aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/tools/python3/Modules/_threadmodule.c
blob: 365f4460088aab0d54ddb3ab37491cf6e2547d81 (plain) (blame)
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
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
/* Thread module */
/* Interface to Sjoerd's portable C thread library */

#include "Python.h"
#include "pycore_interp.h"        // _PyInterpreterState.threads.count
#include "pycore_moduleobject.h"  // _PyModule_GetState()
#include "pycore_pylifecycle.h"
#include "pycore_pystate.h"       // _PyThreadState_SetCurrent()
#include <stddef.h>               // offsetof()
#include "structmember.h"         // PyMemberDef

#ifdef HAVE_SIGNAL_H
#  include <signal.h>             // SIGINT
#endif

// ThreadError is just an alias to PyExc_RuntimeError
#define ThreadError PyExc_RuntimeError


// Forward declarations
static struct PyModuleDef thread_module;


typedef struct {
    PyTypeObject *excepthook_type;
    PyTypeObject *lock_type;
    PyTypeObject *local_type;
    PyTypeObject *local_dummy_type;
} thread_module_state;

static inline thread_module_state*
get_thread_state(PyObject *module)
{
    void *state = _PyModule_GetState(module);
    assert(state != NULL);
    return (thread_module_state *)state;
}


/* Lock objects */

typedef struct {
    PyObject_HEAD
    PyThread_type_lock lock_lock;
    PyObject *in_weakreflist;
    char locked; /* for sanity checking */
} lockobject;

static int
lock_traverse(lockobject *self, visitproc visit, void *arg)
{
    Py_VISIT(Py_TYPE(self));
    return 0;
}

static void
lock_dealloc(lockobject *self)
{
    PyObject_GC_UnTrack(self);
    if (self->in_weakreflist != NULL) {
        PyObject_ClearWeakRefs((PyObject *) self);
    }
    if (self->lock_lock != NULL) {
        /* Unlock the lock so it's safe to free it */
        if (self->locked)
            PyThread_release_lock(self->lock_lock);
        PyThread_free_lock(self->lock_lock);
    }
    PyTypeObject *tp = Py_TYPE(self);
    tp->tp_free((PyObject*)self);
    Py_DECREF(tp);
}

/* Helper to acquire an interruptible lock with a timeout.  If the lock acquire
 * is interrupted, signal handlers are run, and if they raise an exception,
 * PY_LOCK_INTR is returned.  Otherwise, PY_LOCK_ACQUIRED or PY_LOCK_FAILURE
 * are returned, depending on whether the lock can be acquired within the
 * timeout.
 */
static PyLockStatus
acquire_timed(PyThread_type_lock lock, _PyTime_t timeout)
{
    PyThreadState *tstate = _PyThreadState_GET();
    _PyTime_t endtime = 0;
    if (timeout > 0) {
        endtime = _PyDeadline_Init(timeout);
    }

    PyLockStatus r;
    do {
        _PyTime_t microseconds;
        microseconds = _PyTime_AsMicroseconds(timeout, _PyTime_ROUND_CEILING);

        /* first a simple non-blocking try without releasing the GIL */
        r = PyThread_acquire_lock_timed(lock, 0, 0);
        if (r == PY_LOCK_FAILURE && microseconds != 0) {
            Py_BEGIN_ALLOW_THREADS
            r = PyThread_acquire_lock_timed(lock, microseconds, 1);
            Py_END_ALLOW_THREADS
        }

        if (r == PY_LOCK_INTR) {
            /* Run signal handlers if we were interrupted.  Propagate
             * exceptions from signal handlers, such as KeyboardInterrupt, by
             * passing up PY_LOCK_INTR.  */
            if (_PyEval_MakePendingCalls(tstate) < 0) {
                return PY_LOCK_INTR;
            }

            /* If we're using a timeout, recompute the timeout after processing
             * signals, since those can take time.  */
            if (timeout > 0) {
                timeout = _PyDeadline_Get(endtime);

                /* Check for negative values, since those mean block forever.
                 */
                if (timeout < 0) {
                    r = PY_LOCK_FAILURE;
                }
            }
        }
    } while (r == PY_LOCK_INTR);  /* Retry if we were interrupted. */

    return r;
}

static int
lock_acquire_parse_args(PyObject *args, PyObject *kwds,
                        _PyTime_t *timeout)
{
    char *kwlist[] = {"blocking", "timeout", NULL};
    int blocking = 1;
    PyObject *timeout_obj = NULL;
    const _PyTime_t unset_timeout = _PyTime_FromSeconds(-1);

    *timeout = unset_timeout ;

    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|pO:acquire", kwlist,
                                     &blocking, &timeout_obj))
        return -1;

    if (timeout_obj
        && _PyTime_FromSecondsObject(timeout,
                                     timeout_obj, _PyTime_ROUND_TIMEOUT) < 0)
        return -1;

    if (!blocking && *timeout != unset_timeout ) {
        PyErr_SetString(PyExc_ValueError,
                        "can't specify a timeout for a non-blocking call");
        return -1;
    }
    if (*timeout < 0 && *timeout != unset_timeout) {
        PyErr_SetString(PyExc_ValueError,
                        "timeout value must be positive");
        return -1;
    }
    if (!blocking)
        *timeout = 0;
    else if (*timeout != unset_timeout) {
        _PyTime_t microseconds;

        microseconds = _PyTime_AsMicroseconds(*timeout, _PyTime_ROUND_TIMEOUT);
        if (microseconds > PY_TIMEOUT_MAX) {
            PyErr_SetString(PyExc_OverflowError,
                            "timeout value is too large");
            return -1;
        }
    }
    return 0;
}

static PyObject *
lock_PyThread_acquire_lock(lockobject *self, PyObject *args, PyObject *kwds)
{
    _PyTime_t timeout;
    if (lock_acquire_parse_args(args, kwds, &timeout) < 0)
        return NULL;

    PyLockStatus r = acquire_timed(self->lock_lock, timeout);
    if (r == PY_LOCK_INTR) {
        return NULL;
    }

    if (r == PY_LOCK_ACQUIRED)
        self->locked = 1;
    return PyBool_FromLong(r == PY_LOCK_ACQUIRED);
}

PyDoc_STRVAR(acquire_doc,
"acquire(blocking=True, timeout=-1) -> bool\n\
(acquire_lock() is an obsolete synonym)\n\
\n\
Lock the lock.  Without argument, this blocks if the lock is already\n\
locked (even by the same thread), waiting for another thread to release\n\
the lock, and return True once the lock is acquired.\n\
With an argument, this will only block if the argument is true,\n\
and the return value reflects whether the lock is acquired.\n\
The blocking operation is interruptible.");

static PyObject *
lock_PyThread_release_lock(lockobject *self, PyObject *Py_UNUSED(ignored))
{
    /* Sanity check: the lock must be locked */
    if (!self->locked) {
        PyErr_SetString(ThreadError, "release unlocked lock");
        return NULL;
    }

    PyThread_release_lock(self->lock_lock);
    self->locked = 0;
    Py_RETURN_NONE;
}

PyDoc_STRVAR(release_doc,
"release()\n\
(release_lock() is an obsolete synonym)\n\
\n\
Release the lock, allowing another thread that is blocked waiting for\n\
the lock to acquire the lock.  The lock must be in the locked state,\n\
but it needn't be locked by the same thread that unlocks it.");

static PyObject *
lock_locked_lock(lockobject *self, PyObject *Py_UNUSED(ignored))
{
    return PyBool_FromLong((long)self->locked);
}

