Performance issue when fontifing in compile-mode.

Performance issue when fontifing in compile-mode.

[Oleksandr Gavenko]

I use in log file:

-*- mode: compilation-minor; mode: auto-revert-tail; default-directory: 
"~/devel" -*-

This allow easy and fast go to place where logger function make output 
(in GNU format).

But  logs with >2000 lines take 2-20 sec  on parsing after revert.

I check 'compilation-error-regexp-alist'. It contain pattern in 
alphabetical order!
(like come from 'compilation-error-regexp-alist-alist' ??)

Most of my software produce in 'gnu' format.

As I understand patterns checked in order like in 
'compilation-error-regexp-alist'.

And if string is not match any pattern all pattern in 
'compilation-error-regexp-alist'
used!

I check  which pattern in effect by:

(mapc
  (lambda (item)
    (when (string-match (elt item 1) "  [echo] file.c:45: error gg")
      (message "%s" (elt item 0))
      ))
    compilation-error-regexp-alist-alist
    )

Also I temporary put this code to .emacs:

(mapc
  (lambda (item)
    (when (memq item compilation-error-regexp-alist)
      (setq compilation-error-regexp-alist
            (cons item (assq-delete-all item 
compilation-error-regexp-alist)) )
      ))
  ;; Most latest firstly used.
  '(ant gnu)
  )

I try something like:

(setq compilation-error-regexp-alist '(gnu))

and still get same performance (slow).

When I set

(setq compilation-error-regexp-alist nil)

it match faster parse file!

So I try rewrite this regex (add my-gnu pattern before gnu).

(add-to-list 'compilation-error-regexp-alist-alist '(my-gnu 
"^\\([^:]+\\):\\([[:digit:]]+\\):" 1 2))
(add-to-list 'compilation-error-regexp-alist 'my-gnu)

It is about 2 time faster then my slow case.

With '(setq compilation-error-regexp-alist nil)' I still get blue text 
in start of string before ':'.
Who make this?

Re: Performance issue when fontifing in compile-mode.

[Oleksandr Gavenko]

On 18.01.2011 17:23, Oleksandr Gavenko wrote:
> I use in log file:
>
> -*- mode: compilation-minor; mode: auto-revert-tail; default-directory:
> "~/devel" -*-
>
> This allow easy and fast go to place where logger function make output
> (in GNU format).
>
> But logs with >2000 lines take 2-20 sec on parsing after revert.
>

To test you can use shell script:

echo "-*- mode: compilation-minor -*-" >test.txt
seq 1 10000 | while read line; do echo "src/file.c:345: dummy text" 
 >>test.txt; done

and open test.txt file. It take 20 sec to be opened!

Same with

-*- mode: grep -*-

It is too long for parsing simple 270 KiB of text!!!!!

Which things have affect  on performance?

regex parsing or putting properties to buffer text?

Is that true: c-mode highlights only part on file not all?

Re: Performance issue when fontifing in compile-mode.

[Stefan Monnier]

> But  logs with >2000 lines take 2-20 sec  on parsing after revert.

Hmm... 2s might be OK but 20s sounds too high (tho, clearly the time
will be proportional to the length of the text): what file size are we
talking about for the 20s case?

> (setq compilation-error-regexp-alist nil)
> it match faster parse file!

No doubt that will be faster.

> With '(setq compilation-error-regexp-alist nil)' I still get blue text in
> start of string before ':'.
> Who make this?

compilation-mode-font-lock-keywords


        Stefan