[Python-Dev] Python threads end up blocking signals in subprocesses

[Martin v. Löwis]

Michael Hudson <mwh at python.net> writes:

> > I'm not sure what to do about this: We apparently *want* the signals
> > blocked in the thread, but we don't want them to be blocked in the
> > process invoked through system(). Proposals are welcome.
> 
> Does pthread_atfork() help?

Most likely. system(3) is specified as being implemented through
fork()/exec(), so an atfork handler should be invoked in any compliant
implementation. We could install a child handler, which unblocks the
signals we don't want to be blocked.

Now, the question is: What signals precisely we don't want to be
blocked? I think the answer is "All signals that have not explicitly
been blocked by the application".

OTOH, we already have PyOS_AfterFork, which could be used instead of
pthread_atfork. Jeff, would you like to add some code there, to set
all signal handlers into default for which Handlers lists that the
default handling should occur?

Regards,
Martin