/
orchestrate.c
565 lines (492 loc) · 25.2 KB
/
orchestrate.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
#include "moar.h"
#include <platform/threads.h>
/* If we have the job of doing GC for a thread, we add it to our work
* list. */
static void add_work(MVMThreadContext *tc, MVMThreadContext *stolen) {
MVMint32 i;
for (i = 0; i < tc->gc_work_count; i++)
if (tc->gc_work[i].tc == stolen)
return;
if (tc->gc_work == NULL) {
tc->gc_work_size = 16;
tc->gc_work = MVM_malloc(tc->gc_work_size * sizeof(MVMWorkThread));
}
else if (tc->gc_work_count == tc->gc_work_size) {
tc->gc_work_size *= 2;
tc->gc_work = MVM_realloc(tc->gc_work, tc->gc_work_size * sizeof(MVMWorkThread));
}
tc->gc_work[tc->gc_work_count++].tc = stolen;
}
/* Goes through all threads but the current one and notifies them that a
* GC run is starting. Those that are blocked are considered excluded from
* the run, and are not counted. Returns the count of threads that should be
* added to the finished countdown. */
static MVMuint32 signal_one_thread(MVMThreadContext *tc, MVMThreadContext *to_signal) {
/* Loop here since we may not succeed first time (e.g. the status of the
* thread may change between the two ways we try to twiddle it). */
while (1) {
switch (MVM_load(&to_signal->gc_status)) {
case MVMGCStatus_NONE:
/* Try to set it from running to interrupted - the common case. */
if (MVM_cas(&to_signal->gc_status, MVMGCStatus_NONE,
MVMGCStatus_INTERRUPT) == MVMGCStatus_NONE) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Signalled thread %d to interrupt\n", to_signal->thread_id);
return 1;
}
break;
case MVMGCStatus_INTERRUPT:
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : thread %d already interrupted\n", to_signal->thread_id);
return 0;
case MVMGCStatus_UNABLE:
/* Otherwise, it's blocked; try to set it to work Stolen. */
if (MVM_cas(&to_signal->gc_status, MVMGCStatus_UNABLE,
MVMGCStatus_STOLEN) == MVMGCStatus_UNABLE) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : A blocked thread %d spotted; work stolen\n", to_signal->thread_id);
add_work(tc, to_signal);
return 0;
}
break;
/* this case occurs if a child thread is Stolen by its parent
* before we get to it in the chain. */
case MVMGCStatus_STOLEN:
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : thread %d already stolen (it was a spawning child)\n", to_signal->thread_id);
return 0;
default:
MVM_panic(MVM_exitcode_gcorch, "invalid status %"MVM_PRSz" in GC orchestrate\n", MVM_load(&to_signal->gc_status));
return 0;
}
}
}
static MVMuint32 signal_all(MVMThreadContext *tc, MVMThread *threads) {
MVMThread *t = threads;
MVMuint32 count = 0;
while (t) {
switch (MVM_load(&t->body.stage)) {
case MVM_thread_stage_starting:
case MVM_thread_stage_waiting:
case MVM_thread_stage_started:
/* Don't signal ourself. */
if (t->body.tc != tc)
count += signal_one_thread(tc, t->body.tc);
break;
case MVM_thread_stage_exited:
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : queueing to clear nursery of thread %d\n", t->body.tc->thread_id);
add_work(tc, t->body.tc);
break;
case MVM_thread_stage_clearing_nursery:
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : queueing to destroy thread %d\n", t->body.tc->thread_id);
/* last GC run for this thread */
add_work(tc, t->body.tc);
break;
case MVM_thread_stage_destroyed:
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : found a destroyed thread\n");
/* will be cleaned up (removed from the lists) shortly */
break;
default:
MVM_panic(MVM_exitcode_gcorch, "Corrupted MVMThread or running threads list: invalid thread stage %"MVM_PRSz"", MVM_load(&t->body.stage));
}
t = t->body.next;
}
return count;
}
/* Does work in a thread's in-tray, if any. Returns a non-zero value if work
* was found and done, and zero otherwise. */
static int process_in_tray(MVMThreadContext *tc, MVMuint8 gen) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Considering extra work\n");
if (MVM_load(&tc->gc_in_tray)) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Was given extra work by another thread; doing it\n");
MVM_gc_collect(tc, MVMGCWhatToDo_InTray, gen);
return 1;
}
return 0;
}
/* Called by a thread when it thinks it is done with GC. It may get some more
* work yet, though. */
static void clear_intrays(MVMThreadContext *tc, MVMuint8 gen) {
MVMuint32 did_work = 1;
while (did_work) {