PyDoc_STRVAR(locked_doc,
"locked() -> bool\n\
(locked_lock() is an obsolete synonym)\n\
\n\
Return whether the lock is in the locked state.");

static PyObject *
lock_repr(lockobject *self)
{
    return PyUnicode_FromFormat("<%s %s object at %p>",
        self->locked ? "locked" : "unlocked", Py_TYPE(self)->tp_name, self);
}

#ifdef HAVE_FORK
static PyObject *
lock__at_fork_reinit(lockobject *self, PyObject *Py_UNUSED(args))
{
    if (_PyThread_at_fork_reinit(&self->lock_lock) < 0) {
        PyErr_SetString(ThreadError, "failed to reinitialize lock at fork");
        return NULL;
    }

    self->locked = 0;

    Py_RETURN_NONE;
}
#endif  /* HAVE_FORK */


static PyMethodDef lock_methods[] = {
    {"acquire_lock", _PyCFunction_CAST(lock_PyThread_acquire_lock),
     METH_VARARGS | METH_KEYWORDS, acquire_doc},
    {"acquire",      _PyCFunction_CAST(lock_PyThread_acquire_lock),
     METH_VARARGS | METH_KEYWORDS, acquire_doc},
    {"release_lock", (PyCFunction)lock_PyThread_release_lock,
     METH_NOARGS, release_doc},
    {"release",      (PyCFunction)lock_PyThread_release_lock,
     METH_NOARGS, release_doc},
    {"locked_lock",  (PyCFunction)lock_locked_lock,
     METH_NOARGS, locked_doc},
    {"locked",       (PyCFunction)lock_locked_lock,
     METH_NOARGS, locked_doc},
    {"__enter__",    _PyCFunction_CAST(lock_PyThread_acquire_lock),
     METH_VARARGS | METH_KEYWORDS, acquire_doc},
    {"__exit__",    (PyCFunction)lock_PyThread_release_lock,
     METH_VARARGS, release_doc},
#ifdef HAVE_FORK
    {"_at_fork_reinit",    (PyCFunction)lock__at_fork_reinit,
     METH_NOARGS, NULL},
#endif
    {NULL,           NULL}              /* sentinel */
};

PyDoc_STRVAR(lock_doc,
"A lock object is a synchronization primitive.  To create a lock,\n\
call threading.Lock().  Methods are:\n\
\n\
acquire() -- lock the lock, possibly blocking until it can be obtained\n\
release() -- unlock of the lock\n\
locked() -- test whether the lock is currently locked\n\
\n\
A lock is not owned by the thread that locked it; another thread may\n\
unlock it.  A thread attempting to lock a lock that it has already locked\n\
will block until another thread unlocks it.  Deadlocks may ensue.");

static PyMemberDef lock_type_members[] = {
    {"__weaklistoffset__", T_PYSSIZET, offsetof(lockobject, in_weakreflist), READONLY},
    {NULL},
};

static PyType_Slot lock_type_slots[] = {
    {Py_tp_dealloc, (destructor)lock_dealloc},
    {Py_tp_repr, (reprfunc)lock_repr},
    {Py_tp_doc, (void *)lock_doc},
    {Py_tp_methods, lock_methods},
    {Py_tp_traverse, lock_traverse},
    {Py_tp_members, lock_type_members},
    {0, 0}
};

static PyType_Spec lock_type_spec = {
    .name = "_thread.lock",
    .basicsize = sizeof(lockobject),
    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
              Py_TPFLAGS_DISALLOW_INSTANTIATION | Py_TPFLAGS_IMMUTABLETYPE),
    .slots = lock_type_slots,
};

/* Recursive lock objects */

typedef struct {
    PyObject_HEAD
    PyThread_type_lock rlock_lock;
    unsigned long rlock_owner;
    unsigned long rlock_count;
    PyObject *in_weakreflist;
} rlockobject;

static int
rlock_traverse(rlockobject *self, visitproc visit, void *arg)
{
    Py_VISIT(Py_TYPE(self));
    return 0;
}


static void
rlock_dealloc(rlockobject *self)
{
    PyObject_GC_UnTrack(self);
    if (self->in_weakreflist != NULL)
        PyObject_ClearWeakRefs((PyObject *) self);
    /* self->rlock_lock can be NULL if PyThread_allocate_lock() failed
       in rlock_new() */
    if (self->rlock_lock != NULL) {
        /* Unlock the lock so it's safe to free it */
        if (self->rlock_count > 0)
            PyThread_release_lock(self->rlock_lock);

        PyThread_free_lock(self->rlock_lock);
    }
    PyTypeObject *tp = Py_TYPE(self);
    tp->tp_free(self);
    Py_DECREF(tp);
}

static PyObject *
rlock_acquire(rlockobject *self, PyObject *args, PyObject *kwds)
{
    _PyTime_t timeout;
    unsigned long tid;
    PyLockStatus r = PY_LOCK_ACQUIRED;

    if (lock_acquire_parse_args(args, kwds, &timeout) < 0)
        return NULL;

    tid = PyThread_get_thread_ident();
    if (self->rlock_count > 0 && tid == self->rlock_owner) {
        unsigned long count = self->rlock_count + 1;
        if (count <= self->rlock_count) {
            PyErr_SetString(PyExc_OverflowError,
                            "Internal lock count overflowed");
            return NULL;
        }
        self->rlock_count = count;
        Py_RETURN_TRUE;
    }
    r = acquire_timed(self->rlock_lock, timeout);
    if (r == PY_LOCK_ACQUIRED) {
        assert(self->rlock_count == 0);
        self->rlock_owner = tid;
        self->rlock_count = 1;
    }
    else if (r == PY_LOCK_INTR) {
        return NULL;
    }

    return PyBool_FromLong(r == PY_LOCK_ACQUIRED);
}

PyDoc_STRVAR(rlock_acquire_doc,
"acquire(blocking=True) -> bool\n\
\n\
Lock the lock.  `blocking` indicates whether we should wait\n\
for the lock to be available or not.  If `blocking` is False\n\
and another thread holds the lock, the method will return False\n\
immediately.  If `blocking` is True and another thread holds\n\
the lock, the method will wait for the lock to be released,\n\
take it and then return True.\n\
(note: the blocking operation is interruptible.)\n\
\n\
In all other cases, the method will return True immediately.\n\
Precisely, if the current thread already holds the lock, its\n\
internal counter is simply incremented. If nobody holds the lock,\n\
the lock is taken and its internal counter initialized to 1.");

static PyObject *
rlock_release(rlockobject *self, PyObject *Py_UNUSED(ignored))
{
    unsigned long tid = PyThread_get_thread_ident();

    if (self->rlock_count == 0 || self->rlock_owner != tid) {
        PyErr_SetString(PyExc_RuntimeError,
                        "cannot release un-acquired lock");
        return NULL;
    }
    if (--self->rlock_count == 0) {
        self->rlock_owner = 0;
        PyThread_release_lock(self->rlock_lock);
    }
    Py_RETURN_NONE;
}

