GNU bug report logs - #15755
24.3.50; cperl-mode annoyingly slow on my netbook

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jambunathan K <kjambunathan <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Wed, 30 Oct 2013 18:59:56 +0530

On my netbook (HP Mini 110) cperl-mode responds so slowly that it is
very annoying to type.  

Consider this bug as a counter-point to those who argue for making
cperl-mode the default.

ps: I don't have any cperl-mode specific customizations in my .emacs.


In GNU Emacs 24.3.50.4 (i686-pc-linux-gnu, GTK+ Version 2.20.1)
 of 2013-10-30 on debian-6.05
Bzr revision: 114868 rgm <at> gnu.org-20131030102316-8vif7u6ecyo3yieg
Windowing system distributor `The X.Org Foundation', version 11.0.10707000
System Description:	Debian GNU/Linux 6.0.5 (squeeze)

Message #8 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> IRO.UMontreal.CA>
To: Jambunathan K <kjambunathan <at> gmail.com>
Cc: 15755 <at> debbugs.gnu.org
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Wed, 30 Oct 2013 14:13:34 -0400

> On my netbook (HP Mini 110) cperl-mode responds so slowly that it is
> very annoying to type.

Usually, cperl-mode is fast enough (most of my machines are about as
powerful as a typical netbook).  So maybe you're just hitting a bug
(tho, maybe you're hitting a pathological case, as well).

Do you have some test case we can use to reproduce the problem?


        Stefan

Message #11 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Jambunathan K <kjambunathan <at> gmail.com>
To: Stefan Monnier <monnier <at> IRO.UMontreal.CA>
Cc: 15755 <at> debbugs.gnu.org
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Thu, 31 Oct 2013 01:13:47 +0530

[Message part 1 (text/plain, inline)]

Stefan Monnier <monnier <at> IRO.UMontreal.CA> writes:

>> On my netbook (HP Mini 110) cperl-mode responds so slowly that it is
>> very annoying to type.
>
> Usually, cperl-mode is fast enough (most of my machines are about as
> powerful as a typical netbook).  So maybe you're just hitting a bug
> (tho, maybe you're hitting a pathological case, as well).
>
> Do you have some test case we can use to reproduce the problem?

If indeed this is a bug, I would call it a "showstopper" for cperl-mode.

Here is a recipe.  The file used below is the Oddmuse's Wiki engine.

mkdir ~/tmp

cd ~/tmp

wget http://git.savannah.gnu.org/cgit/oddmuse.git/plain/wiki.pl

emacs -Q

Here is a report from M-x view-lossage RET.  I do this:

1. C-x C-f ~/tmp/wiki.pl
2. M-x cperl-mode
3. C-s ApplyRules {
4. C-a
5. Move the cursor down a few lines
6. C-M-e.  Jump to end of defun. Move up a few lines to seek the comment
   line.
7. Type a few characters

(5) is slow. (7) is very slow.  Meaning it takes ages for the 10 or so
characters to be echoed.

Interestingly, after (2) I see the following message reported by
cperl-mode.  I am not sure whether the error is a cause for slow
performance.

Anyways, if I do,

    perl wiki.pl

I don't see the perl complaining about the file being bad.  So there is
a bug somewhere.

Apart from the recipe above, you can try the following

1. Mark the ApplyRules sub.
2. M-x indent-region it.

With perl-mode, (1) and (2) is very quick.  But with cperl-mode things
are bad.



--8<---------------cut here---------------start------------->8---
End of `qw( ... )' string/RE not found: (scan-error Unbalanced parentheses 1543 155427)
--8<---------------cut here---------------end--------------->8---

--8<---------------cut here---------------start------------->8---

[cperl-lossage.txt (text/plain, inline)]

C-x C-f t m p / w i k i . p l <return> <escape> x c
p e r l - m o d e <return> C-s A p p l y R u l e s
SPC { C-a <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <down> <down> C-M-e
<up> <up> <up> C-e SPC i n s e r t i n g SPC t h i
s SPC t e x t SPC t a k e s SPC a SPC l o t SPC o f
SPC t i m e <escape> x v i e w - l o s s a g e <re
turn>

[Message part 3 (text/plain, inline)]

--8<---------------cut here---------------end--------------->8---



>         Stefan

Message #14 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Jambunathan K <kjambunathan <at> gmail.com>
Cc: 15755 <at> debbugs.gnu.org, Jonathan Rockway <jon <at> jrock.us>
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Wed, 30 Oct 2013 21:24:15 -0400

> wget http://git.savannah.gnu.org/cgit/oddmuse.git/plain/wiki.pl

Yup, sure looks like a bug.

