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
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
|
"""Thread module emulating a subset of Java's threading model."""
import os as _os
import sys as _sys
import _thread
import functools
from time import monotonic as _time
from _weakrefset import WeakSet
from itertools import islice as _islice, count as _count
try:
from _collections import deque as _deque
except ImportError:
from collections import deque as _deque
# Note regarding PEP 8 compliant names
# This threading model was originally inspired by Java, and inherited
# the convention of camelCase function and method names from that
# language. Those original names are not in any imminent danger of
# being deprecated (even for Py3k),so this module provides them as an
# alias for the PEP 8 compliant names
# Note that using the new PEP 8 compliant names facilitates substitution
# with the multiprocessing module, which doesn't provide the old
# Java inspired names.
__all__ = ['get_ident', 'active_count', 'Condition', 'current_thread',
'enumerate', 'main_thread', 'TIMEOUT_MAX',
'Event', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread',
'Barrier', 'BrokenBarrierError', 'Timer', 'ThreadError',
'setprofile', 'settrace', 'local', 'stack_size',
'excepthook', 'ExceptHookArgs', 'gettrace', 'getprofile']
# Rename some stuff so "from threading import *" is safe
_start_new_thread = _thread.start_new_thread
_allocate_lock = _thread.allocate_lock
_set_sentinel = _thread._set_sentinel
get_ident = _thread.get_ident
try:
get_native_id = _thread.get_native_id
_HAVE_THREAD_NATIVE_ID = True
__all__.append('get_native_id')
except AttributeError:
_HAVE_THREAD_NATIVE_ID = False
ThreadError = _thread.error
try:
_CRLock = _thread.RLock
except AttributeError:
_CRLock = None
TIMEOUT_MAX = _thread.TIMEOUT_MAX
del _thread
# Support for profile and trace hooks
_profile_hook = None
_trace_hook = None
def setprofile(func):
"""Set a profile function for all threads started from the threading module.
The func will be passed to sys.setprofile() for each thread, before its
run() method is called.
"""
global _profile_hook
_profile_hook = func
def getprofile():
"""Get the profiler function as set by threading.setprofile()."""
return _profile_hook
def settrace(func):
"""Set a trace function for all threads started from the threading module.
The func will be passed to sys.settrace() for each thread, before its run()
method is called.
"""
global _trace_hook
_trace_hook = func
def gettrace():
"""Get the trace function as set by threading.settrace()."""
return _trace_hook
# Synchronization classes
Lock = _allocate_lock
def RLock(*args, **kwargs):
"""Factory function that returns a new reentrant lock.
A reentrant lock must be released by the thread that acquired it. Once a
thread has acquired a reentrant lock, the same thread may acquire it again
without blocking; the thread must release it once for each time it has
acquired it.
"""
if _CRLock is None:
return _PyRLock(*args, **kwargs)
return _CRLock(*args, **kwargs)
class _RLock:
"""This class implements reentrant lock objects.
A reentrant lock must be released by the thread that acquired it. Once a
thread has acquired a reentrant lock, the same thread may acquire it
again without blocking; the thread must release it once for each time it
has acquired it.
"""
def __init__(self):
self._block = _allocate_lock()
self._owner = None
self._count = 0
def __repr__(self):
owner = self._owner
try:
owner = _active[owner].name
except KeyError:
pass
return "<%s %s.%s object owner=%r count=%d at %s>" % (
"locked" if self._block.locked() else "unlocked",
self.__class__.__module__,
self.__class__.__qualname__,
owner,
self._count,
hex(id(self))
)
def _at_fork_reinit(self):
self._block._at_fork_reinit()
self._owner = None
self._count = 0
def acquire(self, blocking=True, timeout=-1):
"""Acquire a lock, blocking or non-blocking.
When invoked without arguments: if this thread already owns the lock,
increment the recursion level by one, and return immediately. Otherwise,
if another thread owns the lock, block until the lock is unlocked. Once
the lock is unlocked (not owned by any thread), then grab ownership, set
the recursion level to one, and return. If more than one thread is
blocked waiting until the lock is unlocked, only one at a time will be
able to grab ownership of the lock. There is no return value in this
case.
When invoked with the blocking argument set to true, do the same thing
as when called without arguments, and return true.
When invoked with the blocking argument set to false, do not block. If a
call without an argument would block, return false immediately;
otherwise, do the same thing as when called without arguments, and
return true.
When invoked with the floating-point timeout argument set to a positive
value, block for at most the number of seconds specified by timeout
and as long as the lock cannot be acquired. Return true if the lock has
been acquired, false if the timeout has elapsed.
"""
me = get_ident()
if self._owner == me:
self._count += 1
return 1
rc = self._block.acquire(blocking, timeout)
if rc:
self._owner = me
self._count = 1
return rc
__enter__ = acquire
def release(self):
"""Release a lock, decrementing the recursion level.
If after the decrement it is zero, reset the lock to unlocked (not owned
by any thread), and if any other threads are blocked waiting for the
lock to become unlocked, allow exactly one of them to proceed. If after
the decrement the recursion level is still nonzero, the lock remains
locked and owned by the calling thread.
Only call this method when the calling thread owns the lock. A
RuntimeError is raised if this method is called when the lock is
unlocked.
There is no return value.
