# Emacs freezes using Sweave and ESS

I am using Emacs + ESS + Sweave to write a document. When I do multiline copy of noweb commands using M-w, switch to R buffer and execute them (C-y, RET), Emacs will sometimes freeze, forcing me to kill Emacs and start over. This also happens with C-c C-c'ing of a text block.

EDIT: I am using Emacs 24.3.1, ESS 14.09, R 3.1.2.

EDIT: After some testing, the following file will reproduce this problem. Specifically, the first chunk will cause Emacs to hang. The only resolution is to first C-g then switch to the R buffer and C-q C-c to return full control.

\documentclass[10pt]{article}
\usepackage{graphicx, verbatim, geometry,amsmath,amssymb, natbib, float, enumerate, courier, underscore}
\usepackage[utf8x]{inputenc}
\geometry{margin=1in}
\setlength{\textwidth}{6.5in}
\setlength{\textheight}{9in}

\begin{document}

<<>>=
library(ggplot2)
dat <- matrix(runif(100), nrow=10)
cc <- apply(dat, 1, function(xx){
sum(cos(xx))
})
@

The quick brown fox jumps over the lazy dog.

<<>>=
bcc <- sapply(cc, function(xx){
fft(xx)
})
@

\end{document}

• Next time it happens, do a kill -USR2 <emacs-pid> which will break most hangs and produce a backtrace. For extra info do M-x profiler-start when you start Emacs and M-x profiler-report after you kill. – PythonNut Feb 1 '15 at 17:03
• It's a long trace. Is there something specific you are looking for? – learner Feb 1 '15 at 17:08
• Something similar happens to me sometimes when I try to yank a shell buffer with a lot of text in it (a log of some sort), I think that it is either clipboard- or history-related. If you wait for a while (this isn't guaranteed to happen) but if you are up for experiment, some times it might pop up a *Warnings* buffer with a text about maximum undo steps exceeded. If that sounds familiar, I think it might make sense to file a bug to Emacs developers. – wvxvw Feb 1 '15 at 20:18
• Does it happen when you send-region instead? I think it's C-c C-r, which should be available from a Rnw document. – Tyler Feb 1 '15 at 20:23
• I should add that Sweave-ing the document doesn't produce a hang up, nor does manually entering calls that when yanked/sent would freeze. – learner Feb 2 '15 at 12:16