Calling pselect/ppoll/epoll_pwait

[Barry]

     On 3 Dec 2022, at 13:13, Weatherby,Gerard <gweatherby at uchc.edu> wrote:

     

     Signalfd and select could probably be made to work if one codes around
     the race conditions pselect is provided to avoid. I’m not sure if using
     the GIL (for CPython) is sufficient or if a dedicated concurrency
     control (e.g. lock, mutex, semaphore) is necessary.

     An alternative is to call the C library function via a wrapper. I had
     need to use setfsuid on a project a couple of years ago and found this
     example:

     [1]https://gist.github.com/atdt/ebafa299e843a767139b

      

   I read this on SO when researching your question.
   Search for epoll and signal.

   (I would post the link but ipad turns the link into an image…)

   I assume that the lack of pepoll means you can use epoll and

   signalfd without race conditions. The trick seems to be setting

   the signal to ignore.

   Barry

      

     From: Python-list <python-list-bounces+gweatherby=uchc.edu at python.org>
     on behalf of Barry <barry at barrys-emacs.org>

     Date: Friday, December 2, 2022 at 7:02 PM
     To: Ian Pilcher <arequipeno at gmail.com>
     Cc: python-list at python.org <python-list at python.org>
     Subject: Re: Calling pselect/ppoll/epoll_pwait

     *** Attention: This is an external email. Use caution responding,
     opening attachments or clicking on links. ***

     > On 2 Dec 2022, at 20:03, Ian Pilcher <arequipeno at gmail.com> wrote:
     >
     > Does Python provide any way to call the "p" variants of the I/O
     > multiplexing functions?
     >
     > Looking at the documentation of the select[1] and selectors[2]
     modules,
     > it appears that they expose only the "non-p" variants.
     >
     > [1]
     [2]https://urldefense.com/v3/__https://docs.python.org/3/library/select.html__;!!Cn_UX_p3!hClFFo4XdiwQAhHxDbHA5zFr490Of9uheHSf84V9cREMHyw1kX-baG5HzXWMt-hFLP30q6DpSUb2G_OD5qBjeA$
     > [2]
     [3]https://urldefense.com/v3/__https://docs.python.org/3/library/selectors.html__;!!Cn_UX_p3!hClFFo4XdiwQAhHxDbHA5zFr490Of9uheHSf84V9cREMHyw1kX-baG5HzXWMt-hFLP30q6DpSUb2G_MwNjgO8A$

     Can you use signalfd and select/poll/epoll?

     Barry

     >
     > --
     >
     ========================================================================
     > Google                                      Where SkyNet meets
     Idiocracy
     >
     ========================================================================
     > --
     >
     [4]https://urldefense.com/v3/__https://mail.python.org/mailman/listinfo/python-list__;!!Cn_UX_p3!hClFFo4XdiwQAhHxDbHA5zFr490Of9uheHSf84V9cREMHyw1kX-baG5HzXWMt-hFLP30q6DpSUb2G_PhasKBfg$
     >

     --
     [5]https://urldefense.com/v3/__https://mail.python.org/mailman/listinfo/python-list__;!!Cn_UX_p3!hClFFo4XdiwQAhHxDbHA5zFr490Of9uheHSf84V9cREMHyw1kX-baG5HzXWMt-hFLP30q6DpSUb2G_PhasKBfg$

References

   Visible links
   1. https://gist.github.com/atdt/ebafa299e843a767139b
   2. https://urldefense.com/v3/__https:/docs.python.org/3/library/select.html__;!!Cn_UX_p3!hClFFo4XdiwQAhHxDbHA5zFr490Of9uheHSf84V9cREMHyw1kX-baG5HzXWMt-hFLP30q6DpSUb2G_OD5qBjeA$
   3. https://urldefense.com/v3/__https:/docs.python.org/3/library/selectors.html__;!!Cn_UX_p3!hClFFo4XdiwQAhHxDbHA5zFr490Of9uheHSf84V9cREMHyw1kX-baG5HzXWMt-hFLP30q6DpSUb2G_MwNjgO8A$
   4. https://urldefense.com/v3/__https:/mail.python.org/mailman/listinfo/python-list__;!!Cn_UX_p3!hClFFo4XdiwQAhHxDbHA5zFr490Of9uheHSf84V9cREMHyw1kX-baG5HzXWMt-hFLP30q6DpSUb2G_PhasKBfg$
   5. https://urldefense.com/v3/__https:/mail.python.org/mailman/listinfo/python-list__;!!Cn_UX_p3!hClFFo4XdiwQAhHxDbHA5zFr490Of9uheHSf84V9cREMHyw1kX-baG5HzXWMt-hFLP30q6DpSUb2G_PhasKBfg$