Re: process_send_string blocks?

[Stephen Leake <stephen_leake@stephe-leake.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Stephen Leake <stephen_leake@stephe-leake.org>
>> 
>> It appears that process-send-string is blocked on a full IO send queue,
>> while the background process is also blocked on a full IO send queue.
>
> Please tell the details of how did you determine this.

mostly a guess, combined with "there's nothting else wrong".

>> On reading process.c, I believe this should not happen, if the OS supports
>> EWOULDBLOCK. 
>> 
>> Is that true, even when there is only one call to process-send-string that
>> sends the entire buffer?
>
> Not sure what are you asking here, since you say you've read the code
> and saw the handling of EWOULDBLOCK.

Because it is often easy to misunderstand code that I am reading for the
first time. For example, I completely missed the threading stuff you
talk about below.

>> I'm running on Windows 7, using the Windows binary
>> emacs-23.4-bin-i386.zip from the FSF FTP site.
>> 
>> Is EWOULDBLOCK supported on this system?
>
> Not on writes to pipes, AFAIK.

Ah, then that's the problem. Hmm, except below you seem to be saying
maybe it's not?

>> I'll try compiling Emacs from source so I can run the debugger; I've
>> never tried that on Windows before.
>
> Please do that with the latest pretest, as 24.3 is by now ancient
> history.

Ok.

> <snip code description>

thanks for the code info; that will help when I get the debugger
running.

> The first thing I'd do is attach GDB to the hung Emacs and see where
> each one of these 2 threads is parked.  (Note that there are more
> threads in a running Emacs than just these 2.)

I'll give that a try.

> Finally, it is better to continue all this on the bug tracker, perhaps
> as part of bug #18396, or a new bug report, if you don't want to mix
> up these 2.

It's not clear whether this is the same bug; I'll file a new one. I have
a reliable reproducer, which I can easily simplify.

-- 
-- Stephe