Ess hangs emacs sometimes

Kjetil Kjernsmo kjetil.kjernsmo at
Thu Jun 21 19:25:52 CEST 2001

On Thu, 21 Jun 2001, Martin Maechler wrote:

>    Kjetil> Actually, I have it here too (ESS 5.1.11, Emacs 19.31.1 [sic!
>    Kjetil> :-) ], R-1.2.1 Patched (2001-01-31), OSF1 alnair V4.0 1091
>    Kjetil> alpha).  Most notably, it happens if R isn't running, or if R
>    Kjetil> is unable to accept input for some reason.
>and you *did* try to `say'
>    C-g
>to emacs ?

Eh, no.... :-) I wasn't aware of its existence... But I did have
extensive sessions of hammering maniacally on the keyboard, so I am
surprised that I haven't hit C-g before. :-)

>There is this principal `design bug' that Emacs waits for R's prompt
>in some situations. E.g. when you have some code that would take 10 minutes
>of CPU for R (or other S implementations) to compute,
>*and* if you send the corresponding code from an [ESS] to an [iESS] buffer,
>then subsequently use something like top (btw, use "lavaps" if you can,
>really cool!) to see what your CPU is doing, you may notice that
>half the CPU is used by emacs and only the other half by the R (or Sqpe..)
>executable.  Pressing C-g in this situations stops emacs' waiting loop
>and let's R have all the CPU cycles..

I see! Smart! Anyway, the way I tested C-g now you made me aware of it,
was to start ESS-elsewhere and upon seeing the shell prompt hit
ess-eval-buffer. That hung Emacs with after a Starting
Evaluation...-message. Previously, Emacs hasn't responded to anything, I
had to kill it from another shell, but indeed, C-g gets me out of it.

>Some of the above has been on this mailing list several years ago,
>and I think the situation happens more rarely,
>and the description may even have been put into the ESS documentation..
>{Tony? anyone from ESS-core ?}

Well, yeah. Sometimes one is in need of protection from ones own
stupidity. :-) It is a matter of knowing when to not eval at the wrong
times, and know how to get out of it gracefully. I have been ignorant in
both aspects, and thanks to Paul for letting me have the opportunity to
come out of the closet and become educated! :-)


Kjetil Kjernsmo
Graduate astronomy-student                    Problems worthy of attack
University of Oslo, Norway            Prove their worth by hitting back
E-mail: kjetikj at                                - Piet Hein
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