MVMThread *cur_thread;
did_work = 0;
cur_thread = (MVMThread *)MVM_load(&tc->instance->threads);
while (cur_thread) {
if (cur_thread->body.tc)
did_work += process_in_tray(cur_thread->body.tc, gen);
cur_thread = cur_thread->body.next;
}
}
}
static void finish_gc(MVMThreadContext *tc, MVMuint8 gen, MVMuint8 is_coordinator) {
MVMuint32 i, did_work;
/* Do any extra work that we have been passed. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : doing any work in thread in-trays\n");
did_work = 1;
while (did_work) {
did_work = 0;
for (i = 0; i < tc->gc_work_count; i++)
did_work += process_in_tray(tc->gc_work[i].tc, gen);
}
/* Decrement gc_finish to say we're done, and wait for termination. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Voting to finish\n");
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
MVM_decr(&tc->instance->gc_finish);
uv_cond_broadcast(&tc->instance->cond_gc_finish);
while (MVM_load(&tc->instance->gc_finish))
uv_cond_wait(&tc->instance->cond_gc_finish, &tc->instance->mutex_gc_orchestrate);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Termination agreed\n");
/* Co-ordinator should do final check over all the in-trays, and trigger
* collection until all is settled. Rest should wait. Additionally, after
* in-trays are settled, coordinator walks threads looking for anything
* that needs adding to the finalize queue. It then will make another
* iteration over in-trays to handle cross-thread references to objects
* needing finalization. For full collections, collected objects are then
* cleaned from all inter-generational sets, and finally any objects to
* be freed at the fixed size allocator's next safepoint are freed. */
if (is_coordinator) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator handling in-tray clearing completion\n");
clear_intrays(tc, gen);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator handling finalizers\n");
MVM_finalize_walk_queues(tc, gen);
clear_intrays(tc, gen);
if (gen == MVMGCGenerations_Both) {
MVMThread *cur_thread = (MVMThread *)MVM_load(&tc->instance->threads);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator handling inter-gen root cleanup\n");
while (cur_thread) {
if (cur_thread->body.tc)
MVM_gc_root_gen2_cleanup(cur_thread->body.tc);
cur_thread = cur_thread->body.next;
}
}
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator handling fixed-size allocator safepoint frees\n");
MVM_fixed_size_safepoint(tc, tc->instance->fsa);
MVM_profile_dump_instrumented_data(tc);
MVM_profile_heap_take_snapshot(tc);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator signalling in-trays clear\n");
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
MVM_store(&tc->instance->gc_intrays_clearing, 0);
uv_cond_broadcast(&tc->instance->cond_gc_intrays_clearing);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
}
else {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Waiting for in-tray clearing completion\n");
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
while (MVM_load(&tc->instance->gc_intrays_clearing))
uv_cond_wait(&tc->instance->cond_gc_intrays_clearing, &tc->instance->mutex_gc_orchestrate);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Got in-tray clearing complete notice\n");
}
/* Reset GC status flags. This is also where thread destruction happens,
* and it needs to happen before we acknowledge this GC run is finished. */
for (i = 0; i < tc->gc_work_count; i++) {
MVMThreadContext *other = tc->gc_work[i].tc;
MVMThread *thread_obj = other->thread_obj;
if (MVM_load(&thread_obj->body.stage) == MVM_thread_stage_clearing_nursery) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : transferring gen2 of thread %d\n", other->thread_id);
MVM_gc_gen2_transfer(other, tc);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : destroying thread %d\n", other->thread_id);
MVM_tc_destroy(other);
tc->gc_work[i].tc = thread_obj->body.tc = NULL;
MVM_store(&thread_obj->body.stage, MVM_thread_stage_destroyed);
}
else {
/* Free gen2 unmarked if full collection. */
if (gen == MVMGCGenerations_Both) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : freeing gen2 of thread %d\n",
other->thread_id);
MVM_gc_collect_free_gen2_unmarked(other, 0);
}
/* Contribute this thread's promoted bytes. */
MVM_add(&tc->instance->gc_promoted_bytes_since_last_full, other->gc_promoted_bytes);
