summaryrefslogtreecommitdiffstats
path: root/Modules/_tracemalloc.c
blob: c5d5671032ebf144562615e0cebad45be9fb520a (plain)
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
#include "Python.h"
#include "hashtable.h"
#include "frameobject.h"
#include "pythread.h"
#include "osdefs.h"

#include "clinic/_tracemalloc.c.h"
/*[clinic input]
module _tracemalloc
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=708a98302fc46e5f]*/

/* Trace memory blocks allocated by PyMem_RawMalloc() */
#define TRACE_RAW_MALLOC

/* Forward declaration */
static void tracemalloc_stop(void);
static void* raw_malloc(size_t size);
static void raw_free(void *ptr);

#ifdef Py_DEBUG
#  define TRACE_DEBUG
#endif

/* Protected by the GIL */
static struct {
    PyMemAllocatorEx mem;
    PyMemAllocatorEx raw;
    PyMemAllocatorEx obj;
} allocators;


#if defined(TRACE_RAW_MALLOC)
/* This lock is needed because tracemalloc_free() is called without
   the GIL held from PyMem_RawFree(). It cannot acquire the lock because it
   would introduce a deadlock in PyThreadState_DeleteCurrent(). */
static PyThread_type_lock tables_lock;
#  define TABLES_LOCK() PyThread_acquire_lock(tables_lock, 1)
#  define TABLES_UNLOCK() PyThread_release_lock(tables_lock)
#else
   /* variables are protected by the GIL */
#  define TABLES_LOCK()
#  define TABLES_UNLOCK()
#endif


#define DEFAULT_DOMAIN 0

/* Pack the frame_t structure to reduce the memory footprint. */
typedef struct
#ifdef __GNUC__
__attribute__((packed))
#endif
{
    uintptr_t ptr;
    unsigned int domain;
} pointer_t;

/* Pack the frame_t structure to reduce the memory footprint on 64-bit
   architectures: 12 bytes instead of 16. */
typedef struct
#ifdef __GNUC__
__attribute__((packed))
#elif defined(_MSC_VER)
#pragma pack(push, 4)
#endif
{
    /* filename cannot be NULL: "<unknown>" is used if the Python frame
       filename is NULL */
    PyObject *filename;
    unsigned int lineno;
} frame_t;
#ifdef _MSC_VER
#pragma pack(pop)
#endif


typedef struct {
    Py_uhash_t hash;
    int nframe;
    frame_t frames[1];
} traceback_t;

#define TRACEBACK_SIZE(NFRAME) \
        (sizeof(traceback_t) + sizeof(frame_t) * (NFRAME - 1))

#define MAX_NFRAME \
        ((INT_MAX - (int)sizeof(traceback_t)) / (int)sizeof(frame_t) + 1)


static PyObject *unknown_filename = NULL;
static traceback_t tracemalloc_empty_traceback;

/* Trace of a memory block */
typedef struct {
    /* Size of the memory block in bytes */
    size_t size;

    /* Traceback where the memory block was allocated */
    traceback_t *traceback;
} trace_t;


/* Size in bytes of currently traced memory.
   Protected by TABLES_LOCK(). */
static size_t tracemalloc_traced_memory = 0;

/* Peak size in bytes of traced memory.
   Protected by TABLES_LOCK(). */
static size_t tracemalloc_peak_traced_memory = 0;

/* Hash table used as a set to intern filenames:
   PyObject* => PyObject*.
   Protected by the GIL */
static _Py_hashtable_t *tracemalloc_filenames = NULL;

/* Buffer to store a new traceback in traceback_new().
   Protected by the GIL. */
static traceback_t *tracemalloc_traceback = NULL;

/* Hash table used as a set to intern tracebacks:
   traceback_t* => traceback_t*
   Protected by the GIL */
static _Py_hashtable_t *tracemalloc_tracebacks = NULL;

/* pointer (void*) => trace (trace_t).
   Protected by TABLES_LOCK(). */
static _Py_hashtable_t *tracemalloc_traces = NULL;


#ifdef TRACE_DEBUG
static void
tracemalloc_error(const char *format, ...)
{
    va_list ap;
    fprintf(stderr, "tracemalloc: ");
    va_start(ap, format);
    vfprintf(stderr, format, ap);
    va_end(ap);
    fprintf(stderr, "\n");
    fflush(stderr);
}
#endif


#if defined(TRACE_RAW_MALLOC)
#define REENTRANT_THREADLOCAL

static Py_tss_t tracemalloc_reentrant_key = Py_tss_NEEDS_INIT;

/* Any non-NULL pointer can be used */
#define REENTRANT Py_True

static int
get_reentrant(void)
{
    void *ptr;

    assert(PyThread_tss_is_created(&tracemalloc_reentrant_key));
    ptr = PyThread_tss_get(&tracemalloc_reentrant_key);
    if (ptr != NULL) {
        assert(ptr == REENTRANT);
        return 1;
    }
    else
        return 0;
}

static void
set_reentrant(int reentrant)
{
    assert(reentrant == 0 || reentrant == 1);
    assert(PyThread_tss_is_created(&tracemalloc_reentrant_key));

    if (reentrant) {
        assert(!get_reentrant());
        PyThread_tss_set(&tracemalloc_reentrant_key, REENTRANT);
    }
    else {
        assert(get_reentrant());
        PyThread_tss_set(&tracemalloc_reentrant_key, NULL);
    }
}

#else

/* TRACE_RAW_MALLOC not defined: variable protected by the GIL */
static int tracemalloc_reentrant = 0;

static int
get_reentrant(void)
{
    return tracemalloc_reentrant;
}

static void
set_reentrant(int reentrant)
{
    assert(reentrant != tracemalloc_reentrant);
    tracemalloc_reentrant = reentrant;
}
#endif


static Py_uhash_t
hashtable_hash_pyobject(_Py_hashtable_t *ht, const void *pkey)
{
    PyObject *obj;

    _Py_HASHTABLE_READ_KEY(ht, pkey, obj);
    return PyObject_Hash(obj);
}


static int
hashtable_compare_unicode(_Py_hashtable_t *ht, const void *pkey,
                          const _Py_hashtable_entry_t *entry)
{
    PyObject *key1, *key2;

    _Py_HASHTABLE_READ_KEY(ht, pkey, key1);
    _Py_HASHTABLE_ENTRY_READ_KEY(ht, entry, key2);

    if (key1 != NULL && key2 != NULL)
        return (PyUnicode_Compare(key1, key2) == 0);
    else
        return key1 == key2;
}


static Py_uhash_t
hashtable_hash_pointer_t(_Py_hashtable_t *ht, const void *pkey)
{
    pointer_t ptr;
    Py_uhash_t hash;

