Re: [h-e-w] CRITICAL BUG: process-send-region hangs ntEmacs if region >64K

[Lennart Borgman]

Could you please try the pretest beta and then report this as a bug
there? (With M-x report-emacs-bug)


On Mon, Jan 11, 2010 at 5:04 PM, Jeffrey J. Kosowsky
<address@hidden> wrote:
> When using process-send-region-process to send a region more than
>  about 64K in size to the command 'cat', emacs hangs forever and is
>  *only* recoverable by going out of emacs to kill the 'cat' process.
>
> The following simple code snippet reproduces the problem where NNNN is
>  bigger than about 64K. Just run it on a region containing sufficient
>  text...
>
>  (progn (setq process (start-process "test" "tempbuff" "cat"))
>  (process-send-region process (point-min) NNNNN))
>
> Note the problem *does* not occur with synchronous use of 'cat' via
> call-process-region nor does it occur if you 'cat' the region onto a
> file (e.g. using "> tempfile" as part of the &rest args). Also, this
> problem does not occur on Linux.
>
> The exact cutoff for when it fails is always within a few thousand
> bytes of 64K but varies by file (and may be related to things like
> encoding).
>
> The problem also occurs if NNNN is smaller than 64K but you send
> multiple separate regions of size >64K in rapid succession.
>
> This seems to be some type of buffering issue.
>
> Also, the bug is not *theoretical* in that it breaks functionality in
> the vm.el (viewmail) program.
>
> I am using:
>  GNU Emacs 23.1.50.1 (i386-mingw-nt5.1.2600) of 2009-09-23 on YAMALOK
> But I also tested the problem on earlier versions of ntemacs (again
>  Linux works fine)
>
> This bug may or may not be related to the following code snippet found
> in the standard tramp.el package:
>      ;; Under Windows XP, accept-process-output doesn't return
>      ;; sometimes.  So we add an additional timeout.
>      (with-timeout ((or timeout 1))
>        (accept-process-output proc timeout timeout-msecs)))
>
>
>