bug#64735: 29.0.92; find invocations are ~15x slower because of ignores

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: sbaugh@catern.com, sbaugh@janestreet.com, dmitry@gutov.dev,
>  michael.albinus@gmx.de, rms@gnu.org, 64735@debbugs.gnu.org
> Date: Sun, 23 Jul 2023 08:11:56 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> But won't the Elisp callback always result in a queue that will
> >> effectively be synchronous?
> >
> > I don't understand the question (what queue?), and understand even
> > less what you are trying to say here.  Please elaborate.
> 
> Consider (async-directory-files-recursively dir regexp callback) with
> callback being (lambda (file) (start-process "Copy" nil "cp" file "/tmp/")).

What is async-directory-files-recursively, and why are we talking
about it?  I was talking about an implementation of
directory-files-recursively as a primitive in C.  That's not async
code.  So I don't understand why we are talking about some
hypothetical async implementation.

> `async-directory-files-recursively' may fire CALLBACK very frequently.
> According to the other benchmarks in this thread, a file from directory
> may be retrieved within 10E-6s or even less. Elisp will have to arrange
> the callbacks to run immediately one after other (in a queue).
> Which will not be very different compared to just running callbacks in a
> synchronous loop.

Regardless of my confusion above, no one said the callback must
necessarily operate on each file as soon as its name was retrieved,
nor even that the callback must be called for each file.