    _Py_HASHTABLE_READ_KEY(ht, pkey, ptr);

    hash = (Py_uhash_t)_Py_HashPointer((void*)ptr.ptr);
    hash ^= ptr.domain;
    return hash;
}


static int
hashtable_compare_pointer_t(_Py_hashtable_t *ht, const void *pkey,
                            const _Py_hashtable_entry_t *entry)
{
    pointer_t ptr1, ptr2;

    _Py_HASHTABLE_READ_KEY(ht, pkey, ptr1);
    _Py_HASHTABLE_ENTRY_READ_KEY(ht, entry, ptr2);

    /* compare pointer before domain, because pointer is more likely to be
       different */
    return (ptr1.ptr == ptr2.ptr && ptr1.domain == ptr2.domain);

}


static _Py_hashtable_t *
hashtable_new(size_t key_size, size_t data_size,
              _Py_hashtable_hash_func hash_func,
              _Py_hashtable_compare_func compare_func)
{
    _Py_hashtable_allocator_t hashtable_alloc = {malloc, free};
    return _Py_hashtable_new_full(key_size, data_size, 0,
                                  hash_func, compare_func,
                                  &hashtable_alloc);
}


static void*
raw_malloc(size_t size)
{
    return allocators.raw.malloc(allocators.raw.ctx, size);
}

static void
raw_free(void *ptr)
{
    allocators.raw.free(allocators.raw.ctx, ptr);
}


static Py_uhash_t
hashtable_hash_traceback(_Py_hashtable_t *ht, const void *pkey)
{
    traceback_t *traceback;

    _Py_HASHTABLE_READ_KEY(ht, pkey, traceback);
    return traceback->hash;
}


static int
hashtable_compare_traceback(_Py_hashtable_t *ht, const void *pkey,
                            const _Py_hashtable_entry_t *entry)
{
    traceback_t *traceback1, *traceback2;
    const frame_t *frame1, *frame2;
    int i;

    _Py_HASHTABLE_READ_KEY(ht, pkey, traceback1);
    _Py_HASHTABLE_ENTRY_READ_KEY(ht, entry, traceback2);

    if (traceback1->nframe != traceback2->nframe)
        return 0;

    for (i=0; i < traceback1->nframe; i++) {
        frame1 = &traceback1->frames[i];
        frame2 = &traceback2->frames[i];

        if (frame1->lineno != frame2->lineno)
            return 0;

        if (frame1->filename != frame2->filename) {
            assert(PyUnicode_Compare(frame1->filename, frame2->filename) != 0);
            return 0;
        }
    }
    return 1;
}


static void
tracemalloc_get_frame(PyFrameObject *pyframe, frame_t *frame)
{
    PyCodeObject *code;
    PyObject *filename;
    _Py_hashtable_entry_t *entry;
    int lineno;

    frame->filename = unknown_filename;
    lineno = PyFrame_GetLineNumber(pyframe);
    if (lineno < 0)
        lineno = 0;
    frame->lineno = (unsigned int)lineno;

    code = pyframe->f_code;
    if (code == NULL) {
#ifdef TRACE_DEBUG
        tracemalloc_error("failed to get the code object of the frame");
#endif
        return;
    }

    if (code->co_filename == NULL) {
#ifdef TRACE_DEBUG
        tracemalloc_error("failed to get the filename of the code object");
#endif
        return;
    }

    filename = code->co_filename;
    assert(filename != NULL);
    if (filename == NULL)
        return;

    if (!PyUnicode_Check(filename)) {
#ifdef TRACE_DEBUG
        tracemalloc_error("filename is not a unicode string");
#endif
        return;
    }
    if (!PyUnicode_IS_READY(filename)) {
        /* Don't make a Unicode string ready to avoid reentrant calls
           to tracemalloc_malloc() or tracemalloc_realloc() */
#ifdef TRACE_DEBUG
        tracemalloc_error("filename is not a ready unicode string");
#endif
        return;
    }

    /* intern the filename */
    entry = _Py_HASHTABLE_GET_ENTRY(tracemalloc_filenames, filename);
    if (entry != NULL) {
        _Py_HASHTABLE_ENTRY_READ_KEY(tracemalloc_filenames, entry, filename);
    }
    else {
        /* tracemalloc_filenames is responsible to keep a reference
           to the filename */
        Py_INCREF(filename);
        if (_Py_HASHTABLE_SET_NODATA(tracemalloc_filenames, filename) < 0) {
            Py_DECREF(filename);
#ifdef TRACE_DEBUG
            tracemalloc_error("failed to intern the filename");
#endif
            return;
        }
    }

    /* the tracemalloc_filenames table keeps a reference to the filename */
    frame->filename = filename;
}


static Py_uhash_t
traceback_hash(traceback_t *traceback)
{
    /* code based on tuplehash() of Objects/tupleobject.c */
    Py_uhash_t x, y;  /* Unsigned for defined overflow behavior. */
    int len = traceback->nframe;
    Py_uhash_t mult = _PyHASH_MULTIPLIER;
    frame_t *frame;

    x = 0x345678UL;
    frame = traceback->frames;
    while (--len >= 0) {
        y = (Py_uhash_t)PyObject_Hash(frame->filename);
        y ^= (Py_uhash_t)frame->lineno;
        frame++;

        x = (x ^ y) * mult;
        /* the cast might truncate len; that doesn't change hash stability */
        mult += (Py_uhash_t)(82520UL + len + len);
    }
    x += 97531UL;
    return x;
}


static void
traceback_get_frames(traceback_t *traceback)
{
    PyThreadState *tstate;
    PyFrameObject *pyframe;

    tstate = PyGILState_GetThisThreadState();
    if (tstate == NULL) {
#ifdef TRACE_DEBUG
        tracemalloc_error("failed to get the current thread state");
#endif
        return;
    }

    for (pyframe = tstate->frame; pyframe != NULL; pyframe = pyframe->f_back) {
        tracemalloc_get_frame(pyframe, &traceback->frames[traceback->nframe]);
        assert(traceback->frames[traceback->nframe].filename != NULL);
        traceback->nframe++;
        if (traceback->nframe == _Py_tracemalloc_config.max_nframe)
            break;
    }
}


static traceback_t *
traceback_new(void)
{
    traceback_t *traceback;
    _Py_hashtable_entry_t *entry;

    assert(PyGILState_Check());

