1 /*
2 * Copyright (c) 2013, 2018, 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
27 #include "gc_implementation/shared/gcTimer.hpp"
28 #include "gc_implementation/shenandoah/shenandoahGCTraceTime.hpp"
29
30 #include "gc_implementation/shenandoah/shenandoahBarrierSet.hpp"
31 #include "gc_implementation/shenandoah/shenandoahClosures.inline.hpp"
32 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp"
33 #include "gc_implementation/shenandoah/shenandoahCollectorPolicy.hpp"
34 #include "gc_implementation/shenandoah/shenandoahConcurrentMark.inline.hpp"
35 #include "gc_implementation/shenandoah/shenandoahControlThread.hpp"
36 #include "gc_implementation/shenandoah/shenandoahFreeSet.hpp"
37 #include "gc_implementation/shenandoah/shenandoahPhaseTimings.hpp"
38 #include "gc_implementation/shenandoah/shenandoahHeap.inline.hpp"
39 #include "gc_implementation/shenandoah/shenandoahHeapRegion.inline.hpp"
40 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.hpp"
41 #include "gc_implementation/shenandoah/shenandoahMarkCompact.hpp"
42 #include "gc_implementation/shenandoah/shenandoahMarkingContext.inline.hpp"
43 #include "gc_implementation/shenandoah/shenandoahMonitoringSupport.hpp"
44 #include "gc_implementation/shenandoah/shenandoahMetrics.hpp"
45 #include "gc_implementation/shenandoah/shenandoahOopClosures.inline.hpp"
46 #include "gc_implementation/shenandoah/shenandoahPacer.inline.hpp"
47 #include "gc_implementation/shenandoah/shenandoahPadding.hpp"
48 #include "gc_implementation/shenandoah/shenandoahParallelCleaning.hpp"
49 #include "gc_implementation/shenandoah/shenandoahRootProcessor.inline.hpp"
50 #include "gc_implementation/shenandoah/shenandoahTaskqueue.hpp"
51 #include "gc_implementation/shenandoah/shenandoahUtils.hpp"
52 #include "gc_implementation/shenandoah/shenandoahVerifier.hpp"
53 #include "gc_implementation/shenandoah/shenandoahCodeRoots.hpp"
54 #include "gc_implementation/shenandoah/shenandoahVMOperations.hpp"
55 #include "gc_implementation/shenandoah/shenandoahWorkGroup.hpp"
56 #include "gc_implementation/shenandoah/shenandoahWorkerPolicy.hpp"
57 #include "gc_implementation/shenandoah/heuristics/shenandoahHeuristics.hpp"
58 #include "gc_implementation/shenandoah/mode/shenandoahIUMode.hpp"
59 #include "gc_implementation/shenandoah/mode/shenandoahPassiveMode.hpp"
60 #include "gc_implementation/shenandoah/mode/shenandoahSATBMode.hpp"
61 #if INCLUDE_JFR
62 #include "gc_implementation/shenandoah/shenandoahJfrSupport.hpp"
63 #endif
64
65 #include "memory/metaspace.hpp"
66 #include "runtime/vmThread.hpp"
67 #include "services/mallocTracker.hpp"
68
69 ShenandoahHeap* ShenandoahHeap::_heap = NULL;
70
71 class ShenandoahPretouchHeapTask : public AbstractGangTask {
72 private:
73 ShenandoahRegionIterator _regions;
74 const size_t _page_size;
75 public:
76 ShenandoahPretouchHeapTask(size_t page_size) :
77 AbstractGangTask("Shenandoah Pretouch Heap"),
78 _page_size(page_size) {}
79
80 virtual void work(uint worker_id) {
81 ShenandoahHeapRegion* r = _regions.next();
82 while (r != NULL) {
83 if (r->is_committed()) {
84 os::pretouch_memory((char *) r->bottom(), (char *) r->end());
85 }
86 r = _regions.next();
87 }
88 }
89 };
90
91 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
92 private:
93 ShenandoahRegionIterator _regions;
94 char* _bitmap_base;
95 const size_t _bitmap_size;
96 const size_t _page_size;
97 public:
98 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
99 AbstractGangTask("Shenandoah Pretouch Bitmap"),
100 _bitmap_base(bitmap_base),
101 _bitmap_size(bitmap_size),
102 _page_size(page_size) {}
103
104 virtual void work(uint worker_id) {
105 ShenandoahHeapRegion* r = _regions.next();
106 while (r != NULL) {
107 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
108 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
109 assert (end <= _bitmap_size, err_msg("end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size));
110
111 if (r->is_committed()) {
112 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end);
113 }
114
115 r = _regions.next();
116 }
117 }
118 };
119
120 jint ShenandoahHeap::initialize() {
121 CollectedHeap::pre_initialize();
122
123 //
124 // Figure out heap sizing
125 //
126
127 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
128 size_t min_byte_size = collector_policy()->min_heap_byte_size();
129 size_t max_byte_size = collector_policy()->max_heap_byte_size();
130 size_t heap_alignment = collector_policy()->heap_alignment();
131
132 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
133
134 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
135 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
136
137 _num_regions = ShenandoahHeapRegion::region_count();
138 assert(_num_regions == (max_byte_size / reg_size_bytes),
139 err_msg("Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
140 _num_regions, max_byte_size, reg_size_bytes));
141 // Now we know the number of regions, initialize the heuristics.
142 initialize_heuristics();
143
144 size_t num_committed_regions = init_byte_size / reg_size_bytes;
145 num_committed_regions = MIN2(num_committed_regions, _num_regions);
146 assert(num_committed_regions <= _num_regions, "sanity");
147 _initial_size = num_committed_regions * reg_size_bytes;
148
149 size_t num_min_regions = min_byte_size / reg_size_bytes;
150 num_min_regions = MIN2(num_min_regions, _num_regions);
151 assert(num_min_regions <= _num_regions, "sanity");
152 _minimum_size = num_min_regions * reg_size_bytes;
153
154 // Default to max heap size.
155 _soft_max_size = _num_regions * reg_size_bytes;
156
157 _committed = _initial_size;
158
159 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
160 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
161 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
162
163 //
164 // Reserve and commit memory for heap
165 //
166
167 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
168 _reserved.set_word_size(0);
169 _reserved.set_start((HeapWord*)heap_rs.base());
170 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
171 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
172 _heap_region_special = heap_rs.special();
173
174 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
175 err_msg("Misaligned heap: " PTR_FORMAT, p2i(base())));
176
177 #if SHENANDOAH_OPTIMIZED_MARKTASK
178 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
179 // Fail if we ever attempt to address more than we can.
180 if ((uintptr_t)(heap_rs.base() + heap_rs.size()) >= ShenandoahMarkTask::max_addressable()) {
181 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
182 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
183 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
184 p2i(heap_rs.base()), p2i(heap_rs.base() + heap_rs.size()), ShenandoahMarkTask::max_addressable());
185 vm_exit_during_initialization("Fatal Error", buf);
186 }
187 #endif
188
189 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
190 if (!_heap_region_special) {
191 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
192 "Cannot commit heap memory");
193 }
194
195 //
196 // Reserve and commit memory for bitmap(s)
197 //
198
199 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
200 _bitmap_size = align_size_up(_bitmap_size, bitmap_page_size);
201
202 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
203
204 guarantee(bitmap_bytes_per_region != 0,
205 err_msg("Bitmap bytes per region should not be zero"));
206 guarantee(is_power_of_2(bitmap_bytes_per_region),
207 err_msg("Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region));
208
209 if (bitmap_page_size > bitmap_bytes_per_region) {
210 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
211 _bitmap_bytes_per_slice = bitmap_page_size;
212 } else {
213 _bitmap_regions_per_slice = 1;
214 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
215 }
216
217 guarantee(_bitmap_regions_per_slice >= 1,
218 err_msg("Should have at least one region per slice: " SIZE_FORMAT,
219 _bitmap_regions_per_slice));
220
221 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
222 err_msg("Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
223 _bitmap_bytes_per_slice, bitmap_page_size));
224
225 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
226 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
227 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
228 _bitmap_region_special = bitmap.special();
229
230 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
231 align_size_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
232 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
233 if (!_bitmap_region_special) {
234 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
235 "Cannot commit bitmap memory");
236 }
237
238 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
239
240 if (ShenandoahVerify) {
241 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
242 if (!verify_bitmap.special()) {
243 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
244 "Cannot commit verification bitmap memory");
245 }
246 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
247 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
248 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
249 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
250 }
251
252 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
253 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
254 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
255 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
256 _aux_bitmap_region_special = aux_bitmap.special();
257 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
258
259 //
260 // Create regions and region sets
261 //
262 size_t region_align = align_size_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
263 size_t region_storage_size = align_size_up(region_align * _num_regions, region_page_size);
264 region_storage_size = align_size_up(region_storage_size, os::vm_allocation_granularity());
265
266 ReservedSpace region_storage(region_storage_size, region_page_size);
267 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
268 if (!region_storage.special()) {
269 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
270 "Cannot commit region memory");
271 }
272
273 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
274 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
275 // If not successful, bite a bullet and allocate at whatever address.
276 {
277 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
278 size_t cset_size = align_size_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
279
280 uintptr_t min = ShenandoahUtils::round_up_power_of_2(cset_align);
281 uintptr_t max = (1u << 30u);
282
283 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
284 char* req_addr = (char*)addr;
285 assert(is_ptr_aligned(req_addr, cset_align), "Should be aligned");
286 ReservedSpace cset_rs(cset_size, cset_align, false, req_addr);
287 if (cset_rs.is_reserved()) {
288 assert(cset_rs.base() == req_addr, err_msg("Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr));
289 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
290 break;
291 }
292 }
293
294 if (_collection_set == NULL) {
295 ReservedSpace cset_rs(cset_size, cset_align, false);
296 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
297 }
298 }
299
300 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
301 _free_set = new ShenandoahFreeSet(this, _num_regions);
302
303 {
304 ShenandoahHeapLocker locker(lock());
305
306 for (size_t i = 0; i < _num_regions; i++) {
307 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
308 bool is_committed = i < num_committed_regions;
309 void* loc = region_storage.base() + i * region_align;
310
311 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
312 assert(is_ptr_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
313
314 _marking_context->initialize_top_at_mark_start(r);
315 _regions[i] = r;
316 assert(!collection_set()->is_in(i), "New region should not be in collection set");
317 }
318
319 // Initialize to complete
320 _marking_context->mark_complete();
321
322 _free_set->rebuild();
323 }
324
325 if (AlwaysPreTouch) {
326 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
327 // before initialize() below zeroes it with initializing thread. For any given region,
328 // we touch the region and the corresponding bitmaps from the same thread.
