Re: Improving Gnus speed

[Francis Moreau <francis.moro@gmail.com>]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> Francis Moreau <francis.moro@gmail.com> writes:
>
>> Even if articles are cached, Gnus takes some times to display the
>> summary buffer:
>>
>> Entering in the group containing cached articles: 4 secs.
>>
>> This group contains 230 unread articles.
>
> That's obscenely slow.  Even if the 230 articles were fetched over the
> net, it shouldn't take anywhere that long.
>
>> Now display all articles in this group by doing '/ o':
>>
>> Gnus asks me:
>>
>>      How many articles from nnml+cache:nntp+news.free.fr:comp.lang.c (default 42555):
>>
>> Type <RET>.
>>
>>      Fetching headers for nnml+cache:nntp+news.free.fr:comp.lang.c...
>>      < 7 secs>
>>      done
>>      < 22 secs>
>>      Generating summary...
>>      < 3 secs>
>>      done
>
> That seems rather slow, too, but Gnus is rather slow when rendering
> large summary buffers, and I've never understood why, really.  Entering
> a 10K group takes a couple of seconds, but entering a 100K group takes
> several minutes.  So there's something exponential going on somewhere...
>
>> I'm interested in improving this, so any suggestions are welcome.
>
> (setq debug-on-quit t) and then `C-g'-ing a few times should tell you
> what function is taking so long.

Here's my first experiments:

While in the fetching headers... process I got the following backtrace:

  string-match("\\(<[^<]+>\\)[  ]*\\'" "...
  gnus-get-newsgroup-headers-xover
  gnus-fetch-headers
  gnus-summary-insert-articles
  gnus-summary-insert-old-articles


and while in the 22 secs processing, hitting C-g gives:

  parse-time-tokenize
  parse-time-string
  mail-header-parse-date
  gnus-thread-latest-date
  gnus-thread-sort-by-most-recent-date
  gnus-sort-threads-recursive
      .
  33 calls to gnus-sort-threads-recursive
      .
  gnus-sort-threads
  gnus-summary-prepare
  gnus-summary-limit
  gnus-summary-insert-old-articles


> `M-x elp-instrument-package RET gnus RET', doing something, and then
> `M-x elp-results' should give you a detailed look.

This fails with the following message:

     "Variable binding depth exceeds max-specpdl-size"

However doing 'M-x elp-results' still shows me:

  gnus-sort-threads-recursive             641         65.774695999  0.1026126302
  gnus-thread-sort-by-most-recent-date    4348        31.652889000  0.0072798732
  gnus-thread-latest-date                 8696        31.436723000  0.0036150785
  gnus-thread-total-score                 82494       17.555852999  0.0002128136
  gnus-thread-total-score-1               82494       17.134565999  0.0002077068
  gnus-summary-insert-articles            1           8.04944       8.04944
  gnus-fetch-headers                      1           8.019706      8.019706
  gnus-get-newsgroup-headers-xover        1           8.005099      8.005099
  gnus-thread-sort-by-total-score         8697        3.4791829999  0.0004000440
  gnus-id-to-thread                       82494       1.3472719999  1.633...e-05
  gnus-float-time                         41229       0.2444190000  5.928...e-06
  gnus-retrieve-headers                   2           0.0244269999  0.0122134999
  gnus-make-threads                       1           0.023105      0.023105
  gnus-sorted-nunion                      1           0.015179      0.015179
  gnus-cache-retrieve-headers             1           0.012292      0.012292
  [...]



-- 
Francis