    /* get frames */
    traceback = tracemalloc_traceback;
    traceback->nframe = 0;
    traceback_get_frames(traceback);
    if (traceback->nframe == 0)
        return &tracemalloc_empty_traceback;
    traceback->hash = traceback_hash(traceback);

    /* intern the traceback */
    entry = _Py_HASHTABLE_GET_ENTRY(tracemalloc_tracebacks, traceback);
    if (entry != NULL) {
        _Py_HASHTABLE_ENTRY_READ_KEY(tracemalloc_tracebacks, entry, traceback);
    }
    else {
        traceback_t *copy;
        size_t traceback_size;

        traceback_size = TRACEBACK_SIZE(traceback->nframe);

        copy = raw_malloc(traceback_size);
        if (copy == NULL) {
#ifdef TRACE_DEBUG
            tracemalloc_error("failed to intern the traceback: malloc failed");
#endif
            return NULL;
        }
        memcpy(copy, traceback, traceback_size);

        if (_Py_HASHTABLE_SET_NODATA(tracemalloc_tracebacks, copy) < 0) {
            raw_free(copy);
#ifdef TRACE_DEBUG
            tracemalloc_error("failed to intern the traceback: putdata failed");
#endif
            return NULL;
        }
        traceback = copy;
    }
    return traceback;
}


static int
tracemalloc_use_domain_cb(_Py_hashtable_t *old_traces,
                           _Py_hashtable_entry_t *entry, void *user_data)
{
    uintptr_t ptr;
    pointer_t key;
    _Py_hashtable_t *new_traces = (_Py_hashtable_t *)user_data;
    const void *pdata = _Py_HASHTABLE_ENTRY_PDATA(old_traces, entry);

    _Py_HASHTABLE_ENTRY_READ_KEY(old_traces, entry, ptr);
    key.ptr = ptr;
    key.domain = DEFAULT_DOMAIN;

    return _Py_hashtable_set(new_traces,
                             sizeof(key), &key,
                             old_traces->data_size, pdata);
}


/* Convert tracemalloc_traces from compact key (uintptr_t) to pointer_t key.
 * Return 0 on success, -1 on error. */
static int
tracemalloc_use_domain(void)
{
    _Py_hashtable_t *new_traces = NULL;

    assert(!_Py_tracemalloc_config.use_domain);

    new_traces = hashtable_new(sizeof(pointer_t),
                               sizeof(trace_t),
                               hashtable_hash_pointer_t,
                               hashtable_compare_pointer_t);
    if (new_traces == NULL) {
        return -1;
    }

    if (_Py_hashtable_foreach(tracemalloc_traces, tracemalloc_use_domain_cb,
                              new_traces) < 0)
    {
        _Py_hashtable_destroy(new_traces);
        return -1;
    }

    _Py_hashtable_destroy(tracemalloc_traces);
    tracemalloc_traces = new_traces;

    _Py_tracemalloc_config.use_domain = 1;

    return 0;
}


static void
tracemalloc_remove_trace(unsigned int domain, uintptr_t ptr)
{
    trace_t trace;
    int removed;

    assert(_Py_tracemalloc_config.tracing);

    if (_Py_tracemalloc_config.use_domain) {
        pointer_t key = {ptr, domain};
        removed = _Py_HASHTABLE_POP(tracemalloc_traces, key, trace);
    }
    else {
        removed = _Py_HASHTABLE_POP(tracemalloc_traces, ptr, trace);
    }
    if (!removed) {
        return;
    }

    assert(tracemalloc_traced_memory >= trace.size);
    tracemalloc_traced_memory -= trace.size;
}

#define REMOVE_TRACE(ptr) \
            tracemalloc_remove_trace(DEFAULT_DOMAIN, (uintptr_t)(ptr))


static int
tracemalloc_add_trace(unsigned int domain, uintptr_t ptr,
                      size_t size)
{
    pointer_t key = {ptr, domain};
    traceback_t *traceback;
    trace_t trace;
    _Py_hashtable_entry_t* entry;
    int res;

    assert(_Py_tracemalloc_config.tracing);

    traceback = traceback_new();
    if (traceback == NULL) {
        return -1;
    }

    if (!_Py_tracemalloc_config.use_domain && domain != DEFAULT_DOMAIN) {
        /* first trace using a non-zero domain whereas traces use compact
           (uintptr_t) keys: switch to pointer_t keys. */
        if (tracemalloc_use_domain() < 0) {
            return -1;
        }
    }

    if (_Py_tracemalloc_config.use_domain) {
        entry = _Py_HASHTABLE_GET_ENTRY(tracemalloc_traces, key);
    }
    else {
        entry = _Py_HASHTABLE_GET_ENTRY(tracemalloc_traces, ptr);
    }

    if (entry != NULL) {
        /* the memory block is already tracked */
        _Py_HASHTABLE_ENTRY_READ_DATA(tracemalloc_traces, entry, trace);
        assert(tracemalloc_traced_memory >= trace.size);
        tracemalloc_traced_memory -= trace.size;

        trace.size = size;
        trace.traceback = traceback;
        _Py_HASHTABLE_ENTRY_WRITE_DATA(tracemalloc_traces, entry, trace);
    }
    else {
        trace.size = size;
        trace.traceback = traceback;

        if (_Py_tracemalloc_config.use_domain) {
            res = _Py_HASHTABLE_SET(tracemalloc_traces, key, trace);
        }
        else {
            res = _Py_HASHTABLE_SET(tracemalloc_traces, ptr, trace);
        }
        if (res != 0) {
            return res;
        }
    }

    assert(tracemalloc_traced_memory <= SIZE_MAX - size);
    tracemalloc_traced_memory += size;
    if (tracemalloc_traced_memory > tracemalloc_peak_traced_memory)
        tracemalloc_peak_traced_memory = tracemalloc_traced_memory;
    return 0;
}

#define ADD_TRACE(ptr, size) \
            tracemalloc_add_trace(DEFAULT_DOMAIN, (uintptr_t)(ptr), size)


static void*
tracemalloc_alloc(int use_calloc, void *ctx, size_t nelem, size_t elsize)
{
    PyMemAllocatorEx *alloc = (PyMemAllocatorEx *)ctx;
    void *ptr;

    assert(elsize == 0 || nelem <= SIZE_MAX / elsize);

    if (use_calloc)
        ptr = alloc->calloc(alloc->ctx, nelem, elsize);
    else
        ptr = alloc->malloc(alloc->ctx, nelem * elsize);
    if (ptr == NULL)
        return NULL;

