https://github.com/python/cpython/commit/83f4fffe3d78ba368c0d4864c42c7c9c9223f7d1 commit: 83f4fffe3d78ba368c0d4864c42c7c9c9223f7d1 branch: main author: Victor Stinner <[email protected]> committer: vstinner <[email protected]> date: 2026-02-18T15:57:48Z summary:
gh-144763: Don't detach the GIL in tracemalloc (#144779) tracemalloc no longer detaches the GIL to acquire its internal lock. Co-authored-by: Kumar Aditya <[email protected]> files: A Misc/NEWS.d/next/Library/2026-02-13-11-14-18.gh-issue-144763.cDwnEE.rst M Python/tracemalloc.c diff --git a/Misc/NEWS.d/next/Library/2026-02-13-11-14-18.gh-issue-144763.cDwnEE.rst b/Misc/NEWS.d/next/Library/2026-02-13-11-14-18.gh-issue-144763.cDwnEE.rst new file mode 100644 index 00000000000000..14eb4f49c8ad3c --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-02-13-11-14-18.gh-issue-144763.cDwnEE.rst @@ -0,0 +1,2 @@ +Fix a race condition in :mod:`tracemalloc`: it no longer detaches the attached +thread state to acquire its internal lock. Patch by Victor Stinner. diff --git a/Python/tracemalloc.c b/Python/tracemalloc.c index cdd96925d1f27a..0afc84e021817c 100644 --- a/Python/tracemalloc.c +++ b/Python/tracemalloc.c @@ -36,7 +36,7 @@ static int _PyTraceMalloc_TraceRef(PyObject *op, PyRefTracerEvent event, the GIL held from PyMem_RawFree(). It cannot acquire the lock because it would introduce a deadlock in _PyThreadState_DeleteCurrent(). */ #define tables_lock _PyRuntime.tracemalloc.tables_lock -#define TABLES_LOCK() PyMutex_Lock(&tables_lock) +#define TABLES_LOCK() PyMutex_LockFlags(&tables_lock, _Py_LOCK_DONT_DETACH) #define TABLES_UNLOCK() PyMutex_Unlock(&tables_lock) @@ -224,13 +224,20 @@ tracemalloc_get_frame(_PyInterpreterFrame *pyframe, frame_t *frame) assert(PyStackRef_CodeCheck(pyframe->f_executable)); frame->filename = &_Py_STR(anon_unknown); - int lineno = PyUnstable_InterpreterFrame_GetLine(pyframe); + int lineno = -1; + PyCodeObject *code = _PyFrame_GetCode(pyframe); + // PyUnstable_InterpreterFrame_GetLine() cannot but used, since it uses + // a critical section which can trigger a deadlock. + int lasti = _PyFrame_SafeGetLasti(pyframe); + if (lasti >= 0) { + lineno = _PyCode_SafeAddr2Line(code, lasti); + } if (lineno < 0) { lineno = 0; } frame->lineno = (unsigned int)lineno; - PyObject *filename = _PyFrame_GetCode(pyframe)->co_filename; + PyObject *filename = code->co_filename; if (filename == NULL) { #ifdef TRACE_DEBUG tracemalloc_error("failed to get the filename of the code object"); @@ -863,7 +870,8 @@ _PyTraceMalloc_Stop(void) TABLES_LOCK(); if (!tracemalloc_config.tracing) { - goto done; + TABLES_UNLOCK(); + return; } /* stop tracing Python memory allocations */ @@ -880,10 +888,12 @@ _PyTraceMalloc_Stop(void) raw_free(tracemalloc_traceback); tracemalloc_traceback = NULL; - (void)PyRefTracer_SetTracer(NULL, NULL); - -done: TABLES_UNLOCK(); + + // Call it after TABLES_UNLOCK() since it calls _PyEval_StopTheWorldAll() + // which would lead to a deadlock with TABLES_LOCK() which doesn't detach + // the thread state. + (void)PyRefTracer_SetTracer(NULL, NULL); } _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
