[dokuwiki] Re: Performance issues

Hi,

Chris Smith wrote:
> Mario Emmenlauer wrote:
>> By replacing the utf8_substr() function with standard-php substr()
>> in feed.php, load on my server dropped from 100 down to almost zero.
>> This is because utf8_substr uses a perl_replace for all caracters in
>> a page just to guess correct page-lenght.
>>
>> But noone seemed to care to much.

> I don't think noone cares, its most likely that quite a bit of effort
> was put into finalising things for the recent release and then the
> hotfix.  After that template and plugin providers probably needed to
> update their work, I know I did.  Now its complete, the lull is most
> likely people taking care of other parts of their lives.


I now realize I sounded unreasonable harsh, sorry for that.
My only justification might be, that the performance-issue had kept
me busy (and awake) for almost a week - I had to restart apache by
the hour, and investigated totally in the dark.
I'm talking about the dedicated server becoming completely useless
after an hour, because the php-timeouts crash apache. I have to admit
the pages were unusually large (50k), but still I wonder how many
people don't realize the problems dokuwiki is causing on their servers.
I'm most likely not the only one who has the rss-feed called once per
minute?!
And, btw, this isn't a new issue - utf8_substr() has been like this at
least in the last three revisions. I just realized now because with
popularity load grew over any acceptable limit :-(

Any form of performance-testing would have shown the unacceptable high
runtime of utf8_substr, and I just want to emphasize that a usefull
performance-test would probably be more important than new features.
Maybe its time for a stable and a testing-branch?

BTW: If noone does before me, I'll write a simple stresstest for
dokuwiki as soon as I find some time. Just a (bash? perl?)script that
calls a given set of pages some hundred times and sums up the response
time. This way it should be easy to find weak links early in development.

> On topic:
> - I notice that the RSS feed is the one thing that significantly affects
> my wiki server.

Jup. Try the fix I posted, it's only downside will be that utf8-
previews in the feed might not be exactly 250 (or whatever) chars
long.

Cheers,
  Mario
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