Mailing List Archive

Slow response
I'm getting incredibly slow responses from the main Wikipedia now and
in the last few days. Why is this? Who is working to fix it? How
can I help?

The request

GET /wiki.png HTTP/1.1
Host: www.wikipedia.com

is lightening fast. But

GET / HTTP/1.1
Host: www.wikipedia.com

can take well over a minute to return. This is strange, since the
start page is seldom updated and could easily be cached in HTML, ready
to send to any client.

Simple but useful measurements can be done with the Linux commands:

time lynx -dump http://www.wikipedia.com/wiki.png >/dev/null
time lynx -dump http://www.wikipedia.com/ >/dev/null

I can run this at regular intervals and report statistics to you, if
this is interesting.

I have worked with finding and removing transaction response time
bottlenecks in C++, Java, and Perl applications, but never in PHP, so
I don't know how hard it is. My general approach is to look at the
system clock when a new request comes in and then again at various
points in the execution path, to find the point where more than 3
seconds have passed. If the code has a function for writing a debug
or trace log message, that is the place to look at the system clock.
Who can do this? Can I assist you in any way?


--
Lars Aronsson (lars@aronsson.se)
Aronsson Datateknik
Teknikringen 1e, SE-583 30 Linuxköping, Sweden
tel +46-70-7891609
http://aronsson.se/ http://elektrosmog.nu/ http://susning.nu/
Re: Slow Response [ In reply to ]
>I'm getting incredibly slow responses from the main Wikipedia now and
>in the last few days. Why is this? Who is working to fix it? How
>can I help?

I don't think anybody is actively working on it right now. Jimbo has
said that he will soon move some other web sites off the wikipedia
server and will then give some of us user accounts on that machine, so
that we can better diagnose the problems. Right now, it is not clear
what we can do. For you, maybe the best would be to download the
current code from cvs, get it to work and familiarize yourself with
it; once we have access to the server we should be able to figure out
what's going on pretty quickly.

Axel
Re: Re: Slow Response [ In reply to ]
What about making some of our update queries 'delayed'?

--
"Jason C. Richey" <jasonr@bomis.com>
Re: Slow Response [ In reply to ]
Ok, Jason switched the logging off; it doesn't seem to have made much
of a difference. A log of the latest long queries can be downloaded
from our sourceforge website:

http://wikipedia.sourceforge.net/long_queries.gz

Regarding the "INSERT DELAYED" idea: I'm not sure that it will help
much: the manual states that it's not that useful for the MyISAM
tables we are using, since those tables allow asynchronous updates
anyway. It's worth a try though.

Another idea is to switch off the query cache (query_cache_size=0):
our tables change so frequently that a caching of queries seems to be
a big loss.

Axel