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Re: slow output in *compilation* buffer
From: |
Dan Nicolaescu |
Subject: |
Re: slow output in *compilation* buffer |
Date: |
Sat, 22 Aug 2009 23:27:08 -0700 (PDT) |
Stefan Monnier <address@hidden> writes:
> > % cumulative self self total
> > time seconds seconds calls s/call s/call name
> > 31.19 2.72 2.72 52618323 0.00 0.00 lookup_char_property
> > 20.30 4.49 1.77 51726150 0.00 0.00 previous_interval
> > 12.16 5.55 1.06 208889310 0.00 0.00 Fcdr
> > 5.85 6.06 0.51 52444384 0.00 0.00 Fassq
> > 5.39 6.53 0.47 4573 0.00 0.00
Fprevious_single_property_change
> > 2.64 6.76 0.23 8860105 0.00 0.00 mark_object
> > 2.52 6.98 0.22 10621 0.00 0.00 Fsetcar
> > 2.29 7.18 0.20 52618300 0.00 0.00 textget
> > 1.83 7.34 0.16 59828 0.00 0.00 re_search_2
> > 1.72 7.49 0.15 305181 0.00 0.00 re_match_2_internal
> > 1.03 7.58 0.09 82087 0.00 0.00 Fbyte_code
> > 0.80 7.65 0.07 9094 0.00 0.00
adjust_for_invis_intang
> > 0.80 7.72 0.07 581767 0.00 0.00 find_interval
> > 0.69 7.78 0.06 295253 0.00 0.00 next_interval
> > 0.69 7.84 0.06 21 0.00 0.02 Fgarbage_collect
> > 0.57 7.89 0.05 23886 0.00 0.00 mark_vectorlike
>
> - not sure why it's GCing that much, but it sounds like something that
> can be improved.
> - the re_* part of the profile is hard to improve with a quick fix,
> I think: it just represents regexp-searching every one of the regexps
> in compilation-error-regexp-alist in turn. Of course, there is a way
> to do that (a lot) faster, by compiling all those regexps into a DFA.
That sounds like a good idea, but it does not look like it will have a
huge impact?
> - why does the gprof data only seem to account for a bit less than 10s
> when you say it takes 25s to complete?
Don't know. I double checked and it's consistent. Maybe oprofile can
reveal more, I might try that too when I get a chance if nobody beats
me to it.
> - 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.
BTW, doing the same search with M-x rgrep is MUCH MUCH slower.
> Another thing: the compilation code currently uses font-lock-keywords,
> but it should probably be changed to use font-lock-syntactic-keywords
> instead (which should make it unnecessary to disable jit-lock).
>
> > So it seems that fontification (and things related to it) are very very
expensive.
>
> compile.el does its work via font-lock, so I do expect most/all of the
> time to be spent there.
They time spent there seems a bit excessive, so maybe something strange
is going on...