Re: Fixxed buffer size for eshell

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 30 Apr 2017 13:02:52 +0300
> From: Anast Gramm <anastasis.gramm2@gmail.com>
> 
> When I run a build command eshell gets filled with thousands of lines
> with the compiler commands.
> 
> This results in a huge buffer (>10mb) thus slowing down emacs.

Large buffers shouldn't slow down Emacs.  They don't here.  And 10MB
is not large by today's standards anyway.

Can you show a recipe for reproducing the problem?

Also, what Emacs version is that?

> As a workaround I use the clear function copied straight out of
> the emacsdev mailing list [1].
> 
> This is not ideal, since I use it after the buffer is filled, and emacs
> is already slow at that point.
> 
> What I want is a fixed buffer size, like in normal terminals where
> you have a set amount of lines.

You could write a function that removes old lines, and have it on
post-command-hook.  But you shouldn't need something like that, so I
think you should report a bug and let the Emacs developers fix it or
tell you how to avoid the slowdown in a more elegant way.