329 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
330
331 _pretouch_heap_page_size = heap_page_size;
332 _pretouch_bitmap_page_size = bitmap_page_size;
333
334 #ifdef LINUX
335 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
336 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
337 // them into huge one. Therefore, we need to pretouch with smaller pages.
338 if (UseTransparentHugePages) {
339 _pretouch_heap_page_size = (size_t)os::vm_page_size();
340 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
341 }
342 #endif
343
344 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
345 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
346
347 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
348 _workers->run_task(&bcl);
349
350 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
351 _workers->run_task(&hcl);
352 }
353
354 //
355 // Initialize the rest of GC subsystems
356 //
357
358 set_barrier_set(new ShenandoahBarrierSet(this));
359
360 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
361 for (uint worker = 0; worker < _max_workers; worker++) {
362 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
363 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
364 }
365
366 // The call below uses stuff (the SATB* things) that are in G1, but probably
367 // belong into a shared location.
368 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
369 SATB_Q_FL_lock,
370 20 /*G1SATBProcessCompletedThreshold */,
371 Shared_SATB_Q_lock);
372
373 _monitoring_support = new ShenandoahMonitoringSupport(this);
374 _phase_timings = new ShenandoahPhaseTimings(max_workers());
375 ShenandoahStringDedup::initialize();
376 ShenandoahCodeRoots::initialize();
377
378 if (ShenandoahPacing) {
379 _pacer = new ShenandoahPacer(this);
380 _pacer->setup_for_idle();
381 } else {
382 _pacer = NULL;
383 }
384
385 _control_thread = new ShenandoahControlThread();
386
387 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
388 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
389 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
390 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
391 );
392
393 return JNI_OK;
394 }
395
396 #ifdef _MSC_VER
397 #pragma warning( push )
398 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
399 #endif
400
401 void ShenandoahHeap::initialize_heuristics() {
402 if (ShenandoahGCMode != NULL) {
403 if (strcmp(ShenandoahGCMode, "satb") == 0) {
404 _gc_mode = new ShenandoahSATBMode();
405 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
406 _gc_mode = new ShenandoahIUMode();
407 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
408 _gc_mode = new ShenandoahPassiveMode();
409 } else {
410 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
411 }
412 } else {
413 ShouldNotReachHere();
414 }
415 _gc_mode->initialize_flags();
416 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
417 vm_exit_during_initialization(
418 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
419 _gc_mode->name()));
420 }
421 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
422 vm_exit_during_initialization(
423 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
424 _gc_mode->name()));
425 }
426 log_info(gc, init)("Shenandoah GC mode: %s",
427 _gc_mode->name());
428
429 _heuristics = _gc_mode->initialize_heuristics();
430
431 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
432 vm_exit_during_initialization(
433 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
434 _heuristics->name()));
435 }
436 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
437 vm_exit_during_initialization(
438 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
439 _heuristics->name()));
440 }
441 log_info(gc, init)("Shenandoah heuristics: %s",
442 _heuristics->name());
443 }
444
445 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
446 SharedHeap(policy),
447 _shenandoah_policy(policy),
448 _heap_region_special(false),
449 _regions(NULL),
450 _free_set(NULL),
451 _collection_set(NULL),
452 _update_refs_iterator(this),
453 _bytes_allocated_since_gc_start(0),
454 _max_workers((uint)MAX2(ConcGCThreads, ParallelGCThreads)),
455 _ref_processor(NULL),
456 _marking_context(NULL),
457 _bitmap_size(0),
458 _bitmap_regions_per_slice(0),
459 _bitmap_bytes_per_slice(0),
460 _bitmap_region_special(false),
461 _aux_bitmap_region_special(false),
462 _liveness_cache(NULL),
463 _aux_bit_map(),
464 _verifier(NULL),
465 _pacer(NULL),
466 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
467 _phase_timings(NULL)
468 {
469 _heap = this;
470
471 log_info(gc, init)("GC threads: " UINTX_FORMAT " parallel, " UINTX_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
472
473 _scm = new ShenandoahConcurrentMark();
474
475 _full_gc = new ShenandoahMarkCompact();
476 _used = 0;
477
478 _max_workers = MAX2(_max_workers, 1U);
479
480 // SharedHeap did not initialize this for us, and we want our own workgang anyway.
481 assert(SharedHeap::_workers == NULL && _workers == NULL, "Should not be initialized yet");
482 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
483 /* are_GC_task_threads */true,
484 /* are_ConcurrentGC_threads */false);
485 if (_workers == NULL) {
486 vm_exit_during_initialization("Failed necessary allocation.");
487 } else {
488 _workers->initialize_workers();
489 }
490 assert(SharedHeap::_workers == _workers, "Sanity: initialized the correct field");
491 }
492
493 #ifdef _MSC_VER
494 #pragma warning( pop )
495 #endif
496
497 class ShenandoahResetBitmapTask : public AbstractGangTask {
498 private:
499 ShenandoahRegionIterator _regions;
500
501 public:
502 ShenandoahResetBitmapTask() :
503 AbstractGangTask("Parallel Reset Bitmap Task") {}
504
505 void work(uint worker_id) {
506 ShenandoahHeapRegion* region = _regions.next();
507 ShenandoahHeap* heap = ShenandoahHeap::heap();
508 ShenandoahMarkingContext* const ctx = heap->marking_context();
509 while (region != NULL) {
510 if (heap->is_bitmap_slice_committed(region)) {
511 ctx->clear_bitmap(region);
512 }
513 region = _regions.next();
514 }
515 }
516 };
517
518 void ShenandoahHeap::reset_mark_bitmap() {
519 assert_gc_workers(_workers->active_workers());
520 mark_incomplete_marking_context();
521
522 ShenandoahResetBitmapTask task;
523 _workers->run_task(&task);
524 }
525
526 void ShenandoahHeap::print_on(outputStream* st) const {
527 st->print_cr("Shenandoah Heap");
528 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
529 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
530 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
531 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
532 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
533 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
534 num_regions(),
535 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
536 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
537
538 st->print("Status: ");
539 if (has_forwarded_objects()) st->print("has forwarded objects, ");
540 if (is_concurrent_mark_in_progress()) st->print("marking, ");
541 if (is_evacuation_in_progress()) st->print("evacuating, ");
542 if (is_update_refs_in_progress()) st->print("updating refs, ");
543 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
544 if (is_full_gc_in_progress()) st->print("full gc, ");
545 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
546
547 if (cancelled_gc()) {
548 st->print("cancelled");
549 } else {
550 st->print("not cancelled");
551 }
552 st->cr();
553
554 st->print_cr("Reserved region:");
555 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
556 p2i(reserved_region().start()),
557 p2i(reserved_region().end()));
558
559 ShenandoahCollectionSet* cset = collection_set();
560 st->print_cr("Collection set:");
561 if (cset != NULL) {
562 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
563 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
564 } else {
565 st->print_cr(" (NULL)");
566 }
567
568 st->cr();
569 MetaspaceAux::print_on(st);
570
571 if (Verbose) {
572 print_heap_regions_on(st);
573 }
574 }
575
576 class ShenandoahInitGCLABClosure : public ThreadClosure {
577 public:
578 void do_thread(Thread* thread) {
579 assert(thread == NULL || !thread->is_Java_thread(), "Don't expect JavaThread this early");
580 if (thread != NULL && thread->is_Worker_thread()) {
581 thread->gclab().initialize(true);
582 }
583 }
584 };
585
586 void ShenandoahHeap::post_initialize() {
587 if (UseTLAB) {
588 MutexLocker ml(Threads_lock);
589
590 ShenandoahInitGCLABClosure init_gclabs;
591 Threads::threads_do(&init_gclabs);
592 }
593
594 _scm->initialize(_max_workers);
595 _full_gc->initialize(_gc_timer);
596
597 ref_processing_init();
598
599 _heuristics->initialize();
600
601 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
602 }
603
604 size_t ShenandoahHeap::used() const {
605 OrderAccess::acquire();
606 return (size_t) _used;
607 }
608
609 size_t ShenandoahHeap::committed() const {
610 OrderAccess::acquire();
611 return _committed;
612 }
613
614 void ShenandoahHeap::increase_committed(size_t bytes) {
615 shenandoah_assert_heaplocked_or_safepoint();
616 _committed += bytes;
617 }
618
619 void ShenandoahHeap::decrease_committed(size_t bytes) {
620 shenandoah_assert_heaplocked_or_safepoint();
621 _committed -= bytes;
622 }
623
624 void ShenandoahHeap::increase_used(size_t bytes) {
625 Atomic::add(bytes, &_used);
626 }
627
628 void ShenandoahHeap::set_used(size_t bytes) {
629 OrderAccess::release_store_fence(&_used, bytes);
630 }
631
632 void ShenandoahHeap::decrease_used(size_t bytes) {
633 assert(used() >= bytes, "never decrease heap size by more than we've left");
634 Atomic::add(-(jlong)bytes, &_used);
635 }
636
637 void ShenandoahHeap::increase_allocated(size_t bytes) {
638 Atomic::add(bytes, &_bytes_allocated_since_gc_start);
639 }
640
641 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
642 size_t bytes = words * HeapWordSize;
643 if (!waste) {
644 increase_used(bytes);
645 }
646 increase_allocated(bytes);
647 if (ShenandoahPacing) {
648 control_thread()->pacing_notify_alloc(words);
649 if (waste) {
650 pacer()->claim_for_alloc(words, true);
651 }
652 }
653 }
654
655 size_t ShenandoahHeap::capacity() const {
656 return committed();
657 }
658
659 size_t ShenandoahHeap::max_capacity() const {
660 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
661 }
662
663 size_t ShenandoahHeap::soft_max_capacity() const {
664 size_t v = OrderAccess::load_acquire((volatile size_t*)&_soft_max_size);
665 assert(min_capacity() <= v && v <= max_capacity(),
666 err_msg("Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
667 min_capacity(), v, max_capacity()));
668 return v;
669 }
670
671 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
672 assert(min_capacity() <= v && v <= max_capacity(),
673 err_msg("Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
674 min_capacity(), v, max_capacity()));
675 OrderAccess::release_store_fence(&_soft_max_size, v);
676 }
677
678 size_t ShenandoahHeap::min_capacity() const {
679 return _minimum_size;
680 }
681
682 size_t ShenandoahHeap::initial_capacity() const {
683 return _initial_size;
684 }
685
686 bool ShenandoahHeap::is_in(const void* p) const {
687 HeapWord* heap_base = (HeapWord*) base();
688 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
689 return p >= heap_base && p < last_region_end;
690 }
691
692 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
693 assert (ShenandoahUncommit, "should be enabled");
694
695 // Application allocates from the beginning of the heap, and GC allocates at
696 // the end of it. It is more efficient to uncommit from the end, so that applications
697 // could enjoy the near committed regions. GC allocations are much less frequent,
698 // and therefore can accept the committing costs.
