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Race in func_get_annotations under free-threading #128714

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Race in func_get_annotations under free-threading#128714
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3.13bugs and security fixes3.14bugs and security fixesinterpreter-core(Objects, Python, Grammar, and Parser dirs)topic-free-threadingtype-bugAn unexpected behavior, bug, or error
@hawkinsp

Description

@hawkinsp
hawkinsp
opened on Jan 10, 2025

Bug report

Bug description:

With CPython 3.13 from commit 65da5db TSAN reports the following race, which looks right: the initialization of p->func_annotations is racy.

Reproducer:

import concurrent.futures
import functools
import threading

num_threads = 8

def closure(b, f):
  b.wait()
  f.__annotations__

with concurrent.futures.ThreadPoolExecutor(max_workers=num_threads) as executor:
  for _ in range(100):
    b = threading.Barrier(num_threads)
    def f(x: int) -> int:
      return x + 1
    for _ in range(num_threads):
      executor.submit(functools.partial(closure, b, f))

TSAN report (first race):

WARNING: ThreadSanitizer: data race (pid=3380651)
  Read of size 8 at 0x7f02728d6840 by thread T5:
    #0 func_get_annotations /usr/local/google/home/phawkins/p/cpython/Objects/funcobject.c:769:13 (python3.13+0x232542) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #1 getset_get /usr/local/google/home/phawkins/p/cpython/Objects/descrobject.c:193:16 (python3.13+0x1ff888) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #2 _PyObject_GenericGetAttrWithDict /usr/local/google/home/phawkins/p/cpython/Objects/object.c:1665:19 (python3.13+0x295e11) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #3 PyObject_GenericGetAttr /usr/local/google/home/phawkins/p/cpython/Objects/object.c:1747:12 (python3.13+0x295c62) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #4 PyObject_GetAttr /usr/local/google/home/phawkins/p/cpython/Objects/object.c:1261:18 (python3.13+0x2945c7) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #5 _PyEval_EvalFrameDefault /usr/local/google/home/phawkins/p/cpython/Python/generated_cases.c.h:3766:28 (python3.13+0x3ee2b0) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #6 _PyEval_EvalFrame /usr/local/google/home/phawkins/p/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3dea3a) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #7 _PyEval_Vector /usr/local/google/home/phawkins/p/cpython/Python/ceval.c:1807:12 (python3.13+0x3dea3a)
    #8 _PyFunction_Vectorcall /usr/local/google/home/phawkins/p/cpython/Objects/call.c (python3.13+0x1eb65f) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #9 _PyObject_VectorcallTstate /usr/local/google/home/phawkins/p/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x572352) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #10 partial_vectorcall /usr/local/google/home/phawkins/p/cpython/./Modules/_functoolsmodule.c:252:16 (python3.13+0x572352)
    #11 _PyVectorcall_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:273:16 (python3.13+0x1eb2d3) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #12 _PyObject_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:348:16 (python3.13+0x1eb2d3)
    #13 PyObject_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:373:12 (python3.13+0x1eb355) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #14 _PyEval_EvalFrameDefault /usr/local/google/home/phawkins/p/cpython/Python/generated_cases.c.h:1355:26 (python3.13+0x3e4af2) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #15 _PyEval_EvalFrame /usr/local/google/home/phawkins/p/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3dea3a) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #16 _PyEval_Vector /usr/local/google/home/phawkins/p/cpython/Python/ceval.c:1807:12 (python3.13+0x3dea3a)
    #17 _PyFunction_Vectorcall /usr/local/google/home/phawkins/p/cpython/Objects/call.c (python3.13+0x1eb65f) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #18 _PyObject_VectorcallTstate /usr/local/google/home/phawkins/p/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1ef62f) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #19 method_vectorcall /usr/local/google/home/phawkins/p/cpython/Objects/classobject.c:70:20 (python3.13+0x1ef62f)
    #20 _PyVectorcall_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:273:16 (python3.13+0x1eb2d3) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #21 _PyObject_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:348:16 (python3.13+0x1eb2d3)
    #22 PyObject_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:373:12 (python3.13+0x1eb355) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #23 thread_run /usr/local/google/home/phawkins/p/cpython/./Modules/_threadmodule.c:337:21 (python3.13+0x564a32) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #24 pythread_wrapper /usr/local/google/home/phawkins/p/cpython/Python/thread_pthread.h:243:5 (python3.13+0x4bddb7) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)