"""
if self._owner != get_ident():
raise RuntimeError("cannot release un-acquired lock")
self._count = count = self._count - 1
if not count:
self._owner = None
self._block.release()
def __exit__(self, t, v, tb):
self.release()
# Internal methods used by condition variables
def _acquire_restore(self, state):
self._block.acquire()
self._count, self._owner = state
def _release_save(self):
if self._count == 0:
raise RuntimeError("cannot release un-acquired lock")
count = self._count
self._count = 0
owner = self._owner
self._owner = None
self._block.release()
return (count, owner)
def _is_owned(self):
return self._owner == get_ident()
_PyRLock = _RLock
class Condition:
"""Class that implements a condition variable.
A condition variable allows one or more threads to wait until they are
notified by another thread.
If the lock argument is given and not None, it must be a Lock or RLock
object, and it is used as the underlying lock. Otherwise, a new RLock object
is created and used as the underlying lock.
"""
def __init__(self, lock=None):
if lock is None:
lock = RLock()
self._lock = lock
# Export the lock's acquire() and release() methods
self.acquire = lock.acquire
self.release = lock.release
# If the lock defines _release_save() and/or _acquire_restore(),
# these override the default implementations (which just call
# release() and acquire() on the lock). Ditto for _is_owned().
try:
self._release_save = lock._release_save
except AttributeError:
pass
try:
self._acquire_restore = lock._acquire_restore
except AttributeError:
pass
try:
self._is_owned = lock._is_owned
except AttributeError:
pass
self._waiters = _deque()
def _at_fork_reinit(self):
self._lock._at_fork_reinit()
self._waiters.clear()
def __enter__(self):
return self._lock.__enter__()
def __exit__(self, *args):
return self._lock.__exit__(*args)
def __repr__(self):
return "<Condition(%s, %d)>" % (self._lock, len(self._waiters))
def _release_save(self):
self._lock.release() # No state to save
def _acquire_restore(self, x):
self._lock.acquire() # Ignore saved state
def _is_owned(self):
# Return True if lock is owned by current_thread.
# This method is called only if _lock doesn't have _is_owned().
if self._lock.acquire(False):
self._lock.release()
return False
else:
return True
def wait(self, timeout=None):
"""Wait until notified or until a timeout occurs.
If the calling thread has not acquired the lock when this method is
called, a RuntimeError is raised.
This method releases the underlying lock, and then blocks until it is
awakened by a notify() or notify_all() call for the same condition
variable in another thread, or until the optional timeout occurs. Once
awakened or timed out, it re-acquires the lock and returns.
When the timeout argument is present and not None, it should be a
floating point number specifying a timeout for the operation in seconds
(or fractions thereof).
When the underlying lock is an RLock, it is not released using its
release() method, since this may not actually unlock the lock when it
was acquired multiple times recursively. Instead, an internal interface
of the RLock class is used, which really unlocks it even when it has
been recursively acquired several times. Another internal interface is
then used to restore the recursion level when the lock is reacquired.
"""
if not self._is_owned():
raise RuntimeError("cannot wait on un-acquired lock")
waiter = _allocate_lock()
waiter.acquire()
self._waiters.append(waiter)
saved_state = self._release_save()
gotit = False
try: # restore state no matter what (e.g., KeyboardInterrupt)
if timeout is None:
waiter.acquire()
gotit = True
else:
if timeout > 0:
gotit = waiter.acquire(True, timeout)
else:
gotit = waiter.acquire(False)
return gotit
finally:
self._acquire_restore(saved_state)
if not gotit:
try:
self._waiters.remove(waiter)
except ValueError:
pass
def wait_for(self, predicate, timeout=None):
"""Wait until a condition evaluates to True.
predicate should be a callable which result will be interpreted as a
boolean value. A timeout may be provided giving the maximum time to
wait.
"""
endtime = None
waittime = timeout
result = predicate()
while not result:
if waittime is not None:
if endtime is None:
endtime = _time() + waittime
else:
waittime = endtime - _time()
if waittime <= 0:
break
self.wait(waittime)
result = predicate()
return result
def notify(self, n=1):
"""Wake up one or more threads waiting on this condition, if any.
If the calling thread has not acquired the lock when this method is
called, a RuntimeError is raised.
This method wakes up at most n of the threads waiting for the condition
variable; it is a no-op if no threads are waiting.
"""
if not self._is_owned():
raise RuntimeError("cannot notify on un-acquired lock")
waiters = self._waiters
while waiters and n > 0:
waiter = waiters[0]
try:
waiter.release()
except RuntimeError:
# gh-92530: The previous call of notify() released the lock,
# but was interrupted before removing it from the queue.
# It can happen if a signal handler raises an exception,
# like CTRL+C which raises KeyboardInterrupt.
pass
else:
n -= 1
try:
waiters.remove(waiter)
except ValueError:
pass
def notify_all(self):
"""Wake up all threads waiting on this condition.
If the calling thread has not acquired the lock when this method
is called, a RuntimeError is raised.
"""
self.notify(len(self._waiters))
def notifyAll(self):
"""Wake up all threads waiting on this condition.
This method is deprecated, use notify_all() instead.
"""
import warnings
warnings.warn('notifyAll() is deprecated, use notify_all() instead',
DeprecationWarning, stacklevel=2)
self.notify_all()
class Semaphore:
"""This class implements semaphore objects.
Semaphores manage a counter representing the number of release() calls minus
the number of acquire() calls, plus an initial value. The acquire() method
blocks if necessary until it can return without making the counter
negative. If not given, value defaults to 1.