> --8<---------------cut here---------------start------------->8---
> End of `qw( ... )' string/RE not found: (scan-error Unbalanced parentheses 1543 155427)
> --8<---------------cut here---------------end--------------->8---

Probably related, indeed.


        Stefan

Message #17 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Jambunathan K <kjambunathan <at> gmail.com>
To: 15755 <at> debbugs.gnu.org,  Jonathan Rockway <jon <at> jrock.us>
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Thu, 31 Oct 2013 07:28:25 +0530

Stefan Monnier <monnier <at> iro.umontreal.ca> writes:

>> --8<---------------cut here---------------start------------->8---
>> End of `qw( ... )' string/RE not found: (scan-error Unbalanced
>> parentheses 1543 155427)
>> --8<---------------cut here---------------end--------------->8---
>
> Probably related, indeed.

If I remove that "offending" qw sentence, the slowness persists.

It is possible that a perceived unbalanced-ness earlier in the document
only heightens an already existing slowness elsewhere.

Message #20 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Nathan Trapuzzano <nbtrap <at> nbtrap.com>
To: Jambunathan K <kjambunathan <at> gmail.com>
Cc: 15755 <at> debbugs.gnu.org, Stefan Monnier <monnier <at> IRO.UMontreal.CA>
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Thu, 31 Oct 2013 07:58:46 -0400

Jambunathan K <kjambunathan <at> gmail.com> writes:

> 5. Move the cursor down a few lines
> 6. C-M-e.  Jump to end of defun. Move up a few lines to seek the comment
>    line.
> 7. Type a few characters
>
> (5) is slow. (7) is very slow.  Meaning it takes ages for the 10 or so
> characters to be echoed.

When I went to reproduce this, I started emacs without the -Q.  What
happened was C-M-e took me to the end of a _different_ defun, and it did
so quickly.  Step 7 wasn't slow for me either.

Indeed, I was able to reproduce this after starting emacs without
loading .emacs.  The funny thing is, the line that seems to be the
difference maker is, of all things:

(defalias 'perl-mode 'cperl-mode)

Without that line, I get the behavior you describe.  With that line, I
get fast but incorrect cperl (C-M-e takes me to the end of the wrong
defun).

Message #23 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Nathan Trapuzzano <nbtrap <at> nbtrap.com>
Cc: 15755 <at> debbugs.gnu.org, Jambunathan K <kjambunathan <at> gmail.com>
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Thu, 31 Oct 2013 12:56:12 -0400

> (defalias 'perl-mode 'cperl-mode)

That means you're not using cperl-mode, but perl-mode, which is
a completely different major mode.

> (C-M-e takes me to the end of the wrong defun).

Please report this perl-mode bug, with a reproducible recipe.


        Stefan

Message #26 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Nathan Trapuzzano <nbtrap <at> nbtrap.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 15755 <at> debbugs.gnu.org, Jambunathan K <kjambunathan <at> gmail.com>
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Thu, 31 Oct 2013 13:23:09 -0400

Stefan Monnier <monnier <at> iro.umontreal.ca> writes:

>> (defalias 'perl-mode 'cperl-mode)
>
> That means you're not using cperl-mode, but perl-mode, which is
> a completely different major mode.
>
>> (C-M-e takes me to the end of the wrong defun).
>
> Please report this perl-mode bug, with a reproducible recipe.
>
>
>         Stefan

I think you have it backwards.  (defalias 'perl-mode 'cperl-mode) causes
cperl-mode to be used where perl-mode would have been used.  What I was
saying was I can only reproduce the original problem when I _remove_
that line from .emacs and do M-x cperl-mode manually after visiting the
file.

