bug#41640: 28.0.50; shell startup very slow when init file is used

[Eli Zaretskii]

> From: Pip Cet <pipcet@gmail.com>
> Date: Thu, 04 Jun 2020 21:21:00 +0000
> Cc: 41640@debbugs.gnu.org
> 
> diff --git a/lisp/comint.el b/lisp/comint.el
> index ea06f8af87..4354a155c3 100644
> --- a/lisp/comint.el
> +++ b/lisp/comint.el
> @@ -809,18 +809,10 @@ comint-exec
>        (goto-char (point-max))
>        (set-marker (process-mark proc) (point))
>        ;; Feed it the startfile.
> -      (cond (startfile
> -          ;;This is guaranteed to wait long enough
> -          ;;but has bad results if the comint does not prompt at all
> -          ;;      (while (= size (buffer-size))
> -          ;;        (sleep-for 1))
> -          ;;I hope 1 second is enough!
> -          (sleep-for 1)
> -          (goto-char (point-max))
> -          (insert-file-contents startfile)
> -          (setq startfile (buffer-substring (point) (point-max)))
> -          (delete-region (point) (point-max))
> -          (comint-send-string proc startfile)))
> +      (when startfile
> +        (comint-send-string proc (with-temp-buffer
> +                                   (insert-file-contents startfile)
> +                                   (buffer-string))))

The code and the comments don't say why we used sleep-for, which your
patch removes.  Did you succeed in understanding what was that for,
and if so, can you describe that reason and the rationale for removing
the sleep?

Thanks.