Re: FAQ: gnuplot vs. emacs' compile command

From: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: Dan Jacobson <jidanni@dman.ddts.net>,
	arafune@debian.org, emacs-devel@gnu.org
Subject: Re: FAQ: gnuplot vs. emacs' compile command
Date: 12 Feb 2004 14:34:11 -0500	[thread overview]
Message-ID: <jwv3c9g857c.fsf-monnier+emacs/devel@asado.iro.umontreal.ca> (raw)
In-Reply-To: <m3fzdgl5n7.fsf@kfs-l.imdomain.dk>

> Did anyone actually look at this bug back in May ?
> FYI, I have included the text at the referenced link here.

What is the bug exactly?
My understanding is of the problem:
when Emacs exits, gnuplot is killed because its stdout is connected to
Emacs (i.e. it receives a SIGPIPE or SIGHUP or somesuch).

        Stefan

> Dan Jacobson <jidanni@dman.ddts.net> writes:

>> Fellas, the gnuplot team may have found ugly emacs process bugs, see
>> <...>
>> 

> : Dan Jacobson <jidanni@dman.ddts.net> wrote:
> : 
> : > Using emacs -eval '(compile "make")'
> : > With: echo "plot 'file';pause -1"|gnuplot -persist
> : > just flashes the graph for a split second.
> : 
> : So let's get into dissecting this further.  The first candidate to
> : remove is 'make'.  It doesn't really do anything useful in this whole
> : setup, so we might as well get rid of it.  Let's replace it by a shell
> : script doing the same things.  And while at it, let's get rid of the
> : separate data file, too:
> : 
> : --- gpaction ---
> : gnuplot -persist <<EOS
> :  plot '-'
> :    1 1
> :    2 2
> :   e
> : EOS
> : ---- end ---
> : 
> : sh gpaction                                 # does the plot and returns
> : emacs -eval '(compile "sh gpaction")'       # doesn't plot, but returns
> : emacs -eval '(shell-command "sh gpaction")' # plot, but no return
> : 
> : For the latter, emacs is unresponsive --- it's obviously waiting for
> : something to happen, which doesn't.  Only after you terminate the
> : gnuplot graph window (key 'q' into it), or press Ctrl-G in emacs to
> : forcibly break out of the wait loop, it will continue.
> : 
> : During that pause, look at the output from 'ps jx' and you'll find
> : that gnuplot_x11 is an orphan --- i.e. it's the only surviving process
> : in its process group.  In "shell-command", emacs apparently doesn't
> : kill it, whereas in "compile", it probably does.
> : -- 
> : Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
> : Even if all the snow were burnt, ashes would remain.

> -- 
> Kim F. Storm  http://www.cua.dk

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