    TABLES_LOCK();
    if (ADD_TRACE(ptr, nelem * elsize) < 0) {
        /* Failed to allocate a trace for the new memory block */
        TABLES_UNLOCK();
        alloc->free(alloc->ctx, ptr);
        return NULL;
    }
    TABLES_UNLOCK();
    return ptr;
}


static void*
tracemalloc_realloc(void *ctx, void *ptr, size_t new_size)
{
    PyMemAllocatorEx *alloc = (PyMemAllocatorEx *)ctx;
    void *ptr2;

    ptr2 = alloc->realloc(alloc->ctx, ptr, new_size);
    if (ptr2 == NULL)
        return NULL;

    if (ptr != NULL) {
        /* an existing memory block has been resized */

        TABLES_LOCK();

        /* tracemalloc_add_trace() updates the trace if there is already
           a trace at address (domain, ptr2) */
        if (ptr2 != ptr) {
            REMOVE_TRACE(ptr);
        }

        if (ADD_TRACE(ptr2, new_size) < 0) {
            /* Memory allocation failed. The error cannot be reported to
               the caller, because realloc() may already have shrunk the
               memory block and so removed bytes.

               This case is very unlikely: a hash entry has just been
               released, so the hash table should have at least one free entry.

               The GIL and the table lock ensures that only one thread is
               allocating memory. */
            Py_UNREACHABLE();
        }
        TABLES_UNLOCK();
    }
    else {
        /* new allocation */

        TABLES_LOCK();
        if (ADD_TRACE(ptr2, new_size) < 0) {
            /* Failed to allocate a trace for the new memory block */
            TABLES_UNLOCK();
            alloc->free(alloc->ctx, ptr2);
            return NULL;
        }
        TABLES_UNLOCK();
    }
    return ptr2;
}


static void
tracemalloc_free(void *ctx, void *ptr)
{
    PyMemAllocatorEx *alloc = (PyMemAllocatorEx *)ctx;

    if (ptr == NULL)
        return;

     /* GIL cannot be locked in PyMem_RawFree() because it would introduce
        a deadlock in PyThreadState_DeleteCurrent(). */

    alloc->free(alloc->ctx, ptr);

    TABLES_LOCK();
    REMOVE_TRACE(ptr);
    TABLES_UNLOCK();
}


static void*
tracemalloc_alloc_gil(int use_calloc, void *ctx, size_t nelem, size_t elsize)
{
    void *ptr;

    if (get_reentrant()) {
        PyMemAllocatorEx *alloc = (PyMemAllocatorEx *)ctx;
        if (use_calloc)
            return alloc->calloc(alloc->ctx, nelem, elsize);
        else
            return alloc->malloc(alloc->ctx, nelem * elsize);
    }

    /* Ignore reentrant call. PyObjet_Malloc() calls PyMem_Malloc() for
       allocations larger than 512 bytes, don't trace the same memory
       allocation twice. */
    set_reentrant(1);

    ptr = tracemalloc_alloc(use_calloc, ctx, nelem, elsize);

    set_reentrant(0);
    return ptr;
}


static void*
tracemalloc_malloc_gil(void *ctx, size_t size)
{
    return tracemalloc_alloc_gil(0, ctx, 1, size);
}


static void*
tracemalloc_calloc_gil(void *ctx, size_t nelem, size_t elsize)
{
    return tracemalloc_alloc_gil(1, ctx, nelem, elsize);
}


static void*
tracemalloc_realloc_gil(void *ctx, void *ptr, size_t new_size)
{
    void *ptr2;

    if (get_reentrant()) {
        /* Reentrant call to PyMem_Realloc() and PyMem_RawRealloc().
           Example: PyMem_RawRealloc() is called internally by pymalloc
           (_PyObject_Malloc() and  _PyObject_Realloc()) to allocate a new
           arena (new_arena()). */
        PyMemAllocatorEx *alloc = (PyMemAllocatorEx *)ctx;

        ptr2 = alloc->realloc(alloc->ctx, ptr, new_size);
        if (ptr2 != NULL && ptr != NULL) {
            TABLES_LOCK();
            REMOVE_TRACE(ptr);
            TABLES_UNLOCK();
        }
        return ptr2;
    }

    /* Ignore reentrant call. PyObjet_Realloc() calls PyMem_Realloc() for
       allocations larger than 512 bytes. Don't trace the same memory
       allocation twice. */
    set_reentrant(1);

    ptr2 = tracemalloc_realloc(ctx, ptr, new_size);

    set_reentrant(0);
    return ptr2;
}


#ifdef TRACE_RAW_MALLOC
static void*
tracemalloc_raw_alloc(int use_calloc, void *ctx, size_t nelem, size_t elsize)
{
    PyGILState_STATE gil_state;
    void *ptr;

    if (get_reentrant()) {
        PyMemAllocatorEx *alloc = (PyMemAllocatorEx *)ctx;
        if (use_calloc)
            return alloc->calloc(alloc->ctx, nelem, elsize);
        else
            return alloc->malloc(alloc->ctx, nelem * elsize);
    }

    /* Ignore reentrant call. PyGILState_Ensure() may call PyMem_RawMalloc()
       indirectly which would call PyGILState_Ensure() if reentrant are not
       disabled. */
    set_reentrant(1);

    gil_state = PyGILState_Ensure();
    ptr = tracemalloc_alloc(use_calloc, ctx, nelem, elsize);
    PyGILState_Release(gil_state);

    set_reentrant(0);
    return ptr;
}


static void*
tracemalloc_raw_malloc(void *ctx, size_t size)
{
    return tracemalloc_raw_alloc(0, ctx, 1, size);
}


static void*
tracemalloc_raw_calloc(void *ctx, size_t nelem, size_t elsize)
{
    return tracemalloc_raw_alloc(1, ctx, nelem, elsize);
}


static void*
tracemalloc_raw_realloc(void *ctx, void *ptr, size_t new_size)
{
    PyGILState_STATE gil_state;
    void *ptr2;

    if (get_reentrant()) {
        /* Reentrant call to PyMem_RawRealloc(). */
        PyMemAllocatorEx *alloc = (PyMemAllocatorEx *)ctx;

        ptr2 = alloc->realloc(alloc->ctx, ptr, new_size);

        if (ptr2 != NULL && ptr != NULL) {
            TABLES_LOCK();
            REMOVE_TRACE(ptr);
            TABLES_UNLOCK();
        }
        return ptr2;
    }