699
700 size_t count = 0;
701 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
702 ShenandoahHeapRegion* r = get_region(i - 1);
703 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
704 ShenandoahHeapLocker locker(lock());
705 if (r->is_empty_committed()) {
706 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
707 break;
708 }
709
710 r->make_uncommitted();
711 count++;
712 }
713 }
714 SpinPause(); // allow allocators to take the lock
715 }
716
717 if (count > 0) {
718 _control_thread->notify_heap_changed();
719 }
720 }
721
722 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
723 // Retain tlab and allocate object in shared space if
724 // the amount free in the tlab is too large to discard.
725 if (thread->gclab().free() > thread->gclab().refill_waste_limit()) {
726 thread->gclab().record_slow_allocation(size);
727 return NULL;
728 }
729
730 // Discard gclab and allocate a new one.
731 // To minimize fragmentation, the last GCLAB may be smaller than the rest.
732 size_t new_gclab_size = thread->gclab().compute_size(size);
733
734 thread->gclab().clear_before_allocation();
735
736 if (new_gclab_size == 0) {
737 return NULL;
738 }
739
740 // Allocated object should fit in new GCLAB, and new_gclab_size should be larger than min
741 size_t min_size = MAX2(size + ThreadLocalAllocBuffer::alignment_reserve(), ThreadLocalAllocBuffer::min_size());
742 new_gclab_size = MAX2(new_gclab_size, min_size);
743
744 // Allocate a new GCLAB...
745 size_t actual_size = 0;
746 HeapWord* obj = allocate_new_gclab(min_size, new_gclab_size, &actual_size);
747
748 if (obj == NULL) {
749 return NULL;
750 }
751
752 assert (size <= actual_size, "allocation should fit");
753
754 if (ZeroTLAB) {
755 // ..and clear it.
756 Copy::zero_to_words(obj, actual_size);
757 } else {
758 // ...and zap just allocated object.
759 #ifdef ASSERT
760 // Skip mangling the space corresponding to the object header to
761 // ensure that the returned space is not considered parsable by
762 // any concurrent GC thread.
763 size_t hdr_size = oopDesc::header_size();
764 Copy::fill_to_words(obj + hdr_size, actual_size - hdr_size, badHeapWordVal);
765 #endif // ASSERT
766 }
767 thread->gclab().fill(obj, obj + size, actual_size);
768 return obj;
769 }
770
771 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t word_size) {
772 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(word_size);
773 return allocate_memory(req);
774 }
775
776 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
777 size_t word_size,
778 size_t* actual_size) {
779 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
780 HeapWord* res = allocate_memory(req);
781 if (res != NULL) {
782 *actual_size = req.actual_size();
783 } else {
784 *actual_size = 0;
785 }
786 return res;
787 }
788
789 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
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);
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);
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 WB 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 err_msg("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 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
876 private:
877 ShenandoahHeap* const _heap;
878 Thread* const _thread;
879 public:
880 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
881 _heap(heap), _thread(Thread::current()) {}
882
883 void do_object(oop p) {
884 shenandoah_assert_marked(NULL, p);
885 if (!p->is_forwarded()) {
886 _heap->evacuate_object(p, _thread);
887 }
888 }
889 };
890
891 class ShenandoahEvacuationTask : public AbstractGangTask {
892 private:
893 ShenandoahHeap* const _sh;
894 ShenandoahCollectionSet* const _cs;
895 bool _concurrent;
896 public:
897 ShenandoahEvacuationTask(ShenandoahHeap* sh,
898 ShenandoahCollectionSet* cs,
899 bool concurrent) :
900 AbstractGangTask("Parallel Evacuation Task"),
901 _sh(sh),
902 _cs(cs),
903 _concurrent(concurrent)
904 {}
905
906 void work(uint worker_id) {
907 ShenandoahEvacOOMScope oom_evac_scope;
908 if (_concurrent) {
909 ShenandoahConcurrentWorkerSession worker_session(worker_id);
910 do_work();
911 } else {
912 ShenandoahParallelWorkerSession worker_session(worker_id);
913 do_work();
914 }
915 }
916
917 private:
918 void do_work() {
919 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
920 ShenandoahHeapRegion* r;
921 while ((r =_cs->claim_next()) != NULL) {
922 assert(r->has_live(), err_msg("Region " SIZE_FORMAT " should have been reclaimed early", r->index()));
923 _sh->marked_object_iterate(r, &cl);
924
925 if (ShenandoahPacing) {
926 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
927 }
928
929 if (_sh->cancelled_gc()) {
930 break;
931 }
932 }
933 }
934 };
935
936 void ShenandoahHeap::trash_cset_regions() {
937 ShenandoahHeapLocker locker(lock());
938
939 ShenandoahCollectionSet* set = collection_set();
940 ShenandoahHeapRegion* r;
941 set->clear_current_index();
942 while ((r = set->next()) != NULL) {
943 r->make_trash();
944 }
945 collection_set()->clear();
946 }
947
948 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
949 st->print_cr("Heap Regions:");
950 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
951 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
952 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
953 st->print_cr("SN=alloc sequence number");
954
955 for (size_t i = 0; i < num_regions(); i++) {
956 get_region(i)->print_on(st);
957 }
958 }
959
960 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
961 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
962
963 oop humongous_obj = oop(start->bottom());
964 size_t size = humongous_obj->size();
965 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
966 size_t index = start->index() + required_regions - 1;
967
968 assert(!start->has_live(), "liveness must be zero");
969
970 for(size_t i = 0; i < required_regions; i++) {
971 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
972 // as it expects that every region belongs to a humongous region starting with a humongous start region.
