Date: Sun, 11 Jan 2009 19:41:25 -0500
From: Christopher Faylor <cgf-use-the-mailinglist-please@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: Signal handling in Win32 GUI programs
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On Sun, Jan 11, 2009 at 08:53:49PM +0000, Andy Koppe wrote:
>>>I've added a thread doing 'for (;;) pause();', but unfortunately that
>>>doesn't seem to do the trick.  Do I need to go into Cygwin internals
>>>and wait directly on the Win32 event(s) used for signals?
>>sigwait() will probably work better than pause.
>
>That indeed works, thank you very much! I didn't know that function,
>very handy.  With that and threads, signal handlers with all their
>vagaries aren't really needed anymore, are they?

I have it on my todo list to see why pause doesn't work.  I'd like to do
some signal revamping someday but I don't want to destabilize 1.7.0 to
do that.

>And speaking of threads, does it make a difference whether one uses
>Pthreads or Win32 threads?  I mean apart from portability and the small
>overhead Pthreads presumably incur.

You really have to use pthreads.  Using non-posix methods is always asking
for trouble in Cygwin.

>MinTTY's got three such little helper threads hanging about now, doing
>waitpid() on the child process, read() on the child pty, and the
>abovementioned sigwait().  Would there be any point in trying to
>consolidate them into a single sigwait() process, using SIGCHLD and
>asynchronous reads?

Hmm.  I guess you could just do a sigwait on SIGCHLD and consolidate the
signal handling with that.  I don't think it makes sense to set up async
I/O just to do reads on the pty.  That would eliminate one thread at
least.

cgf

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