dhcpd memory leak

[sthaug at nethelp.no]

> Are you using OMAPI?

Enabled in the config file. Memory leak shows up even if the OMAPI
interface isn't actually *used* though.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no



> 
> -----Original Message-----
> From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On
> Behalf Of sthaug at nethelp.no
> Sent: Monday, March 24, 2008 4:44 PM
> To: dhcp-users at isc.org
> Subject: dhcpd memory leak (was: Re: dhcpd process hitting data size
> limit)
> 
> Following up on a thread from early March:
> 
> > At my servers the size of the dhcpd process is about 20 MBytes at 
> > startup. After about a week the size has increased to about 1 Gbyte.
> If 
> > the dhcpd has not been restarted due to config changes, I usually have
> 
> > to restart once a week due the the memory use. The problem with size 
> > growing has been there as far back as I can remember.
> 
> Having monitored my DHCP servers rather intensively lately, I'm seeing
> a similar behavior - looks like a rather clear memory leak. The first
> few hours after startup, the memory usage is constant, e.g.
> 
> 20080309.0940 93972 93508 /usr/local/sbin/dhcpd
> 20080309.0945 93972 93508 /usr/local/sbin/dhcpd
> 20080309.0950 93972 93508 /usr/local/sbin/dhcpd
> 20080309.0955 93972 93508 /usr/local/sbin/dhcpd
> 20080309.1000 93972 93508 /usr/local/sbin/dhcpd
> 20080309.1005 93972 93508 /usr/local/sbin/dhcpd
> 
> where the numbers are date/time, process virtual size (VSZ), process
> real memory size (RSS). After a few hours, *something* happens which
> clearly triggers a rather significant memory leak:
> 
> 20080309.1735 93972 93508 /usr/local/sbin/dhcpd
> 20080309.1740 93972 93508 /usr/local/sbin/dhcpd
> 20080309.1745 93972 93508 /usr/local/sbin/dhcpd
> 20080309.1750 93972 93508 /usr/local/sbin/dhcpd
> 20080309.1755 93972 93508 /usr/local/sbin/dhcpd
> 20080309.1800 94456 93992 /usr/local/sbin/dhcpd
> 20080309.1805 94936 94472 /usr/local/sbin/dhcpd
> 20080309.1810 95420 94960 /usr/local/sbin/dhcpd
> 20080309.1815 95892 95432 /usr/local/sbin/dhcpd
> 20080309.1820 96368 95908 /usr/local/sbin/dhcpd
> 20080309.1825 96868 96408 /usr/local/sbin/dhcpd
> 
> When the memory leak behavior has started, it lasts until the process
> is restarted. I'm seeing a memory leak of around 80 kBytes per minute
> with around 100k active leases and 24 hour lease time, in a failover
> configuration. Both servers in the configuration show a similar memory
> leak - however, the memory leak doesn't start at the same time on both
> servers even if the dhcpd processes are restarted at approximately the
> same time.
> 
> So far I have inspected dhcpd syslog messages for the time when the
> memory leak starts, and also looked at tcpdump traces of the actual
> traffic to and from the servers. Everything appears normal, as far as
> I can see.
> 
> Any good suggestions on how to start debugging this? Both servers run
> dhcp-3.1.0, OS is FreeBSD 6.3.
> 
> Steinar Haug, Nethelp consulting, sthaug at nethelp.no
> 
> 
>