[collectd] Max number of UDP sockets per collectd-process (NOT the file descriptor limit)

Stian Øvrevåge sovrevage at gmail.com
Thu Apr 12 11:21:28 CEST 2012

Hi list,

Banging my head against the wall for weeks now trying to get a working
medium scale collectd-installation working...

I thought I had fixed the max number of sockets/connecting when tuning
/etc/security/limits.conf. It now reads:

    ulimit -n

I have the instances of collectd now. One of them is set to poll 2300
hosts. Of which an unknown number is offline at any time. I'm watching
strace as well as netstat and everything seems fine and "netstat -anop
udp|wc -l" counts the number of udp sockets created until the number
hits about 1092. Here it stalls and syslog logs thousand lines of

    "Apr 12 11:07:41 collectd-new collectd[1488]: snmp plugin: host
x.y.z: snmp_sess_synch_response failed:"

within a few seconds. Number of UDP sockets from then on are stable.

If I also start the other two instances the number of sockets grows to
1292. Which leads me to believe that there is a per-process(or
thread?) limit somewhere.

Information on the internet on the issue is scarce other than the file
descriptor limit which I believe is unrelated.

Stian Øvrevåge

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