PyDoc_STRVAR(rlock_release_doc,
"release()\n\
\n\
Release the lock, allowing another thread that is blocked waiting for\n\
the lock to acquire the lock.  The lock must be in the locked state,\n\
and must be locked by the same thread that unlocks it; otherwise a\n\
`RuntimeError` is raised.\n\
\n\
Do note that if the lock was acquire()d several times in a row by the\n\
current thread, release() needs to be called as many times for the lock\n\
to be available for other threads.");

static PyObject *
rlock_acquire_restore(rlockobject *self, PyObject *args)
{
    unsigned long owner;
    unsigned long count;
    int r = 1;

    if (!PyArg_ParseTuple(args, "(kk):_acquire_restore", &count, &owner))
        return NULL;

    if (!PyThread_acquire_lock(self->rlock_lock, 0)) {
        Py_BEGIN_ALLOW_THREADS
        r = PyThread_acquire_lock(self->rlock_lock, 1);
        Py_END_ALLOW_THREADS
    }
    if (!r) {
        PyErr_SetString(ThreadError, "couldn't acquire lock");
        return NULL;
    }
    assert(self->rlock_count == 0);
    self->rlock_owner = owner;
    self->rlock_count = count;
    Py_RETURN_NONE;
}

PyDoc_STRVAR(rlock_acquire_restore_doc,
"_acquire_restore(state) -> None\n\
\n\
For internal use by `threading.Condition`.");

static PyObject *
rlock_release_save(rlockobject *self, PyObject *Py_UNUSED(ignored))
{
    unsigned long owner;
    unsigned long count;

    if (self->rlock_count == 0) {
        PyErr_SetString(PyExc_RuntimeError,
                        "cannot release un-acquired lock");
        return NULL;
    }

    owner = self->rlock_owner;
    count = self->rlock_count;
    self->rlock_count = 0;
    self->rlock_owner = 0;
    PyThread_release_lock(self->rlock_lock);
    return Py_BuildValue("kk", count, owner);
}

PyDoc_STRVAR(rlock_release_save_doc,
"_release_save() -> tuple\n\
\n\
For internal use by `threading.Condition`.");

static PyObject *
rlock_recursion_count(rlockobject *self, PyObject *Py_UNUSED(ignored))
{
    unsigned long tid = PyThread_get_thread_ident();
    return PyLong_FromUnsignedLong(
        self->rlock_owner == tid ? self->rlock_count : 0UL);
}

PyDoc_STRVAR(rlock_recursion_count_doc,
"_recursion_count() -> int\n\
\n\
For internal use by reentrancy checks.");

static PyObject *
rlock_is_owned(rlockobject *self, PyObject *Py_UNUSED(ignored))
{
    unsigned long tid = PyThread_get_thread_ident();

    if (self->rlock_count > 0 && self->rlock_owner == tid) {
        Py_RETURN_TRUE;
    }
    Py_RETURN_FALSE;
}

PyDoc_STRVAR(rlock_is_owned_doc,
"_is_owned() -> bool\n\
\n\
For internal use by `threading.Condition`.");

static PyObject *
rlock_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    rlockobject *self = (rlockobject *) type->tp_alloc(type, 0);
    if (self == NULL) {
        return NULL;
    }
    self->in_weakreflist = NULL;
    self->rlock_owner = 0;
    self->rlock_count = 0;

    self->rlock_lock = PyThread_allocate_lock();
    if (self->rlock_lock == NULL) {
        Py_DECREF(self);
        PyErr_SetString(ThreadError, "can't allocate lock");
        return NULL;
    }
    return (PyObject *) self;
}

static PyObject *
rlock_repr(rlockobject *self)
{
    return PyUnicode_FromFormat("<%s %s object owner=%ld count=%lu at %p>",
        self->rlock_count ? "locked" : "unlocked",
        Py_TYPE(self)->tp_name, self->rlock_owner,
        self->rlock_count, self);
}


#ifdef HAVE_FORK
static PyObject *
rlock__at_fork_reinit(rlockobject *self, PyObject *Py_UNUSED(args))
{
    if (_PyThread_at_fork_reinit(&self->rlock_lock) < 0) {
        PyErr_SetString(ThreadError, "failed to reinitialize lock at fork");
        return NULL;
    }

    self->rlock_owner = 0;
    self->rlock_count = 0;

    Py_RETURN_NONE;
}
#endif  /* HAVE_FORK */


static PyMethodDef rlock_methods[] = {
    {"acquire",      _PyCFunction_CAST(rlock_acquire),
     METH_VARARGS | METH_KEYWORDS, rlock_acquire_doc},
    {"release",      (PyCFunction)rlock_release,
     METH_NOARGS, rlock_release_doc},
    {"_is_owned",     (PyCFunction)rlock_is_owned,
     METH_NOARGS, rlock_is_owned_doc},
    {"_acquire_restore", (PyCFunction)rlock_acquire_restore,
     METH_VARARGS, rlock_acquire_restore_doc},
    {"_release_save", (PyCFunction)rlock_release_save,
     METH_NOARGS, rlock_release_save_doc},
    {"_recursion_count", (PyCFunction)rlock_recursion_count,
     METH_NOARGS, rlock_recursion_count_doc},
    {"__enter__",    _PyCFunction_CAST(rlock_acquire),
     METH_VARARGS | METH_KEYWORDS, rlock_acquire_doc},
    {"__exit__",    (PyCFunction)rlock_release,
     METH_VARARGS, rlock_release_doc},
#ifdef HAVE_FORK
    {"_at_fork_reinit",    (PyCFunction)rlock__at_fork_reinit,
     METH_NOARGS, NULL},
#endif
    {NULL,           NULL}              /* sentinel */
};


static PyMemberDef rlock_type_members[] = {
    {"__weaklistoffset__", T_PYSSIZET, offsetof(rlockobject, in_weakreflist), READONLY},
    {NULL},
};

static PyType_Slot rlock_type_slots[] = {
    {Py_tp_dealloc, (destructor)rlock_dealloc},
    {Py_tp_repr, (reprfunc)rlock_repr},
    {Py_tp_methods, rlock_methods},
    {Py_tp_alloc, PyType_GenericAlloc},
    {Py_tp_new, rlock_new},
    {Py_tp_members, rlock_type_members},
    {Py_tp_traverse, rlock_traverse},
    {0, 0},
};

static PyType_Spec rlock_type_spec = {
    .name = "_thread.RLock",
    .basicsize = sizeof(rlockobject),
    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
              Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_IMMUTABLETYPE),
    .slots = rlock_type_slots,
};

static lockobject *
newlockobject(PyObject *module)
{
    thread_module_state *state = get_thread_state(module);

    PyTypeObject *type = state->lock_type;
    lockobject *self = (lockobject *)type->tp_alloc(type, 0);
    if (self == NULL) {
        return NULL;
    }

    self->lock_lock = PyThread_allocate_lock();
    self->locked = 0;
    self->in_weakreflist = NULL;

    if (self->lock_lock == NULL) {
        Py_DECREF(self);
        PyErr_SetString(ThreadError, "can't allocate lock");
        return NULL;
    }
    return self;
}

/* Thread-local objects */

/* Quick overview:

   We need to be able to reclaim reference cycles as soon as possible
   (both when a thread is being terminated, or a thread-local object
    becomes unreachable from user data).  Constraints:
   - it must not be possible for thread-state dicts to be involved in
     reference cycles (otherwise the cyclic GC will refuse to consider
     objects referenced from a reachable thread-state dict, even though
     local_dealloc would clear them)
   - the death of a thread-state dict must still imply destruction of the
     corresponding local dicts in all thread-local objects.

