bug#8890: 23.3; message writing slows emacs

[Dave Abrahams]

on Fri Sep 16 2011, Eli Zaretskii <eliz-AT-gnu.org> wrote:

>> From: Stefan Monnier <monnier@iro.umontreal.ca>
>
>> Date: Fri, 16 Sep 2011 09:18:51 -0400
>> Cc: 8890@debbugs.gnu.org
>> 
>> "A few milliseconds" sounds negligible, but if it's done at every
>> iteration of a loop whose body takes less than a millisecond to run
>> (we can do a lot of work in a millisecond on today's machines), then
>> it's a major slowdown.
>
> Then programmers who run those loops should update the progress less
> aggressively.  Redisplay (and infrastructure in general) lack the
> context that would allow them to make good decisions as to when defer
> repeated display.  Only the calling application can know that.

There's a middle path: provide a `progress-message' function.  That
allows the caller to provide the semantic context that this particular
message isn't critical without burdening every single application with
building its own throttling updater.

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com