New submission from STINNER Victor <[email protected]>:
bpo-3605 modified PyErr_Occurred() to return NULL if the current Python thread
state ("tstate") is NULL:
commit 8e0bdfd1d473ddffaf3501768678f8a970019da8
Author: Jeffrey Yasskin <[email protected]>
Date: Thu May 13 18:31:05 2010 +0000
Make PyErr_Occurred return NULL if there is no current thread. Previously
it
would Py_FatalError, which called PyErr_Occurred, resulting in a
semi-infinite
recursion.
Fixes issue 3605.
This change made PyErr_Occurred() inefficient: PyErr_Occurred() was a simple
attribute read (tstate->curexc_type), and now there is an additional if per
call.
I recently added _PyErr_Occurred(tstate) which is similar to PyErr_Occurred()
but requires to pass tstate explicitly. I expected this function to be as
simple as:
static inline PyObject* _PyErr_Occurred(PyThreadState *tstate)
{
return tstate->curexc_type;
}
but the current implementation is:
static inline PyObject* _PyErr_Occurred(PyThreadState *tstate)
{
return tstate == NULL ? NULL : tstate->curexc_type;
}
--
PyErr_Occurred() is currently implemented as:
PyObject* _Py_HOT_FUNCTION
PyErr_Occurred(void)
{
PyThreadState *tstate = _PyThreadState_GET();
return _PyErr_Occurred(tstate);
}
_PyThreadState_GET() must only be called with the GIL hold. This macro is
designed to be efficient: it doesn't check if tstate is NULL.
_PyThreadState_GET() is only NULL if the thread has no Python thread state yet,
or if the GIL is released.
IMHO PyErr_Occurred() must not be called if the GIL is released.
----------
components: Interpreter Core
messages: 356180
nosy: vstinner
priority: normal
severity: normal
status: open
title: PyErr_Occurred(): tstate must be non-NULL
versions: Python 3.9
_______________________________________
Python tracker <[email protected]>
<https://bugs.python.org/issue38733>
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