unexpected instance shutdown and max number of connections
jehiah at gmail.com
Tue May 29 01:08:04 UTC 2007
On 5/28/07, Ricardo Niederberger Cabral <rnc000 at gmail.com> wrote:
> I'm running memcached on a clustered production system with the following setup:
> - Each instance is started with "memcached -d -p 11320 -u cartola -c
> 1024 -m 1024 -l 127.0.0.1 -k"
> - Java clients (v 1.3.2) under JRE 1.4
> - Kernel 2.6.9-22. Distro CentOS release 4.2 (Final)
> - 5 identical Linux boxes, each with one JBoss and one memcached
> (1.2.0 compiled) instance.
> - memcached instances with only 100 MB avg of bytes used on the cache
> - low cpu usage and nothing abnormal showing on iostat
> So I have the following questions:
> 1) Is there any reason (or has anyone experienced this before) for
> memcached clients not respecting the maximum number of connections
> when configured to connect to multiple instances ? (each memcached
> server had more than n * configured_max_per_client incoming
> connections). If I change the setup to have each Java client pointing
> to only the memcached instance on the local machine, the maximum is
> 2) After a few days memcached instances stop accepting incoming
> connections. Could it be related to the fact that I was using white
> spaces on some of the keys ? (we get several "CLIENT_ERROR bad command
> line format" errors). Maybe one of these invalid commands triggers
> some internal condition where instances start to misbehave.
> 3) In order to avoid keys with space characters on it, would it be a
> bad idea to have all keys hashed (with Java's String.hashCode())
> before being used on memcached ?
> Thanks in advance and best regards,
> Ricardo Cabral
on items 1 and 2... if you are running out of connections on server
(memcached) side; just increase the 1024 limit you specify on the
command line. You can check the number active connections at any time
by querying the memcached stats.
More information about the memcached