   Our implementation uses small "localdummy" objects in order to break
   the reference chain. These trivial objects are hashable (using the
   default scheme of identity hashing) and weakrefable.
   Each thread-state holds a separate localdummy for each local object
   (as a /strong reference/),
   and each thread-local object holds a dict mapping /weak references/
   of localdummies to local dicts.

   Therefore:
   - only the thread-state dict holds a strong reference to the dummies
   - only the thread-local object holds a strong reference to the local dicts
   - only outside objects (application- or library-level) hold strong
     references to the thread-local objects
   - as soon as a thread-state dict is destroyed, the weakref callbacks of all
     dummies attached to that thread are called, and destroy the corresponding
     local dicts from thread-local objects
   - as soon as a thread-local object is destroyed, its local dicts are
     destroyed and its dummies are manually removed from all thread states
   - the GC can do its work correctly when a thread-local object is dangling,
     without any interference from the thread-state dicts

   As an additional optimization, each localdummy holds a borrowed reference
   to the corresponding localdict.  This borrowed reference is only used
   by the thread-local object which has created the localdummy, which should
   guarantee that the localdict still exists when accessed.
*/

typedef struct {
    PyObject_HEAD
    PyObject *localdict;        /* Borrowed reference! */
    PyObject *weakreflist;      /* List of weak references to self */
} localdummyobject;

static void
localdummy_dealloc(localdummyobject *self)
{
    if (self->weakreflist != NULL)
        PyObject_ClearWeakRefs((PyObject *) self);
    PyTypeObject *tp = Py_TYPE(self);
    tp->tp_free((PyObject*)self);
    Py_DECREF(tp);
}

static PyMemberDef local_dummy_type_members[] = {
    {"__weaklistoffset__", T_PYSSIZET, offsetof(localdummyobject, weakreflist), READONLY},
    {NULL},
};

static PyType_Slot local_dummy_type_slots[] = {
    {Py_tp_dealloc, (destructor)localdummy_dealloc},
    {Py_tp_doc, "Thread-local dummy"},
    {Py_tp_members, local_dummy_type_members},
    {0, 0}
};

static PyType_Spec local_dummy_type_spec = {
    .name = "_thread._localdummy",
    .basicsize = sizeof(localdummyobject),
    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION |
              Py_TPFLAGS_IMMUTABLETYPE),
    .slots = local_dummy_type_slots,
};


typedef struct {
    PyObject_HEAD
    PyObject *key;
    PyObject *args;
    PyObject *kw;
    PyObject *weakreflist;      /* List of weak references to self */
    /* A {localdummy weakref -> localdict} dict */
    PyObject *dummies;
    /* The callback for weakrefs to localdummies */
    PyObject *wr_callback;
} localobject;

/* Forward declaration */
static PyObject *_ldict(localobject *self, thread_module_state *state);
static PyObject *_localdummy_destroyed(PyObject *meth_self, PyObject *dummyweakref);

/* Create and register the dummy for the current thread.
   Returns a borrowed reference of the corresponding local dict */
static PyObject *
_local_create_dummy(localobject *self, thread_module_state *state)
{
    PyObject *ldict = NULL, *wr = NULL;
    localdummyobject *dummy = NULL;
    PyTypeObject *type = state->local_dummy_type;

    PyObject *tdict = PyThreadState_GetDict();
    if (tdict == NULL) {
        PyErr_SetString(PyExc_SystemError,
                        "Couldn't get thread-state dictionary");
        goto err;
    }

    ldict = PyDict_New();
    if (ldict == NULL) {
        goto err;
    }
    dummy = (localdummyobject *) type->tp_alloc(type, 0);
    if (dummy == NULL) {
        goto err;
    }
    dummy->localdict = ldict;
    wr = PyWeakref_NewRef((PyObject *) dummy, self->wr_callback);
    if (wr == NULL) {
        goto err;
    }

    /* As a side-effect, this will cache the weakref's hash before the
       dummy gets deleted */
    int r = PyDict_SetItem(self->dummies, wr, ldict);
    if (r < 0) {
        goto err;
    }
    Py_CLEAR(wr);
    r = PyDict_SetItem(tdict, self->key, (PyObject *) dummy);
    if (r < 0) {
        goto err;
    }
    Py_CLEAR(dummy);

    Py_DECREF(ldict);
    return ldict;

err:
    Py_XDECREF(ldict);
    Py_XDECREF(wr);
    Py_XDECREF(dummy);
    return NULL;
}

static PyObject *
local_new(PyTypeObject *type, PyObject *args, PyObject *kw)
{
    static PyMethodDef wr_callback_def = {
        "_localdummy_destroyed", (PyCFunction) _localdummy_destroyed, METH_O
    };

    if (type->tp_init == PyBaseObject_Type.tp_init) {
        int rc = 0;
        if (args != NULL)
            rc = PyObject_IsTrue(args);
        if (rc == 0 && kw != NULL)
            rc = PyObject_IsTrue(kw);
        if (rc != 0) {
            if (rc > 0) {
                PyErr_SetString(PyExc_TypeError,
                          "Initialization arguments are not supported");
            }
            return NULL;
        }
    }

    PyObject *module = PyType_GetModuleByDef(type, &thread_module);
    thread_module_state *state = get_thread_state(module);

    localobject *self = (localobject *)type->tp_alloc(type, 0);
    if (self == NULL) {
        return NULL;
    }

    self->args = Py_XNewRef(args);
    self->kw = Py_XNewRef(kw);
    self->key = PyUnicode_FromFormat("thread.local.%p", self);
    if (self->key == NULL) {
        goto err;
    }

    self->dummies = PyDict_New();
    if (self->dummies == NULL) {
        goto err;
    }

    /* We use a weak reference to self in the callback closure
       in order to avoid spurious reference cycles */
    PyObject *wr = PyWeakref_NewRef((PyObject *) self, NULL);
    if (wr == NULL) {
        goto err;
    }
    self->wr_callback = PyCFunction_NewEx(&wr_callback_def, wr, NULL);
    Py_DECREF(wr);
    if (self->wr_callback == NULL) {
        goto err;
    }
    if (_local_create_dummy(self, state) == NULL) {
        goto err;
    }
    return (PyObject *)self;

  err:
    Py_DECREF(self);
    return NULL;
}

static int
local_traverse(localobject *self, visitproc visit, void *arg)
{
    Py_VISIT(Py_TYPE(self));
    Py_VISIT(self->args);
    Py_VISIT(self->kw);
    Py_VISIT(self->dummies);
    return 0;
}

static int
local_clear(localobject *self)
{
    Py_CLEAR(self->args);
    Py_CLEAR(self->kw);
    Py_CLEAR(self->dummies);
    Py_CLEAR(self->wr_callback);
    /* Remove all strong references to dummies from the thread states */
    if (self->key) {
        PyInterpreterState *interp = _PyInterpreterState_GET();
        _PyRuntimeState *runtime = &_PyRuntime;
        HEAD_LOCK(runtime);
        PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
        HEAD_UNLOCK(runtime);
        while (tstate) {
            if (tstate->dict) {
                PyObject *v = _PyDict_Pop(tstate->dict, self->key, Py_None);
                if (v != NULL) {
                    Py_DECREF(v);
                }
                else {
                    PyErr_Clear();
                }
            }
            HEAD_LOCK(runtime);
            tstate = PyThreadState_Next(tstate);
            HEAD_UNLOCK(runtime);
        }
    }
    return 0;
}

static void
local_dealloc(localobject *self)
{
    /* Weakrefs must be invalidated right now, otherwise they can be used
       from code called below, which is very dangerous since Py_REFCNT(self) == 0 */
    if (self->weakreflist != NULL) {
        PyObject_ClearWeakRefs((PyObject *) self);
    }