"""
# After Tim Peters' semaphore class, but not quite the same (no maximum)
def __init__(self, value=1):
if value < 0:
raise ValueError("semaphore initial value must be >= 0")
self._cond = Condition(Lock())
self._value = value
def __repr__(self):
cls = self.__class__
return (f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}:"
f" value={self._value}>")
def acquire(self, blocking=True, timeout=None):
"""Acquire a semaphore, decrementing the internal counter by one.
When invoked without arguments: if the internal counter is larger than
zero on entry, decrement it by one and return immediately. If it is zero
on entry, block, waiting until some other thread has called release() to
make it larger than zero. This is done with proper interlocking so that
if multiple acquire() calls are blocked, release() will wake exactly one
of them up. The implementation may pick one at random, so the order in
which blocked threads are awakened should not be relied on. There is no
return value in this case.
When invoked with blocking set to true, do the same thing as when called
without arguments, and return true.
When invoked with blocking set to false, do not block. If a call without
an argument would block, return false immediately; otherwise, do the
same thing as when called without arguments, and return true.
When invoked with a timeout other than None, it will block for at
most timeout seconds. If acquire does not complete successfully in
that interval, return false. Return true otherwise.
"""
if not blocking and timeout is not None:
raise ValueError("can't specify timeout for non-blocking acquire")
rc = False
endtime = None
with self._cond:
while self._value == 0:
if not blocking:
break
if timeout is not None:
if endtime is None:
endtime = _time() + timeout
else:
timeout = endtime - _time()
if timeout <= 0:
break
self._cond.wait(timeout)
else:
self._value -= 1
rc = True
return rc
__enter__ = acquire
def release(self, n=1):
"""Release a semaphore, incrementing the internal counter by one or more.
When the counter is zero on entry and another thread is waiting for it
to become larger than zero again, wake up that thread.
"""
if n < 1:
raise ValueError('n must be one or more')
with self._cond:
self._value += n
for i in range(n):
self._cond.notify()
def __exit__(self, t, v, tb):
self.release()
class BoundedSemaphore(Semaphore):
"""Implements a bounded semaphore.
A bounded semaphore checks to make sure its current value doesn't exceed its
initial value. If it does, ValueError is raised. In most situations
semaphores are used to guard resources with limited capacity.
If the semaphore is released too many times it's a sign of a bug. If not
given, value defaults to 1.
Like regular semaphores, bounded semaphores manage a counter representing
the number of release() calls minus the number of acquire() calls, plus an
initial value. The acquire() method blocks if necessary until it can return
without making the counter negative. If not given, value defaults to 1.
"""
def __init__(self, value=1):
Semaphore.__init__(self, value)
self._initial_value = value
def __repr__(self):
cls = self.__class__
return (f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}:"
f" value={self._value}/{self._initial_value}>")
def release(self, n=1):
"""Release a semaphore, incrementing the internal counter by one or more.
When the counter is zero on entry and another thread is waiting for it
to become larger than zero again, wake up that thread.
If the number of releases exceeds the number of acquires,
raise a ValueError.
"""
if n < 1:
raise ValueError('n must be one or more')
with self._cond:
if self._value + n > self._initial_value:
raise ValueError("Semaphore released too many times")
self._value += n
for i in range(n):
self._cond.notify()
class Event:
"""Class implementing event objects.
Events manage a flag that can be set to true with the set() method and reset
to false with the clear() method. The wait() method blocks until the flag is
true. The flag is initially false.
"""
# After Tim Peters' event class (without is_posted())
def __init__(self):
self._cond = Condition(Lock())
self._flag = False
def __repr__(self):
cls = self.__class__
status = 'set' if self._flag else 'unset'
return f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}: {status}>"
def _at_fork_reinit(self):
# Private method called by Thread._reset_internal_locks()
self._cond._at_fork_reinit()
def is_set(self):
"""Return true if and only if the internal flag is true."""
return self._flag
def isSet(self):
"""Return true if and only if the internal flag is true.
This method is deprecated, use is_set() instead.
"""
import warnings
warnings.warn('isSet() is deprecated, use is_set() instead',
DeprecationWarning, stacklevel=2)
return self.is_set()
def set(self):
"""Set the internal flag to true.
All threads waiting for it to become true are awakened. Threads
that call wait() once the flag is true will not block at all.
"""
with self._cond:
self._flag = True
self._cond.notify_all()
def clear(self):
"""Reset the internal flag to false.
Subsequently, threads calling wait() will block until set() is called to
set the internal flag to true again.
"""
with self._cond:
self._flag = False
def wait(self, timeout=None):
"""Block until the internal flag is true.
If the internal flag is true on entry, return immediately. Otherwise,
block until another thread calls set() to set the flag to true, or until
the optional timeout occurs.
When the timeout argument is present and not None, it should be a
floating point number specifying a timeout for the operation in seconds
(or fractions thereof).
This method returns the internal flag on exit, so it will always return
True except if a timeout is given and the operation times out.
"""
with self._cond:
signaled = self._flag
if not signaled:
signaled = self._cond.wait(timeout)
return signaled
# A barrier class. Inspired in part by the pthread_barrier_* api and
# the CyclicBarrier class from Java. See
# http://sourceware.org/pthreads-win32/manual/pthread_barrier_init.html and
# http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/
# CyclicBarrier.html
# for information.
# We maintain two main states, 'filling' and 'draining' enabling the barrier
# to be cyclic. Threads are not allowed into it until it has fully drained
# since the previous cycle. In addition, a 'resetting' state exists which is
# similar to 'draining' except that threads leave with a BrokenBarrierError,
# and a 'broken' state in which all threads get the exception.
class Barrier:
"""Implements a Barrier.