  Previous write of size 8 at 0x7f02728d6840 by thread T7:
    #0 func_get_annotation_dict /usr/local/google/home/phawkins/p/cpython/Objects/funcobject.c:535:9 (python3.13+0x22f46f) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #1 func_get_annotations /usr/local/google/home/phawkins/p/cpython/Objects/funcobject.c:774:19 (python3.13+0x23256c) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #2 getset_get /usr/local/google/home/phawkins/p/cpython/Objects/descrobject.c:193:16 (python3.13+0x1ff888) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #3 _PyObject_GenericGetAttrWithDict /usr/local/google/home/phawkins/p/cpython/Objects/object.c:1665:19 (python3.13+0x295e11) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #4 PyObject_GenericGetAttr /usr/local/google/home/phawkins/p/cpython/Objects/object.c:1747:12 (python3.13+0x295c62) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #5 PyObject_GetAttr /usr/local/google/home/phawkins/p/cpython/Objects/object.c:1261:18 (python3.13+0x2945c7) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #6 _PyEval_EvalFrameDefault /usr/local/google/home/phawkins/p/cpython/Python/generated_cases.c.h:3766:28 (python3.13+0x3ee2b0) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #7 _PyEval_EvalFrame /usr/local/google/home/phawkins/p/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3dea3a) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #8 _PyEval_Vector /usr/local/google/home/phawkins/p/cpython/Python/ceval.c:1807:12 (python3.13+0x3dea3a)
    #9 _PyFunction_Vectorcall /usr/local/google/home/phawkins/p/cpython/Objects/call.c (python3.13+0x1eb65f) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #10 _PyObject_VectorcallTstate /usr/local/google/home/phawkins/p/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x572352) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #11 partial_vectorcall /usr/local/google/home/phawkins/p/cpython/./Modules/_functoolsmodule.c:252:16 (python3.13+0x572352)
    #12 _PyVectorcall_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:273:16 (python3.13+0x1eb2d3) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #13 _PyObject_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:348:16 (python3.13+0x1eb2d3)
    #14 PyObject_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:373:12 (python3.13+0x1eb355) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #15 _PyEval_EvalFrameDefault /usr/local/google/home/phawkins/p/cpython/Python/generated_cases.c.h:1355:26 (python3.13+0x3e4af2) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #16 _PyEval_EvalFrame /usr/local/google/home/phawkins/p/cpython/./Include/internal/pycore_ceval.h:119:16 (python3.13+0x3dea3a) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #17 _PyEval_Vector /usr/local/google/home/phawkins/p/cpython/Python/ceval.c:1807:12 (python3.13+0x3dea3a)
    #18 _PyFunction_Vectorcall /usr/local/google/home/phawkins/p/cpython/Objects/call.c (python3.13+0x1eb65f) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #19 _PyObject_VectorcallTstate /usr/local/google/home/phawkins/p/cpython/./Include/internal/pycore_call.h:168:11 (python3.13+0x1ef62f) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #20 method_vectorcall /usr/local/google/home/phawkins/p/cpython/Objects/classobject.c:70:20 (python3.13+0x1ef62f)
    #21 _PyVectorcall_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:273:16 (python3.13+0x1eb2d3) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #22 _PyObject_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:348:16 (python3.13+0x1eb2d3)
    #23 PyObject_Call /usr/local/google/home/phawkins/p/cpython/Objects/call.c:373:12 (python3.13+0x1eb355) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #24 thread_run /usr/local/google/home/phawkins/p/cpython/./Modules/_threadmodule.c:337:21 (python3.13+0x564a32) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)
    #25 pythread_wrapper /usr/local/google/home/phawkins/p/cpython/Python/thread_pthread.h:243:5 (python3.13+0x4bddb7) (BuildId: 19c569fa942016d8ac49d19fd40ccb1ddded939b)

CPython versions tested on:

3.13

Operating systems tested on:

Linux

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