    PyObject_GC_UnTrack(self);

    local_clear(self);
    Py_XDECREF(self->key);

    PyTypeObject *tp = Py_TYPE(self);
    tp->tp_free((PyObject*)self);
    Py_DECREF(tp);
}

/* Returns a borrowed reference to the local dict, creating it if necessary */
static PyObject *
_ldict(localobject *self, thread_module_state *state)
{
    PyObject *tdict = PyThreadState_GetDict();
    if (tdict == NULL) {
        PyErr_SetString(PyExc_SystemError,
                        "Couldn't get thread-state dictionary");
        return NULL;
    }

    PyObject *ldict;
    PyObject *dummy = PyDict_GetItemWithError(tdict, self->key);
    if (dummy == NULL) {
        if (PyErr_Occurred()) {
            return NULL;
        }
        ldict = _local_create_dummy(self, state);
        if (ldict == NULL)
            return NULL;

        if (Py_TYPE(self)->tp_init != PyBaseObject_Type.tp_init &&
            Py_TYPE(self)->tp_init((PyObject*)self,
                                   self->args, self->kw) < 0) {
            /* we need to get rid of ldict from thread so
               we create a new one the next time we do an attr
               access */
            PyDict_DelItem(tdict, self->key);
            return NULL;
        }
    }
    else {
        assert(Py_IS_TYPE(dummy, state->local_dummy_type));
        ldict = ((localdummyobject *) dummy)->localdict;
    }

    return ldict;
}

static int
local_setattro(localobject *self, PyObject *name, PyObject *v)
{
    PyObject *module = PyType_GetModuleByDef(Py_TYPE(self), &thread_module);
    thread_module_state *state = get_thread_state(module);

    PyObject *ldict = _ldict(self, state);
    if (ldict == NULL) {
        return -1;
    }

    int r = PyObject_RichCompareBool(name, &_Py_ID(__dict__), Py_EQ);
    if (r == -1) {
        return -1;
    }
    if (r == 1) {
        PyErr_Format(PyExc_AttributeError,
                     "'%.100s' object attribute '%U' is read-only",
                     Py_TYPE(self)->tp_name, name);
        return -1;
    }

    return _PyObject_GenericSetAttrWithDict((PyObject *)self, name, v, ldict);
}

static PyObject *local_getattro(localobject *, PyObject *);

static PyMemberDef local_type_members[] = {
    {"__weaklistoffset__", T_PYSSIZET, offsetof(localobject, weakreflist), READONLY},
    {NULL},
};

static PyType_Slot local_type_slots[] = {
    {Py_tp_dealloc, (destructor)local_dealloc},
    {Py_tp_getattro, (getattrofunc)local_getattro},
    {Py_tp_setattro, (setattrofunc)local_setattro},
    {Py_tp_doc, "Thread-local data"},
    {Py_tp_traverse, (traverseproc)local_traverse},
    {Py_tp_clear, (inquiry)local_clear},
    {Py_tp_new, local_new},
    {Py_tp_members, local_type_members},
    {0, 0}
};

static PyType_Spec local_type_spec = {
    .name = "_thread._local",
    .basicsize = sizeof(localobject),
    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC |
              Py_TPFLAGS_IMMUTABLETYPE),
    .slots = local_type_slots,
};

static PyObject *
local_getattro(localobject *self, PyObject *name)
{
    PyObject *module = PyType_GetModuleByDef(Py_TYPE(self), &thread_module);
    thread_module_state *state = get_thread_state(module);

    PyObject *ldict = _ldict(self, state);
    if (ldict == NULL)
        return NULL;

    int r = PyObject_RichCompareBool(name, &_Py_ID(__dict__), Py_EQ);
    if (r == 1) {
        return Py_NewRef(ldict);
    }
    if (r == -1) {
        return NULL;
    }

    if (!Py_IS_TYPE(self, state->local_type)) {
        /* use generic lookup for subtypes */
        return _PyObject_GenericGetAttrWithDict((PyObject *)self, name,
                                                ldict, 0);
    }

    /* Optimization: just look in dict ourselves */
    PyObject *value = PyDict_GetItemWithError(ldict, name);
    if (value != NULL) {
        return Py_NewRef(value);
    }
    if (PyErr_Occurred()) {
        return NULL;
    }

    /* Fall back on generic to get __class__ and __dict__ */
    return _PyObject_GenericGetAttrWithDict(
        (PyObject *)self, name, ldict, 0);
}

/* Called when a dummy is destroyed. */
static PyObject *
_localdummy_destroyed(PyObject *localweakref, PyObject *dummyweakref)
{
    assert(PyWeakref_CheckRef(localweakref));
    PyObject *obj = PyWeakref_GET_OBJECT(localweakref);
    if (obj == Py_None) {
        Py_RETURN_NONE;
    }

    /* If the thread-local object is still alive and not being cleared,
       remove the corresponding local dict */
    localobject *self = (localobject *)Py_NewRef(obj);
    if (self->dummies != NULL) {
        PyObject *ldict;
        ldict = PyDict_GetItemWithError(self->dummies, dummyweakref);
        if (ldict != NULL) {
            PyDict_DelItem(self->dummies, dummyweakref);
        }
        if (PyErr_Occurred())
            PyErr_WriteUnraisable(obj);
    }
    Py_DECREF(obj);
    Py_RETURN_NONE;
}

/* Module functions */

struct bootstate {
    PyThreadState *tstate;
    PyObject *func;
    PyObject *args;
    PyObject *kwargs;
};


static void
thread_bootstate_free(struct bootstate *boot, int decref)
{
    if (decref) {
        Py_DECREF(boot->func);
        Py_DECREF(boot->args);
        Py_XDECREF(boot->kwargs);
    }
    PyMem_RawFree(boot);
}


static void
thread_run(void *boot_raw)
{
    struct bootstate *boot = (struct bootstate *) boot_raw;
    PyThreadState *tstate = boot->tstate;

    // gh-108987: If _thread.start_new_thread() is called before or while
    // Python is being finalized, thread_run() can called *after*.
    // _PyRuntimeState_SetFinalizing() is called. At this point, all Python
    // threads must exit, except of the thread calling Py_Finalize() whch holds
    // the GIL and must not exit.
    //
    // At this stage, tstate can be a dangling pointer (point to freed memory),
    // it's ok to call _PyThreadState_MustExit() with a dangling pointer.
    if (_PyThreadState_MustExit(tstate)) {
        // Don't call PyThreadState_Clear() nor _PyThreadState_DeleteCurrent().
        // These functions are called on tstate indirectly by Py_Finalize()
        // which calls _PyInterpreterState_Clear().
        //
        // Py_DECREF() cannot be called because the GIL is not held: leak
        // references on purpose. Python is being finalized anyway.
        thread_bootstate_free(boot, 0);
        goto exit;
    }

    _PyThreadState_Bind(tstate);
    PyEval_AcquireThread(tstate);
    tstate->interp->threads.count++;