Useful for synchronizing a fixed number of threads at known synchronization
points. Threads block on 'wait()' and are simultaneously awoken once they
have all made that call.
"""
def __init__(self, parties, action=None, timeout=None):
"""Create a barrier, initialised to 'parties' threads.
'action' is a callable which, when supplied, will be called by one of
the threads after they have all entered the barrier and just prior to
releasing them all. If a 'timeout' is provided, it is used as the
default for all subsequent 'wait()' calls.
"""
self._cond = Condition(Lock())
self._action = action
self._timeout = timeout
self._parties = parties
self._state = 0 # 0 filling, 1 draining, -1 resetting, -2 broken
self._count = 0
def __repr__(self):
cls = self.__class__
if self.broken:
return f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}: broken>"
return (f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}:"
f" waiters={self.n_waiting}/{self.parties}>")
def wait(self, timeout=None):
"""Wait for the barrier.
When the specified number of threads have started waiting, they are all
simultaneously awoken. If an 'action' was provided for the barrier, one
of the threads will have executed that callback prior to returning.
Returns an individual index number from 0 to 'parties-1'.
"""
if timeout is None:
timeout = self._timeout
with self._cond:
self._enter() # Block while the barrier drains.
index = self._count
self._count += 1
try:
if index + 1 == self._parties:
# We release the barrier
self._release()
else:
# We wait until someone releases us
self._wait(timeout)
return index
finally:
self._count -= 1
# Wake up any threads waiting for barrier to drain.
self._exit()
# Block until the barrier is ready for us, or raise an exception
# if it is broken.
def _enter(self):
while self._state in (-1, 1):
# It is draining or resetting, wait until done
self._cond.wait()
#see if the barrier is in a broken state
if self._state < 0:
raise BrokenBarrierError
assert self._state == 0
# Optionally run the 'action' and release the threads waiting
# in the barrier.
def _release(self):
try:
if self._action:
self._action()
# enter draining state
self._state = 1
self._cond.notify_all()
except:
#an exception during the _action handler. Break and reraise
self._break()
raise
# Wait in the barrier until we are released. Raise an exception
# if the barrier is reset or broken.
def _wait(self, timeout):
if not self._cond.wait_for(lambda : self._state != 0, timeout):
#timed out. Break the barrier
self._break()
raise BrokenBarrierError
if self._state < 0:
raise BrokenBarrierError
assert self._state == 1
# If we are the last thread to exit the barrier, signal any threads
# waiting for the barrier to drain.
def _exit(self):
if self._count == 0:
if self._state in (-1, 1):
#resetting or draining
self._state = 0
self._cond.notify_all()
def reset(self):
"""Reset the barrier to the initial state.
Any threads currently waiting will get the BrokenBarrier exception
raised.
"""
with self._cond:
if self._count > 0:
if self._state == 0:
#reset the barrier, waking up threads
self._state = -1
elif self._state == -2:
#was broken, set it to reset state
#which clears when the last thread exits
self._state = -1
else:
self._state = 0
self._cond.notify_all()
def abort(self):
"""Place the barrier into a 'broken' state.
Useful in case of error. Any currently waiting threads and threads
attempting to 'wait()' will have BrokenBarrierError raised.
"""
with self._cond:
self._break()
def _break(self):
# An internal error was detected. The barrier is set to
# a broken state all parties awakened.
self._state = -2
self._cond.notify_all()
@property
def parties(self):
"""Return the number of threads required to trip the barrier."""
return self._parties
@property
def n_waiting(self):
"""Return the number of threads currently waiting at the barrier."""
# We don't need synchronization here since this is an ephemeral result
# anyway. It returns the correct value in the steady state.
if self._state == 0:
return self._count
return 0
@property
def broken(self):
"""Return True if the barrier is in a broken state."""
return self._state == -2
# exception raised by the Barrier class
class BrokenBarrierError(RuntimeError):
pass
# Helper to generate new thread names
_counter = _count(1).__next__
def _newname(name_template):
return name_template % _counter()
# Active thread administration.
#
# bpo-44422: Use a reentrant lock to allow reentrant calls to functions like
# threading.enumerate().
_active_limbo_lock = RLock()
_active = {} # maps thread id to Thread object
_limbo = {}
_dangling = WeakSet()
# Set of Thread._tstate_lock locks of non-daemon threads used by _shutdown()
# to wait until all Python thread states get deleted:
# see Thread._set_tstate_lock().
_shutdown_locks_lock = _allocate_lock()
_shutdown_locks = set()
def _maintain_shutdown_locks():
"""
Drop any shutdown locks that don't correspond to running threads anymore.
Calling this from time to time avoids an ever-growing _shutdown_locks
set when Thread objects are not joined explicitly. See bpo-37788.
This must be called with _shutdown_locks_lock acquired.
"""
# If a lock was released, the corresponding thread has exited
to_remove = [lock for lock in _shutdown_locks if not lock.locked()]
_shutdown_locks.difference_update(to_remove)
# Main class for threads
class Thread:
"""A class that represents a thread of control.
This class can be safely subclassed in a limited fashion. There are two ways
to specify the activity: by passing a callable object to the constructor, or
by overriding the run() method in a subclass.
"""
_initialized = False
def __init__(self, group=None, target=None, name=None,
args=(), kwargs=None, *, daemon=None):
"""This constructor should always be called with keyword arguments. Arguments are:
*group* should be None; reserved for future extension when a ThreadGroup
class is implemented.