973 ShenandoahHeapRegion* region = get_region(index --);
974
975 assert(region->is_humongous(), "expect correct humongous start or continuation");
976 assert(!region->is_cset(), "Humongous region should not be in collection set");
977
978 region->make_trash_immediate();
979 }
980 }
981
982 class ShenandoahRetireGCLABClosure : public ThreadClosure {
983 private:
984 bool _retire;
985 public:
986 ShenandoahRetireGCLABClosure(bool retire) : _retire(retire) {};
987
988 void do_thread(Thread* thread) {
989 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
990 thread->gclab().make_parsable(_retire);
991 }
992 };
993
994 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
995 if (UseTLAB) {
996 CollectedHeap::ensure_parsability(retire_tlabs);
997 ShenandoahRetireGCLABClosure cl(retire_tlabs);
998 Threads::java_threads_do(&cl);
999 _workers->threads_do(&cl);
1000 }
1001 }
1002
1003 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1004 private:
1005 ShenandoahRootEvacuator* _rp;
1006
1007 public:
1008 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1009 AbstractGangTask("Shenandoah evacuate and update roots"),
1010 _rp(rp) {}
1011
1012 void work(uint worker_id) {
1013 ShenandoahParallelWorkerSession worker_session(worker_id);
1014 ShenandoahEvacOOMScope oom_evac_scope;
1015 ShenandoahEvacuateUpdateRootsClosure cl;
1016
1017 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1018 _rp->roots_do(worker_id, &cl);
1019 }
1020 };
1021
1022 void ShenandoahHeap::evacuate_and_update_roots() {
1023 COMPILER2_PRESENT(DerivedPointerTable::clear());
1024
1025 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1026
1027 {
1028 ShenandoahRootEvacuator rp(ShenandoahPhaseTimings::init_evac);
1029 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1030 workers()->run_task(&roots_task);
1031 }
1032
1033 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1034 }
1035
1036 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1037 // Returns size in bytes
1038 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1039 }
1040
1041 size_t ShenandoahHeap::max_tlab_size() const {
1042 // Returns size in words
1043 return ShenandoahHeapRegion::max_tlab_size_words();
1044 }
1045
1046 class ShenandoahResizeGCLABClosure : public ThreadClosure {
1047 public:
1048 void do_thread(Thread* thread) {
1049 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
1050 thread->gclab().resize();
1051 }
1052 };
1053
1054 void ShenandoahHeap::resize_all_tlabs() {
1055 CollectedHeap::resize_all_tlabs();
1056
1057 ShenandoahResizeGCLABClosure cl;
1058 Threads::java_threads_do(&cl);
1059 _workers->threads_do(&cl);
1060 }
1061
1062 class ShenandoahAccumulateStatisticsGCLABClosure : public ThreadClosure {
1063 public:
1064 void do_thread(Thread* thread) {
1065 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
1066 thread->gclab().accumulate_statistics();
1067 thread->gclab().initialize_statistics();
1068 }
1069 };
1070
1071 void ShenandoahHeap::accumulate_statistics_all_gclabs() {
1072 ShenandoahAccumulateStatisticsGCLABClosure cl;
1073 Threads::java_threads_do(&cl);
1074 _workers->threads_do(&cl);
1075 }
1076
1077 void ShenandoahHeap::collect(GCCause::Cause cause) {
1078 _control_thread->request_gc(cause);
1079 }
1080
1081 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1082 //assert(false, "Shouldn't need to do full collections");
1083 }
1084
1085 CollectorPolicy* ShenandoahHeap::collector_policy() const {
1086 return _shenandoah_policy;
1087 }
1088
1089 void ShenandoahHeap::resize_tlabs() {
1090 CollectedHeap::resize_all_tlabs();
1091 }
1092
1093 void ShenandoahHeap::accumulate_statistics_tlabs() {
1094 CollectedHeap::accumulate_statistics_all_tlabs();
1095 }
1096
1097 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1098 ShenandoahHeapRegion* r = heap_region_containing(addr);
1099 if (r != NULL) {
1100 return r->block_start(addr);
1101 }
1102 return NULL;
1103 }
1104
1105 size_t ShenandoahHeap::block_size(const HeapWord* addr) const {
1106 ShenandoahHeapRegion* r = heap_region_containing(addr);
1107 return r->block_size(addr);
1108 }
1109
1110 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1111 ShenandoahHeapRegion* r = heap_region_containing(addr);
1112 return r->block_is_obj(addr);
1113 }
1114
1115 jlong ShenandoahHeap::millis_since_last_gc() {
1116 double v = heuristics()->time_since_last_gc() * 1000;
1117 assert(0 <= v && v <= max_jlong, err_msg("value should fit: %f", v));
1118 return (jlong)v;
1119 }
1120
1121 void ShenandoahHeap::prepare_for_verify() {
1122 if (SafepointSynchronize::is_at_safepoint()) {
1123 make_parsable(false);
1124 }
1125 }
1126
1127 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1128 workers()->print_worker_threads_on(st);
1129 if (ShenandoahStringDedup::is_enabled()) {
1130 ShenandoahStringDedup::print_worker_threads_on(st);
1131 }
1132 }
1133
1134 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1135 workers()->threads_do(tcl);
1136 if (ShenandoahStringDedup::is_enabled()) {
1137 ShenandoahStringDedup::threads_do(tcl);
1138 }
1139 }
1140
1141 void ShenandoahHeap::print_tracing_info() const {
1142 if (PrintGC || TraceGen0Time || TraceGen1Time) {
1143 ResourceMark rm;
1144 outputStream* out = gclog_or_tty;
1145 phase_timings()->print_global_on(out);
1146
1147 out->cr();
1148 out->cr();
1149
1150 shenandoah_policy()->print_gc_stats(out);
1151
1152 out->cr();
1153 out->cr();
1154 }
1155 }
1156
1157 void ShenandoahHeap::verify(bool silent, VerifyOption vo) {
1158 if (ShenandoahSafepoint::is_at_shenandoah_safepoint() || ! UseTLAB) {
1159 if (ShenandoahVerify) {
1160 verifier()->verify_generic(vo);
1161 } else {
1162 // TODO: Consider allocating verification bitmaps on demand,
1163 // and turn this on unconditionally.
1164 }
1165 }
1166 }
1167 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1168 return _free_set->capacity();
1169 }
1170
1171 class ObjectIterateScanRootClosure : public ExtendedOopClosure {
1172 private:
1173 MarkBitMap* _bitmap;
1174 Stack<oop,mtGC>* _oop_stack;
1175
1176 template <class T>
1177 void do_oop_work(T* p) {
1178 T o = oopDesc::load_heap_oop(p);
1179 if (!oopDesc::is_null(o)) {
1180 oop obj = oopDesc::decode_heap_oop_not_null(o);
1181 obj = (oop) ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1182 assert(obj->is_oop(), "must be a valid oop");
1183 if (!_bitmap->isMarked((HeapWord*) obj)) {
1184 _bitmap->mark((HeapWord*) obj);
1185 _oop_stack->push(obj);
1186 }
1187 }
1188 }
1189 public:
1190 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1191 _bitmap(bitmap), _oop_stack(oop_stack) {}
1192 void do_oop(oop* p) { do_oop_work(p); }
1193 void do_oop(narrowOop* p) { do_oop_work(p); }
1194 };
1195
1196 /*
1197 * This is public API, used in preparation of object_iterate().
1198 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1199 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1200 * control, we call SH::make_parsable().
1201 */
1202 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1203 // No-op.
1204 }
1205
1206 /*
1207 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1208 *
1209 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1210 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1211 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1212 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1213 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1214 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1215 * wiped the bitmap in preparation for next marking).
1216 *
1217 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1218 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1219 * is allowed to report dead objects, but is not required to do so.
1220 */
1221 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1222 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1223 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1224 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1225 return;
1226 }
1227
1228 // Reset bitmap
1229 _aux_bit_map.clear();
1230
1231 Stack<oop,mtGC> oop_stack;
1232
1233 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1234
1235 {
1236 // First, we process GC roots according to current GC cycle.
1237 // This populates the work stack with initial objects.
1238 // It is important to relinquish the associated locks before diving
1239 // into heap dumper.
1240 ShenandoahHeapIterationRootScanner rp;
1241 rp.roots_do(&oops);
1242 }
1243
1244 // Work through the oop stack to traverse heap.
1245 while (! oop_stack.is_empty()) {
1246 oop obj = oop_stack.pop();
1247 assert(obj->is_oop(), "must be a valid oop");
1248 cl->do_object(obj);
1249 obj->oop_iterate(&oops);
1250 }
1251
1252 assert(oop_stack.is_empty(), "should be empty");
1253
1254 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1255 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1256 }
1257 }
1258
1259 void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) {
1260 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1261 object_iterate(cl);
1262 }
1263
1264 void ShenandoahHeap::oop_iterate(ExtendedOopClosure* cl) {
1265 ObjectToOopClosure cl2(cl);
1266 object_iterate(&cl2);
1267 }
1268
1269 void ShenandoahHeap::gc_prologue(bool b) {
1270 Unimplemented();
1271 }
1272
1273 void ShenandoahHeap::gc_epilogue(bool b) {
1274 Unimplemented();
1275 }
1276
1277 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1278 for (size_t i = 0; i < num_regions(); i++) {
1279 ShenandoahHeapRegion* current = get_region(i);
1280 blk->heap_region_do(current);
1281 }
1282 }
1283
1284 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1285 private:
1286 ShenandoahHeap* const _heap;
1287 ShenandoahHeapRegionClosure* const _blk;
1288
1289 shenandoah_padding(0);
1290 volatile jint _index;
1291 shenandoah_padding(1);
1292
1293 public:
1294 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1295 AbstractGangTask("Parallel Region Task"),
1296 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1297
1298 void work(uint worker_id) {
1299 jint stride = (jint)ShenandoahParallelRegionStride;
1300
1301 jint max = (jint)_heap->num_regions();
1302 while (_index < max) {
1303 jint cur = Atomic::add(stride, &_index) - stride;
1304 jint start = cur;
1305 jint end = MIN2(cur + stride, max);
1306 if (start >= max) break;
1307
1308 for (jint i = cur; i < end; i++) {
1309 ShenandoahHeapRegion* current = _heap->get_region((size_t)i);
1310 _blk->heap_region_do(current);
1311 }
1312 }
1313 }
1314 };
1315
1316 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1317 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1318 if (num_regions() > ShenandoahParallelRegionStride) {
1319 ShenandoahParallelHeapRegionTask task(blk);
1320 workers()->run_task(&task);
1321 } else {
1322 heap_region_iterate(blk);
1323 }
1324 }
1325
1326 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1327 private:
1328 ShenandoahMarkingContext* const _ctx;
1329 public:
1330 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1331
1332 void heap_region_do(ShenandoahHeapRegion* r) {
1333 assert(!r->has_live(),
1334 err_msg("Region " SIZE_FORMAT " should have no live data", r->index()));
1335 if (r->is_active()) {
1336 // Check if region needs updating its TAMS. We have updated it already during concurrent
1337 // reset, so it is very likely we don't need to do another write here.
1338 if (_ctx->top_at_mark_start(r) != r->top()) {
1339 _ctx->capture_top_at_mark_start(r);
1340 }
1341 } else {
1342 assert(_ctx->top_at_mark_start(r) == r->top(),
1343 err_msg("Region " SIZE_FORMAT " should already have correct TAMS", r->index()));
1344 }
1345 }
1346
1347 bool is_thread_safe() { return true; }
1348 };
1349
1350 void ShenandoahHeap::op_init_mark() {
1351 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1352 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1353
1354 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1355 assert(!marking_context()->is_complete(), "should not be complete");
1356 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1357
1358 if (ShenandoahVerify) {
1359 verifier()->verify_before_concmark();
1360 }
1361
1362 {
1363 ShenandoahGCPhase phase(ShenandoahPhaseTimings::accumulate_stats);
1364 accumulate_statistics_tlabs();
1365 }
1366
1367 if (VerifyBeforeGC) {
1368 Universe::verify();
1369 }
1370
1371 set_concurrent_mark_in_progress(true);
1372 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1373 if (UseTLAB) {
1374 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1375 make_parsable(true);
1376 }
1377
1378 {
1379 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
1380 ShenandoahInitMarkUpdateRegionStateClosure cl;
1381 parallel_heap_region_iterate(&cl);
1382 }
1383
1384 // Make above changes visible to worker threads
1385 OrderAccess::fence();
1386
1387 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1388
1389 if (UseTLAB) {
1390 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1391 resize_tlabs();
1392 }
1393
1394 if (ShenandoahPacing) {
1395 pacer()->setup_for_mark();
1396 }
1397 }
1398
1399 void ShenandoahHeap::op_mark() {
1400 concurrent_mark()->mark_from_roots();
1401 }
1402
1403 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1404 private:
1405 ShenandoahMarkingContext* const _ctx;
1406 ShenandoahHeapLock* const _lock;
1407
1408 public:
1409 ShenandoahFinalMarkUpdateRegionStateClosure() :
1410 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1411
1412 void heap_region_do(ShenandoahHeapRegion* r) {
1413 if (r->is_active()) {
1414 // All allocations past TAMS are implicitly live, adjust the region data.
