Re: footnote fontify causing massive slowdown

[Alan L Tyree <alantyree@gmail.com>]

On 05/12/15 23:58, Nicolas Goaziou wrote:
> Hello,
>
> Derek Feichtinger <derek.feichtinger@psi.ch> writes:
>
>> While diagnosing a server condition, I was listing parts of a system log
>> via a babel expression. The 130 lines in the babel output are wrapped in
>> an example block. This block caused massive slowdown of scrolling and
>> other operations.
>>
>> Using the emacs profiler I see:
>>
>> - redisplay_internal (C function) 8232  88%
>>   - jit-lock-function 8226  88%
>>    - jit-lock-fontify-now 8226  88%
>>     - funcall 8226  88%
>>      - #<compiled 0x1cc274f>                                      8226  88%
>>       - run-hook-with-args 8226  88%
>>        - font-lock-fontify-region 8226  88%
>>         - font-lock-default-fontify-region 8226  88%
>>          - font-lock-fontify-keywords-region 8226  88%
>>           - org-activate-footnote-links 8158  87%
>>            - org-footnote-next-reference-or-definition 8158  87%
>>             - byte-code 8158  87%
>>              - org-footnote-at-reference-p 4114  44%
>>               - org-footnote-in-valid-context-p 4106  44%
>>                + org-inside-LaTeX-fragment-p 2380  25%
>>                + org-in-block-p 1563  16%
>>                + org-in-verbatim-emphasis 159   1%
>>                  org-at-comment-p 4   0%
>>
>> Checking for footnote pattern matches (org-footnote-re) in the wrapped
>> block, I see that
>> every line matches based on the very simple and trivial pattern of
>> number enclosed in angular brackets, so all the process numbers
>> following the "sshd" in these lines like "sshd[1234]" do match and cause load.
>>
>> #################
>>      /var/log/secure-20151129:Nov 23 02:25:36 some-host sshd[20089]: Rhosts
>> authentication refused for userXYZ: bad ownership or modes for home directory.
>>      /var/log/secure-20151129:Nov 23 02:25:36 some-host sshd[20089]: Rhosts
>> authentication refused for userXYZ: bad ownership or modes for home directory.
>>      /var/log/secure-20151129:Nov 23 02:25:41 some-host sshd[20089]:
>> pam_ldap: error trying to bind as user "xxxxx" (Invalid credentials)
>> #################
>>
>> Since this kind of pattern is so common in logs and 130 lines are really not
>> a large number, it makes it hard to use
>> org for this purpose. Can this be turned off selectively, or can it be
>> prevented in example blocks?
> This is a limitation of our current way to fontify a buffer. Changing it
> implies some serious work, which I'd rather spend on switching to
> syntax-based (instead of regexp-based) fontification.
>
> However, this report raises an interesting question about footnotes:
> should we still support plain (e.g., "[1]") footnotes in Org documents?
>
> The pattern is very common an regularly introduces false positives.
> Also, IIRC, it was introduced for non-Org buffers (e.g., in Message mode
> buffers), to provide some common features with "footnote.el" library.
>
> I think we could remove this kind of footnotes, and yet preserve
> `org-footnote-normalize' to change Org footnotes into these ones, for
> foreign documents.
>
> WDYT?
>
>
> Regards,
>
I would be delighted to see the 'plain' footnote format abolished. I use 
org for writing legal text which often has things like Bank of New South 
Wales v Laing [1954] AC 135. Rasmus helped me with a patch to ignore 
these kinds of references, but they remain a nuisance.

Special case, I know, but +1 for getting rid of the things.

Cheers,
Alan

-- 
Alan L Tyree                    http://www2.austlii.edu.au/~alan
Tel:  04 2748 6206              sip:typhoon@iptel.org