bug#29095: Bug: The '20a09de953f437109a098fa8c4d380663d921481' merge increased my Emacs configuration loading time from 9 s to 60 s

[Noam Postavsky <npostavs@users.sourceforge.net>]

Alexander Shukaev <emacs@Alexander.Shukaev.name> writes:

>> What confuses me though, is how a 100ms delay is adding ~50s to your
>> starup time?!  Or are you just creating 500 frames on startup?
>
> Hah, of course not.  So I took some additional time to investigate
> where this comes from and in turned out to be very simple:
>
> (setq-default minibuffer-auto-raise t)
>
> causes this.  I think this needs to be addressed.  Either by
> documenting this side effect or finding a better solution.

Ah, so if I understand correctly, because of the minibuffer-auto-raise
setting, every time a message is printed Emacs tries to make the frame
visible, and because of x-wait-for-event-timeout, it waits for 100ms
each time.  So if you get around ~500 messages during startup, it would
take about 50 seconds, thus explaining the increase you observed?

Perhaps the thing to do is simply to disable x-wait-for-event-timeout if
we end up hitting the timeout.  Under most window managers the frame
becomes visible much faster than 100ms anyway, as far as I know.

> I figured out why this GC issue was happening.  It's a bug with
> `magit-filenotify' package, which I've already reported and found
> workaround for.  So apart from my concerns about
> `minibuffer-auto-raise' and `x-wait-for-event-timeout', looks good so
> far.

Ah yes, I saw that.  It looks like it's not actually a GC issue as such,
but an (asynchronous) infinite loop that generates a lot of garbage (and
hence work for the GC).

https://github.com/ruediger/magit-filenotify/issues/20