1415 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1416 HeapWord *tams = _ctx->top_at_mark_start(r);
1417 HeapWord *top = r->top();
1418 if (top > tams) {
1419 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1420 }
1421
1422 // We are about to select the collection set, make sure it knows about
1423 // current pinning status. Also, this allows trashing more regions that
1424 // now have their pinning status dropped.
1425 if (r->is_pinned()) {
1426 if (r->pin_count() == 0) {
1427 ShenandoahHeapLocker locker(_lock);
1428 r->make_unpinned();
1429 }
1430 } else {
1431 if (r->pin_count() > 0) {
1432 ShenandoahHeapLocker locker(_lock);
1433 r->make_pinned();
1434 }
1435 }
1436
1437 // Remember limit for updating refs. It's guaranteed that we get no
1438 // from-space-refs written from here on.
1439 r->set_update_watermark_at_safepoint(r->top());
1440 } else {
1441 assert(!r->has_live(),
1442 err_msg("Region " SIZE_FORMAT " should have no live data", r->index()));
1443 assert(_ctx->top_at_mark_start(r) == r->top(),
1444 err_msg("Region " SIZE_FORMAT " should have correct TAMS", r->index()));
1445 }
1446 }
1447
1448 bool is_thread_safe() { return true; }
1449 };
1450
1451 void ShenandoahHeap::op_final_mark() {
1452 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1453 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1454
1455 // It is critical that we
1456 // evacuate roots right after finishing marking, so that we don't
1457 // get unmarked objects in the roots.
1458
1459 if (!cancelled_gc()) {
1460 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1461
1462 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->reset_taskqueue_stats());
1463
1464 if (ShenandoahVerify) {
1465 verifier()->verify_roots_no_forwarded();
1466 }
1467
1468 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->print_taskqueue_stats());
1469
1470 {
1471 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states);
1472 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1473 parallel_heap_region_iterate(&cl);
1474
1475 assert_pinned_region_status();
1476 }
1477
1478 // Force the threads to reacquire their TLABs outside the collection set.
1479 {
1480 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1481 make_parsable(true);
1482 }
1483
1484 {
1485 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset);
1486 ShenandoahHeapLocker locker(lock());
1487 _collection_set->clear();
1488 heuristics()->choose_collection_set(_collection_set);
1489 }
1490
1491 {
1492 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset);
1493 ShenandoahHeapLocker locker(lock());
1494 _free_set->rebuild();
1495 }
1496
1497 // If collection set has candidates, start evacuation.
1498 // Otherwise, bypass the rest of the cycle.
1499 if (!collection_set()->is_empty()) {
1500 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1501
1502 if (ShenandoahVerify) {
1503 verifier()->verify_before_evacuation();
1504 }
1505
1506 set_evacuation_in_progress(true);
1507 // From here on, we need to update references.
1508 set_has_forwarded_objects(true);
1509
1510 if (!is_degenerated_gc_in_progress()) {
1511 evacuate_and_update_roots();
1512 }
1513
1514 if (ShenandoahPacing) {
1515 pacer()->setup_for_evac();
1516 }
1517
1518 if (ShenandoahVerify) {
1519 verifier()->verify_roots_no_forwarded();
1520 verifier()->verify_during_evacuation();
1521 }
1522 } else {
1523 if (ShenandoahVerify) {
1524 verifier()->verify_after_concmark();
1525 }
1526
1527 if (VerifyAfterGC) {
1528 Universe::verify();
1529 }
1530 }
1531
1532 } else {
1533 concurrent_mark()->cancel();
1534 complete_marking();
1535
1536 if (process_references()) {
1537 // Abandon reference processing right away: pre-cleaning must have failed.
1538 ReferenceProcessor *rp = ref_processor();
1539 rp->disable_discovery();
1540 rp->abandon_partial_discovery();
1541 rp->verify_no_references_recorded();
1542 }
1543 }
1544 }
1545
1546 void ShenandoahHeap::op_conc_evac() {
1547 ShenandoahEvacuationTask task(this, _collection_set, true);
1548 workers()->run_task(&task);
1549 }
1550
1551 void ShenandoahHeap::op_stw_evac() {
1552 ShenandoahEvacuationTask task(this, _collection_set, false);
1553 workers()->run_task(&task);
1554 }
1555
1556 void ShenandoahHeap::op_updaterefs() {
1557 update_heap_references(true);
1558 }
1559
1560 void ShenandoahHeap::op_cleanup_early() {
1561 free_set()->recycle_trash();
1562 }
1563
1564 void ShenandoahHeap::op_cleanup_complete() {
1565 free_set()->recycle_trash();
1566 }
1567
1568 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1569 private:
1570 ShenandoahMarkingContext* const _ctx;
1571 public:
1572 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1573
1574 void heap_region_do(ShenandoahHeapRegion* r) {
1575 if (r->is_active()) {
1576 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1577 // anyway to capture any updates that happened since now.
1578 r->clear_live_data();
1579 _ctx->capture_top_at_mark_start(r);
1580 }
1581 }
1582
1583 bool is_thread_safe() { return true; }
1584 };
1585
1586 void ShenandoahHeap::op_reset() {
1587 if (ShenandoahPacing) {
1588 pacer()->setup_for_reset();
1589 }
1590 reset_mark_bitmap();
1591
1592 ShenandoahResetUpdateRegionStateClosure cl;
1593 parallel_heap_region_iterate(&cl);
1594 }
1595
1596 void ShenandoahHeap::op_preclean() {
1597 if (ShenandoahPacing) {
1598 pacer()->setup_for_preclean();
1599 }
1600 concurrent_mark()->preclean_weak_refs();
1601 }
1602
1603 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1604 ShenandoahMetricsSnapshot metrics;
1605 metrics.snap_before();
1606
1607 full_gc()->do_it(cause);
1608
1609 metrics.snap_after();
1610
1611 if (metrics.is_good_progress()) {
1612 _progress_last_gc.set();
1613 } else {
1614 // Nothing to do. Tell the allocation path that we have failed to make
1615 // progress, and it can finally fail.
1616 _progress_last_gc.unset();
1617 }
1618 }
1619
1620 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1621 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1622 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1623 // some phase, we have to upgrade the Degenerate GC to Full GC.
1624
1625 clear_cancelled_gc();
1626
1627 ShenandoahMetricsSnapshot metrics;
1628 metrics.snap_before();
1629
1630 switch (point) {
1631 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1632 // but enters it at different points, depending on which concurrent phase had
1633 // degenerated.
1634
1635 case _degenerated_outside_cycle:
1636 // We have degenerated from outside the cycle, which means something is bad with
1637 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1638 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1639 // we can do the most aggressive degen cycle, which includes processing references and
1640 // class unloading, unless those features are explicitly disabled.
1641 //
1642 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1643 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1644 set_process_references(heuristics()->can_process_references());
1645 set_unload_classes(heuristics()->can_unload_classes());
1646
1647 if (_heap->process_references()) {
1648 ReferenceProcessor* rp = _heap->ref_processor();
1649 rp->set_active_mt_degree(_heap->workers()->active_workers());
1650
1651 // enable ("weak") refs discovery
1652 rp->enable_discovery(true /*verify_no_refs*/, true);
1653 rp->setup_policy(_heap->collector_policy()->should_clear_all_soft_refs());
1654 }
1655
1656 op_reset();
1657
1658 op_init_mark();
1659 if (cancelled_gc()) {
1660 op_degenerated_fail();
1661 return;
1662 }
1663
1664 case _degenerated_mark:
1665 op_final_mark();
1666 if (cancelled_gc()) {
1667 op_degenerated_fail();
1668 return;
1669 }
1670
1671 op_cleanup_early();
1672
1673 case _degenerated_evac:
1674 // If heuristics thinks we should do the cycle, this flag would be set,
1675 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1676 if (is_evacuation_in_progress()) {
1677
1678 // Degeneration under oom-evac protocol might have left some objects in
1679 // collection set un-evacuated. Restart evacuation from the beginning to
1680 // capture all objects. For all the objects that are already evacuated,
1681 // it would be a simple check, which is supposed to be fast. This is also
1682 // safe to do even without degeneration, as CSet iterator is at beginning
1683 // in preparation for evacuation anyway.
1684 //
1685 // Before doing that, we need to make sure we never had any cset-pinned
1686 // regions. This may happen if allocation failure happened when evacuating
1687 // the about-to-be-pinned object, oom-evac protocol left the object in
1688 // the collection set, and then the pin reached the cset region. If we continue
1689 // the cycle here, we would trash the cset and alive objects in it. To avoid
1690 // it, we fail degeneration right away and slide into Full GC to recover.
