From 35ab1e55aa0a359762c9eb6b2b5f7490440d6b1c Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Tue, 24 Mar 2020 17:12:19 +0100 Subject: [PATCH] bpo-20526: Fix PyThreadState_Clear(): don't decref frame (GH-19120) (GH-19136) PyThreadState.frame is a borrowed reference, not a strong reference: PyThreadState_Clear() must not call Py_CLEAR(tstate->frame). Remove test_threading.test_warnings_at_exit(): we cannot warranty that the Python thread state of daemon threads is cleared in a reliable way during Python shutdown. (cherry picked from commit 5804f878e779712e803be927ca8a6df389d82cdf) (cherry picked from commit e97c8b0688bc62959ced477d842fcd37992ef649) --- Include/pystate.h | 1 + Python/pystate.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 2 deletions(-) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2020-03-23-18-08-34.bpo-20526.NHNZIv.rst --- a/Include/pystate.h +++ b/Include/pystate.h @@ -88,6 +88,7 @@ typedef struct _ts { struct _ts *next; PyInterpreterState *interp; + /* Borrowed reference to the current frame (it can be NULL) */ struct _frame *frame; int recursion_depth; char overflowed; /* The stack has overflowed. Allow 50 more calls --- a/Python/pystate.c +++ b/Python/pystate.c @@ -409,11 +409,19 @@ _PyState_ClearModules(void) void PyThreadState_Clear(PyThreadState *tstate) { - if (Py_VerboseFlag && tstate->frame != NULL) + if (Py_VerboseFlag && tstate->frame != NULL) { + /* bpo-20526: After the main thread calls + _PyRuntimeState_SetFinalizing() in Py_FinalizeEx(), threads must + exit when trying to take the GIL. If a thread exit in the middle of + _PyEval_EvalFrameDefault(), tstate->frame is not reset to its + previous value. It is more likely with daemon threads, but it can + happen with regular threads if threading._shutdown() fails + (ex: interrupted by CTRL+C). */ fprintf(stderr, "PyThreadState_Clear: warning: thread still has a frame\n"); + } - Py_CLEAR(tstate->frame); + /* Don't clear tstate->frame: it is a borrowed reference */ Py_CLEAR(tstate->dict); Py_CLEAR(tstate->async_exc);