    /* Ignore reentrant call. PyGILState_Ensure() may call PyMem_RawMalloc()
       indirectly which would call PyGILState_Ensure() if reentrant calls are
       not disabled. */
    set_reentrant(1);

    gil_state = PyGILState_Ensure();
    ptr2 = tracemalloc_realloc(ctx, ptr, new_size);
    PyGILState_Release(gil_state);

    set_reentrant(0);
    return ptr2;
}
#endif   /* TRACE_RAW_MALLOC */


static int
tracemalloc_clear_filename(_Py_hashtable_t *ht, _Py_hashtable_entry_t *entry,
                           void *user_data)
{
    PyObject *filename;

    _Py_HASHTABLE_ENTRY_READ_KEY(ht, entry, filename);
    Py_DECREF(filename);
    return 0;
}


static int
traceback_free_traceback(_Py_hashtable_t *ht, _Py_hashtable_entry_t *entry,
                         void *user_data)
{
    traceback_t *traceback;

    _Py_HASHTABLE_ENTRY_READ_KEY(ht, entry, traceback);
    raw_free(traceback);
    return 0;
}


/* reentrant flag must be set to call this function and GIL must be held */
static void
tracemalloc_clear_traces(void)
{
    /* The GIL protects variables againt concurrent access */
    assert(PyGILState_Check());

    TABLES_LOCK();
    _Py_hashtable_clear(tracemalloc_traces);
    tracemalloc_traced_memory = 0;
    tracemalloc_peak_traced_memory = 0;
    TABLES_UNLOCK();

    _Py_hashtable_foreach(tracemalloc_tracebacks, traceback_free_traceback, NULL);
    _Py_hashtable_clear(tracemalloc_tracebacks);

    _Py_hashtable_foreach(tracemalloc_filenames, tracemalloc_clear_filename, NULL);
    _Py_hashtable_clear(tracemalloc_filenames);
}


static int
tracemalloc_init(void)
{
    if (_Py_tracemalloc_config.initialized == TRACEMALLOC_FINALIZED) {
        PyErr_SetString(PyExc_RuntimeError,
                        "the tracemalloc module has been unloaded");
        return -1;
    }

    if (_Py_tracemalloc_config.initialized == TRACEMALLOC_INITIALIZED)
        return 0;

    PyMem_GetAllocator(PYMEM_DOMAIN_RAW, &allocators.raw);

#ifdef REENTRANT_THREADLOCAL
    if (PyThread_tss_create(&tracemalloc_reentrant_key) != 0) {
#ifdef MS_WINDOWS
        PyErr_SetFromWindowsErr(0);
#else
        PyErr_SetFromErrno(PyExc_OSError);
#endif
        return -1;
    }
#endif

#if defined(TRACE_RAW_MALLOC)
    if (tables_lock == NULL) {
        tables_lock = PyThread_allocate_lock();
        if (tables_lock == NULL) {
            PyErr_SetString(PyExc_RuntimeError, "cannot allocate lock");
            return -1;
        }
    }
#endif

    tracemalloc_filenames = hashtable_new(sizeof(PyObject *), 0,
                                          hashtable_hash_pyobject,
                                          hashtable_compare_unicode);

    tracemalloc_tracebacks = hashtable_new(sizeof(traceback_t *), 0,
                                           hashtable_hash_traceback,
                                           hashtable_compare_traceback);

    if (_Py_tracemalloc_config.use_domain) {
        tracemalloc_traces = hashtable_new(sizeof(pointer_t),
                                           sizeof(trace_t),
                                           hashtable_hash_pointer_t,
                                           hashtable_compare_pointer_t);
    }
    else {
        tracemalloc_traces = hashtable_new(sizeof(uintptr_t),
                                           sizeof(trace_t),
                                           _Py_hashtable_hash_ptr,
                                           _Py_hashtable_compare_direct);
    }

    if (tracemalloc_filenames == NULL || tracemalloc_tracebacks == NULL
       || tracemalloc_traces == NULL) {
        PyErr_NoMemory();
        return -1;
    }

    unknown_filename = PyUnicode_FromString("<unknown>");
    if (unknown_filename == NULL)
        return -1;
    PyUnicode_InternInPlace(&unknown_filename);

    tracemalloc_empty_traceback.nframe = 1;
    /* borrowed reference */
    tracemalloc_empty_traceback.frames[0].filename = unknown_filename;
    tracemalloc_empty_traceback.frames[0].lineno = 0;
    tracemalloc_empty_traceback.hash = traceback_hash(&tracemalloc_empty_traceback);

    _Py_tracemalloc_config.initialized = TRACEMALLOC_INITIALIZED;
    return 0;
}


static void
tracemalloc_deinit(void)
{
    if (_Py_tracemalloc_config.initialized != TRACEMALLOC_INITIALIZED)
        return;
    _Py_tracemalloc_config.initialized = TRACEMALLOC_FINALIZED;

    tracemalloc_stop();

    /* destroy hash tables */
    _Py_hashtable_destroy(tracemalloc_tracebacks);
    _Py_hashtable_destroy(tracemalloc_filenames);
    _Py_hashtable_destroy(tracemalloc_traces);

#if defined(TRACE_RAW_MALLOC)
    if (tables_lock != NULL) {
        PyThread_free_lock(tables_lock);
        tables_lock = NULL;
    }
#endif

#ifdef REENTRANT_THREADLOCAL
    PyThread_tss_delete(&tracemalloc_reentrant_key);
#endif

    Py_XDECREF(unknown_filename);
}


static int
tracemalloc_start(int max_nframe)
{
    PyMemAllocatorEx alloc;
    size_t size;

    if (max_nframe < 1 || max_nframe > MAX_NFRAME) {
        PyErr_Format(PyExc_ValueError,
                     "the number of frames must be in range [1; %i]",
                     (int)MAX_NFRAME);
        return -1;
    }

    if (tracemalloc_init() < 0) {
        return -1;
    }

    if (_Py_tracemalloc_config.tracing) {
        /* hook already installed: do nothing */
        return 0;
    }

    assert(1 <= max_nframe && max_nframe <= MAX_NFRAME);
    _Py_tracemalloc_config.max_nframe = max_nframe;

    /* allocate a buffer to store a new traceback */
    size = TRACEBACK_SIZE(max_nframe);
    assert(tracemalloc_traceback == NULL);
    tracemalloc_traceback = raw_malloc(size);
    if (tracemalloc_traceback == NULL) {
        PyErr_NoMemory();
        return -1;
    }

