René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Socket file descriptor races in GIL-enabled build","articleBody":"# Bug report\n\nIn the free threading build, but not the default GIL-enabled build, the reads and writes `sock_fd` use relaxed atomics. \n\nThis can lead to data races because the `sock_fd` field is read when the GIL is released.\n\nhttps://github.com/python/cpython/blob/e1c09fff054ebcb90e72bba25ef7332bcabec92b/Modules/socketmodule.c#L571-L587\n\nhttps://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174\n\nThread sanitizer:\n\n```\nWARNING: ThreadSanitizer: data race (pid=10596)\n  Read of size 4 at 0x7feeb9bc4470 by thread T32:\n    #0 get_sock_fd /home/runner/work/cpython/cpython/./Modules/socketmodule.c:603:15 (_socket.cpython-314d-x86_64-linux-gnu.so+0x147a2) (BuildId: 5fd9421785689189a09a4eaff953e770708561c7)\n    #1 sock_send_impl /home/runner/work/cpython/cpython/./Modules/socketmodule.c:4568:24 (_socket.cpython-314d-x86_64-linux-gnu.so+0x147a2)\n    #2 sock_call_ex /home/runner/work/cpython/cpython/./Modules/socketmodule.c:10[13](https://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174#step:14:14):19 (_socket.cpython-314d-x86_64-linux-gnu.so+0x120e0) (BuildId: 5fd9421785689189a09a4eaff953e770708561c7)\n    #3 sock_call /home/runner/work/cpython/cpython/./Modules/socketmodule.c:1065:12 (_socket.cpython-3[14](https://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174#step:14:15)d-x86_64-linux-gnu.so+0x120e0)\n    #4 sock_send /home/runner/work/cpython/cpython/./Modules/socketmodule.c:4594:9 (_socket.cpython-314d-x86_64-linux-gnu.so+0xf18c) (BuildId: 5fd9421785689189a09a4eaff953e770708561c7)\n    #5 method_vectorcall_VARARGS /home/runner/work/cpython/cpython/Objects/descrobject.c:325:24 (python+0x265e8f) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #6 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:169:11 (python+0x24db5b) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #7 PyObject_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c:327:12 (python+0x24f340) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #8 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:3886:35 (python+0x47f974) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #9 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #10 _PyEval_Vector /home/runner/work/cpython/cpython/Python/ceval.c:1967:12 (python+0x46ab79)\n    #11 _PyFunction_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c (python+0x24f82c) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #12 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:169:11 (python+0x2550cb) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #13 method_vectorcall /home/runner/work/cpython/cpython/Objects/classobject.c:94:18 (python+0x2537c1) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #14 _PyVectorcall_Call /home/runner/work/cpython/cpython/Objects/call.c:273:16 (python+0x24f247) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #[15](https://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174#step:14:16) _PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:348:16 (python+0x24f458) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #[16](https://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174#step:14:17) PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:373:12 (python+0x24f657) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #17 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:2475:32 (python+0x477cac) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #18 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #19 _PyEval_Vector /home/runner/work/cpython/cpython/Python/ceval.c:1967:12 (python+0x46ab79)\n    #20 _PyFunction_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c (python+0x24f82c) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #21 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:169:11 (python+0x2550cb) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #22 method_vectorcall /home/runner/work/cpython/cpython/Objects/classobject.c:94:18 (python+0x2537c1) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #23 _PyVectorcall_Call /home/runner/work/cpython/cpython/Objects/call.c:273:16 (python+0x24f247) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #24 _PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:348:16 (python+0x24f458) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #25 PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:373:12 (python+0x24f657) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #26 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:2475:32 (python+0x477cac) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #27 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #28 _PyEval_Vector /home/runner/work/cpython/cpython/Python/ceval.c:1967:12 (python+0x46ab79)\n    #29 _PyFunction_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c (python+0x24f82c) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #30 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:169:11 (python+0x2550cb) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #31 method_vectorcall /home/runner/work/cpython/cpython/Objects/classobject.c:72:20 (python+0x253745) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #32 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:169:11 (python+0x4e42d9) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #33 context_run /home/runner/work/cpython/cpython/Python/context.c:728:29 (python+0x4e42d9)\n    #34 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:3551:35 (python+0x47dd02) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #35 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #40 call_method /home/runner/work/cpython/cpython/Objects/typeobject.c:3006:19 (python+0x362dc3) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #41 slot_tp_call /home/runner/work/cpython/cpython/Objects/typeobject.c:10268:12 (python+0x362dc3)\n    #42 _PyObject_MakeTpCall /home/runner/work/cpython/cpython/Objects/call.c:242:18 (python+0x24e2ba) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #43 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:167:16 (python+0x24dbbd) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #44 PyObject_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c:327:12 (python+0x24f340) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #45 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:3886:35 (python+0x47f974) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #46 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #47 _PyEval_Vector /home/runner/work/cpython/cpython/Python/ceval.c:1967:12 (python+0x46ab79)\n    #48 _PyFunction_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c (python+0x24f82c) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #49 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:169:11 (python+0x2550cb) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #50 method_vectorcall /home/runner/work/cpython/cpython/Objects/classobject.c:94:18 (python+0x2537c1) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #51 _PyVectorcall_Call /home/runner/work/cpython/cpython/Objects/call.c:273:16 (python+0x24f247) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #52 _PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:348:16 (python+0x24f458) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #53 PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:373:12 (python+0x24f657) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #54 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:2475:32 (python+0x477cac) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #55 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #56 _PyEval_Vector /home/runner/work/cpython/cpython/Python/ceval.c:1967:12 (python+0x46ab79)\n    #57 _PyFunction_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c (python+0x24f82c) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #58 _PyObject_VectorcallDictTstate /home/runner/work/cpython/cpython/Objects/call.c:135:15 (python+0x24de89) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #59 _PyObject_Call_Prepend /home/runner/work/cpython/cpython/Objects/call.c:504:24 (python+0x24fc4d) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #60 call_method /home/runner/work/cpython/cpython/Objects/typeobject.c:3006:19 (python+0x362dc3) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #61 slot_tp_call /home/runner/work/cpython/cpython/Objects/typeobject.c:10268:12 (python+0x362dc3)\n    #62 _PyObject_MakeTpCall /home/runner/work/cpython/cpython/Objects/call.c:242:18 (python+0x24e2ba) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #63 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:167:16 (python+0x24dbbd) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #64 PyObject_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c:327:12 (python+0x24f340) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #65 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:3886:35 (python+0x47f974) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #66 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #67 _PyEval_Vector /home/runner/work/cpython/cpython/Python/ceval.c:1967:12 (python+0x46ab79)\n    #68 _PyFunction_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c (python+0x24f82c) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #69 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:169:11 (python+0x2550cb) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #70 method_vectorcall /home/runner/work/cpython/cpython/Objects/classobject.c:94:18 (python+0x2537c1) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #71 _PyVectorcall_Call /home/runner/work/cpython/cpython/Objects/call.c:273:16 (python+0x24f247) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #72 _PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:348:16 (python+0x24f458) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #73 PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:373:12 (python+0x24f657) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #74 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:2475:32 (python+0x477cac) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #75 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #76 _PyEval_Vector /home/runner/work/cpython/cpython/Python/ceval.c:1967:12 (python+0x46ab79)\n    #77 _PyFunction_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c (python+0x24f82c) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #78 _PyObject_VectorcallDictTstate /home/runner/work/cpython/cpython/Objects/call.c:135:15 (python+0x24de89) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #79 _PyObject_Call_Prepend /home/runner/work/cpython/cpython/Objects/call.c:504:24 (python+0x24fc4d) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #80 call_method /home/runner/work/cpython/cpython/Objects/typeobject.c:3006:19 (python+0x362dc3) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #81 slot_tp_call /home/runner/work/cpython/cpython/Objects/typeobject.c:10268:12 (python+0x362dc3)\n    #82 _PyObject_MakeTpCall /home/runner/work/cpython/cpython/Objects/call.c:242:18 (python+0x24e2ba) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #83 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:167:16 (python+0x24dbbd) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #84 PyObject_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c:327:12 (python+0x24f340) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #85 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:1451:35 (python+0x47265b) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #86 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #87 _PyEval_Vector /home/runner/work/cpython/cpython/Python/ceval.c:1967:12 (python+0x46ab79)\n    #88 PyEval_EvalCode /home/runner/work/cpython/cpython/Python/ceval.c:870:21 (python+0x46a727) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #89 builtin_exec_impl /home/runner/work/cpython/cpython/Python/bltinmodule.c:1158:[17](https://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174#step:14:18) (python+0x463291) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #90 builtin_exec /home/runner/work/cpython/cpython/Python/clinic/bltinmodule.c.h:568:20 (python+0x463291)\n    #91 cfunction_vectorcall_FASTCALL_KEYWORDS /home/runner/work/cpython/cpython/Objects/methodobject.c:470:24 (python+0x2ef6c7) (BuildId: aaa34bd06c4565b8343ea0751a4b01[18](https://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174#step:14:19)212c23b3)\n    #92 _PyObject_VectorcallTstate /home/runner/work/cpython/cpython/./Include/internal/pycore_call.h:169:11 (python+0x24db5b) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #93 PyObject_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c:327:12 (python+0x24f340) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #94 _PyEval_EvalFrameDefault /home/runner/work/cpython/cpython/Python/generated_cases.c.h:1451:35 (python+0x47265b) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #95 _PyEval_EvalFrame /home/runner/work/cpython/cpython/./Include/internal/pycore_ceval.h:1[19](https://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174#step:14:20):16 (python+0x46ab79) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #96 _PyEval_Vector /home/runner/work/cpython/cpython/Python/ceval.c:1967:12 (python+0x46ab79)\n    #97 _PyFunction_Vectorcall /home/runner/work/cpython/cpython/Objects/call.c (python+0x24f82c) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #98 _PyVectorcall_Call /home/runner/work/cpython/cpython/Objects/call.c:273:16 (python+0x24f247) (BuildId: aaa34bd06c4565b8343ea0751a4b0118[21](https://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174#step:14:22)2c23b3)\n    #99 _PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:348:16 (python+0x24f458) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #100 PyObject_Call /home/runner/work/cpython/cpython/Objects/call.c:373:12 (python+0x24f657) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #101 pymain_run_module /home/runner/work/cpython/cpython/Modules/main.c:345:14 (python+0x5d44b7) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c[23](https://github.com/python/cpython/actions/runs/14630615998/job/41052077715?pr=131174#step:14:24)b3)\n    #102 pymain_run_python /home/runner/work/cpython/cpython/Modules/main.c (python+0x5d3285) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #103 Py_RunMain /home/runner/work/cpython/cpython/Modules/main.c:767:5 (python+0x5d3285)\n    #104 pymain_main /home/runner/work/cpython/cpython/Modules/main.c:797:12 (python+0x5d4369) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #105 Py_BytesMain /home/runner/work/cpython/cpython/Modules/main.c:821:12 (python+0x5d43e9) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n    #106 main /home/runner/work/cpython/cpython/./Programs/python.c:15:12 (python+0x168de0) (BuildId: aaa34bd06c4565b8343ea0751a4b0118212c23b3)\n\nSUMMARY: ThreadSanitizer: data race /home/runner/work/cpython/cpython/./Modules/socketmodule.c:603:15 in get_sock_fd\n==================\nThreadSanitizer: reported 1 warnings\n```\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-133208\n* gh-133683\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/colesbury","@type":"Person","name":"colesbury"},"datePublished":"2025-04-24T17:59:56.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/132886/cpython/issues/132886"}