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BUG: fix remaining data races in mtrand.pyx#30426

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charris merged 1 commit intonumpy:mainfrom
kumaraditya303:mtrand
Dec 14, 2025
Merged

BUG: fix remaining data races in mtrand.pyx#30426
charris merged 1 commit intonumpy:mainfrom
kumaraditya303:mtrand

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@kumaraditya303 kumaraditya303 commented Dec 13, 2025

This PR fixes the remaining data races in mtrand.pyx, mostly adding by using self.lock which is used in other places.
This was missed in #30085 (comment) as I had done testing on x86-64 but it is reproducible on arm64.

WARNING: ThreadSanitizer: data race (pid=50513)
  Write of size 4 at 0x000127d2a878 by thread T1515:
    #0 mt19937_seed mt19937.c:10 (_mt19937.cpython-314t-darwin.so:arm64+0x165a4)
    #1 __pyx_pf_5numpy_6random_8_mt19937_7MT19937_2_legacy_seeding _mt19937.pyx.c:5787 (_mt19937.cpython-314t-darwin.so:arm64+0xde88)
    #2 __pyx_pw_5numpy_6random_8_mt19937_7MT19937_3_legacy_seeding _mt19937.pyx.c:5446 (_mt19937.cpython-314t-darwin.so:arm64+0xae08)
    #3 __Pyx_CyFunction_Vectorcall_FASTCALL_KEYWORDS _mt19937.pyx.c:12586 (_mt19937.cpython-314t-darwin.so:arm64+0x164f0)
    #4 PyObject_VectorcallMethod call.c:856 (libpython3.14t.dylib:arm64+0x8cc24)
    #5 __pyx_pw_5numpy_6random_6mtrand_11RandomState_13seed mtrand.pyx.c:7832 (mtrand.cpython-314t-darwin.so:arm64+0x18fcc)
    #6 __Pyx_CyFunction_Vectorcall_FASTCALL_KEYWORDS mtrand.pyx.c:35313 (mtrand.cpython-314t-darwin.so:arm64+0x67e84)
    #7 __Pyx_PyObject_FastCallDict mtrand.pyx.c:31122 (mtrand.cpython-314t-darwin.so:arm64+0xfdc8)
    #8 __pyx_pw_5numpy_6random_6mtrand_1seed mtrand.pyx.c:26433 (mtrand.cpython-314t-darwin.so:arm64+0x68788)
    #9 __Pyx_CyFunction_Vectorcall_FASTCALL_KEYWORDS mtrand.pyx.c:35313 (mtrand.cpython-314t-darwin.so:arm64+0x67e84)
    #10 PyObject_Vectorcall call.c:327 (libpython3.14t.dylib:arm64+0x8af00)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:1619 (libpython3.14t.dylib:arm64+0x27cc00)
    #12 gen_send_ex2 genobject.c:259 (libpython3.14t.dylib:arm64+0xbf558)
    #13 gen_iternext genobject.c:635 (libpython3.14t.dylib:arm64+0xbce28)
    #14 builtin_next bltinmodule.c:1687 (libpython3.14t.dylib:arm64+0x2733a4)
    #15 _PyEval_EvalFrameDefault generated_cases.c.h:2263 (libpython3.14t.dylib:arm64+0x27eb1c)
    #16 _PyEval_Vector ceval.c:2083 (libpython3.14t.dylib:arm64+0x278928)
    #17 _PyFunction_Vectorcall call.c (libpython3.14t.dylib:arm64+0x8b54c)
    #18 method_vectorcall classobject.c:73 (libpython3.14t.dylib:arm64+0x8f9c0)
    #19 _PyObject_Call call.c:348 (libpython3.14t.dylib:arm64+0x8b1c0)
    #20 PyObject_Call call.c:373 (libpython3.14t.dylib:arm64+0x8b234)
    #21 _PyEval_EvalFrameDefault generated_cases.c.h:2654 (libpython3.14t.dylib:arm64+0x27f9b0)
    #22 _PyEval_Vector ceval.c:2083 (libpython3.14t.dylib:arm64+0x278928)
    #23 _PyFunction_Vectorcall call.c (libpython3.14t.dylib:arm64+0x8b54c)
    #24 method_vectorcall classobject.c:73 (libpython3.14t.dylib:arm64+0x8f9c0)
    #25 context_run context.c:728 (libpython3.14t.dylib:arm64+0x2c3d18)
    #26 _PyEval_EvalFrameDefault generated_cases.c.h:3744 (libpython3.14t.dylib:arm64+0x282c64)
    #27 _PyEval_Vector ceval.c:2083 (libpython3.14t.dylib:arm64+0x278928)
    #28 _PyFunction_Vectorcall call.c (libpython3.14t.dylib:arm64+0x8b54c)
    #29 method_vectorcall classobject.c:73 (libpython3.14t.dylib:arm64+0x8f9c0)
    #30 _PyObject_Call call.c:348 (libpython3.14t.dylib:arm64+0x8b1c0)
    #31 PyObject_Call call.c:373 (libpython3.14t.dylib:arm64+0x8b234)
    #32 thread_run _threadmodule.c:359 (libpython3.14t.dylib:arm64+0x419b3c)
    #33 pythread_wrapper thread_pthread.h:242 (libpython3.14t.dylib:arm64+0x369a20)

