Re: signal handling in plpython

On 14 October 2016 16:22:12 EEST, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>Heikki Linnakangas <hlinnaka(at)iki(dot)fi> writes:
>> On 10/14/2016 04:05 PM, Tom Lane wrote:
>>> I wrote:
>>>> Py_AddPendingCall is safe to call from a signal handler? That
>would
>>>> be ... quite remarkable.
>
>> Yes, I believe it is.
>
>>
>https://github.com/python/cpython/blob/4b71e63b0616aa2a44c9b13675e4c8e3c0157481/Python/ceval.c#L422
>
>I don't know whether to laugh or cry, but that code is a joke. Just
>silently fail if you can't get the lock?

Heh, ok, let me rephrase: I believe it's *intended* to be callable from a signal handler :). Whether it actually works is another question. Perhaps there's some mitigating conditions there, I don't know.

For our use case, it's actually not too bad if Py_AddPendingCall gives up and does nothing. Then the python function will simply not be interrupted until next SPI call, which is the current situation anyway.

- Heikki