*target* is the callable object to be invoked by the run()
method. Defaults to None, meaning nothing is called.
*name* is the thread name. By default, a unique name is constructed of
the form "Thread-N" where N is a small decimal number.
*args* is a list or tuple of arguments for the target invocation. Defaults to ().
*kwargs* is a dictionary of keyword arguments for the target
invocation. Defaults to {}.
If a subclass overrides the constructor, it must make sure to invoke
the base class constructor (Thread.__init__()) before doing anything
else to the thread.
"""
assert group is None, "group argument must be None for now"
if kwargs is None:
kwargs = {}
if name:
name = str(name)
else:
name = _newname("Thread-%d")
if target is not None:
try:
target_name = target.__name__
name += f" ({target_name})"
except AttributeError:
pass
self._target = target
self._name = name
self._args = args
self._kwargs = kwargs
if daemon is not None:
self._daemonic = daemon
else:
self._daemonic = current_thread().daemon
self._ident = None
if _HAVE_THREAD_NATIVE_ID:
self._native_id = None
self._tstate_lock = None
self._started = Event()
self._is_stopped = False
self._initialized = True
# Copy of sys.stderr used by self._invoke_excepthook()
self._stderr = _sys.stderr
self._invoke_excepthook = _make_invoke_excepthook()
# For debugging and _after_fork()
_dangling.add(self)
def _reset_internal_locks(self, is_alive):
# private! Called by _after_fork() to reset our internal locks as
# they may be in an invalid state leading to a deadlock or crash.
self._started._at_fork_reinit()
if is_alive:
# bpo-42350: If the fork happens when the thread is already stopped
# (ex: after threading._shutdown() has been called), _tstate_lock
# is None. Do nothing in this case.
if self._tstate_lock is not None:
self._tstate_lock._at_fork_reinit()
self._tstate_lock.acquire()
else:
# The thread isn't alive after fork: it doesn't have a tstate
# anymore.
self._is_stopped = True
self._tstate_lock = None
def __repr__(self):
assert self._initialized, "Thread.__init__() was not called"
status = "initial"
if self._started.is_set():
status = "started"
self.is_alive() # easy way to get ._is_stopped set when appropriate
if self._is_stopped:
status = "stopped"
if self._daemonic:
status += " daemon"
if self._ident is not None:
status += " %s" % self._ident
return "<%s(%s, %s)>" % (self.__class__.__name__, self._name, status)
def start(self):
"""Start the thread's activity.
It must be called at most once per thread object. It arranges for the
object's run() method to be invoked in a separate thread of control.
This method will raise a RuntimeError if called more than once on the
same thread object.
"""
if not self._initialized:
raise RuntimeError("thread.__init__() not called")
if self._started.is_set():
raise RuntimeError("threads can only be started once")
with _active_limbo_lock:
_limbo[self] = self
try:
_start_new_thread(self._bootstrap, ())
except Exception:
with _active_limbo_lock:
del _limbo[self]
raise
self._started.wait()
def run(self):
"""Method representing the thread's activity.
You may override this method in a subclass. The standard run() method
invokes the callable object passed to the object's constructor as the
target argument, if any, with sequential and keyword arguments taken
from the args and kwargs arguments, respectively.
"""
try:
if self._target is not None:
self._target(*self._args, **self._kwargs)
finally:
# Avoid a refcycle if the thread is running a function with
# an argument that has a member that points to the thread.
del self._target, self._args, self._kwargs
def _bootstrap(self):
# Wrapper around the real bootstrap code that ignores
# exceptions during interpreter cleanup. Those typically
# happen when a daemon thread wakes up at an unfortunate
# moment, finds the world around it destroyed, and raises some
# random exception *** while trying to report the exception in
# _bootstrap_inner() below ***. Those random exceptions
# don't help anybody, and they confuse users, so we suppress
# them. We suppress them only when it appears that the world
# indeed has already been destroyed, so that exceptions in
# _bootstrap_inner() during normal business hours are properly
# reported. Also, we only suppress them for daemonic threads;
# if a non-daemonic encounters this, something else is wrong.
try:
self._bootstrap_inner()
except:
if self._daemonic and _sys is None:
return
raise
def _set_ident(self):
self._ident = get_ident()
if _HAVE_THREAD_NATIVE_ID:
def _set_native_id(self):
self._native_id = get_native_id()
def _set_tstate_lock(self):
"""
Set a lock object which will be released by the interpreter when
the underlying thread state (see pystate.h) gets deleted.
"""
self._tstate_lock = _set_sentinel()
self._tstate_lock.acquire()
if not self.daemon:
with _shutdown_locks_lock:
_maintain_shutdown_locks()
_shutdown_locks.add(self._tstate_lock)
def _bootstrap_inner(self):
try:
self._set_ident()
self._set_tstate_lock()
if _HAVE_THREAD_NATIVE_ID:
self._set_native_id()
self._started.set()
with _active_limbo_lock:
_active[self._ident] = self
del _limbo[self]
if _trace_hook:
_sys.settrace(_trace_hook)
if _profile_hook:
_sys.setprofile(_profile_hook)
try:
self.run()
except:
self._invoke_excepthook(self)
finally:
self._delete()
def _stop(self):