1691
1692 {
1693 sync_pinned_region_status();
1694 collection_set()->clear_current_index();
1695
1696 ShenandoahHeapRegion* r;
1697 while ((r = collection_set()->next()) != NULL) {
1698 if (r->is_pinned()) {
1699 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1700 op_degenerated_fail();
1701 return;
1702 }
1703 }
1704
1705 collection_set()->clear_current_index();
1706 }
1707
1708 op_stw_evac();
1709 if (cancelled_gc()) {
1710 op_degenerated_fail();
1711 return;
1712 }
1713 }
1714
1715 // If heuristics thinks we should do the cycle, this flag would be set,
1716 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1717 if (has_forwarded_objects()) {
1718 op_init_updaterefs();
1719 if (cancelled_gc()) {
1720 op_degenerated_fail();
1721 return;
1722 }
1723 }
1724
1725 case _degenerated_updaterefs:
1726 if (has_forwarded_objects()) {
1727 op_final_updaterefs();
1728 if (cancelled_gc()) {
1729 op_degenerated_fail();
1730 return;
1731 }
1732 }
1733
1734 op_cleanup_complete();
1735 break;
1736
1737 default:
1738 ShouldNotReachHere();
1739 }
1740
1741 if (ShenandoahVerify) {
1742 verifier()->verify_after_degenerated();
1743 }
1744
1745 if (VerifyAfterGC) {
1746 Universe::verify();
1747 }
1748
1749 metrics.snap_after();
1750
1751 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1752 // because that probably means the heap is overloaded and/or fragmented.
1753 if (!metrics.is_good_progress()) {
1754 _progress_last_gc.unset();
1755 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1756 op_degenerated_futile();
1757 } else {
1758 _progress_last_gc.set();
1759 }
1760 }
1761
1762 void ShenandoahHeap::op_degenerated_fail() {
1763 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1764 shenandoah_policy()->record_degenerated_upgrade_to_full();
1765 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1766 }
1767
1768 void ShenandoahHeap::op_degenerated_futile() {
1769 shenandoah_policy()->record_degenerated_upgrade_to_full();
1770 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1771 }
1772
1773 void ShenandoahHeap::complete_marking() {
1774 if (is_concurrent_mark_in_progress()) {
1775 set_concurrent_mark_in_progress(false);
1776 }
1777
1778 if (!cancelled_gc()) {
1779 // If we needed to update refs, and concurrent marking has been cancelled,
1780 // we need to finish updating references.
1781 set_has_forwarded_objects(false);
1782 mark_complete_marking_context();
1783 }
1784 }
1785
1786 void ShenandoahHeap::force_satb_flush_all_threads() {
1787 if (!is_concurrent_mark_in_progress()) {
1788 // No need to flush SATBs
1789 return;
1790 }
1791
1792 // Do not block if Threads lock is busy. This avoids the potential deadlock
1793 // when this code is called from the periodic task, and something else is
1794 // expecting the periodic task to complete without blocking. On the off-chance
1795 // Threads lock is busy momentarily, try to acquire several times.
1796 for (int t = 0; t < 10; t++) {
1797 if (Threads_lock->try_lock()) {
1798 JavaThread::set_force_satb_flush_all_threads(true);
1799 Threads_lock->unlock();
1800
1801 // The threads are not "acquiring" their thread-local data, but it does not
1802 // hurt to "release" the updates here anyway.
1803 OrderAccess::fence();
1804 break;
1805 }
1806 os::naked_short_sleep(1);
1807 }
1808 }
1809
1810 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1811 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1812 _gc_state.set_cond(mask, value);
1813 JavaThread::set_gc_state_all_threads(_gc_state.raw_value());
1814 }
1815
1816 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1817 if (has_forwarded_objects()) {
1818 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
1819 } else {
1820 set_gc_state_mask(MARKING, in_progress);
1821 }
1822 JavaThread::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1823 }
1824
1825 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1826 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1827 set_gc_state_mask(EVACUATION, in_progress);
1828 }
1829
1830 void ShenandoahHeap::ref_processing_init() {
1831 MemRegion mr = reserved_region();
1832
1833 assert(_max_workers > 0, "Sanity");
1834
1835 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1836 bool mt_discovery = _max_workers > 1;
1837
1838 _ref_processor =
1839 new ReferenceProcessor(mr, // span
1840 mt_processing, // MT processing
1841 _max_workers, // Degree of MT processing
1842 mt_discovery, // MT discovery
1843 _max_workers, // Degree of MT discovery
1844 false, // Reference discovery is not atomic
1845 NULL); // No closure, should be installed before use
1846
1847 log_info(gc, init)("Reference processing: %s discovery, %s processing",
1848 mt_discovery ? "parallel" : "serial",
1849 mt_processing ? "parallel" : "serial");
1850
1851 shenandoah_assert_rp_isalive_not_installed();
1852 }
1853
1854 void ShenandoahHeap::acquire_pending_refs_lock() {
1855 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::acquirePLL);
1856 }
1857
1858 void ShenandoahHeap::release_pending_refs_lock() {
1859 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
1860 }
1861
1862 GCTracer* ShenandoahHeap::tracer() {
1863 return shenandoah_policy()->tracer();
1864 }
1865
1866 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1867 return _free_set->used();
1868 }
1869
1870 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1871 if (try_cancel_gc()) {
1872 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1873 log_info(gc)("%s", msg.buffer());
1874 Events::log(Thread::current(), "%s", msg.buffer());
1875 }
1876 }
1877
1878 uint ShenandoahHeap::max_workers() {
1879 return _max_workers;
1880 }
1881
1882 void ShenandoahHeap::stop() {
1883 // The shutdown sequence should be able to terminate when GC is running.
1884
1885 // Step 0. Notify policy to disable event recording.
1886 _shenandoah_policy->record_shutdown();
1887
1888 // Step 1. Notify control thread that we are in shutdown.
1889 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1890 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1891 _control_thread->prepare_for_graceful_shutdown();
1892
1893 // Step 2. Notify GC workers that we are cancelling GC.
1894 cancel_gc(GCCause::_shenandoah_stop_vm);
1895
1896 // Step 3. Wait until GC worker exits normally.
1897 _control_thread->stop();
1898
1899 // Step 4. Stop String Dedup thread if it is active
1900 if (ShenandoahStringDedup::is_enabled()) {
1901 ShenandoahStringDedup::stop();
1902 }
1903 }
1904
1905 void ShenandoahHeap::unload_classes_and_cleanup_tables(bool full_gc) {
1906 assert(heuristics()->can_unload_classes(), "Class unloading should be enabled");
1907
1908 ShenandoahGCPhase root_phase(full_gc ?
1909 ShenandoahPhaseTimings::full_gc_purge :
1910 ShenandoahPhaseTimings::purge);
1911
1912 ShenandoahIsAliveSelector alive;
1913 BoolObjectClosure* is_alive = alive.is_alive_closure();
1914
1915 // Cleaning of klasses depends on correct information from MetadataMarkOnStack. The CodeCache::mark_on_stack
1916 // part is too slow to be done serially, so it is handled during the ShenandoahParallelCleaning phase.
1917 // Defer the cleaning until we have complete on_stack data.
1918 MetadataOnStackMark md_on_stack(false /* Don't visit the code cache at this point */);
1919
1920 bool purged_class;
1921
1922 // Unload classes and purge SystemDictionary.
1923 {
1924 ShenandoahGCPhase phase(full_gc ?
1925 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1926 ShenandoahPhaseTimings::purge_class_unload);
1927 purged_class = SystemDictionary::do_unloading(is_alive,
1928 false /* Defer klass cleaning */);
1929 }
1930 {
1931 ShenandoahGCPhase phase(full_gc ?
1932 ShenandoahPhaseTimings::full_gc_purge_par :
1933 ShenandoahPhaseTimings::purge_par);
1934 uint active = _workers->active_workers();
1935 ShenandoahParallelCleaningTask unlink_task(is_alive, true, true, active, purged_class);
1936 _workers->run_task(&unlink_task);
