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Possible data race between split_keys_entry_added and dict_dict_merge under free-threading, 3.13 #132245

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Possible data race between split_keys_entry_added and dict_dict_merge under free-threading, 3.13#132245
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3.13only security fixes3.14bugs and security fixesinterpreter-core(Objects, Python, Grammar, and Parser dirs)topic-free-threadingtype-bugAn unexpected behavior, bug, or error

Description

@vfdev-5
vfdev-5
opened on Apr 7, 2025

Bug report

Bug description:

I built 3.13 branch and observed the following race under free-threading in cpython 3.13 (Python 3.13.2+ experimental free-threading build (heads/3.13:6afab81f72c, Apr 7 2025, 13:34:51) [Clang 18.1.3 (1ubuntu1)])

TSAN Report 
WARNING: ThreadSanitizer: data race (pid=98556)
  Atomic write of size 8 at 0x7fffb695e118 by thread T2 (mutexes: read M0):
    #0 _Py_atomic_store_ssize_relaxed /project/cpython/./Include/cpython/pyatomic_gcc.h:481:3 (python3.13+0x273c84) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #1 split_keys_entry_added /project/cpython/Objects/dictobject.c:225:5 (python3.13+0x273c84)
    #2 insert_split_key /project/cpython/Objects/dictobject.c:1743:9 (python3.13+0x273c84)
    #3 insertdict /project/cpython/Objects/dictobject.c:1796:25 (python3.13+0x263ec6) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #4 dict_dict_merge /project/cpython/./Include/cpython/pyatomic_gcc.h (python3.13+0x2698e2) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #5 dict_merge /project/cpython/Objects/dictobject.c:3807:15 (python3.13+0x2698e2)
    #6 PyDict_Merge /project/cpython/Objects/dictobject.c:3897:12 (python3.13+0x27767c) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #7 dict_update_arg /project/cpython/Objects/dictobject.c (python3.13+0x27767c)
    #8 dict_update_common /project/cpython/Objects/dictobject.c:3555:18 (python3.13+0x27767c)
    #9 dict_update /project/cpython/Objects/dictobject.c:3573:9 (python3.13+0x27733c) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #10 method_vectorcall_VARARGS_KEYWORDS /project/cpython/Objects/descrobject.c:358:14 (python3.13+0x2009ca) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #11 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1eb0fa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #12 PyObject_Vectorcall /project/cpython/Objects/call.c:327:12 (python3.13+0x1eb0fa)
    #13 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:813:23 (python3.13+0x3e38f2) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #14 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #15 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #16 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #17 _PyVectorcall_Call /project/cpython/Objects/call.c:285:24 (python3.13+0x1eb336) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #18 _PyObject_Call /project/cpython/Objects/call.c:348:16 (python3.13+0x1eb336)
    #19 PyObject_Call /project/cpython/Objects/call.c:373:12 (python3.13+0x1eb465) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #20 bounded_lru_cache_wrapper /project/cpython/./Modules/_functoolsmodule.c:1068:14 (python3.13+0x577a42) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #21 lru_cache_call /project/cpython/./Modules/_functoolsmodule.c:1334:14 (python3.13+0x5762aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #22 _PyObject_Call /project/cpython/Objects/call.c:361:18 (python3.13+0x1eb39b) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #23 PyObject_Call /project/cpython/Objects/call.c:373:12 (python3.13+0x1eb465) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #24 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:1355:26 (python3.13+0x3e5b12) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #25 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #26 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #27 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #28 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x575e83) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #29 partial_vectorcall /project/cpython/./Modules/_functoolsmodule.c:262:25 (python3.13+0x575e83)
    #30 _PyVectorcall_Call /project/cpython/Objects/call.c:285:24 (python3.13+0x1eb336) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #31 _PyObject_Call /project/cpython/Objects/call.c:348:16 (python3.13+0x1eb336)
    #32 PyObject_Call /project/cpython/Objects/call.c:373:12 (python3.13+0x1eb465) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #33 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:1355:26 (python3.13+0x3e5b12) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #34 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #35 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #36 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #37 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1ef685) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #38 method_vectorcall /project/cpython/Objects/classobject.c:62:18 (python3.13+0x1ef685)
    #39 _PyVectorcall_Call /project/cpython/Objects/call.c:285:24 (python3.13+0x1eb336) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #40 _PyObject_Call /project/cpython/Objects/call.c:348:16 (python3.13+0x1eb336)
    #41 PyObject_Call /project/cpython/Objects/call.c:373:12 (python3.13+0x1eb465) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #42 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:1355:26 (python3.13+0x3e5b12) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #43 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #44 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #45 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #46 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1ef685) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #47 method_vectorcall /project/cpython/Objects/classobject.c:62:18 (python3.13+0x1ef685)
    #48 _PyVectorcall_Call /project/cpython/Objects/call.c:285:24 (python3.13+0x1eb336) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #49 _PyObject_Call /project/cpython/Objects/call.c:348:16 (python3.13+0x1eb336)
    #50 PyObject_Call /project/cpython/Objects/call.c:373:12 (python3.13+0x1eb465) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #51 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:1355:26 (python3.13+0x3e5b12) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #52 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #53 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #54 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #55 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1ef7f0) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #56 method_vectorcall /project/cpython/Objects/classobject.c:92:18 (python3.13+0x1ef7f0)
    #57 _PyVectorcall_Call /project/cpython/Objects/call.c:273:16 (python3.13+0x1eb3e3) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #58 _PyObject_Call /project/cpython/Objects/call.c:348:16 (python3.13+0x1eb3e3)
    #59 PyObject_Call /project/cpython/Objects/call.c:373:12 (python3.13+0x1eb465) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #60 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:1355:26 (python3.13+0x3e5b12) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #61 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #62 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #63 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #64 _PyObject_VectorcallDictTstate /project/cpython/Objects/call.c:135:15 (python3.13+0x1ea2ed) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #65 _PyObject_Call_Prepend /project/cpython/Objects/call.c:504:24 (python3.13+0x1ebde7) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #66 slot_tp_call /project/cpython/Objects/typeobject.c:9556:15 (python3.13+0x2f9738) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #67 _PyObject_MakeTpCall /project/cpython/Objects/call.c:242:18 (python3.13+0x1ea55c) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #68 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:166:16 (python3.13+0x1eb1b8) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #69 PyObject_Vectorcall /project/cpython/Objects/call.c:327:12 (python3.13+0x1eb1b8)
    #70 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:813:23 (python3.13+0x3e38f2) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #71 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #72 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #73 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #74 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1ef73f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #75 method_vectorcall /project/cpython/Objects/classobject.c:70:20 (python3.13+0x1ef73f)
    #76 _PyVectorcall_Call /project/cpython/Objects/call.c:273:16 (python3.13+0x1eb3e3) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #77 _PyObject_Call /project/cpython/Objects/call.c:348:16 (python3.13+0x1eb3e3)
    #78 PyObject_Call /project/cpython/Objects/call.c:373:12 (python3.13+0x1eb465) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #79 thread_run /project/cpython/./Modules/_threadmodule.c:337:21 (python3.13+0x568562) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #80 pythread_wrapper /project/cpython/Python/thread_pthread.h:243:5 (python3.13+0x4c1477) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)