#ifdef TRACE_RAW_MALLOC
    alloc.malloc = tracemalloc_raw_malloc;
    alloc.calloc = tracemalloc_raw_calloc;
    alloc.realloc = tracemalloc_raw_realloc;
    alloc.free = tracemalloc_free;

    alloc.ctx = &allocators.raw;
    PyMem_GetAllocator(PYMEM_DOMAIN_RAW, &allocators.raw);
    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &alloc);
#endif

    alloc.malloc = tracemalloc_malloc_gil;
    alloc.calloc = tracemalloc_calloc_gil;
    alloc.realloc = tracemalloc_realloc_gil;
    alloc.free = tracemalloc_free;

    alloc.ctx = &allocators.mem;
    PyMem_GetAllocator(PYMEM_DOMAIN_MEM, &allocators.mem);
    PyMem_SetAllocator(PYMEM_DOMAIN_MEM, &alloc);

    alloc.ctx = &allocators.obj;
    PyMem_GetAllocator(PYMEM_DOMAIN_OBJ, &allocators.obj);
    PyMem_SetAllocator(PYMEM_DOMAIN_OBJ, &alloc);

    /* everything is ready: start tracing Python memory allocations */
    _Py_tracemalloc_config.tracing = 1;

    return 0;
}


static void
tracemalloc_stop(void)
{
    if (!_Py_tracemalloc_config.tracing)
        return;

    /* stop tracing Python memory allocations */
    _Py_tracemalloc_config.tracing = 0;

    /* unregister the hook on memory allocators */
#ifdef TRACE_RAW_MALLOC
    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &allocators.raw);
#endif
    PyMem_SetAllocator(PYMEM_DOMAIN_MEM, &allocators.mem);
    PyMem_SetAllocator(PYMEM_DOMAIN_OBJ, &allocators.obj);

    tracemalloc_clear_traces();

    /* release memory */
    raw_free(tracemalloc_traceback);
    tracemalloc_traceback = NULL;
}



/*[clinic input]
_tracemalloc.is_tracing

Return True if the tracemalloc module is tracing Python memory allocations.
[clinic start generated code]*/

static PyObject *
_tracemalloc_is_tracing_impl(PyObject *module)
/*[clinic end generated code: output=2d763b42601cd3ef input=af104b0a00192f63]*/
{
    return PyBool_FromLong(_Py_tracemalloc_config.tracing);
}


/*[clinic input]
_tracemalloc.clear_traces

Clear traces of memory blocks allocated by Python.
[clinic start generated code]*/

static PyObject *
_tracemalloc_clear_traces_impl(PyObject *module)
/*[clinic end generated code: output=a86080ee41b84197 input=0dab5b6c785183a5]*/
{
    if (!_Py_tracemalloc_config.tracing)
        Py_RETURN_NONE;

    set_reentrant(1);
    tracemalloc_clear_traces();
    set_reentrant(0);

    Py_RETURN_NONE;
}


static PyObject*
frame_to_pyobject(frame_t *frame)
{
    PyObject *frame_obj, *lineno_obj;

    frame_obj = PyTuple_New(2);
    if (frame_obj == NULL)
        return NULL;

    Py_INCREF(frame->filename);
    PyTuple_SET_ITEM(frame_obj, 0, frame->filename);

    lineno_obj = PyLong_FromUnsignedLong(frame->lineno);
    if (lineno_obj == NULL) {
        Py_DECREF(frame_obj);
        return NULL;
    }
    PyTuple_SET_ITEM(frame_obj, 1, lineno_obj);

    return frame_obj;
}


static PyObject*
traceback_to_pyobject(traceback_t *traceback, _Py_hashtable_t *intern_table)
{
    int i;
    PyObject *frames, *frame;

    if (intern_table != NULL) {
        if (_Py_HASHTABLE_GET(intern_table, traceback, frames)) {
            Py_INCREF(frames);
            return frames;
        }
    }

    frames = PyTuple_New(traceback->nframe);
    if (frames == NULL)
        return NULL;

    for (i=0; i < traceback->nframe; i++) {
        frame = frame_to_pyobject(&traceback->frames[i]);
        if (frame == NULL) {
            Py_DECREF(frames);
            return NULL;
        }
        PyTuple_SET_ITEM(frames, i, frame);
    }

    if (intern_table != NULL) {
        if (_Py_HASHTABLE_SET(intern_table, traceback, frames) < 0) {
            Py_DECREF(frames);
            PyErr_NoMemory();
            return NULL;
        }
        /* intern_table keeps a new reference to frames */
        Py_INCREF(frames);
    }
    return frames;
}


static PyObject*
trace_to_pyobject(unsigned int domain, trace_t *trace,
                  _Py_hashtable_t *intern_tracebacks)
{
    PyObject *trace_obj = NULL;
    PyObject *obj;

    trace_obj = PyTuple_New(3);
    if (trace_obj == NULL)
        return NULL;

    obj = PyLong_FromSize_t(domain);
    if (obj == NULL) {
        Py_DECREF(trace_obj);
        return NULL;
    }
    PyTuple_SET_ITEM(trace_obj, 0, obj);

    obj = PyLong_FromSize_t(trace->size);
    if (obj == NULL) {
        Py_DECREF(trace_obj);
        return NULL;
    }
    PyTuple_SET_ITEM(trace_obj, 1, obj);

    obj = traceback_to_pyobject(trace->traceback, intern_tracebacks);
    if (obj == NULL) {
        Py_DECREF(trace_obj);
        return NULL;
    }
    PyTuple_SET_ITEM(trace_obj, 2, obj);

    return trace_obj;
}


typedef struct {
    _Py_hashtable_t *traces;
    _Py_hashtable_t *tracebacks;
    PyObject *list;
} get_traces_t;

static int
tracemalloc_get_traces_fill(_Py_hashtable_t *traces, _Py_hashtable_entry_t *entry,
                            void *user_data)
{
    get_traces_t *get_traces = user_data;
    unsigned int domain;
    trace_t trace;
    PyObject *tracemalloc_obj;
    int res;

    if (_Py_tracemalloc_config.use_domain) {
        pointer_t key;
        _Py_HASHTABLE_ENTRY_READ_KEY(traces, entry, key);
        domain = key.domain;
    }
    else {
        domain = DEFAULT_DOMAIN;
    }
    _Py_HASHTABLE_ENTRY_READ_DATA(traces, entry, trace);

    tracemalloc_obj = trace_to_pyobject(domain, &trace, get_traces->tracebacks);
    if (tracemalloc_obj == NULL)
        return 1;

    res = PyList_Append(get_traces->list, tracemalloc_obj);
    Py_DECREF(tracemalloc_obj);
    if (res < 0)
        return 1;

    return 0;
}


static int
tracemalloc_pyobject_decref_cb(_Py_hashtable_t *tracebacks,
                               _Py_hashtable_entry_t *entry,
                               void *user_data)
{
    PyObject *obj;
    _Py_HASHTABLE_ENTRY_READ_DATA(tracebacks, entry, obj);
    Py_DECREF(obj);
    return 0;
}



/*[clinic input]
_tracemalloc._get_traces

Get traces of all memory blocks allocated by Python.