# After calling ._stop(), .is_alive() returns False and .join() returns
# immediately. ._tstate_lock must be released before calling ._stop().
#
# Normal case: C code at the end of the thread's life
# (release_sentinel in _threadmodule.c) releases ._tstate_lock, and
# that's detected by our ._wait_for_tstate_lock(), called by .join()
# and .is_alive(). Any number of threads _may_ call ._stop()
# simultaneously (for example, if multiple threads are blocked in
# .join() calls), and they're not serialized. That's harmless -
# they'll just make redundant rebindings of ._is_stopped and
# ._tstate_lock. Obscure: we rebind ._tstate_lock last so that the
# "assert self._is_stopped" in ._wait_for_tstate_lock() always works
# (the assert is executed only if ._tstate_lock is None).
#
# Special case: _main_thread releases ._tstate_lock via this
# module's _shutdown() function.
lock = self._tstate_lock
if lock is not None:
assert not lock.locked()
self._is_stopped = True
self._tstate_lock = None
if not self.daemon:
with _shutdown_locks_lock:
# Remove our lock and other released locks from _shutdown_locks
_maintain_shutdown_locks()
def _delete(self):
"Remove current thread from the dict of currently running threads."
with _active_limbo_lock:
del _active[get_ident()]
# There must not be any python code between the previous line
# and after the lock is released. Otherwise a tracing function
# could try to acquire the lock again in the same thread, (in
# current_thread()), and would block.
def join(self, timeout=None):
"""Wait until the thread terminates.
This blocks the calling thread until the thread whose join() method is
called terminates -- either normally or through an unhandled exception
or until the optional timeout occurs.
When the timeout argument is present and not None, it should be a
floating point number specifying a timeout for the operation in seconds
(or fractions thereof). As join() always returns None, you must call
is_alive() after join() to decide whether a timeout happened -- if the
thread is still alive, the join() call timed out.
When the timeout argument is not present or None, the operation will
block until the thread terminates.
A thread can be join()ed many times.
join() raises a RuntimeError if an attempt is made to join the current
thread as that would cause a deadlock. It is also an error to join() a
thread before it has been started and attempts to do so raises the same
exception.
"""
if not self._initialized:
raise RuntimeError("Thread.__init__() not called")
if not self._started.is_set():
raise RuntimeError("cannot join thread before it is started")
if self is current_thread():
raise RuntimeError("cannot join current thread")
if timeout is None:
self._wait_for_tstate_lock()
else:
# the behavior of a negative timeout isn't documented, but
# historically .join(timeout=x) for x<0 has acted as if timeout=0
self._wait_for_tstate_lock(timeout=max(timeout, 0))
def _wait_for_tstate_lock(self, block=True, timeout=-1):
# Issue #18808: wait for the thread state to be gone.
# At the end of the thread's life, after all knowledge of the thread
# is removed from C data structures, C code releases our _tstate_lock.
# This method passes its arguments to _tstate_lock.acquire().
# If the lock is acquired, the C code is done, and self._stop() is
# called. That sets ._is_stopped to True, and ._tstate_lock to None.
lock = self._tstate_lock
if lock is None:
# already determined that the C code is done
assert self._is_stopped
return
try:
if lock.acquire(block, timeout):
lock.release()
self._stop()
except:
if lock.locked():
# bpo-45274: lock.acquire() acquired the lock, but the function
# was interrupted with an exception before reaching the
# lock.release(). It can happen if a signal handler raises an
# exception, like CTRL+C which raises KeyboardInterrupt.
lock.release()
self._stop()
raise
@property
def name(self):
"""A string used for identification purposes only.
It has no semantics. Multiple threads may be given the same name. The
initial name is set by the constructor.
"""
assert self._initialized, "Thread.__init__() not called"
return self._name
@name.setter
def name(self, name):
assert self._initialized, "Thread.__init__() not called"
self._name = str(name)
@property
def ident(self):
"""Thread identifier of this thread or None if it has not been started.
This is a nonzero integer. See the get_ident() function. Thread
identifiers may be recycled when a thread exits and another thread is
created. The identifier is available even after the thread has exited.
"""
assert self._initialized, "Thread.__init__() not called"
return self._ident
if _HAVE_THREAD_NATIVE_ID:
@property
def native_id(self):
"""Native integral thread ID of this thread, or None if it has not been started.
This is a non-negative integer. See the get_native_id() function.
This represents the Thread ID as reported by the kernel.
"""
assert self._initialized, "Thread.__init__() not called"
return self._native_id
def is_alive(self):
"""Return whether the thread is alive.
This method returns True just before the run() method starts until just
after the run() method terminates. See also the module function
enumerate().
"""
assert self._initialized, "Thread.__init__() not called"
if self._is_stopped or not self._started.is_set():
return False
self._wait_for_tstate_lock(False)
return not self._is_stopped
@property
def daemon(self):
"""A boolean value indicating whether this thread is a daemon thread.
This must be set before start() is called, otherwise RuntimeError is
raised. Its initial value is inherited from the creating thread; the
main thread is not a daemon thread and therefore all threads created in
the main thread default to daemon = False.
The entire Python program exits when only daemon threads are left.
"""
assert self._initialized, "Thread.__init__() not called"
return self._daemonic
@daemon.setter
def daemon(self, daemonic):
if not self._initialized:
raise RuntimeError("Thread.__init__() not called")
if self._started.is_set():
raise RuntimeError("cannot set daemon status of active thread")
self._daemonic = daemonic
def isDaemon(self):
"""Return whether this thread is a daemon.
This method is deprecated, use the daemon attribute instead.
