[Python-Dev] Issue #8863 adds a new?PYTHONNOFAULTHANDLER?environment variable (original) (raw)

Alexander Belopolsky alexander.belopolsky at gmail.com
Mon Dec 20 19:09:32 CET 2010

On Mon, Dec 20, 2010 at 12:51 PM, Victor Stinner <vstinner at edenwall.com> wrote: ..

Are you sure that a signal handler changes the registers? At least Linux saves integer and float registers before calling the signal handler, and then restores them. What if the program crashes (again) in the signal handler before having a chance to restore registers? Also, can you point to documentation that describes register restoring behavior? I am not sure all registers are (or even can be) restored.

The fault handler only changes some registers and write some bytes on the stack. The stack pointer is restored at exit, so I don't think that it causes troubles to use a core dump.

Dump a core file doesn't rely on process registers or mappings. Why do you think that it will break the core dump function?

Because I had actual experience with that using R. Your code may be better, but R brings up a dialog on segfault asking whether to produce a core dump. Occasionally, that core dump would be completely unusable because it would point to an unrelated point in the code. I don't have a specific case handy because long ago I disabled segfault handlers in the local R installation. (I actually use RPy which loads R into Python as a shared library, so the two handlers will conflict anyways.)

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