  Previous read of size 8 at 0x7fffb695e118 by thread T1 (mutexes: read M0):
    #0 dict_dict_merge /project/cpython/Objects/dictobject.c:3776:42 (python3.13+0x2699cb) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #1 dict_merge /project/cpython/Objects/dictobject.c:3807:15 (python3.13+0x2699cb)
    #2 PyDict_Merge /project/cpython/Objects/dictobject.c:3897:12 (python3.13+0x27767c) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #3 dict_update_arg /project/cpython/Objects/dictobject.c (python3.13+0x27767c)
    #4 dict_update_common /project/cpython/Objects/dictobject.c:3555:18 (python3.13+0x27767c)
    #5 dict_update /project/cpython/Objects/dictobject.c:3573:9 (python3.13+0x27733c) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #6 method_vectorcall_VARARGS_KEYWORDS /project/cpython/Objects/descrobject.c:358:14 (python3.13+0x2009ca) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #7 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1eb0fa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #8 PyObject_Vectorcall /project/cpython/Objects/call.c:327:12 (python3.13+0x1eb0fa)
    #9 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:813:23 (python3.13+0x3e38f2) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #10 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #11 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #12 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #13 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1ef7f0) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #14 method_vectorcall /project/cpython/Objects/classobject.c:92:18 (python3.13+0x1ef7f0)
    #15 _PyVectorcall_Call /project/cpython/Objects/call.c:273:16 (python3.13+0x1eb3e3) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #16 _PyObject_Call /project/cpython/Objects/call.c:348:16 (python3.13+0x1eb3e3)
    #17 PyObject_Call /project/cpython/Objects/call.c:373:12 (python3.13+0x1eb465) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #18 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:1355:26 (python3.13+0x3e5b12) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #19 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #20 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #21 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #22 _PyObject_VectorcallDictTstate /project/cpython/Objects/call.c:135:15 (python3.13+0x1ea2ed) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #23 _PyObject_Call_Prepend /project/cpython/Objects/call.c:504:24 (python3.13+0x1ebde7) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #24 slot_tp_call /project/cpython/Objects/typeobject.c:9556:15 (python3.13+0x2f9738) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #25 _PyObject_MakeTpCall /project/cpython/Objects/call.c:242:18 (python3.13+0x1ea55c) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #26 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:166:16 (python3.13+0x1eb1b8) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #27 PyObject_Vectorcall /project/cpython/Objects/call.c:327:12 (python3.13+0x1eb1b8)
    #28 _PyEval_EvalFrameDefault /project/cpython/Python/generated_cases.c.h:813:23 (python3.13+0x3e38f2) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #29 _PyEval_EvalFrame /project/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3df9aa) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #30 _PyEval_Vector /project/cpython/Python/ceval.c:1814:12 (python3.13+0x3df9aa)
    #31 _PyFunction_Vectorcall /project/cpython/Objects/call.c (python3.13+0x1eb76f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #32 _PyObject_VectorcallTstate /project/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1ef73f) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #33 method_vectorcall /project/cpython/Objects/classobject.c:70:20 (python3.13+0x1ef73f)
    #34 _PyVectorcall_Call /project/cpython/Objects/call.c:273:16 (python3.13+0x1eb3e3) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #35 _PyObject_Call /project/cpython/Objects/call.c:348:16 (python3.13+0x1eb3e3)
    #36 PyObject_Call /project/cpython/Objects/call.c:373:12 (python3.13+0x1eb465) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #37 thread_run /project/cpython/./Modules/_threadmodule.c:337:21 (python3.13+0x568562) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)
    #38 pythread_wrapper /project/cpython/Python/thread_pthread.h:243:5 (python3.13+0x4c1477) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0)