/* Collect nursery. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : collecting nursery uncopied of thread %d\n",
other->thread_id);
MVM_gc_collect_free_nursery_uncopied(other, tc->gc_work[i].limit);
/* Handle exited threads. */
if (MVM_load(&thread_obj->body.stage) == MVM_thread_stage_exited) {
/* Don't bother freeing gen2; we'll do it next time */
MVM_store(&thread_obj->body.stage, MVM_thread_stage_clearing_nursery);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : set thread %d clearing nursery stage to %d\n",
other->thread_id, (int)MVM_load(&thread_obj->body.stage));
}
/* Mark thread free to continue. */
MVM_cas(&other->gc_status, MVMGCStatus_STOLEN, MVMGCStatus_UNABLE);
MVM_cas(&other->gc_status, MVMGCStatus_INTERRUPT, MVMGCStatus_NONE);
}
}
/* Signal acknowledgement of completing the cleanup,
* except for STables, and if we're the final to do
* so, free the STables, which have been linked. */
if (MVM_decr(&tc->instance->gc_ack) == 2) {
/* Set it to zero (we're guaranteed the only ones trying to write to
* it here). Actual STable free in MVM_gc_enter_from_allocator. */
MVM_store(&tc->instance->gc_ack, 0);
/* Also clear in GC flag. */
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
tc->instance->in_gc = 0;
uv_cond_broadcast(&tc->instance->cond_blocked_can_continue);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
}
}
/* Called by a thread to indicate it is about to enter a blocking operation.
* This tells any thread that is coordinating a GC run that this thread will
* be unable to participate. */
void MVM_gc_mark_thread_blocked(MVMThreadContext *tc) {
/* This may need more than one attempt. */
while (1) {
/* Try to set it from running to unable - the common case. */
if (MVM_cas(&tc->gc_status, MVMGCStatus_NONE,
MVMGCStatus_UNABLE) == MVMGCStatus_NONE)
return;
/* The only way this can fail is if another thread just decided we're to
* participate in a GC run. */
if (MVM_load(&tc->gc_status) == MVMGCStatus_INTERRUPT)
MVM_gc_enter_from_interrupt(tc);
else
MVM_panic(MVM_exitcode_gcorch,
"Invalid GC status observed while blocking thread; aborting");
}
}
/* Called by a thread to indicate it has completed a block operation and is
* thus able to particpate in a GC run again. Note that this case needs some
* special handling if it comes out of this mode when a GC run is taking place. */
void MVM_gc_mark_thread_unblocked(MVMThreadContext *tc) {
/* Try to set it from unable to running. */
while (MVM_cas(&tc->gc_status, MVMGCStatus_UNABLE,
MVMGCStatus_NONE) != MVMGCStatus_UNABLE) {
/* We can't, presumably because a GC run is going on. We should wait
* for that to finish before we go on; try using a condvar for it. */
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
if (tc->instance->in_gc) {
uv_cond_wait(&tc->instance->cond_blocked_can_continue,
&tc->instance->mutex_gc_orchestrate);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
}
else {
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
MVM_platform_thread_yield();
}
}
}
/* Checks if a thread has marked itself as blocked. Considers that the GC may
* have stolen its work and marked it as such also. So what this really
* answers is, "did this thread mark itself blocked, and since then not mark
* itself unblocked", which is useful if you need to conditionally unblock
* or re-block. If the status changes from blocked to stolen or stolen to
* blocked between checking this and calling unblock, it's safe anyway since
* these cases are handled in MVM_gc_mark_thread_unblocked. Note that this
* relies on a thread itself only ever calling block/unblock. */
MVMint32 MVM_gc_is_thread_blocked(MVMThreadContext *tc) {
AO_t gc_status = MVM_load(&(tc->gc_status));
return gc_status == MVMGCStatus_UNABLE ||
gc_status == MVMGCStatus_STOLEN;
}
static MVMint32 is_full_collection(MVMThreadContext *tc) {
MVMuint64 percent_growth, promoted;
size_t rss;
/* If it's below the absolute minimum, quickly return. */
promoted = (MVMuint64)MVM_load(&tc->instance->gc_promoted_bytes_since_last_full);
if (promoted < MVM_GC_GEN2_THRESHOLD_MINIMUM)
return 0;
/* If we're heap profiling then don't consider the resident set size, as
* it will be hugely distorted by the profile data we record. */
if (MVM_profile_heap_profiling(tc))
return 1;
/* Otherwise, consider percentage of resident set size. */
