Re: [babel] [PATCH] Fix sh block execution in session

[Eric Schulte <schulte.eric@gmail.com>]

Hi Julien,

Thanks for this patch, the current method of waiting for output in shell
code blocks could certainly use improvement.  After a series of simple
tests I can confirm that this does appear to work for me.  I have a
couple of questions.

1. do you have a minimal example of a shell code block which works after
   your patch but not before?

2. I assume that the changes to ob-comit were required for your ob-sh
   changes to work and were not intended to affect other languages?

3. When switching the order of the prompt and eoe check in ob-comint,
   did you try *only* looking for the eoe indicator?  It seems to me
   that once that is present the check for a followup prompt may not be
   required and it may make sense to simply remove that code.

All in all I agree that the ob-sh changes look like an improvement and
should be applied.  I'm less sure of the changes to ob-comint, simply
because I don't understand the mechanism through which swapping the
regexp checks changes behavior.  However if the ob-sh changes depend
upon the ob-comint changes there is no point in applying them piecemeal.

Situations like this (innocuous looking changes with potentially
wide-ranging potential implications) make me wish Babel had a more
mature and better-maintained test suite.

Thanks -- Eric

Julien Barnier <julien@nozav.org> writes:

> Hi,
>
> When evaluating shell code blocks in org-babel, the execution seems to hang
> indefinitely. The following patch is trying to fix this problem by modifying
> the way shell code is send to comint and the way the end-of-evaluation
> indicator is looking for.
>
> As I am far from an emacs lisp expert and as the patch modifies the widely use
> org-babel-comint-with-output function, it certainly needs some testing. I've
> made some tests with shell and R code blocks, but I'm not sure it's enough.
>
> Thanks !
>
> Julien
>
>
> Fix sh block execution in a session
>
> * lisp/ob-sh.el (org-babel-sh-evaluate) : when sending input to comint, wait
> until previous line execution is finished
> * lisp/ob-comint.el (org-babel-comint-with-output) : when looking for
> end-of-evaluation indicator, search forward for the indicator before searching
> forward for the prompt
> ---
>  lisp/ob-comint.el |    4 ++--
>  lisp/ob-sh.el     |    8 +++++++-
>  2 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/lisp/ob-comint.el b/lisp/ob-comint.el
> index d12ed47..21ff0f6 100644
> --- a/lisp/ob-comint.el
> +++ b/lisp/ob-comint.el
> @@ -93,9 +93,9 @@ or user `keyboard-quit' during execution of body."
>  			  (goto-char comint-last-input-end)
>  			  (not (save-excursion
>  				 (and (re-search-forward
> -				       comint-prompt-regexp nil t)
> +				       (regexp-quote ,eoe-indicator) nil t)
>  				      (re-search-forward
> -				       (regexp-quote ,eoe-indicator) nil t)))))
> +				       comint-prompt-regexp nil t)))))
>  		   (accept-process-output (get-buffer-process (current-buffer)))
>  		   ;; thought the following this would allow async
>  		   ;; background running, but I was wrong...
> diff --git a/lisp/ob-sh.el b/lisp/ob-sh.el
> index 10c08d4..b2d1591 100644
> --- a/lisp/ob-sh.el
> +++ b/lisp/ob-sh.el
> @@ -170,7 +170,13 @@ return the value of the last statement in BODY."
>  	    (session org-babel-sh-eoe-output t body)
>  	  (mapc
>  	   (lambda (line)
> -	     (insert line) (comint-send-input nil t) (sleep-for 0.25))
> +	     (insert line)
> +	     (comint-send-input nil t)
> +	     (while (save-excursion
> +		      (goto-char comint-last-input-end)
> +		      (not (re-search-forward
> +			    comint-prompt-regexp nil t)))
> +	       (accept-process-output (get-buffer-process (current-buffer)))))
>  	   (append
>  	    (split-string (org-babel-trim body) "\n")
>  	    (list org-babel-sh-eoe-indicator))))

-- 
Eric Schulte
http://cs.unm.edu/~eschulte/