[Dnsmasq-discuss] dnsmasq hogging the cpu all of a sudden

Simon Kelley simon at thekelleys.org.uk
Tue Jan 8 12:14:54 GMT 2008

Sue & Bruce Horsburgh wrote:
> Folks,
> I've been running a Ubuntu server in a fairly simple home system (4
> windows & 1 linux client) using dnsmasq for about a year. It's been
> exactly what I needed and totally stable. I upgraded it a little while
> back to the then latest ubuntu release (7.04?) which includes dnsmasq
> version 2.37. Still well and good. I haven't touched it since them (as
> all good servers should be).
> A couple of weeks ago, I lost internet access, and I traced it back to
> dnsmasq not answering DNS requests. What's more, it had started using
> 100% cpu. A restart fixed the problem, and I just put it down to stray
> cosmic rays... :-) However, it's happening every few days now. The
> syslog files give no indication of anything out if the ordinary. The
> dhcp server continues to renew leases whilst it's refusing DNS requests,
> so it's not entirely dead.
> Two questions. Is there a way I can get more information out of it as to
> what might be going wrong (ie some way to increase the verbosity of log
> messages)? Secondly, (and I'll apologise in advance for the dumb
> question, but) I know that you have released new versions, but ubuntu
> hasn't included them in their release list so it isn't a simple matter
> of 'apt-get install'. Bearing in mind that this is my 'production'
> server (and if it dies then I can't access the internet to install
> anything else), is there a safe way to upgrade? (I used to have a test
> server, but sadly no longer).

We're ahead of you: from the changelog for version 2.38:

            Fix rare hang in cache code, a 2.37 regression. This
            probably needs an infinite DHCP lease and some bad luck to
            trigger. Thanks to Detlef Reichelt for bug reports and


The best solution is to upgrade, and lobby Ubuntu to do the same. (As I
recall, the fix is a one-character change, so backporting it to an
updated Ubuntu 2.37 package would be trivial. I can supply details if neede.

As far as I know, Ubuntu takes the Debian package unaltered, so a later
Debian package should just work, or at worst, be compilable from source.



More information about the Dnsmasq-discuss mailing list