
2716 op_traversal();
2717 }
2718
2719 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2720 static const char *msg = "Concurrent uncommit";
2721 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2722 EventMark em("%s", msg);
2723
2724 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2725
2726 op_uncommit(shrink_before);
2727 }
2728
2729 void ShenandoahHeap::try_inject_alloc_failure() {
2730 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2731 _inject_alloc_failure.set();
2732 os::naked_short_sleep(1);
2733 if (cancelled_gc()) {
2734 log_info(gc)("Allocation failure was successfully injected");
2735 }
2736 }
2737 }
2738
2739 bool ShenandoahHeap::should_inject_alloc_failure() {
2740 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2741 }
2742
2743 void ShenandoahHeap::initialize_serviceability() {
2744 _memory_pool = new ShenandoahMemoryPool(this);
2745 _cycle_memory_manager.add_pool(_memory_pool);
2746 _stw_memory_manager.add_pool(_memory_pool);
2747 }
2748
2749 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2750 GrowableArray<GCMemoryManager*> memory_managers(2);
2751 memory_managers.append(&_cycle_memory_manager);
2752 memory_managers.append(&_stw_memory_manager);
2753 return memory_managers;
2754 }
2755
2756 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2757 GrowableArray<MemoryPool*> memory_pools(1);
2758 memory_pools.append(_memory_pool);
2759 return memory_pools;
2760 }
2761
2762 MemoryUsage ShenandoahHeap::memory_usage() {
2763 return _memory_pool->get_memory_usage();
2764 }
2765
2766 void ShenandoahHeap::enter_evacuation() {
2767 _oom_evac_handler.enter_evacuation();
2768 }
2769
2770 void ShenandoahHeap::leave_evacuation() {
2771 _oom_evac_handler.leave_evacuation();
2772 }
2773
2774 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2775 _heap(ShenandoahHeap::heap()),
2776 _index(0) {}
2777
2778 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2779 _heap(heap),
2780 _index(0) {}
2781
2782 void ShenandoahRegionIterator::reset() {
2783 _index = 0;
2784 }
2785
2786 bool ShenandoahRegionIterator::has_next() const {
2787 return _index < _heap->num_regions();
2788 }
2789
2790 char ShenandoahHeap::gc_state() const {
2791 return _gc_state.raw_value();
2792 }
2793
2794 void ShenandoahHeap::deduplicate_string(oop str) {
2795 assert(java_lang_String::is_instance(str), "invariant");
2796
2797 if (ShenandoahStringDedup::is_enabled()) {
2798 ShenandoahStringDedup::deduplicate(str);
2799 }
2800 }
2801
2802 const char* ShenandoahHeap::init_mark_event_message() const {
2803 bool update_refs = has_forwarded_objects();
2804 bool proc_refs = process_references();
2805 bool unload_cls = unload_classes();
2806
2807 if (update_refs && proc_refs && unload_cls) {
2808 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
2809 } else if (update_refs && proc_refs) {
2810 return "Pause Init Mark (update refs) (process weakrefs)";
2811 } else if (update_refs && unload_cls) {
2812 return "Pause Init Mark (update refs) (unload classes)";
2813 } else if (proc_refs && unload_cls) {
2814 return "Pause Init Mark (process weakrefs) (unload classes)";
2815 } else if (update_refs) {
2816 return "Pause Init Mark (update refs)";
2817 } else if (proc_refs) {
2818 return "Pause Init Mark (process weakrefs)";
2819 } else if (unload_cls) {
2820 return "Pause Init Mark (unload classes)";
2821 } else {
2822 return "Pause Init Mark";
2823 }
2824 }
2825
2826 const char* ShenandoahHeap::final_mark_event_message() const {
2827 bool update_refs = has_forwarded_objects();
2828 bool proc_refs = process_references();
2829 bool unload_cls = unload_classes();
2830
2831 if (update_refs && proc_refs && unload_cls) {
2832 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
2833 } else if (update_refs && proc_refs) {
2834 return "Pause Final Mark (update refs) (process weakrefs)";
2835 } else if (update_refs && unload_cls) {
2836 return "Pause Final Mark (update refs) (unload classes)";
2837 } else if (proc_refs && unload_cls) {
2838 return "Pause Final Mark (process weakrefs) (unload classes)";
2839 } else if (update_refs) {
2840 return "Pause Final Mark (update refs)";
2841 } else if (proc_refs) {
2842 return "Pause Final Mark (process weakrefs)";
2843 } else if (unload_cls) {
2844 return "Pause Final Mark (unload classes)";
2845 } else {
2846 return "Pause Final Mark";
2847 }
2848 }
2849
2850 const char* ShenandoahHeap::conc_mark_event_message() const {
2851 bool update_refs = has_forwarded_objects();
2852 bool proc_refs = process_references();
2853 bool unload_cls = unload_classes();
2854
2855 if (update_refs && proc_refs && unload_cls) {
2856 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
2857 } else if (update_refs && proc_refs) {
2858 return "Concurrent marking (update refs) (process weakrefs)";
2859 } else if (update_refs && unload_cls) {
2860 return "Concurrent marking (update refs) (unload classes)";
2861 } else if (proc_refs && unload_cls) {
2862 return "Concurrent marking (process weakrefs) (unload classes)";
2863 } else if (update_refs) {
2864 return "Concurrent marking (update refs)";
2865 } else if (proc_refs) {
2866 return "Concurrent marking (process weakrefs)";
2867 } else if (unload_cls) {
2868 return "Concurrent marking (unload classes)";
2869 } else {
2870 return "Concurrent marking";
2871 }
2872 }
2873
2874 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
2875 switch (point) {
2876 case _degenerated_unset:
2877 return "Pause Degenerated GC (<UNSET>)";
2878 case _degenerated_traversal:
2879 return "Pause Degenerated GC (Traversal)";
2880 case _degenerated_outside_cycle:
2881 return "Pause Degenerated GC (Outside of Cycle)";
2882 case _degenerated_mark:
2883 return "Pause Degenerated GC (Mark)";
2884 case _degenerated_evac:
2885 return "Pause Degenerated GC (Evacuation)";
2886 case _degenerated_updaterefs:
2887 return "Pause Degenerated GC (Update Refs)";
2888 default:
2889 ShouldNotReachHere();
2890 return "ERROR";
2891 }
2892 }
2893
2894 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2895 #ifdef ASSERT
2896 assert(_liveness_cache != NULL, "sanity");
2897 assert(worker_id < _max_workers, "sanity");
2898 for (uint i = 0; i < num_regions(); i++) {
2899 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2900 }
2901 #endif
2902 return _liveness_cache[worker_id];
2903 }
2904
2905 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2906 assert(worker_id < _max_workers, "sanity");
2907 assert(_liveness_cache != NULL, "sanity");
2908 jushort* ld = _liveness_cache[worker_id];
2909 for (uint i = 0; i < num_regions(); i++) {
2910 ShenandoahHeapRegion* r = get_region(i);
2911 jushort live = ld[i];
2912 if (live > 0) {
2913 r->increase_live_data_gc_words(live);
2914 ld[i] = 0;
2915 }
2916 }
2917 }