an angel dressed in the blackest lace (lithiana) wrote in wikitech,

Why is the site so slow?

edit: this page is quite out of date now. most of the slowness at the moment (October 2005) is caused by lack of servers.

There seems to be quite a few misconceptions about why the servers are so slow and/or why there are so many database errors at the moment. First, the site is not slow because of:

  • A full disk. There was a full disk, it's now resolved. We aren't running out of disk space (yet). Tim's new history compression mechanism will help immensely here.

  • Lack of servers. Although this has been a problem in the past, and surely will be in the future, it's not the current issue.

  • Lack of bandwidth. However the forthcoming gigabit uplink will be nice.

  • A crawler using all the resources. Yes, there was one, it's now gone.


What is making the site slow is mainly configuration and software issues. The primitive load balancing in use doesn't make good use of the hardware - some apaches are at 100% CPU while others are nearly idle; the 512MB apaches start swapping, while the 1GB ones are fine, but reducing the number of connections means that the 1GB ones run at half capacity. A proper solution to distribute requests based on load is needed. Yes, it's annoying. Sorry. It's being worked on. If anyone wants to help, please do.

The "deadlock found while trying to get lock" errors are transient - they're annoying, but reloading a few times should fix it. The ideal solution here is that the software should do it for you, but this is somewhat non-trivial to fix and hasn't been done yet.

I have a database error / my new article doesn't show up / history is missing
Wait a while and try again. It will fix itself, eventually. Please don't recreate the same article 50 times.
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