"""
import warnings
warnings.warn('isDaemon() is deprecated, get the daemon attribute instead',
DeprecationWarning, stacklevel=2)
return self.daemon
def setDaemon(self, daemonic):
"""Set whether this thread is a daemon.
This method is deprecated, use the .daemon property instead.
"""
import warnings
warnings.warn('setDaemon() is deprecated, set the daemon attribute instead',
DeprecationWarning, stacklevel=2)
self.daemon = daemonic
def getName(self):
"""Return a string used for identification purposes only.
This method is deprecated, use the name attribute instead.
"""
import warnings
warnings.warn('getName() is deprecated, get the name attribute instead',
DeprecationWarning, stacklevel=2)
return self.name
def setName(self, name):
"""Set the name string for this thread.
This method is deprecated, use the name attribute instead.
"""
import warnings
warnings.warn('setName() is deprecated, set the name attribute instead',
DeprecationWarning, stacklevel=2)
self.name = name
try:
from _thread import (_excepthook as excepthook,
_ExceptHookArgs as ExceptHookArgs)
except ImportError:
# Simple Python implementation if _thread._excepthook() is not available
from traceback import print_exception as _print_exception
from collections import namedtuple
_ExceptHookArgs = namedtuple(
'ExceptHookArgs',
'exc_type exc_value exc_traceback thread')
def ExceptHookArgs(args):
return _ExceptHookArgs(*args)
def excepthook(args, /):
"""
Handle uncaught Thread.run() exception.
"""
if args.exc_type == SystemExit:
# silently ignore SystemExit
return
if _sys is not None and _sys.stderr is not None:
stderr = _sys.stderr
elif args.thread is not None:
stderr = args.thread._stderr
if stderr is None:
# do nothing if sys.stderr is None and sys.stderr was None
# when the thread was created
return
else:
# do nothing if sys.stderr is None and args.thread is None
return
if args.thread is not None:
name = args.thread.name
else:
name = get_ident()
print(f"Exception in thread {name}:",
file=stderr, flush=True)
_print_exception(args.exc_type, args.exc_value, args.exc_traceback,
file=stderr)
stderr.flush()
# Original value of threading.excepthook
__excepthook__ = excepthook
def _make_invoke_excepthook():
# Create a local namespace to ensure that variables remain alive
# when _invoke_excepthook() is called, even if it is called late during
# Python shutdown. It is mostly needed for daemon threads.
old_excepthook = excepthook
old_sys_excepthook = _sys.excepthook
if old_excepthook is None:
raise RuntimeError("threading.excepthook is None")
if old_sys_excepthook is None:
raise RuntimeError("sys.excepthook is None")
sys_exc_info = _sys.exc_info
local_print = print
local_sys = _sys
def invoke_excepthook(thread):
global excepthook
try:
hook = excepthook
if hook is None:
hook = old_excepthook
args = ExceptHookArgs([*sys_exc_info(), thread])
hook(args)
except Exception as exc:
exc.__suppress_context__ = True
del exc
if local_sys is not None and local_sys.stderr is not None:
stderr = local_sys.stderr
else:
stderr = thread._stderr
local_print("Exception in threading.excepthook:",
file=stderr, flush=True)
if local_sys is not None and local_sys.excepthook is not None:
sys_excepthook = local_sys.excepthook
else:
sys_excepthook = old_sys_excepthook
sys_excepthook(*sys_exc_info())
finally:
# Break reference cycle (exception stored in a variable)
args = None
return invoke_excepthook
# The timer class was contributed by Itamar Shtull-Trauring
class Timer(Thread):
"""Call a function after a specified number of seconds:
t = Timer(30.0, f, args=None, kwargs=None)
t.start()
t.cancel() # stop the timer's action if it's still waiting
"""
def __init__(self, interval, function, args=None, kwargs=None):
Thread.__init__(self)
self.interval = interval
self.function = function
self.args = args if args is not None else []
self.kwargs = kwargs if kwargs is not None else {}
self.finished = Event()
def cancel(self):
"""Stop the timer if it hasn't finished yet."""
self.finished.set()
def run(self):
self.finished.wait(self.interval)
if not self.finished.is_set():
self.function(*self.args, **self.kwargs)
self.finished.set()
# Special thread class to represent the main thread
class _MainThread(Thread):
def __init__(self):
Thread.__init__(self, name="MainThread", daemon=False)
self._set_tstate_lock()
self._started.set()
self._set_ident()
if _HAVE_THREAD_NATIVE_ID:
self._set_native_id()
with _active_limbo_lock:
_active[self._ident] = self
# Dummy thread class to represent threads not started here.
# These aren't garbage collected when they die, nor can they be waited for.
# If they invoke anything in threading.py that calls current_thread(), they
# leave an entry in the _active dict forever after.
# Their purpose is to return *something* from current_thread().
# They are marked as daemon threads so we won't wait for them
# when we exit (conform previous semantics).
class _DummyThread(Thread):
def __init__(self):
Thread.__init__(self, name=_newname("Dummy-%d"), daemon=True)
self._started.set()
self._set_ident()
if _HAVE_THREAD_NATIVE_ID:
self._set_native_id()
with _active_limbo_lock:
_active[self._ident] = self
def _stop(self):
pass
def is_alive(self):
assert not self._is_stopped and self._started.is_set()
return True
def join(self, timeout=None):
assert False, "cannot join a dummy thread"
# Global API functions
def current_thread():
"""Return the current Thread object, corresponding to the caller's thread of control.