I know that there were already a bunch of data race fixes in dictobject and happy to close this issue if it is already fixed.
I do not have a minimal reproducer, but can try to get it if needed.

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Similar previously reported race: #130547

Activity

  1. vfdev-5
    added
    type-bugAn unexpected behavior, bug, or error
    on Apr 7, 2025
  2. picnixz
    added
    interpreter-core(Objects, Python, Grammar, and Parser dirs)
    3.13only security fixes
    topic-free-threading
    3.14bugs and security fixes
    on Apr 7, 2025

  3. hawkinsp commented on Apr 16, 2025

    @hawkinsp
    hawkinsp
    on Apr 16, 2025
    Contributor

    Certainly #0 dict_dict_merge /project/cpython/Objects/dictobject.c:3776:42 (python3.13+0x2699cb) (BuildId: ec7bf2b242541cde4f3e3f0459fbc7b3819b41b0) is a non-atomic read (

    cpython/Objects/dictobject.c

    Line 3776 in f9578dc

    if (orig_size != other->ma_keys->dk_nentries) {
    ), so that probably needs to be atomic at the least.

  4. colesbury commented on Apr 16, 2025

    @colesbury
    colesbury
    on Apr 16, 2025
    Contributor

    That check looks wrong to me. There should only be an error if the actual dictionary was mutated. Not if the shared keys were changed.

  5. colesbury commented on Apr 16, 2025

    @colesbury
    colesbury
    on Apr 16, 2025
    Contributor

    Filed:

  6. colesbury commented on Apr 16, 2025

    @colesbury
    colesbury
    on Apr 16, 2025
    Contributor

    The non-atomic read is only an issue with shared keys objects, but checking dk_nentries before and after isn't reliable in that case.

    (It's not an issue for other dictionaries because dict_dict_merge is called with the dictionary locks held)

  7. vfdev-5 commented on May 16, 2025

    @vfdev-5
    vfdev-5
    on May 16, 2025
    ContributorAuthor

    We also see this now on 3.14 branch in JAX CI: https://github.com/jax-ml/jax/actions/runs/15061081634/job/42336229305

  8. colesbury commented on Jun 16, 2025

    @colesbury
    colesbury
    on Jun 16, 2025
    Contributor

    I think this should be fixed now in 3.13, 3.14, and main. I'm going to mark this as a duplicate of #132617 because I think the race was due to an incorrect mutation check.

  9. colesbury
    closed this as a duplicateof dict.update() mutation check too broad #132617 on Jun 16, 2025
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    3.13only security fixes3.14bugs and security fixesinterpreter-core(Objects, Python, Grammar, and Parser dirs)topic-free-threadingtype-bugAn unexpected behavior, bug, or error

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