#430: Threaded mainloop API steals signals unnecessarily
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Reporter: jcornwall | Owner: lennart
Type: defect | Status: closed
Priority: normal | Milestone:
Component: libpulse | Severity: normal
Resolution: invalid | Keywords:
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Changes (by lennart):
* status: new => closed
* resolution: => invalid
Comment:
Hmm, we explicitly block all signals in the threaded poll to make sure we
don't interfere with normal signal delivery. (the reason for that is that
signal handlers are process wide, and if a process receives a signal it is
not defined which thread it will be deliered too. To make sure that the
signals are only delivered to threads that are maintained by the
application programmer himself we thus block signals in all threads we
maintain.) This is for compatibility reasons. Now, as it turns out, Mono
doesn't like that since it (mis)uses signals for debugging purposes. If
that's the case however it probably is a better idea to temporarily enable
signals when control is passed to mono code from the threaded event loop
and block them again afterwards. i.e. each time you call into mono from
one of the threaded callbacks do a:
{{{
sigfillset(&mask);
pthread_sigmask(SIG_UNBLOCK, &mask, &saved);
...
/* call into mono here */
...
pthread_sigmask(SIG_SETMASK, &saved, NULL);
}}}
Of course it would be more appropriate only to unblock the signals that
mono really needs instead of all of them.
I don't think it would be a good idea to merge the patch you suggested.
While it be good for compatibility with mono it will most likely create
problems in other software. Also, blocking all signals feels more correct
to me. And finally, changing behaviour in the middle of everything seems
like the worst solution to me.
--
Ticket URL: <http://pulseaudio.org/ticket/430#comment:1>
PulseAudio <http://pulseaudio.org/>
The PulseAudio Sound Server
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