if (uv_resident_set_memory(&rss) < 0 || rss == 0)
rss = 50 * 1024 * 1024;
percent_growth = (100 * promoted) / (MVMuint64)rss;
return percent_growth >= MVM_GC_GEN2_THRESHOLD_PERCENT;
}
static void run_gc(MVMThreadContext *tc, MVMuint8 what_to_do) {
MVMuint8 gen;
MVMuint32 i, n;
unsigned int interval_id;
#if MVM_GC_DEBUG
if (tc->in_spesh)
MVM_panic(1, "Must not GC when in the specializer/JIT\n");
#endif
/* Decide nursery or full collection. */
gen = tc->instance->gc_full_collect ? MVMGCGenerations_Both : MVMGCGenerations_Nursery;
if (tc->instance->gc_full_collect) {
interval_id = MVM_telemetry_interval_start(tc, "start full collection");
} else {
interval_id = MVM_telemetry_interval_start(tc, "start minor collection");
}
/* Do GC work for ourselves and any work threads. */
for (i = 0, n = tc->gc_work_count ; i < n; i++) {
MVMThreadContext *other = tc->gc_work[i].tc;
tc->gc_work[i].limit = other->nursery_alloc;
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : starting collection for thread %d\n",
other->thread_id);
other->gc_promoted_bytes = 0;
MVM_gc_collect(other, (other == tc ? what_to_do : MVMGCWhatToDo_NoInstance), gen);
}
/* Wait for everybody to agree we're done. */
finish_gc(tc, gen, what_to_do == MVMGCWhatToDo_All);
MVM_telemetry_interval_stop(tc, interval_id, "finished run_gc");
}
/* This is called when the allocator finds it has run out of memory and wants
* to trigger a GC run. In this case, it's possible (probable, really) that it
* will need to do that triggering, notifying other running threads that the
* time has come to GC. */
void MVM_gc_enter_from_allocator(MVMThreadContext *tc) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Entered from allocate\n");
MVM_telemetry_timestamp(tc, "gc_enter_from_allocator");
/* Try to start the GC run. */
if (MVM_trycas(&tc->instance->gc_start, 0, 1)) {
MVMThread *last_starter = NULL;
MVMuint32 num_threads = 0;
/* Stash us as the thread to blame for this GC run (used to give it a
* potential nursery size boost). */
tc->instance->thread_to_blame_for_gc = tc;
/* Need to wait for other threads to reset their gc_status. */
while (MVM_load(&tc->instance->gc_ack)) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : waiting for other thread's gc_ack\n");
MVM_platform_thread_yield();
}
/* We are the winner of the GC starting race. This gives us some
* extra responsibilities as well as doing the usual things.
* First, increment GC sequence number. */
MVM_incr(&tc->instance->gc_seq_number);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : GC thread elected coordinator: starting gc seq %d\n",
(int)MVM_load(&tc->instance->gc_seq_number));
/* Decide if it will be a full collection. */
tc->instance->gc_full_collect = is_full_collection(tc);
MVM_telemetry_timestamp(tc, "won the gc starting race");
/* If profiling, record that GC is starting. */
if (tc->instance->profiling)
MVM_profiler_log_gc_start(tc, tc->instance->gc_full_collect, 1);
/* Ensure our stolen list is empty. */
tc->gc_work_count = 0;
/* Flag that we didn't agree on this run that all the in-trays are
* cleared (a responsibility of the co-ordinator. */
MVM_store(&tc->instance->gc_intrays_clearing, 1);
/* We'll take care of our own work. */
add_work(tc, tc);
/* Find other threads, and signal or steal. Also set in GC flag. */
uv_mutex_lock(&tc->instance->mutex_threads);
tc->instance->in_gc = 1;
num_threads = signal_all(tc, tc->instance->threads);
uv_mutex_unlock(&tc->instance->mutex_threads);
/* Bump the thread count and signal any threads waiting for that. */
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
MVM_add(&tc->instance->gc_start, num_threads);
uv_cond_broadcast(&tc->instance->cond_gc_start);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
/* If there's an event loop thread, wake it up to participate. */
if (tc->instance->event_loop_wakeup)
uv_async_send(tc->instance->event_loop_wakeup);
/* Wait for other threads to be ready. */
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
while (MVM_load(&tc->instance->gc_start) > 1)
uv_cond_wait(&tc->instance->cond_gc_start, &tc->instance->mutex_gc_orchestrate);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
/* Sanity check finish votes. */
if (MVM_load(&tc->instance->gc_finish) != 0)
MVM_panic(MVM_exitcode_gcorch, "Finish votes was %"MVM_PRSz"\n",
