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Re: slow output in *compilation* buffer
From: |
Dan Nicolaescu |
Subject: |
Re: slow output in *compilation* buffer |
Date: |
Wed, 26 Aug 2009 00:33:08 -0700 (PDT) |
Stefan Monnier <address@hidden> writes:
> >> - It seems that they the calls to the interval code come from
> >> compilation-error-properties, but that function should only be called
> >> for regexps that do match, which shouldn't be that many. Can you look
> >> at the text to see if there really are that many matches? BTW, we
> >> should probably be able to make compile.el a bit lazier (i.e. the
> >> font-lock-phase part of the code should do a bit less work by moving
> >> it to the next-error-phase code).
> > The output is about 4500 lines, they all match.
>
> Ah, I see. So yes, the likely solution is to make compile.el lazier:
> use font-lock-syntactic-keywords and jit-lock (so the text past the end
> of the window doesn't need to be scanned right away), and postpone more
> of the work to next-error.
elp says that most time is spent in `compilation-error-properties', if
that helps...
> > BTW, doing the same search with M-x rgrep is MUCH MUCH slower.
>
> That sucks. What does rgrep do so differently to make it even worse?
My guess would be more highlighting: it also highlights the matched words on
each line.
> > > They time spent there seems a bit excessive, so maybe something
strange
> > is going on...
>
> That's also possible.
% cumulative self self total
time seconds seconds calls s/call s/call name
33.02 2.46 2.46 50974295 0.00 0.00 lookup_char_property
21.61 4.07 1.61 50847996 0.00 0.00 previous_interval
13.83 5.10 1.03 204112526 0.00 0.00 Fcdr
7.25 5.64 0.54 50946735 0.00 0.00 Fassq
6.17 6.10 0.46 4509 0.00 0.00
Fprevious_single_property_change
elp says there are 9018 calls to `compilation-error-properties'
The file has 4509 lines, and it's fontified twice (M-x compilation-mode + M-x
font-lock-fontify-buffer)
That means 50974295/4509 = 11305 lookup_char_property calls per
Fprevious_single_property_change ...
that sounds a bit excessive.
Now lets just double the input file (cat input input > input2) and
perform the same experiment on the new file.
% cumulative self self total
time seconds seconds calls s/call s/call name
37.86 12.09 12.09 203594871 0.00 0.00 lookup_char_property
21.20 18.86 6.77 203351394 0.00 0.00 previous_interval
17.38 24.41 5.55 814793814 0.00 0.00 Fcdr
5.98 26.32 1.91 9018 0.00 0.00
Fprevious_single_property_change
203594871/9018 = 22576