  Previous read of size 4 at 0x000127d2a878 by thread T1514:
    #0 __pyx_getprop_5numpy_6random_8_mt19937_7MT19937_state _mt19937.pyx.c:7269 (_mt19937.cpython-314t-darwin.so:arm64+0x13110)
    #1 getset_get descrobject.c:194 (libpython3.14t.dylib:arm64+0xa10dc)
    #2 _PyObject_GenericGetAttrWithDict object.c:1709 (libpython3.14t.dylib:arm64+0x139114)
    #3 PyObject_GenericGetAttr object.c:1795 (libpython3.14t.dylib:arm64+0x138f34)
    #4 __pyx_pw_5numpy_6random_6mtrand_11RandomState_15get_state mtrand.pyx.c:8173 (mtrand.cpython-314t-darwin.so:arm64+0x1a034)
    #5 __Pyx_CyFunction_Vectorcall_FASTCALL_KEYWORDS mtrand.pyx.c:35313 (mtrand.cpython-314t-darwin.so:arm64+0x67e84)
    #6 PyObject_Vectorcall call.c:327 (libpython3.14t.dylib:arm64+0x8af00)
    #7 _PyEval_EvalFrameDefault generated_cases.c.h:1619 (libpython3.14t.dylib:arm64+0x27cc00)
    #8 gen_send_ex2 genobject.c:259 (libpython3.14t.dylib:arm64+0xbf558)
    #9 gen_iternext genobject.c:635 (libpython3.14t.dylib:arm64+0xbce28)
    #10 builtin_next bltinmodule.c:1687 (libpython3.14t.dylib:arm64+0x2733a4)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:2263 (libpython3.14t.dylib:arm64+0x27eb1c)
    #12 _PyEval_Vector ceval.c:2083 (libpython3.14t.dylib:arm64+0x278928)
    #13 _PyFunction_Vectorcall call.c (libpython3.14t.dylib:arm64+0x8b54c)
    #14 method_vectorcall classobject.c:73 (libpython3.14t.dylib:arm64+0x8f9c0)
    #15 _PyObject_Call call.c:348 (libpython3.14t.dylib:arm64+0x8b1c0)
    #16 PyObject_Call call.c:373 (libpython3.14t.dylib:arm64+0x8b234)
    #17 _PyEval_EvalFrameDefault generated_cases.c.h:2654 (libpython3.14t.dylib:arm64+0x27f9b0)
    #18 _PyEval_Vector ceval.c:2083 (libpython3.14t.dylib:arm64+0x278928)
    #19 _PyFunction_Vectorcall call.c (libpython3.14t.dylib:arm64+0x8b54c)
    #20 method_vectorcall classobject.c:73 (libpython3.14t.dylib:arm64+0x8f9c0)
    #21 context_run context.c:728 (libpython3.14t.dylib:arm64+0x2c3d18)
    #22 _PyEval_EvalFrameDefault generated_cases.c.h:3744 (libpython3.14t.dylib:arm64+0x282c64)
    #23 _PyEval_Vector ceval.c:2083 (libpython3.14t.dylib:arm64+0x278928)
    #24 _PyFunction_Vectorcall call.c (libpython3.14t.dylib:arm64+0x8b54c)
    #25 method_vectorcall classobject.c:73 (libpython3.14t.dylib:arm64+0x8f9c0)
    #26 _PyObject_Call call.c:348 (libpython3.14t.dylib:arm64+0x8b1c0)
    #27 PyObject_Call call.c:373 (libpython3.14t.dylib:arm64+0x8b234)
    #28 thread_run _threadmodule.c:359 (libpython3.14t.dylib:arm64+0x419b3c)
    #29 pythread_wrapper thread_pthread.h:242 (libpython3.14t.dylib:arm64+0x369a20)

@kumaraditya303 kumaraditya303 mentioned this pull request Dec 13, 2025
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rkern
rkern approved these changes Dec 13, 2025
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I'm not sure about the test failures (maybe they're intermittent?), but these look like the correct changes corresponding to the other np.random fix.

@charris charris added the 09 - Backport-Candidate PRs tagged should be backported label Dec 13, 2025
@charris charris merged commit ffd9fd2 into numpy:main Dec 14, 2025
83 of 89 checks passed
@charris charris added this to the 2.4.0 release milestone Dec 14, 2025
charris pushed a commit to charris/numpy that referenced this pull request Dec 14, 2025
@kumaraditya303 @charris
fix more data races in mtrand.pyx (numpy#30426)
f94a148
@charris charris mentioned this pull request Dec 14, 2025
Merged
@charris charris removed the 09 - Backport-Candidate PRs tagged should be backported label Dec 14, 2025
charris added a commit that referenced this pull request Dec 14, 2025
@charris
Merge pull request #30432 from charris/backport-30426
d04a429 
BUG: fix remaining data races in mtrand.pyx (#30426)
@kumaraditya303 kumaraditya303 deleted the mtrand branch December 15, 2025 05:35
@rgommers rgommers added the 39 - free-threading PRs and issues related to support for free-threading CPython (a.k.a. no-GIL, PEP 703) label Dec 15, 2025
MaanasArora pushed a commit to MaanasArora/numpy that referenced this pull request Dec 17, 2025
@kumaraditya303 @MaanasArora
fix more data races in mtrand.pyx (numpy#30426)
1b5ac26
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