If the caller's thread of control was not created through the threading
module, a dummy thread object with limited functionality is returned.
"""
try:
return _active[get_ident()]
except KeyError:
return _DummyThread()
def currentThread():
"""Return the current Thread object, corresponding to the caller's thread of control.
This function is deprecated, use current_thread() instead.
"""
import warnings
warnings.warn('currentThread() is deprecated, use current_thread() instead',
DeprecationWarning, stacklevel=2)
return current_thread()
def active_count():
"""Return the number of Thread objects currently alive.
The returned count is equal to the length of the list returned by
enumerate().
"""
with _active_limbo_lock:
return len(_active) + len(_limbo)
def activeCount():
"""Return the number of Thread objects currently alive.
This function is deprecated, use active_count() instead.
"""
import warnings
warnings.warn('activeCount() is deprecated, use active_count() instead',
DeprecationWarning, stacklevel=2)
return active_count()
def _enumerate():
# Same as enumerate(), but without the lock. Internal use only.
return list(_active.values()) + list(_limbo.values())
def enumerate():
"""Return a list of all Thread objects currently alive.
The list includes daemonic threads, dummy thread objects created by
current_thread(), and the main thread. It excludes terminated threads and
threads that have not yet been started.
"""
with _active_limbo_lock:
return list(_active.values()) + list(_limbo.values())
_threading_atexits = []
_SHUTTING_DOWN = False
def _register_atexit(func, *arg, **kwargs):
"""CPython internal: register *func* to be called before joining threads.
The registered *func* is called with its arguments just before all
non-daemon threads are joined in `_shutdown()`. It provides a similar
purpose to `atexit.register()`, but its functions are called prior to
threading shutdown instead of interpreter shutdown.
For similarity to atexit, the registered functions are called in reverse.
"""
if _SHUTTING_DOWN:
raise RuntimeError("can't register atexit after shutdown")
call = functools.partial(func, *arg, **kwargs)
_threading_atexits.append(call)
from _thread import stack_size
# Create the main thread object,
# and make it available for the interpreter
# (Py_Main) as threading._shutdown.
_main_thread = _MainThread()
def _shutdown():
"""
Wait until the Python thread state of all non-daemon threads get deleted.
"""
# Obscure: other threads may be waiting to join _main_thread. That's
# dubious, but some code does it. We can't wait for C code to release
# the main thread's tstate_lock - that won't happen until the interpreter
# is nearly dead. So we release it here. Note that just calling _stop()
# isn't enough: other threads may already be waiting on _tstate_lock.
if _main_thread._is_stopped:
# _shutdown() was already called
return
global _SHUTTING_DOWN
_SHUTTING_DOWN = True
# Call registered threading atexit functions before threads are joined.
# Order is reversed, similar to atexit.
for atexit_call in reversed(_threading_atexits):
atexit_call()
# Main thread
if _main_thread.ident == get_ident():
tlock = _main_thread._tstate_lock
# The main thread isn't finished yet, so its thread state lock can't
# have been released.
assert tlock is not None
assert tlock.locked()
tlock.release()
_main_thread._stop()
else:
# bpo-1596321: _shutdown() must be called in the main thread.
# If the threading module was not imported by the main thread,
# _main_thread is the thread which imported the threading module.
# In this case, ignore _main_thread, similar behavior than for threads
# spawned by C libraries or using _thread.start_new_thread().
pass
# Join all non-deamon threads
while True:
with _shutdown_locks_lock:
locks = list(_shutdown_locks)
_shutdown_locks.clear()
if not locks:
break
for lock in locks:
# mimic Thread.join()
lock.acquire()
lock.release()
# new threads can be spawned while we were waiting for the other
# threads to complete
def main_thread():
"""Return the main thread object.
In normal conditions, the main thread is the thread from which the
Python interpreter was started.
"""
return _main_thread
# get thread-local implementation, either from the thread
# module, or from the python fallback
try:
from _thread import _local as local
except ImportError:
from _threading_local import local
def _after_fork():
"""
Cleanup threading module state that should not exist after a fork.
"""
# Reset _active_limbo_lock, in case we forked while the lock was held
# by another (non-forked) thread. http://bugs.python.org/issue874900
global _active_limbo_lock, _main_thread
global _shutdown_locks_lock, _shutdown_locks
_active_limbo_lock = RLock()
# fork() only copied the current thread; clear references to others.
new_active = {}
try:
current = _active[get_ident()]
except KeyError:
# fork() was called in a thread which was not spawned
# by threading.Thread. For example, a thread spawned
# by thread.start_new_thread().
current = _MainThread()
_main_thread = current
# reset _shutdown() locks: threads re-register their _tstate_lock below
_shutdown_locks_lock = _allocate_lock()
_shutdown_locks = set()
with _active_limbo_lock:
# Dangling thread instances must still have their locks reset,
# because someone may join() them.
threads = set(_enumerate())
threads.update(_dangling)
for thread in threads:
# Any lock/condition variable may be currently locked or in an
# invalid state, so we reinitialize them.
if thread is current:
# There is only one active thread. We reset the ident to
# its new value since it can have changed.
thread._reset_internal_locks(True)
ident = get_ident()
thread._ident = ident
new_active[ident] = thread
else:
# All the others are already stopped.
thread._reset_internal_locks(False)
thread._stop()
_limbo.clear()
_active.clear()
_active.update(new_active)
assert len(_active) == 1
if hasattr(_os, "register_at_fork"):
_os.register_at_fork(after_in_child=_after_fork)
|