1937 }
1938
1939 {
1940 ShenandoahGCPhase phase(full_gc ?
1941 ShenandoahPhaseTimings::full_gc_purge_metadata :
1942 ShenandoahPhaseTimings::purge_metadata);
1943 ClassLoaderDataGraph::free_deallocate_lists();
1944 }
1945
1946 if (ShenandoahStringDedup::is_enabled()) {
1947 ShenandoahGCPhase phase(full_gc ?
1948 ShenandoahPhaseTimings::full_gc_purge_string_dedup :
1949 ShenandoahPhaseTimings::purge_string_dedup);
1950 ShenandoahStringDedup::parallel_cleanup();
1951 }
1952
1953 {
1954 ShenandoahGCPhase phase(full_gc ?
1955 ShenandoahPhaseTimings::full_gc_purge_cldg :
1956 ShenandoahPhaseTimings::purge_cldg);
1957 ClassLoaderDataGraph::purge();
1958 }
1959 }
1960
1961 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1962 set_gc_state_mask(HAS_FORWARDED, cond);
1963 }
1964
1965 void ShenandoahHeap::set_process_references(bool pr) {
1966 _process_references.set_cond(pr);
1967 }
1968
1969 void ShenandoahHeap::set_unload_classes(bool uc) {
1970 _unload_classes.set_cond(uc);
1971 }
1972
1973 bool ShenandoahHeap::process_references() const {
1974 return _process_references.is_set();
1975 }
1976
1977 bool ShenandoahHeap::unload_classes() const {
1978 return _unload_classes.is_set();
1979 }
1980
1981 address ShenandoahHeap::in_cset_fast_test_addr() {
1982 ShenandoahHeap* heap = ShenandoahHeap::heap();
1983 assert(heap->collection_set() != NULL, "Sanity");
1984 return (address) heap->collection_set()->biased_map_address();
1985 }
1986
1987 address ShenandoahHeap::cancelled_gc_addr() {
1988 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1989 }
1990
1991 address ShenandoahHeap::gc_state_addr() {
1992 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1993 }
1994
1995 size_t ShenandoahHeap::conservative_max_heap_alignment() {
1996 size_t align = ShenandoahMaxRegionSize;
1997 if (UseLargePages) {
1998 align = MAX2(align, os::large_page_size());
1999 }
2000 return align;
2001 }
2002
2003 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2004 return OrderAccess::load_acquire(&_bytes_allocated_since_gc_start);
2005 }
2006
2007 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2008 OrderAccess::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2009 }
2010
2011 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2012 _degenerated_gc_in_progress.set_cond(in_progress);
2013 }
2014
2015 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2016 _full_gc_in_progress.set_cond(in_progress);
2017 }
2018
2019 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2020 assert (is_full_gc_in_progress(), "should be");
2021 _full_gc_move_in_progress.set_cond(in_progress);
2022 }
2023
2024 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2025 set_gc_state_mask(UPDATEREFS, in_progress);
2026 }
2027
2028 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2029 ShenandoahCodeRoots::add_nmethod(nm);
2030 }
2031
2032 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2033 ShenandoahCodeRoots::remove_nmethod(nm);
2034 }
2035
2036 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2037 heap_region_containing(o)->record_pin();
2038 return o;
2039 }
2040
2041 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2042 heap_region_containing(o)->record_unpin();
2043 }
2044
2045 void ShenandoahHeap::sync_pinned_region_status() {
2046 ShenandoahHeapLocker locker(lock());
2047
2048 for (size_t i = 0; i < num_regions(); i++) {
2049 ShenandoahHeapRegion *r = get_region(i);
2050 if (r->is_active()) {
2051 if (r->is_pinned()) {
2052 if (r->pin_count() == 0) {
2053 r->make_unpinned();
2054 }
2055 } else {
2056 if (r->pin_count() > 0) {
2057 r->make_pinned();
2058 }
2059 }
2060 }
2061 }
2062
2063 assert_pinned_region_status();
2064 }
2065
2066 #ifdef ASSERT
2067 void ShenandoahHeap::assert_pinned_region_status() {
2068 for (size_t i = 0; i < num_regions(); i++) {
2069 ShenandoahHeapRegion* r = get_region(i);
2070 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2071 err_msg("Region " SIZE_FORMAT " pinning status is inconsistent", i));
2072 }
2073 }
2074 #endif
2075
2076 GCTimer* ShenandoahHeap::gc_timer() const {
2077 return _gc_timer;
2078 }
2079
2080 #ifdef ASSERT
2081 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2082 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2083
2084 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2085 if (UseDynamicNumberOfGCThreads ||
2086 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2087 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2088 } else {
2089 // Use ParallelGCThreads inside safepoints
2090 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2091 }
2092 } else {
2093 if (UseDynamicNumberOfGCThreads ||
2094 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2095 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2096 } else {
2097 // Use ConcGCThreads outside safepoints
2098 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2099 }
2100 }
2101 }
2102 #endif
2103
2104 ShenandoahVerifier* ShenandoahHeap::verifier() {
2105 guarantee(ShenandoahVerify, "Should be enabled");
2106 assert (_verifier != NULL, "sanity");
2107 return _verifier;
2108 }
2109
2110 ShenandoahUpdateHeapRefsClosure::ShenandoahUpdateHeapRefsClosure() :
2111 _heap(ShenandoahHeap::heap()) {}
2112
2113 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2114 private:
2115 ShenandoahHeap* _heap;
2116 ShenandoahRegionIterator* _regions;
2117 bool _concurrent;
2118
2119 public:
2120 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2121 AbstractGangTask("Concurrent Update References Task"),
2122 _heap(ShenandoahHeap::heap()),
2123 _regions(regions),
2124 _concurrent(concurrent) {
2125 }
2126
2127 void work(uint worker_id) {
2128 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2129 ShenandoahUpdateHeapRefsClosure cl;
2130 ShenandoahHeapRegion* r = _regions->next();
2131 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2132 while (r != NULL) {
2133 HeapWord* update_watermark = r->get_update_watermark();
2134 assert (update_watermark >= r->bottom(), "sanity");
2135 if (r->is_active() && !r->is_cset()) {
2136 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2137 }
2138 if (ShenandoahPacing) {
2139 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2140 }
2141 if (_heap->cancelled_gc()) {
2142 return;
2143 }
2144 r = _regions->next();
2145 }
2146 }
2147 };
2148
2149 void ShenandoahHeap::update_heap_references(bool concurrent) {
2150 ShenandoahUpdateHeapRefsTask task(&_update_refs_iterator, concurrent);
2151 workers()->run_task(&task);
2152 }
2153
2154 void ShenandoahHeap::op_init_updaterefs() {
2155 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2156
2157 set_evacuation_in_progress(false);
2158
2159 if (ShenandoahVerify) {
2160 if (!is_degenerated_gc_in_progress()) {
2161 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2162 }
2163 verifier()->verify_before_updaterefs();
2164 }
2165
2166 set_update_refs_in_progress(true);
2167
2168 {
2169 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2170
2171 make_parsable(true);
2172
2173 // Reset iterator.
2174 _update_refs_iterator.reset();
2175 }
2176
2177 if (ShenandoahPacing) {
2178 pacer()->setup_for_updaterefs();
2179 }
2180 }
2181
2182 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2183 private:
2184 ShenandoahHeapLock* const _lock;
2185
2186 public:
2187 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2188
2189 void heap_region_do(ShenandoahHeapRegion* r) {
2190 // Drop unnecessary "pinned" state from regions that does not have CP marks
2191 // anymore, as this would allow trashing them.
2192
2193 if (r->is_active()) {
2194 if (r->is_pinned()) {
2195 if (r->pin_count() == 0) {
2196 ShenandoahHeapLocker locker(_lock);
2197 r->make_unpinned();
2198 }
2199 } else {
2200 if (r->pin_count() > 0) {
2201 ShenandoahHeapLocker locker(_lock);
2202 r->make_pinned();
2203 }
2204 }
2205 }
2206 }
2207
2208 bool is_thread_safe() { return true; }
2209 };
2210
2211 void ShenandoahHeap::op_final_updaterefs() {
2212 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2213
2214 // Check if there is left-over work, and finish it
2215 if (_update_refs_iterator.has_next()) {
2216 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2217
2218 // Finish updating references where we left off.
2219 clear_cancelled_gc();
2220 update_heap_references(false);
2221 }
2222
2223 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2224 // everything. On degenerated paths, cancelled gc would not be set anyway.
2225 if (cancelled_gc()) {
2226 clear_cancelled_gc();
2227 }
2228 assert(!cancelled_gc(), "Should have been done right before");
2229
2230 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2231 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2232 }
2233
2234 if (is_degenerated_gc_in_progress()) {
2235 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2236 } else {
2237 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2238 }
2239
2240 // Has to be done before cset is clear
2241 if (ShenandoahVerify) {
2242 verifier()->verify_roots_in_to_space();
2243 }
2244
2245 {
2246 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2247 trash_cset_regions();
2248 }
2249
2250 set_has_forwarded_objects(false);
2251 set_update_refs_in_progress(false);
2252
2253 if (ShenandoahVerify) {
2254 verifier()->verify_after_updaterefs();
2255 }
2256
2257 if (VerifyAfterGC) {
2258 Universe::verify();
2259 }
2260
2261 {
2262 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states);
2263 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2264 parallel_heap_region_iterate(&cl);
2265
2266 assert_pinned_region_status();
2267 }
2268
2269 {
2270 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset);
2271 ShenandoahHeapLocker locker(lock());
2272 _free_set->rebuild();
2273 }
2274 }
2275
2276 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2277 print_on(st);
2278 print_heap_regions_on(st);
2279 }
2280
2281 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2282 size_t slice = r->index() / _bitmap_regions_per_slice;
2283
2284 size_t regions_from = _bitmap_regions_per_slice * slice;
2285 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2286 for (size_t g = regions_from; g < regions_to; g++) {
2287 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2288 if (skip_self && g == r->index()) continue;
2289 if (get_region(g)->is_committed()) {
2290 return true;
2291 }
2292 }
2293 return false;
2294 }
2295
2296 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2297 shenandoah_assert_heaplocked();
2298
2299 // Bitmaps in special regions do not need commits
2300 if (_bitmap_region_special) {
2301 return true;
2302 }
2303
2304 if (is_bitmap_slice_committed(r, true)) {
2305 // Some other region from the group is already committed, meaning the bitmap
2306 // slice is already committed, we exit right away.
2307 return true;
2308 }
2309
2310 // Commit the bitmap slice:
2311 size_t slice = r->index() / _bitmap_regions_per_slice;
2312 size_t off = _bitmap_bytes_per_slice * slice;
2313 size_t len = _bitmap_bytes_per_slice;
2314 char* start = (char*) _bitmap_region.start() + off;
2315
2316 if (!os::commit_memory(start, len, false)) {
2317 return false;
2318 }
2319
2320 if (AlwaysPreTouch) {
2321 os::pretouch_memory(start, start + len);
2322 }
2323
2324 return true;
2325 }
2326
2327 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2328 shenandoah_assert_heaplocked();
2329
2330 // Bitmaps in special regions do not need uncommits
2331 if (_bitmap_region_special) {
2332 return true;
2333 }
2334
2335 if (is_bitmap_slice_committed(r, true)) {
2336 // Some other region from the group is still committed, meaning the bitmap
2337 // slice is should stay committed, exit right away.
