Remy Maucherat wrote:
> > The slowdown I was reporting seems to have become more repeatable. This
> > is good, because it meant I could track down (though not fix - I don't
> > know the tomcat code nearly well enough) the problem. It's also not so
> > good, because it MAY be that there are actually two problems.
> >
> > It turns out that the hosts which were seeing a huge slowdown didn't
> > have any dns entries (they're internal to our network), and weren't in
> > my /etc/hosts. As soon as I added a host to /etc/hosts (on the server),
> > the problem stopped (for that host only). This is with a tomcat 4.0
> > snapshot from today, but I didn't try using the http/1.0 connector (I
> > can still do this if you think it'd be useful, Remy).
> >
> > So, my guess is that it's trying to reverse-resolve the host, and just
> > waiting until it times out for some reason (logging, perhaps?). I'd
> > still consider this a serious bug, but a somewhat less crucial one since
> > there's an easy workaround for it.
> >
> > However, the symptoms here were entirely reproducible - the original
> > problem was not. So I think there may be a second problem - if so, I'll
> > let you know, but it may not be terribly soon because of the fact that
> > it isn't reproducible. For the moment, I think it's safe to assume that
> > it was just the single problem.
>
> I hope there isn't a second problem, because it looks like it would be quite
> hard to reproduce and debug ;)
>
> The host resolution problem is definitely something I'll have to fix ASAP. I
> don't really know yet which part of Tomcat is doing the lookup.
> I would have been very surprised if it was a Slide problem (but of course,
> you never know).
>
The only place Tomcat should be doing the DNS lookup is if you actually call
request.getRemoteHost() anywhere -- at least, that is the way that the original
code worked. If you only call request.getRemoteAddr(), or you never call either
of them, then the DNS lookup is not necessary.
NOTE: It looks like the default access log valve is doing remote host lookups
:-(. You might try commenting that out of your server.xml file.
>
> Thanks a lot for the bug report :)
> Remy
Craig
