Re: Delivering SIGIO when several threads are active?

[Eli Zaretskii <eliz@gnu.org>]

> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Fri, 30 Dec 2016 09:54:01 -0800
> 
> Eli Zaretskii wrote:
> > When SIGIO is received by some thread, we currently deliver it to the
> > main thread, see deliver_input_available_signal and
> > deliver_process_signal.  Is that appropriate when more than one thread
> > is active?
> 
> Such signals have been delivered to the main thread for quite some time, and 
> this has worked well enough; is there something different about the concurrency 
> code that now makes this behavior inappropriate?

I don't know, that's why I asked.  For example, what if another thread
is waiting on the keyboard descriptor and wants to handle keyboard
input, or wants to receive X events?

> On GNU/Linux, process signals get sent to the main thread unless the main thread 
> is blocking them (or if a few less-common situations arise, e.g., the main 
> thread is exiting).

And what happens in those exceptional cases?

> Hmm, I see that the recent changes use mixed terminology. Until now, Emacs has 
> called the initial thread the "main thread", but the recent code sometimes calls 
> it the "primary thread". We shouldn't have two names for the same thing. I'll 
> look into fixing that.

"Primary thread" is the name of the main thread.