[Python-Dev] Issue #8863 adds a new PYTHONNOFAULTHANDLER environment variable

[Victor Stinner]

Le lundi 20 décembre 2010 à 02:05 +0100, "Martin v. Löwis" a écrit :
> The problem is that merely being POSIX compliant would not be enough
> to allow calling a function in a signal handler. Instead, the function
> *also* needs to be async-signal safe.

Yes, this issue was fixed in an older version of my patch. Starting at
version 9, the signal handler only call signal-safe functions.

> Looking at your function list, my other concern is that you are calling
> Python API without holding the GIL, IIUC. In particular, you are
> accessing _PyThreadState_Current, which may not point to the current
> thread if the current thread has released the GIL.

Ah? Where does _PyThreadState_Current point to if the GIL is not hold
when the fault handler is called? My patch changes also Py_FatalError()
to display the Python backtrace.

It looks that _PyThreadState_Current can be NULL if the GIL is released.
In this case, _Py_DumpBacktrace() just do nothing. There is also a
gil_last_holder variable: can it be used to get the thread state
(especially if the thread state was deleted)?

I don't think that it will possible the acquire the GIL in
Py_FatalError() or in the fault handler.

Victor