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Subject: |
24.3.50; js2-mode parser is several times slower in lexical-binding mode |
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Date: |
Fri, 06 Sep 2013 23:59:20 +0300 |
If I append -*- lexical-binding: t -*- to the first line of js2-mode.el
and eval the buffer, parsing a file takes several (3 to 4) times longer.
To measure:
0. Install js2-mode, e.g. from GNU ELPA.
1. Save
http://mootools.net/download/get/mootools-core-1.4.5-full-nocompat.js to
some local directory, open it in Emacs.
2. If it opens in some other mode than js2-mode, M-x js2-mode.
3. Don't touch the keys, wait until the file is parsed (the parsing gets
interrupted and rescheduled on input). When redisplay works again, we
can re-parse the file again and measure the time it takes.
4. eval-expression (js2-time (js2-reparse t)), wait until the message
area displays the amount of seconds the process took.
To measure the performance in interpreted mode, open js2-mode.el, M-x
eval-buffer and go through the above scenario (1-4).
To measure the performance in compiled mode, M-x byte-compile-file, then
(load "js2-mode.elc"), then go through the scenario.
My measurements:
lexical-binding | no | yes |
Interpreted | 1 sec | 4.26 sec |
Compiled | 0.63 sec | 1.76 sec |
--
In GNU Emacs 24.3.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.6.4)
of 2013-09-06 on axl
Bzr revision: 114159 address@hidden
Windowing system distributor `The X.Org Foundation', version 11.0.11303000
System Description: Ubuntu 13.04
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--- Begin Message ---
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Subject: |
Re: bug#15294: 24.3.50; js2-mode parser is several times slower in lexical-binding mode |
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Date: |
Sun, 14 Dec 2014 09:08:23 -0500 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) |
>>> Not sure if I should close this issue now or at least wait until
>>> byte-compile--use-old-handlers is nil by default.
>> won't run on older Emacsen. I think I'd like to see 24.4 release before
>> making the change. But please do set it in your .emacs ASAP so it gets
>> wider testing.
> Just a reminder: I've been running with that setting for a while now,
So have I.
> with no problems that I can remember.
Well, I fixed a bug in it a while ago (some issue with "volatile", fixed
before the 24.4 release), but other than that, indeed it works fine.
The default value has been changed in "master" a couple months ago, already.
Stefan
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