If you have a DNS out, you will get DNS timeout.  Removing the specific
entry might help, at least until it is resolved.


On Wed, Mar 22, 2023 at 10:17 AM Tim Funk <[email protected]> wrote:

> I did try adding to SOLR_OPTS to be "-Djava.net.preferIPv4Stack=true
> -Dnetworkaddress.cache.ttl=3600" and they didn't seem to have any effect
> during the triage.
>
> -Tim
>
> On Wed, Mar 22, 2023 at 12:44 PM Tim Casey <[email protected]> wrote:
>
> > There are some settings which are common to apply to the JVM.  You might
> > try those first.
> > If you do a search for JVM java DNS settings it will come up.
> >
> > On Wed, Mar 22, 2023 at 7:01 AM Tim Funk <[email protected]> wrote:
> >
> > > I ran into an interesting situation today with respect to latency due
> to
> > > failed DNS lookups.
> > >
> > > THE SETUP
> > > Using RHEL8, openjdk 11, solr 9.1.1. The solr instance was standalone
> in
> > a
> > > mostly out of the box config. (No SSL, only http)
> > >
> > > I had 3 entries in /etc/resolv.conf and the first one in the list was
> > > "broken". It was timing out on requests.
> > >
> > > The situation - When I would issue a query - I'd have upwards of a 5
> > second
> > > pause prior to completion of the request. Which feels like a timeout
> > being
> > > hit.  For example, while on the server "10.0.0.200"
> > > curl -v '
> > >
> http://10.0.0.200:8983/solr/mycore/select?q=*:*&fq=locale_s:en-us&rows=1
> > '
> > >
> > > I then edited jetty.xml to
> > > remove "org.eclipse.jetty.server.handler.InetAccessHandler" (since I
> > wasn't
> > > using an ACL anyways). From there - results seemed to get a little
> > better.
> > > I tended to get instant responses, but occasionally, I'd still see the
> > > multi-second delay.
> > >
> > > I'm not sure how to track down this second piece of latency when DNS
> > fails.
> > > Is this an opportunity to also remove these lookups to improve
> > performance?
> > >
> > >
> > > -Tim
> > >
> >
>

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