MVM_load(&tc->instance->gc_finish));
/* gc_ack gets an extra so the final acknowledger
* can also free the STables. */
MVM_store(&tc->instance->gc_finish, num_threads + 1);
MVM_store(&tc->instance->gc_ack, num_threads + 2);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : finish votes is %d\n",
(int)MVM_load(&tc->instance->gc_finish));
/* Now we're ready to start, zero promoted since last full collection
* counter if this is a full collect. */
if (tc->instance->gc_full_collect)
MVM_store(&tc->instance->gc_promoted_bytes_since_last_full, 0);
/* This is a safe point for us to free any STables that have been marked
* for deletion in the previous collection (since we let finalization -
* which appends to this list - happen after we set threads on their
* way again, it's not safe to do it in the previous collection). */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Freeing STables if needed\n");
MVM_gc_collect_free_stables(tc);
/* Signal to the rest to start */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : coordinator signalling start\n");
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
if (MVM_decr(&tc->instance->gc_start) != 1)
MVM_panic(MVM_exitcode_gcorch, "Start votes was %"MVM_PRSz"\n", MVM_load(&tc->instance->gc_start));
uv_cond_broadcast(&tc->instance->cond_gc_start);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
/* Start collecting. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : coordinator entering run_gc\n");
run_gc(tc, MVMGCWhatToDo_All);
/* If profiling, record that GC is over. */
if (tc->instance->profiling)
MVM_profiler_log_gc_end(tc);
MVM_telemetry_timestamp(tc, "gc finished");
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : GC complete (coordinator)\n");
}
else {
/* Another thread beat us to starting the GC sync process. Thus, act as
* if we were interrupted to GC. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Lost coordinator election\n");
MVM_gc_enter_from_interrupt(tc);
}
}
/* This is called when a thread hits an interrupt at a GC safe point. This means
* that another thread is already trying to start a GC run, so we don't need to
* try and do that, just enlist in the run. */
void MVM_gc_enter_from_interrupt(MVMThreadContext *tc) {
AO_t curr;
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Entered from interrupt\n");
MVM_telemetry_timestamp(tc, "gc_enter_from_interrupt");
/* If profiling, record that GC is starting. */
if (tc->instance->profiling)
MVM_profiler_log_gc_start(tc, is_full_collection(tc), 0);
/* We'll certainly take care of our own work. */
tc->gc_work_count = 0;
add_work(tc, tc);
/* Indicate that we're ready to GC. Only want to decrement it if it's 2 or
* greater (0 should never happen; 1 means the coordinator is still counting
* up how many threads will join in, so we should wait until it decides to
* decrement.) */
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
while (MVM_load(&tc->instance->gc_start) < 2)
uv_cond_wait(&tc->instance->cond_gc_start, &tc->instance->mutex_gc_orchestrate);
MVM_decr(&tc->instance->gc_start);
uv_cond_broadcast(&tc->instance->cond_gc_start);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
/* Wait for all threads to indicate readiness to collect. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Waiting for other threads\n");
uv_mutex_lock(&tc->instance->mutex_gc_orchestrate);
while (MVM_load(&tc->instance->gc_start))
uv_cond_wait(&tc->instance->cond_gc_start, &tc->instance->mutex_gc_orchestrate);
uv_mutex_unlock(&tc->instance->mutex_gc_orchestrate);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Entering run_gc\n");
run_gc(tc, MVMGCWhatToDo_NoInstance);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : GC complete\n");
/* If profiling, record that GC is over. */
if (tc->instance->profiling)
MVM_profiler_log_gc_end(tc);
}
/* Run the global destruction phase. */
void MVM_gc_global_destruction(MVMThreadContext *tc) {
char *nursery_tmp;
/* Fake a nursery collection run by swapping the semi-
* space nurseries. */
nursery_tmp = tc->nursery_fromspace;
tc->nursery_fromspace = tc->nursery_tospace;
tc->nursery_tospace = nursery_tmp;
/* Run the objects' finalizers */
MVM_gc_collect_free_nursery_uncopied(tc, tc->nursery_alloc);
MVM_gc_root_gen2_cleanup(tc);
MVM_gc_collect_free_gen2_unmarked(tc, 1);
MVM_gc_collect_free_stables(tc);
}