    PyObject *res = PyObject_Call(boot->func, boot->args, boot->kwargs);
    if (res == NULL) {
        if (PyErr_ExceptionMatches(PyExc_SystemExit))
            /* SystemExit is ignored silently */
            PyErr_Clear();
        else {
            _PyErr_WriteUnraisableMsg("in thread started by", boot->func);
        }
    }
    else {
        Py_DECREF(res);
    }

    thread_bootstate_free(boot, 1);

    tstate->interp->threads.count--;
    PyThreadState_Clear(tstate);
    _PyThreadState_DeleteCurrent(tstate);

exit:
    // bpo-44434: Don't call explicitly PyThread_exit_thread(). On Linux with
    // the glibc, pthread_exit() can abort the whole process if dlopen() fails
    // to open the libgcc_s.so library (ex: EMFILE error).
    return;
}

static PyObject *
thread_daemon_threads_allowed(PyObject *module, PyObject *Py_UNUSED(ignored))
{
    PyInterpreterState *interp = _PyInterpreterState_Get();
    if (interp->feature_flags & Py_RTFLAGS_DAEMON_THREADS) {
        Py_RETURN_TRUE;
    }
    else {
        Py_RETURN_FALSE;
    }
}

PyDoc_STRVAR(daemon_threads_allowed_doc,
"daemon_threads_allowed()\n\
\n\
Return True if daemon threads are allowed in the current interpreter,\n\
and False otherwise.\n");

static PyObject *
thread_PyThread_start_new_thread(PyObject *self, PyObject *fargs)
{
    PyObject *func, *args, *kwargs = NULL;

    if (!PyArg_UnpackTuple(fargs, "start_new_thread", 2, 3,
                           &func, &args, &kwargs))
        return NULL;
    if (!PyCallable_Check(func)) {
        PyErr_SetString(PyExc_TypeError,
                        "first arg must be callable");
        return NULL;
    }
    if (!PyTuple_Check(args)) {
        PyErr_SetString(PyExc_TypeError,
                        "2nd arg must be a tuple");
        return NULL;
    }
    if (kwargs != NULL && !PyDict_Check(kwargs)) {
        PyErr_SetString(PyExc_TypeError,
                        "optional 3rd arg must be a dictionary");
        return NULL;
    }

    if (PySys_Audit("_thread.start_new_thread", "OOO",
                    func, args, kwargs ? kwargs : Py_None) < 0) {
        return NULL;
    }

    PyInterpreterState *interp = _PyInterpreterState_GET();
    if (!_PyInterpreterState_HasFeature(interp, Py_RTFLAGS_THREADS)) {
        PyErr_SetString(PyExc_RuntimeError,
                        "thread is not supported for isolated subinterpreters");
        return NULL;
    }
    if (_PyInterpreterState_GetFinalizing(interp) != NULL) {
        PyErr_SetString(PyExc_RuntimeError,
                        "can't create new thread at interpreter shutdown");
        return NULL;
    }

    // gh-109795: Use PyMem_RawMalloc() instead of PyMem_Malloc(),
    // because it should be possible to call thread_bootstate_free()
    // without holding the GIL.
    struct bootstate *boot = PyMem_RawMalloc(sizeof(struct bootstate));
    if (boot == NULL) {
        return PyErr_NoMemory();
    }
    boot->tstate = _PyThreadState_New(interp);
    if (boot->tstate == NULL) {
        PyMem_RawFree(boot);
        if (!PyErr_Occurred()) {
            return PyErr_NoMemory();
        }
        return NULL;
    }
    boot->func = Py_NewRef(func);
    boot->args = Py_NewRef(args);
    boot->kwargs = Py_XNewRef(kwargs);

    unsigned long ident = PyThread_start_new_thread(thread_run, (void*) boot);
    if (ident == PYTHREAD_INVALID_THREAD_ID) {
        PyErr_SetString(ThreadError, "can't start new thread");
        PyThreadState_Clear(boot->tstate);
        thread_bootstate_free(boot, 1);
        return NULL;
    }
    return PyLong_FromUnsignedLong(ident);
}

PyDoc_STRVAR(start_new_doc,
"start_new_thread(function, args[, kwargs])\n\
(start_new() is an obsolete synonym)\n\
\n\
Start a new thread and return its identifier.  The thread will call the\n\
function with positional arguments from the tuple args and keyword arguments\n\
taken from the optional dictionary kwargs.  The thread exits when the\n\
function returns; the return value is ignored.  The thread will also exit\n\
when the function raises an unhandled exception; a stack trace will be\n\
printed unless the exception is SystemExit.\n");

static PyObject *
thread_PyThread_exit_thread(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    PyErr_SetNone(PyExc_SystemExit);
    return NULL;
}

PyDoc_STRVAR(exit_doc,
"exit()\n\
(exit_thread() is an obsolete synonym)\n\
\n\
This is synonymous to ``raise SystemExit''.  It will cause the current\n\
thread to exit silently unless the exception is caught.");

static PyObject *
thread_PyThread_interrupt_main(PyObject *self, PyObject *args)
{
    int signum = SIGINT;
    if (!PyArg_ParseTuple(args, "|i:signum", &signum)) {
        return NULL;
    }

    if (PyErr_SetInterruptEx(signum)) {
        PyErr_SetString(PyExc_ValueError, "signal number out of range");
        return NULL;
    }
    Py_RETURN_NONE;
}

PyDoc_STRVAR(interrupt_doc,
"interrupt_main(signum=signal.SIGINT, /)\n\
\n\
Simulate the arrival of the given signal in the main thread,\n\
where the corresponding signal handler will be executed.\n\
If *signum* is omitted, SIGINT is assumed.\n\
A subthread can use this function to interrupt the main thread.\n\
\n\
Note: the default signal handler for SIGINT raises ``KeyboardInterrupt``."
);

static lockobject *newlockobject(PyObject *module);

static PyObject *
thread_PyThread_allocate_lock(PyObject *module, PyObject *Py_UNUSED(ignored))
{
    return (PyObject *) newlockobject(module);
}

PyDoc_STRVAR(allocate_doc,
"allocate_lock() -> lock object\n\
(allocate() is an obsolete synonym)\n\
\n\
Create a new lock object. See help(type(threading.Lock())) for\n\
information about locks.");

static PyObject *
thread_get_ident(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    unsigned long ident = PyThread_get_thread_ident();
    if (ident == PYTHREAD_INVALID_THREAD_ID) {
        PyErr_SetString(ThreadError, "no current thread ident");
        return NULL;
    }
    return PyLong_FromUnsignedLong(ident);
}

PyDoc_STRVAR(get_ident_doc,
"get_ident() -> integer\n\
\n\
Return a non-zero integer that uniquely identifies the current thread\n\
amongst other threads that exist simultaneously.\n\
This may be used to identify per-thread resources.\n\
Even though on some platforms threads identities may appear to be\n\
allocated consecutive numbers starting at 1, this behavior should not\n\
be relied upon, and the number should be seen purely as a magic cookie.\n\
A thread's identity may be reused for another thread after it exits.");

#ifdef PY_HAVE_THREAD_NATIVE_ID
static PyObject *
thread_get_native_id(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    unsigned long native_id = PyThread_get_thread_native_id();
    return PyLong_FromUnsignedLong(native_id);
}

PyDoc_STRVAR(get_native_id_doc,
"get_native_id() -> integer\n\
\n\
Return a non-negative integer identifying the thread as reported\n\
by the OS (kernel). This may be used to uniquely identify a\n\
particular thread within a system.");
#endif

static PyObject *
thread__count(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    PyInterpreterState *interp = _PyInterpreterState_GET();
    return PyLong_FromLong(interp->threads.count);
}