Return a list of (size: int, traceback: tuple) tuples.
traceback is a tuple of (filename: str, lineno: int) tuples.

Return an empty list if the tracemalloc module is disabled.
[clinic start generated code]*/

static PyObject *
_tracemalloc__get_traces_impl(PyObject *module)
/*[clinic end generated code: output=e9929876ced4b5cc input=6c7d2230b24255aa]*/
{
    get_traces_t get_traces;
    int err;

    get_traces.traces = NULL;
    get_traces.tracebacks = NULL;
    get_traces.list = PyList_New(0);
    if (get_traces.list == NULL)
        goto error;

    if (!_Py_tracemalloc_config.tracing)
        return get_traces.list;

    /* the traceback hash table is used temporarily to intern traceback tuple
       of (filename, lineno) tuples */
    get_traces.tracebacks = hashtable_new(sizeof(traceback_t *),
                                          sizeof(PyObject *),
                                          _Py_hashtable_hash_ptr,
                                          _Py_hashtable_compare_direct);
    if (get_traces.tracebacks == NULL) {
        PyErr_NoMemory();
        goto error;
    }

    TABLES_LOCK();
    get_traces.traces = _Py_hashtable_copy(tracemalloc_traces);
    TABLES_UNLOCK();

    if (get_traces.traces == NULL) {
        PyErr_NoMemory();
        goto error;
    }

    set_reentrant(1);
    err = _Py_hashtable_foreach(get_traces.traces,
                                tracemalloc_get_traces_fill, &get_traces);
    set_reentrant(0);
    if (err)
        goto error;

    goto finally;

error:
    Py_CLEAR(get_traces.list);

finally:
    if (get_traces.tracebacks != NULL) {
        _Py_hashtable_foreach(get_traces.tracebacks,
                              tracemalloc_pyobject_decref_cb, NULL);
        _Py_hashtable_destroy(get_traces.tracebacks);
    }
    if (get_traces.traces != NULL) {
        _Py_hashtable_destroy(get_traces.traces);
    }

    return get_traces.list;
}


static traceback_t*
tracemalloc_get_traceback(unsigned int domain, uintptr_t ptr)
{
    trace_t trace;
    int found;

    if (!_Py_tracemalloc_config.tracing)
        return NULL;

    TABLES_LOCK();
    if (_Py_tracemalloc_config.use_domain) {
        pointer_t key = {ptr, domain};
        found = _Py_HASHTABLE_GET(tracemalloc_traces, key, trace);
    }
    else {
        found = _Py_HASHTABLE_GET(tracemalloc_traces, ptr, trace);
    }
    TABLES_UNLOCK();

    if (!found)
        return NULL;

    return trace.traceback;
}



/*[clinic input]
_tracemalloc._get_object_traceback

    obj: object
    /

Get the traceback where the Python object obj was allocated.

Return a tuple of (filename: str, lineno: int) tuples.
Return None if the tracemalloc module is disabled or did not
trace the allocation of the object.
[clinic start generated code]*/

static PyObject *
_tracemalloc__get_object_traceback(PyObject *module, PyObject *obj)
/*[clinic end generated code: output=41ee0553a658b0aa input=29495f1b21c53212]*/
{
    PyTypeObject *type;
    void *ptr;
    traceback_t *traceback;

    type = Py_TYPE(obj);
    if (PyType_IS_GC(type)) {
        ptr = (void *)((char *)obj - sizeof(PyGC_Head));
    }
    else {
        ptr = (void *)obj;
    }

    traceback = tracemalloc_get_traceback(DEFAULT_DOMAIN, (uintptr_t)ptr);
    if (traceback == NULL)
        Py_RETURN_NONE;

    return traceback_to_pyobject(traceback, NULL);
}


#define PUTS(fd, str) _Py_write_noraise(fd, str, (int)strlen(str))

static void
_PyMem_DumpFrame(int fd, frame_t * frame)
{
    PUTS(fd, "  File \"");
    _Py_DumpASCII(fd, frame->filename);
    PUTS(fd, "\", line ");
    _Py_DumpDecimal(fd, frame->lineno);
    PUTS(fd, "\n");
}

/* Dump the traceback where a memory block was allocated into file descriptor
   fd. The function may block on TABLES_LOCK() but it is unlikely. */
void
_PyMem_DumpTraceback(int fd, const void *ptr)
{
    traceback_t *traceback;
    int i;

    if (!_Py_tracemalloc_config.tracing) {
        PUTS(fd, "Enable tracemalloc to get the memory block "
                 "allocation traceback\n\n");
        return;
    }

    traceback = tracemalloc_get_traceback(DEFAULT_DOMAIN, (uintptr_t)ptr);
    if (traceback == NULL)
        return;

    PUTS(fd, "Memory block allocated at (most recent call first):\n");
    for (i=0; i < traceback->nframe; i++) {
        _PyMem_DumpFrame(fd, &traceback->frames[i]);
    }
    PUTS(fd, "\n");
}

#undef PUTS



/*[clinic input]
_tracemalloc.start

    nframe: int = 1
    /

Start tracing Python memory allocations.

Also set the maximum number of frames stored in the traceback of a
trace to nframe.
[clinic start generated code]*/

static PyObject *
_tracemalloc_start_impl(PyObject *module, int nframe)
/*[clinic end generated code: output=caae05c23c159d3c input=40d849b5b29d1933]*/
{
    if (tracemalloc_start(nframe) < 0) {
        return NULL;
    }
    Py_RETURN_NONE;
}


/*[clinic input]
_tracemalloc.stop

Stop tracing Python memory allocations.

Also clear traces of memory blocks allocated by Python.
[clinic start generated code]*/

static PyObject *
_tracemalloc_stop_impl(PyObject *module)
/*[clinic end generated code: output=c3c42ae03e3955cd input=7478f075e51dae18]*/
{
    tracemalloc_stop();
    Py_RETURN_NONE;
}


/*[clinic input]
_tracemalloc.get_traceback_limit

Get the maximum number of frames stored in the traceback of a trace.

