Bug report
Bug description:
NTHREADS = 8
ROUNDS = 5000
S = struct.Struct("i")
BUF = b"\x00\x00\x00\x00" * 500 # 500 "i" items; small so it exhausts fast
def drain(it, barrier):
barrier.wait()
for _ in it:
pass
def main():
for _ in range(ROUNDS):
it = S.iter_unpack(BUF)
barrier = threading.Barrier(NTHREADS)
threads = [threading.Thread(target=drain, args=(it, barrier))
for _ in range(NTHREADS)]
for t in threads:
t.start()
for t in threads:
t.join()
print("survived this run")Structs have come up before #149816 (comment) with some WF issues related to structs although they are focused around initialising as far as I can see.
TSAN
WARNING: ThreadSanitizer: data race (pid=7225)
Write of size 8 at 0x000112338508 by thread T4:
#0 unpackiter_iternext _struct.c:2278 (_struct.cpython-316td-darwin.so:arm64+0xa274)
#1 _PyForIter_VirtualIteratorNext ceval.c:3775 (python.exe:arm64+0x100391868)
#2 _PyEval_EvalFrameDefault generated_cases.c.h:6352 (python.exe:arm64+0x10037276c)
#3 _PyEval_Vector ceval.c:2172 (python.exe:arm64+0x100359070)
#4 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000edce8)
#5 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1000ebe60)
#6 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x1000ef4d4)
#7 method_vectorcall classobject.c:55 (python.exe:arm64+0x1000f1fd8)
#8 context_run context.c:731 (python.exe:arm64+0x1003c9298)
#9 method_vectorcall_FASTCALL_KEYWORDS descrobject.c:421 (python.exe:arm64+0x100109bcc)
#10 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1000ebe60)
#11 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x1000ed7ac)
#12 _Py_VectorCallInstrumentation_StackRefSteal ceval.c:768 (python.exe:arm64+0x100359bb8)
#13 _PyEval_EvalFrameDefault generated_cases.c.h:1906 (python.exe:arm64+0x10036338c)
#14 _PyEval_Vector ceval.c:2172 (python.exe:arm64+0x100359070)
#15 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000edce8)
#16 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1000ebe60)
#17 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x1000ef4d4)
#18 method_vectorcall classobject.c:55 (python.exe:arm64+0x1000f1fd8)
#19 _PyVectorcall_Call call.c:273 (python.exe:arm64+0x1000ed654)
#20 _PyObject_Call call.c:348 (python.exe:arm64+0x1000ed89c)
#21 PyObject_Call call.c:373 (python.exe:arm64+0x1000edaac)
#22 thread_run _threadmodule.c:388 (python.exe:arm64+0x1005c0474)
#23 pythread_wrapper thread_pthread.h:234 (python.exe:arm64+0x1004c68a4)
Previous write of size 8 at 0x000112338508 by thread T3:
#0 unpackiter_iternext _struct.c:2278 (_struct.cpython-316td-darwin.so:arm64+0xa274)
#1 _PyForIter_VirtualIteratorNext ceval.c:3775 (python.exe:arm64+0x100391868)
#2 _PyEval_EvalFrameDefault generated_cases.c.h:6352 (python.exe:arm64+0x10037276c)
#3 _PyEval_Vector ceval.c:2172 (python.exe:arm64+0x100359070)
#4 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000edce8)
#5 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1000ebe60)
#6 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x1000ef4d4)
#7 method_vectorcall classobject.c:55 (python.exe:arm64+0x1000f1fd8)
#8 context_run context.c:731 (python.exe:arm64+0x1003c9298)
#9 method_vectorcall_FASTCALL_KEYWORDS descrobject.c:421 (python.exe:arm64+0x100109bcc)
#10 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1000ebe60)
#11 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x1000ed7ac)
#12 _Py_VectorCallInstrumentation_StackRefSteal ceval.c:768 (python.exe:arm64+0x100359bb8)
#13 _PyEval_EvalFrameDefault generated_cases.c.h:1906 (python.exe:arm64+0x10036338c)
#14 _PyEval_Vector ceval.c:2172 (python.exe:arm64+0x100359070)
#15 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000edce8)
#16 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1000ebe60)
#17 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x1000ef4d4)
#18 method_vectorcall classobject.c:55 (python.exe:arm64+0x1000f1fd8)
#19 _PyVectorcall_Call call.c:273 (python.exe:arm64+0x1000ed654)
#20 _PyObject_Call call.c:348 (python.exe:arm64+0x1000ed89c)
#21 PyObject_Call call.c:373 (python.exe:arm64+0x1000edaac)
#22 thread_run _threadmodule.c:388 (python.exe:arm64+0x1005c0474)
#23 pythread_wrapper thread_pthread.h:234 (python.exe:arm64+0x1004c68a4)
SUMMARY: ThreadSanitizer: data race _struct.c:2270 in unpackiter_iternext
==================
ThreadSanitizer:DEADLYSIGNAL
==7225==ERROR: ThreadSanitizer: SEGV on unknown address 0xffffabbbbbbbbd20 (pc 0x000103d5cf2c bp 0x00016d179400 sp 0x00016d1793f0 T32990319)
==7225==The signal is caused by a READ memory access.
#0 OUTLINED_FUNCTION_10 <null> (libclang_rt.tsan_osx_dynamic.dylib:arm64e+0x78f2c)
#1 _PyType_GetDict typeobject.c:542 (python.exe:arm64+0x10021f68c)
#2 _Py_Specialize_LoadAttr specialize.c:1006 (python.exe:arm64+0x10049fe58)
#3 _PyEval_EvalFrameDefault generated_cases.c.h:8671 (python.exe:arm64+0x100379ee0)
#4 _PyEval_Vector ceval.c:2172 (python.exe:arm64+0x100359070)
#5 PyEval_EvalCode ceval.c:679 (python.exe:arm64+0x100358954)
#6 run_eval_code_obj pythonrun.c:1406 (python.exe:arm64+0x10049bc44)
#7 run_mod pythonrun.c:1509 (python.exe:arm64+0x10049b7f4)
#8 _PyRun_File pythonrun.c:1332 (python.exe:arm64+0x1004975a4)
#9 _PyRun_SimpleFile pythonrun.c:544 (python.exe:arm64+0x100495b78)
#10 _PyRun_AnyFile pythonrun.c:92 (python.exe:arm64+0x1004953d8)
#11 pymain_run_file main.c:494 (python.exe:arm64+0x1004e320c)
#12 Py_RunMain main.c:891 (python.exe:arm64+0x1004e270c)
#13 pymain_main main.c:921 (python.exe:arm64+0x1004e2c70)
#14 Py_BytesMain main.c:945 (python.exe:arm64+0x1004e2d1c)
#15 main python.c:15 (python.exe:arm64+0x100000a64)
#16 start <null> (dyld:arm64e+0x8d50)
CPython versions tested on:
CPython main branch
Operating systems tested on:
macOS
Linked PRs
Bug report
Bug description:
Structs have come up before #149816 (comment) with some WF issues related to structs although they are focused around initialising as far as I can see.
TSAN
CPython versions tested on:
CPython main branch
Operating systems tested on:
macOS
Linked PRs