[ale] Sendmail latency

[Jim Popovitch]

On Tue, 2005-01-25 at 09:53 -0500, Ryan Fish wrote:
> > I am 99% convinvced that what you need is a local caching name server on
> > the mailserver.  Add it, then put 127.0.0.1 as your first nameserver
> > in /etc/resolv.conf.
> 
> - Is there any way to see if such a thing is already in place yet just not
> "on"?  Also, named.conf is used on the mail server and holds dns information
> for all of the domains hosted by this client.  Therefore, I still do not
> feel good about renaming it and starting over with something new...

One way to tell is whether you get results for 

  #host www.test.com 127.0.0.1

Another would be to check that "allow-recursion" is setup for 127.0.0.1
in named.conf.  Finally look for the zone "*.*" in named.conf.

I would also verify that the "forwards" section of named.conf has the
correct upstream nameservers identified.

> Another observation/question...  It appears as though sendmail is only
> accepting a single connection as I never see more than one instance of it
> running at any one time.  I have worded, to a lesser degree, with mail
> servers using sendmail in the past and am accustomed to seeing multiple
> copies of sendmail listed when I do a "top" or "ps ax|grep mail".  Sendmail
> should accept multiple connections by default so what, if anything, would
> keep it from doing so in 8.12.11-4?

By most defaults, there will be 1 sendmail process to listen to port
eth0 port 25, and 2nd process to handle /var/spool/clientmqueue/.
Additionally sendmail will spawn processes (up until
max_daemon_children) to handle queue delivery.  Is it possible that the
senmail upgrade overwrote your previous sendmail.cf file?  Check the
date on /etc/mail/sendmail.cf 

> The Java app in use is multi-threaded and therefore, uses at least 5
> single-threaded agents at one time to send msgs to the mail server for
> sendmail to handle.  However, at this time, only one of those agents is
> allowed to be active at one time...

That could be your problem.  Sendmail should allow simultaneous inbound
connections (up to connection_rate_throttle).  Is the Java app doing a
lot of dns lookups?  Is the Java app server DNS-resolvable from the
sendmail box?

-Jim P.