By the way, this patch and the last one that I submitted on the sievec core dumping problem refer to the released 2.2.8 version of Cyrus. I did forget to mention that in the last post...
Anyways, we ran into another problem on Tru64 that we are going to have to dig deeper and probably call HP on. Basically, the server wouldn't take long before it would run out of file descriptors to open new files. It did not matter if it was an LMTPD process or one of the IMAPD processes. When I check one of the processes, I would see over a hundred open descriptors for /etc/hosts and over a hundred open descriptors for /etc/ipnodes.
The problem was tracked back to the getnameinfo() function. Everytime a new connection was established with one of the Cyrus services, getnameinfo() would be called to resolve the incoming client to a hostname and IP address.
From what I could tell, the getnameinfo() call would open the /etc/hosts
and /etc/ipnodes files, but neglect to close them. Since process reuse themselves after the connection is closed, this can add up... especially with 2 fd's per connection getting consumed.
Commenting out the getnameinfo() calls that are resolving connections to hostnames solves the problem. Keep in mind that not all getnameinfo() calls were bad, since some of them strictly deal with the IP addresses, meaning that those calls don't actually do hostname lookups. I just commented out the ones that would end up leaking file descriptors.
The final solution that I chose was to actually implement a new imapd.conf option called "hostname_lookups" that allows the hostname lookups to be turned off if the admin desires. It is enabled by default. This works great for us. The biggest reason why I wanted to go this route is for performance reasons... We have turned off hostname lookups in several of our applications, as it is just really expensive to be doing DNS lookups on a super busy system when the only thing it is being used for is for logging. Whether or not we fix the Tru64 bug, I will be much happier not doing hostname lookups :)
The patch is attached...
Scott
--
+-----------------------------------------------------------------------+
Scott W. Adkins http://www.cns.ohiou.edu/~sadkins/
UNIX Systems Engineer mailto:[EMAIL PROTECTED]
ICQ 7626282 Work (740)593-9478 Fax (740)593-1944
+-----------------------------------------------------------------------+
PGP Public Key available at http://www.cns.ohiou.edu/~sadkins/pgp/
HOSTNAME_LOOKUP.patch
Description: Binary data
Description: PGP signature