PyDoc_STRVAR(_count_doc,
"_count() -> integer\n\
\n\
\
Return the number of currently running Python threads, excluding\n\
the main thread. The returned number comprises all threads created\n\
through `start_new_thread()` as well as `threading.Thread`, and not\n\
yet finished.\n\
\n\
This function is meant for internal and specialized purposes only.\n\
In most applications `threading.enumerate()` should be used instead.");

static void
release_sentinel(void *wr_raw)
{
    PyObject *wr = _PyObject_CAST(wr_raw);
    /* Tricky: this function is called when the current thread state
       is being deleted.  Therefore, only simple C code can safely
       execute here. */
    PyObject *obj = PyWeakref_GET_OBJECT(wr);
    lockobject *lock;
    if (obj != Py_None) {
        lock = (lockobject *) obj;
        if (lock->locked) {
            PyThread_release_lock(lock->lock_lock);
            lock->locked = 0;
        }
    }
    /* Deallocating a weakref with a NULL callback only calls
       PyObject_GC_Del(), which can't call any Python code. */
    Py_DECREF(wr);
}

static PyObject *
thread__set_sentinel(PyObject *module, PyObject *Py_UNUSED(ignored))
{
    PyObject *wr;
    PyThreadState *tstate = _PyThreadState_GET();
    lockobject *lock;

    if (tstate->on_delete_data != NULL) {
        /* We must support the re-creation of the lock from a
           fork()ed child. */
        assert(tstate->on_delete == &release_sentinel);
        wr = (PyObject *) tstate->on_delete_data;
        tstate->on_delete = NULL;
        tstate->on_delete_data = NULL;
        Py_DECREF(wr);
    }
    lock = newlockobject(module);
    if (lock == NULL)
        return NULL;
    /* The lock is owned by whoever called _set_sentinel(), but the weakref
       hangs to the thread state. */
    wr = PyWeakref_NewRef((PyObject *) lock, NULL);
    if (wr == NULL) {
        Py_DECREF(lock);
        return NULL;
    }
    tstate->on_delete_data = (void *) wr;
    tstate->on_delete = &release_sentinel;
    return (PyObject *) lock;
}

PyDoc_STRVAR(_set_sentinel_doc,
"_set_sentinel() -> lock\n\
\n\
Set a sentinel lock that will be released when the current thread\n\
state is finalized (after it is untied from the interpreter).\n\
\n\
This is a private API for the threading module.");

static PyObject *
thread_stack_size(PyObject *self, PyObject *args)
{
    size_t old_size;
    Py_ssize_t new_size = 0;
    int rc;

    if (!PyArg_ParseTuple(args, "|n:stack_size", &new_size))
        return NULL;

    if (new_size < 0) {
        PyErr_SetString(PyExc_ValueError,
                        "size must be 0 or a positive value");
        return NULL;
    }

    old_size = PyThread_get_stacksize();

    rc = PyThread_set_stacksize((size_t) new_size);
    if (rc == -1) {
        PyErr_Format(PyExc_ValueError,
                     "size not valid: %zd bytes",
                     new_size);
        return NULL;
    }
    if (rc == -2) {
        PyErr_SetString(ThreadError,
                        "setting stack size not supported");
        return NULL;
    }

    return PyLong_FromSsize_t((Py_ssize_t) old_size);
}

PyDoc_STRVAR(stack_size_doc,
"stack_size([size]) -> size\n\
\n\
Return the thread stack size used when creating new threads.  The\n\
optional size argument specifies the stack size (in bytes) to be used\n\
for subsequently created threads, and must be 0 (use platform or\n\
configured default) or a positive integer value of at least 32,768 (32k).\n\
If changing the thread stack size is unsupported, a ThreadError\n\
exception is raised.  If the specified size is invalid, a ValueError\n\
exception is raised, and the stack size is unmodified.  32k bytes\n\
 currently the minimum supported stack size value to guarantee\n\
sufficient stack space for the interpreter itself.\n\
\n\
Note that some platforms may have particular restrictions on values for\n\
the stack size, such as requiring a minimum stack size larger than 32 KiB or\n\
requiring allocation in multiples of the system memory page size\n\
- platform documentation should be referred to for more information\n\
(4 KiB pages are common; using multiples of 4096 for the stack size is\n\
the suggested approach in the absence of more specific information).");

static int
thread_excepthook_file(PyObject *file, PyObject *exc_type, PyObject *exc_value,
                       PyObject *exc_traceback, PyObject *thread)
{
    /* print(f"Exception in thread {thread.name}:", file=file) */
    if (PyFile_WriteString("Exception in thread ", file) < 0) {
        return -1;
    }

    PyObject *name = NULL;
    if (thread != Py_None) {
        if (_PyObject_LookupAttr(thread, &_Py_ID(name), &name) < 0) {
            return -1;
        }
    }
    if (name != NULL) {
        if (PyFile_WriteObject(name, file, Py_PRINT_RAW) < 0) {
            Py_DECREF(name);
            return -1;
        }
        Py_DECREF(name);
    }
    else {
        unsigned long ident = PyThread_get_thread_ident();
        PyObject *str = PyUnicode_FromFormat("%lu", ident);
        if (str != NULL) {
            if (PyFile_WriteObject(str, file, Py_PRINT_RAW) < 0) {
                Py_DECREF(str);
                return -1;
            }
            Py_DECREF(str);
        }
        else {
            PyErr_Clear();

            if (PyFile_WriteString("<failed to get thread name>", file) < 0) {
                return -1;
            }
        }
    }

    if (PyFile_WriteString(":\n", file) < 0) {
        return -1;
    }

    /* Display the traceback */
    _PyErr_Display(file, exc_type, exc_value, exc_traceback);

    /* Call file.flush() */
    PyObject *res = PyObject_CallMethodNoArgs(file, &_Py_ID(flush));
    if (!res) {
        return -1;
    }
    Py_DECREF(res);

    return 0;
}


PyDoc_STRVAR(ExceptHookArgs__doc__,
"ExceptHookArgs\n\
\n\
Type used to pass arguments to threading.excepthook.");

static PyStructSequence_Field ExceptHookArgs_fields[] = {
    {"exc_type", "Exception type"},
    {"exc_value", "Exception value"},
    {"exc_traceback", "Exception traceback"},
    {"thread", "Thread"},
    {0}
};

static PyStructSequence_Desc ExceptHookArgs_desc = {
    .name = "_thread._ExceptHookArgs",
    .doc = ExceptHookArgs__doc__,
    .fields = ExceptHookArgs_fields,
    .n_in_sequence = 4
};


static PyObject *
thread_excepthook(PyObject *module, PyObject *args)
{
    thread_module_state *state = get_thread_state(module);

    if (!Py_IS_TYPE(args, state->excepthook_type)) {
        PyErr_SetString(PyExc_TypeError,
                        "_thread.excepthook argument type "
                        "must be ExceptHookArgs");
        return NULL;
    }

    /* Borrowed reference */
    PyObject *exc_type = PyStructSequence_GET_ITEM(args, 0);
    if (exc_type == PyExc_SystemExit) {
        /* silently ignore SystemExit */
        Py_RETURN_NONE;
    }