2338 return true;
2339 }
2340
2341 // Uncommit the bitmap slice:
2342 size_t slice = r->index() / _bitmap_regions_per_slice;
2343 size_t off = _bitmap_bytes_per_slice * slice;
2344 size_t len = _bitmap_bytes_per_slice;
2345 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2346 return false;
2347 }
2348 return true;
2349 }
2350
2351 void ShenandoahHeap::vmop_entry_init_mark() {
2352 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2353 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2354
2355 try_inject_alloc_failure();
2356 VM_ShenandoahInitMark op;
2357 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2358 }
2359
2360 void ShenandoahHeap::vmop_entry_final_mark() {
2361 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2362 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2363
2364 try_inject_alloc_failure();
2365 VM_ShenandoahFinalMarkStartEvac op;
2366 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2367 }
2368
2369 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2370 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2371 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2372
2373 try_inject_alloc_failure();
2374 VM_ShenandoahInitUpdateRefs op;
2375 VMThread::execute(&op);
2376 }
2377
2378 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2379 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2380 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2381
2382 try_inject_alloc_failure();
2383 VM_ShenandoahFinalUpdateRefs op;
2384 VMThread::execute(&op);
2385 }
2386
2387 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2388 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2389 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2390
2391 try_inject_alloc_failure();
2392 VM_ShenandoahFullGC op(cause);
2393 VMThread::execute(&op);
2394 }
2395
2396 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2397 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2398 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2399
2400 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2401 VMThread::execute(°enerated_gc);
2402 }
2403
2404 void ShenandoahHeap::entry_init_mark() {
2405 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2406
2407 const char* msg = init_mark_event_message();
2408 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2409 EventMark em("%s", msg);
2410
2411 ShenandoahWorkerScope scope(workers(),
2412 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2413 "init marking");
2414
2415 op_init_mark();
2416 }
2417
2418 void ShenandoahHeap::entry_final_mark() {
2419 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2420
2421 const char* msg = final_mark_event_message();
2422 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2423 EventMark em("%s", msg);
2424
2425 ShenandoahWorkerScope scope(workers(),
2426 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2427 "final marking");
2428
2429 op_final_mark();
2430 }
2431
2432 void ShenandoahHeap::entry_init_updaterefs() {
2433 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2434
2435 static const char* msg = "Pause Init Update Refs";
2436 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2437 EventMark em("%s", msg);
2438
2439 // No workers used in this phase, no setup required
2440
2441 op_init_updaterefs();
2442 }
2443
2444 void ShenandoahHeap::entry_final_updaterefs() {
2445 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2446
2447 static const char* msg = "Pause Final Update Refs";
2448 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2449 EventMark em("%s", msg);
2450
2451 ShenandoahWorkerScope scope(workers(),
2452 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2453 "final reference update");
2454
2455 op_final_updaterefs();
2456 }
2457
2458 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2459 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2460
2461 static const char* msg = "Pause Full";
2462 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true);
2463 EventMark em("%s", msg);
2464
2465 ShenandoahWorkerScope scope(workers(),
2466 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2467 "full gc");
2468
2469 op_full(cause);
2470 }
2471
2472 void ShenandoahHeap::entry_degenerated(int point) {
2473 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2474
2475 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2476 const char* msg = degen_event_message(dpoint);
2477 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true);
2478 EventMark em("%s", msg);
2479
2480 ShenandoahWorkerScope scope(workers(),
2481 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2482 "stw degenerated gc");
2483
2484 set_degenerated_gc_in_progress(true);
2485 op_degenerated(dpoint);
2486 set_degenerated_gc_in_progress(false);
2487 }
2488
2489 void ShenandoahHeap::entry_mark() {
2490 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2491
2492 const char* msg = conc_mark_event_message();
2493 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2494 EventMark em("%s", msg);
2495
2496 ShenandoahWorkerScope scope(workers(),
2497 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2498 "concurrent marking");
2499
2500 try_inject_alloc_failure();
2501 op_mark();
2502 }
2503
2504 void ShenandoahHeap::entry_evac() {
2505 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2506 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2507
2508 static const char *msg = "Concurrent evacuation";
2509 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2510 EventMark em("%s", msg);
2511
2512 ShenandoahWorkerScope scope(workers(),
2513 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2514 "concurrent evacuation");
2515
2516 try_inject_alloc_failure();
2517 op_conc_evac();
2518 }
2519
2520 void ShenandoahHeap::entry_updaterefs() {
2521 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2522
2523 static const char* msg = "Concurrent update references";
2524 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2525 EventMark em("%s", msg);
2526
2527 ShenandoahWorkerScope scope(workers(),
2528 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2529 "concurrent reference update");
2530
2531 try_inject_alloc_failure();
2532 op_updaterefs();
2533 }
2534
2535 void ShenandoahHeap::entry_cleanup_early() {
2536 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup_early);
2537
2538 static const char* msg = "Concurrent cleanup";
2539 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2540 EventMark em("%s", msg);
2541
2542 // This phase does not use workers, no need for setup
2543
2544 try_inject_alloc_failure();
2545 op_cleanup_early();
2546 }
2547
2548 void ShenandoahHeap::entry_cleanup_complete() {
2549 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup_complete);
2550
2551 static const char* msg = "Concurrent cleanup";
2552 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2553 EventMark em("%s", msg);
2554
2555 // This phase does not use workers, no need for setup
2556
2557 try_inject_alloc_failure();
2558 op_cleanup_complete();
2559 }
2560
2561 void ShenandoahHeap::entry_reset() {
2562 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2563
2564 static const char* msg = "Concurrent reset";
2565 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2566 EventMark em("%s", msg);
2567
2568 ShenandoahWorkerScope scope(workers(),
2569 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2570 "concurrent reset");
2571
2572 try_inject_alloc_failure();
2573 op_reset();
2574 }
2575
2576 void ShenandoahHeap::entry_preclean() {
2577 if (ShenandoahPreclean && process_references()) {
2578 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2579
2580 static const char* msg = "Concurrent precleaning";
2581 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2582 EventMark em("%s", msg);
2583
2584 ShenandoahWorkerScope scope(workers(),
2585 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2586 "concurrent preclean",
2587 /* check_workers = */ false);
2588
2589 try_inject_alloc_failure();
2590 op_preclean();
2591 }
2592 }
2593
2594 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2595 static const char *msg = "Concurrent uncommit";
2596 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2597 EventMark em("%s", msg);
2598
2599 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2600
2601 op_uncommit(shrink_before, shrink_until);
2602 }
2603
2604 void ShenandoahHeap::try_inject_alloc_failure() {
2605 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2606 _inject_alloc_failure.set();
2607 os::naked_short_sleep(1);
2608 if (cancelled_gc()) {
2609 log_info(gc)("Allocation failure was successfully injected");
2610 }
2611 }
2612 }
2613
2614 bool ShenandoahHeap::should_inject_alloc_failure() {
2615 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2616 }
2617
2618 void ShenandoahHeap::enter_evacuation() {
2619 _oom_evac_handler.enter_evacuation();
2620 }
2621
2622 void ShenandoahHeap::leave_evacuation() {
2623 _oom_evac_handler.leave_evacuation();
2624 }
2625
2626 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2627 _heap(ShenandoahHeap::heap()),
2628 _index(0) {}
2629
2630 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2631 _heap(heap),
2632 _index(0) {}
2633
2634 void ShenandoahRegionIterator::reset() {
2635 _index = 0;
2636 }
2637
2638 bool ShenandoahRegionIterator::has_next() const {
2639 return _index < (jint)_heap->num_regions();
2640 }
2641
2642 char ShenandoahHeap::gc_state() {
2643 return _gc_state.raw_value();
2644 }
2645
2646 const char* ShenandoahHeap::init_mark_event_message() const {
2647 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2648
2649 bool proc_refs = process_references();
2650 bool unload_cls = unload_classes();
2651
2652 if (proc_refs && unload_cls) {
2653 return "Pause Init Mark (process weakrefs) (unload classes)";
2654 } else if (proc_refs) {
2655 return "Pause Init Mark (process weakrefs)";
2656 } else if (unload_cls) {
2657 return "Pause Init Mark (unload classes)";
2658 } else {
2659 return "Pause Init Mark";
2660 }
2661 }
2662
2663 const char* ShenandoahHeap::final_mark_event_message() const {
2664 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2665
2666 bool proc_refs = process_references();
2667 bool unload_cls = unload_classes();
2668
2669 if (proc_refs && unload_cls) {
2670 return "Pause Final Mark (process weakrefs) (unload classes)";
2671 } else if (proc_refs) {
2672 return "Pause Final Mark (process weakrefs)";
2673 } else if (unload_cls) {
2674 return "Pause Final Mark (unload classes)";
2675 } else {
2676 return "Pause Final Mark";
2677 }
2678 }
2679
2680 const char* ShenandoahHeap::conc_mark_event_message() const {
2681 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2682
2683 bool proc_refs = process_references();
2684 bool unload_cls = unload_classes();
2685
2686 if (proc_refs && unload_cls) {
2687 return "Concurrent marking (process weakrefs) (unload classes)";
2688 } else if (proc_refs) {
2689 return "Concurrent marking (process weakrefs)";
2690 } else if (unload_cls) {
2691 return "Concurrent marking (unload classes)";
2692 } else {
2693 return "Concurrent marking";
2694 }
2695 }
2696
2697 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
2698 switch (point) {
2699 case _degenerated_unset:
2700 return "Pause Degenerated GC (<UNSET>)";
2701 case _degenerated_outside_cycle:
2702 return "Pause Degenerated GC (Outside of Cycle)";
2703 case _degenerated_mark:
2704 return "Pause Degenerated GC (Mark)";
2705 case _degenerated_evac:
2706 return "Pause Degenerated GC (Evacuation)";
2707 case _degenerated_updaterefs:
2708 return "Pause Degenerated GC (Update Refs)";
2709 default:
2710 ShouldNotReachHere();
2711 return "ERROR";
2712 }
2713 }
2714
2715 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2716 #ifdef ASSERT
2717 assert(_liveness_cache != NULL, "sanity");
2718 assert(worker_id < _max_workers, "sanity");
2719 for (uint i = 0; i < num_regions(); i++) {
2720 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2721 }
2722 #endif
2723 return _liveness_cache[worker_id];
2724 }
2725
2726 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2727 assert(worker_id < _max_workers, "sanity");
2728 assert(_liveness_cache != NULL, "sanity");
2729 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2730 for (uint i = 0; i < num_regions(); i++) {
2731 ShenandoahLiveData live = ld[i];
2732 if (live > 0) {
2733 ShenandoahHeapRegion* r = get_region(i);
2734 r->increase_live_data_gc_words(live);
2735 ld[i] = 0;
2736 }
2737 }
2738 }