Message #29 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Nathan Trapuzzano <nbtrap <at> nbtrap.com>
Cc: 15755 <at> debbugs.gnu.org, Jambunathan K <kjambunathan <at> gmail.com>
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Thu, 31 Oct 2013 15:16:01 -0400

> I think you have it backwards.  (defalias 'perl-mode 'cperl-mode) causes

Indeed, sorry,


        Stefan "who seems to need some sleep"

Message #32 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Jambunathan K <kjambunathan <at> gmail.com>
To: Stefan Monnier <monnier <at> IRO.UMontreal.CA>
Cc: 15755 <at> debbugs.gnu.org
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Sun, 10 Nov 2013 11:01:14 +0530

A quick update:  Some magic has happened between the following revisions:

   114868 rgm <at> gnu.org-20131030102316-8vif7u6ecyo3yieg
   115051 jan.h.d <at> swipnet.se-20131109111953-cysfi19meuidy96q

The slowdown with the recipe above is not that noticeable now.  Is this
magic or is there an explanation?


Jambunathan K <kjambunathan <at> gmail.com> writes:

> Stefan Monnier <monnier <at> IRO.UMontreal.CA> writes:
>
>>> On my netbook (HP Mini 110) cperl-mode responds so slowly that it is
>>> very annoying to type.
>>
>> Usually, cperl-mode is fast enough (most of my machines are about as
>> powerful as a typical netbook).  So maybe you're just hitting a bug
>> (tho, maybe you're hitting a pathological case, as well).
>>
>> Do you have some test case we can use to reproduce the problem?
>
> If indeed this is a bug, I would call it a "showstopper" for cperl-mode.
>
> Here is a recipe.  The file used below is the Oddmuse's Wiki engine.
>
> mkdir ~/tmp
>
> cd ~/tmp
>
> wget http://git.savannah.gnu.org/cgit/oddmuse.git/plain/wiki.pl
>
> emacs -Q
>
> Here is a report from M-x view-lossage RET.  I do this:
>
> 1. C-x C-f ~/tmp/wiki.pl
> 2. M-x cperl-mode
> 3. C-s ApplyRules {
> 4. C-a
> 5. Move the cursor down a few lines
> 6. C-M-e.  Jump to end of defun. Move up a few lines to seek the comment
>    line.
> 7. Type a few characters
>
> (5) is slow. (7) is very slow.  Meaning it takes ages for the 10 or so
> characters to be echoed.
>
> Interestingly, after (2) I see the following message reported by
> cperl-mode.  I am not sure whether the error is a cause for slow
> performance.
>
> Anyways, if I do,
>
>     perl wiki.pl
>
> I don't see the perl complaining about the file being bad.  So there is
> a bug somewhere.
>
> Apart from the recipe above, you can try the following
>
> 1. Mark the ApplyRules sub.
> 2. M-x indent-region it.
>
> With perl-mode, (1) and (2) is very quick.  But with cperl-mode things
> are bad.
>
>
>
> End of `qw( ... )' string/RE not found: (scan-error Unbalanced parentheses 1543 155427)
>
> --8<---------------cut here---------------start------------->8---
> C-x C-f t m p / w i k i . p l <return> <escape> x c
> p e r l - m o d e <return> C-s A p p l y R u l e s
> SPC { C-a <down> <down> <down> <down> <down> <down>
> <down> <down> <down> <down> <down> <down> <down> C-M-e
> <up> <up> <up> C-e SPC i n s e r t i n g SPC t h i
> s SPC t e x t SPC t a k e s SPC a SPC l o t SPC o f
> SPC t i m e <escape> x v i e w - l o s s a g e <re
> turn>
> --8<---------------cut here---------------end--------------->8---
>
>
>
>>         Stefan

Message #35 received at 15755 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Jambunathan K <kjambunathan <at> gmail.com>
Cc: 15755 <at> debbugs.gnu.org
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Sun, 10 Nov 2013 08:56:18 -0500

> A quick update:  Some magic has happened between the following revisions:

>    114868 rgm <at> gnu.org-20131030102316-8vif7u6ecyo3yieg
>    115051 jan.h.d <at> swipnet.se-20131109111953-cysfi19meuidy96q

> The slowdown with the recipe above is not that noticeable now.  Is this
> magic or is there an explanation?

There's been a bug fix for an inf-loop in cperl-mode, indeed.  I'm not
sure if "not that noticeable now" means that the fix also fixed your
problem, or if your problem remains.


        Stefan

Message #40 received at 15755-done <at> debbugs.gnu.org (full text, mbox):

From: Jambunathan K <kjambunathan <at> gmail.com>
To: 15755-done <at> debbugs.gnu.org
Subject: Re: bug#15755: 24.3.50; cperl-mode annoyingly slow on my netbook
Date: Fri, 15 Nov 2013 10:42:05 +0530

OP here.  Closed.

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