By default, a trace of an allocated memory block only stores
the most recent frame: the limit is 1.
[clinic start generated code]*/

static PyObject *
_tracemalloc_get_traceback_limit_impl(PyObject *module)
/*[clinic end generated code: output=d556d9306ba95567 input=da3cd977fc68ae3b]*/
{
    return PyLong_FromLong(_Py_tracemalloc_config.max_nframe);
}



/*[clinic input]
_tracemalloc.get_tracemalloc_memory

Get the memory usage in bytes of the tracemalloc module.

This memory is used internally to trace memory allocations.
[clinic start generated code]*/

static PyObject *
_tracemalloc_get_tracemalloc_memory_impl(PyObject *module)
/*[clinic end generated code: output=e3f14e280a55f5aa input=5d919c0f4d5132ad]*/
{
    size_t size;

    size = _Py_hashtable_size(tracemalloc_tracebacks);
    size += _Py_hashtable_size(tracemalloc_filenames);

    TABLES_LOCK();
    size += _Py_hashtable_size(tracemalloc_traces);
    TABLES_UNLOCK();

    return PyLong_FromSize_t(size);
}



/*[clinic input]
_tracemalloc.get_traced_memory

Get the current size and peak size of memory blocks traced by tracemalloc.

Returns a tuple: (current: int, peak: int).
[clinic start generated code]*/

static PyObject *
_tracemalloc_get_traced_memory_impl(PyObject *module)
/*[clinic end generated code: output=5b167189adb9e782 input=61ddb5478400ff66]*/
{
    Py_ssize_t size, peak_size;

    if (!_Py_tracemalloc_config.tracing)
        return Py_BuildValue("ii", 0, 0);

    TABLES_LOCK();
    size = tracemalloc_traced_memory;
    peak_size = tracemalloc_peak_traced_memory;
    TABLES_UNLOCK();

    return Py_BuildValue("nn", size, peak_size);
}


static PyMethodDef module_methods[] = {
    _TRACEMALLOC_IS_TRACING_METHODDEF
    _TRACEMALLOC_CLEAR_TRACES_METHODDEF
    _TRACEMALLOC__GET_TRACES_METHODDEF
    _TRACEMALLOC__GET_OBJECT_TRACEBACK_METHODDEF
    _TRACEMALLOC_START_METHODDEF
    _TRACEMALLOC_STOP_METHODDEF
    _TRACEMALLOC_GET_TRACEBACK_LIMIT_METHODDEF
    _TRACEMALLOC_GET_TRACEMALLOC_MEMORY_METHODDEF
    _TRACEMALLOC_GET_TRACED_MEMORY_METHODDEF
    /* sentinel */
    {NULL, NULL}
};

PyDoc_STRVAR(module_doc,
"Debug module to trace memory blocks allocated by Python.");

static struct PyModuleDef module_def = {
    PyModuleDef_HEAD_INIT,
    "_tracemalloc",
    module_doc,
    0, /* non-negative size to be able to unload the module */
    module_methods,
    NULL,
};

PyMODINIT_FUNC
PyInit__tracemalloc(void)
{
    PyObject *m;
    m = PyModule_Create(&module_def);
    if (m == NULL)
        return NULL;

    if (tracemalloc_init() < 0)
        return NULL;

    return m;
}


int
_PyTraceMalloc_Init(int nframe)
{
    assert(PyGILState_Check());
    if (nframe == 0) {
        return 0;
    }
    return tracemalloc_start(nframe);
}


void
_PyTraceMalloc_Fini(void)
{
    assert(PyGILState_Check());
    tracemalloc_deinit();
}

int
PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
                    size_t size)
{
    int res;
    PyGILState_STATE gil_state;

    if (!_Py_tracemalloc_config.tracing) {
        /* tracemalloc is not tracing: do nothing */
        return -2;
    }

    gil_state = PyGILState_Ensure();

    TABLES_LOCK();
    res = tracemalloc_add_trace(domain, ptr, size);
    TABLES_UNLOCK();

    PyGILState_Release(gil_state);
    return res;
}


int
PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr)
{
    if (!_Py_tracemalloc_config.tracing) {
        /* tracemalloc is not tracing: do nothing */
        return -2;
    }

    TABLES_LOCK();
    tracemalloc_remove_trace(domain, ptr);
    TABLES_UNLOCK();

    return 0;
}


/* If the object memory block is already traced, update its trace
   with the current Python traceback.

   Do nothing if tracemalloc is not tracing memory allocations
   or if the object memory block is not already traced. */
int
_PyTraceMalloc_NewReference(PyObject *op)
{
    assert(PyGILState_Check());

    if (!_Py_tracemalloc_config.tracing) {
        /* tracemalloc is not tracing: do nothing */
        return -1;
    }

    uintptr_t ptr;
    PyTypeObject *type = Py_TYPE(op);
    if (PyType_IS_GC(type)) {
        ptr = (uintptr_t)((char *)op - sizeof(PyGC_Head));
    }
    else {
        ptr = (uintptr_t)op;
    }

    _Py_hashtable_entry_t* entry;
    int res = -1;

    TABLES_LOCK();
    if (_Py_tracemalloc_config.use_domain) {
        pointer_t key = {ptr, DEFAULT_DOMAIN};
        entry = _Py_HASHTABLE_GET_ENTRY(tracemalloc_traces, key);
    }
    else {
        entry = _Py_HASHTABLE_GET_ENTRY(tracemalloc_traces, ptr);
    }

    if (entry != NULL) {
        /* update the traceback of the memory block */
        traceback_t *traceback = traceback_new();
        if (traceback != NULL) {
            trace_t trace;
            _Py_HASHTABLE_ENTRY_READ_DATA(tracemalloc_traces, entry, trace);
            trace.traceback = traceback;
            _Py_HASHTABLE_ENTRY_WRITE_DATA(tracemalloc_traces, entry, trace);
            res = 0;
        }
    }
    /* else: cannot track the object, its memory block size is unknown */
    TABLES_UNLOCK();

    return res;
}


PyObject*
_PyTraceMalloc_GetTraceback(unsigned int domain, uintptr_t ptr)
{
    traceback_t *traceback;

    traceback = tracemalloc_get_traceback(domain, ptr);
    if (traceback == NULL)
        Py_RETURN_NONE;

    return traceback_to_pyobject(traceback, NULL);
}