Memcache
Memcache is a system used by Dreamwidth to lessen the amount of database access needed, by temporarily storing frequently-accessed information in memory for quick access. It was developed by Brad Fitzpatrick and is used in many high-profile websites, including Slashdot, Wikipedia, and, of course, LiveJournal (for which it was developed). Dreamwidth Studios also uses this system.
Using Memcache on a Dreamhack
To use memcache on a Dreamhack, do the following:
- Contact the owner of the Dreamhack box you're using for a port to use with the
memcached
program; this will usually be Mark. - Use
screen
to run this command:
memcached -m 8 -l 127.0.0.1 -p <port>
- ...replacing <port> with the port number assigned to you in the previous step. If you need help with
screen
, feel free to contact Mark. (A wiki page on this should be available in the future.)
- Edit your
ext/local/etc/config-local.pl
file (copy it first fromext/dw-nonfree/etc/config-local.pl
if it doesn't exist) and look for the line:
#@MEMCACHE_SERVERS = ('hostname:port');
- Change this to:
@MEMCACHE_SERVERS = ('127.0.0.1:<port>');
- again replacing <port> with the appropriate port number. (Make sure also that the line is uncommented by removing the # at the front.)
- If your Apache server is currently running, restart it:
stop-apache start-apache
Your Dreamhack should now be set up for memcache.
Using Memcache on your own setup
First, install the daemon:
sudo apt-get install memcached
You can run it in kind of a debug mode like this:
memcached -vv -m 25 -l 127.0.0.1 -p 8080
Or in the background like this:
memcached -d -m 25 -l 127.0.0.1 -p 8080
For more help on the options,
memcached -h
You'll also have to set up your installation to use it. First, copy ext/dw-nonfree/etc/config-local.pl to ext/local/etc/config-local.pl if the latter doesn't exist. Then edit the file using your favorite editor (the example uses vi):
vi ext/local/etc/config-local.pl
And edit the appropriate information:
# MemCache information, if you have MemCache servers running @MEMCACHE_SERVERS = ('127.0.0.1:8080'); $MEMCACHE_COMPRESS_THRESHOLD = 1_000; # bytes
You will need to restart your web server in order for these changes to take effect.
Note that the memcache server doesn't have to be on your web server; you can set it up and configure it with the IP of a different server.