    /* Borrowed references */
    PyObject *exc_value = PyStructSequence_GET_ITEM(args, 1);
    PyObject *exc_tb = PyStructSequence_GET_ITEM(args, 2);
    PyObject *thread = PyStructSequence_GET_ITEM(args, 3);

    PyThreadState *tstate = _PyThreadState_GET();
    PyObject *file = _PySys_GetAttr(tstate, &_Py_ID(stderr));
    if (file == NULL || file == Py_None) {
        if (thread == Py_None) {
            /* do nothing if sys.stderr is None and thread is None */
            Py_RETURN_NONE;
        }

        file = PyObject_GetAttrString(thread, "_stderr");
        if (file == NULL) {
            return NULL;
        }
        if (file == Py_None) {
            Py_DECREF(file);
            /* do nothing if sys.stderr is None and sys.stderr was None
               when the thread was created */
            Py_RETURN_NONE;
        }
    }
    else {
        Py_INCREF(file);
    }

    int res = thread_excepthook_file(file, exc_type, exc_value, exc_tb,
                                     thread);
    Py_DECREF(file);
    if (res < 0) {
        return NULL;
    }

    Py_RETURN_NONE;
}

PyDoc_STRVAR(excepthook_doc,
"excepthook(exc_type, exc_value, exc_traceback, thread)\n\
\n\
Handle uncaught Thread.run() exception.");

static PyObject *
thread__is_main_interpreter(PyObject *module, PyObject *Py_UNUSED(ignored))
{
    PyInterpreterState *interp = _PyInterpreterState_GET();
    return PyBool_FromLong(_Py_IsMainInterpreter(interp));
}

PyDoc_STRVAR(thread__is_main_interpreter_doc,
"_is_main_interpreter()\n\
\n\
Return True if the current interpreter is the main Python interpreter.");

static PyMethodDef thread_methods[] = {
    {"start_new_thread",        (PyCFunction)thread_PyThread_start_new_thread,
     METH_VARARGS, start_new_doc},
    {"start_new",               (PyCFunction)thread_PyThread_start_new_thread,
     METH_VARARGS, start_new_doc},
    {"daemon_threads_allowed",  (PyCFunction)thread_daemon_threads_allowed,
     METH_NOARGS, daemon_threads_allowed_doc},
    {"allocate_lock",           thread_PyThread_allocate_lock,
     METH_NOARGS, allocate_doc},
    {"allocate",                thread_PyThread_allocate_lock,
     METH_NOARGS, allocate_doc},
    {"exit_thread",             thread_PyThread_exit_thread,
     METH_NOARGS, exit_doc},
    {"exit",                    thread_PyThread_exit_thread,
     METH_NOARGS, exit_doc},
    {"interrupt_main",          (PyCFunction)thread_PyThread_interrupt_main,
     METH_VARARGS, interrupt_doc},
    {"get_ident",               thread_get_ident,
     METH_NOARGS, get_ident_doc},
#ifdef PY_HAVE_THREAD_NATIVE_ID
    {"get_native_id",           thread_get_native_id,
     METH_NOARGS, get_native_id_doc},
#endif
    {"_count",                  thread__count,
     METH_NOARGS, _count_doc},
    {"stack_size",              (PyCFunction)thread_stack_size,
     METH_VARARGS, stack_size_doc},
    {"_set_sentinel",           thread__set_sentinel,
     METH_NOARGS, _set_sentinel_doc},
    {"_excepthook",             thread_excepthook,
     METH_O, excepthook_doc},
    {"_is_main_interpreter",    thread__is_main_interpreter,
     METH_NOARGS, thread__is_main_interpreter_doc},
    {NULL,                      NULL}           /* sentinel */
};


/* Initialization function */

static int
thread_module_exec(PyObject *module)
{
    thread_module_state *state = get_thread_state(module);
    PyObject *d = PyModule_GetDict(module);

    // Initialize the C thread library
    PyThread_init_thread();

    // Lock
    state->lock_type = (PyTypeObject *)PyType_FromSpec(&lock_type_spec);
    if (state->lock_type == NULL) {
        return -1;
    }
    if (PyDict_SetItemString(d, "LockType", (PyObject *)state->lock_type) < 0) {
        return -1;
    }

    // RLock
    PyTypeObject *rlock_type = (PyTypeObject *)PyType_FromSpec(&rlock_type_spec);
    if (rlock_type == NULL) {
        return -1;
    }
    if (PyModule_AddType(module, rlock_type) < 0) {
        Py_DECREF(rlock_type);
        return -1;
    }
    Py_DECREF(rlock_type);

    // Local dummy
    state->local_dummy_type = (PyTypeObject *)PyType_FromSpec(&local_dummy_type_spec);
    if (state->local_dummy_type == NULL) {
        return -1;
    }

    // Local
    state->local_type = (PyTypeObject *)PyType_FromModuleAndSpec(module, &local_type_spec, NULL);
    if (state->local_type == NULL) {
        return -1;
    }
    if (PyModule_AddType(module, state->local_type) < 0) {
        return -1;
    }

    // Add module attributes
    if (PyDict_SetItemString(d, "error", ThreadError) < 0) {
        return -1;
    }

    // _ExceptHookArgs type
    state->excepthook_type = PyStructSequence_NewType(&ExceptHookArgs_desc);
    if (state->excepthook_type == NULL) {
        return -1;
    }
    if (PyModule_AddType(module, state->excepthook_type) < 0) {
        return -1;
    }

    // TIMEOUT_MAX
    double timeout_max = (double)PY_TIMEOUT_MAX * 1e-6;
    double time_max = _PyTime_AsSecondsDouble(_PyTime_MAX);
    timeout_max = Py_MIN(timeout_max, time_max);
    // Round towards minus infinity
    timeout_max = floor(timeout_max);

    if (_PyModule_Add(module, "TIMEOUT_MAX",
                        PyFloat_FromDouble(timeout_max)) < 0) {
        return -1;
    }

    return 0;
}


static int
thread_module_traverse(PyObject *module, visitproc visit, void *arg)
{
    thread_module_state *state = get_thread_state(module);
    Py_VISIT(state->excepthook_type);
    Py_VISIT(state->lock_type);
    Py_VISIT(state->local_type);
    Py_VISIT(state->local_dummy_type);
    return 0;
}

static int
thread_module_clear(PyObject *module)
{
    thread_module_state *state = get_thread_state(module);
    Py_CLEAR(state->excepthook_type);
    Py_CLEAR(state->lock_type);
    Py_CLEAR(state->local_type);
    Py_CLEAR(state->local_dummy_type);
    return 0;
}

static void
thread_module_free(void *module)
{
    thread_module_clear((PyObject *)module);
}



PyDoc_STRVAR(thread_doc,
"This module provides primitive operations to write multi-threaded programs.\n\
The 'threading' module provides a more convenient interface.");

static PyModuleDef_Slot thread_module_slots[] = {
    {Py_mod_exec, thread_module_exec},
    {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
    {0, NULL}
};

static struct PyModuleDef thread_module = {
    PyModuleDef_HEAD_INIT,
    .m_name = "_thread",
    .m_doc = thread_doc,
    .m_size = sizeof(thread_module_state),
    .m_methods = thread_methods,
    .m_traverse = thread_module_traverse,
    .m_clear = thread_module_clear,
    .m_free = thread_module_free,
    .m_slots = thread_module_slots,
};

PyMODINIT_FUNC
PyInit__thread(void)
{
    return PyModuleDef_Init(&thread_module);
}