Does mentioning port number with FQDN resolve multiple connections

[Karthik K G <kg...@gmail.com>]

Hi Team,

We have a scenario where we give the Zookeeper FQDN to our Solr Application.
When we use this we are seeing that zookeeper is accepting connections from
all Solr nodes every minute.

When we provide the Zookeeper FQDN with the port number, we are seeing that
there is a single connection created with Solr. Is this something that has
been already seen earlier on.

I have tested it out on my local cluster and identified this issue. Has
anyone seen this issue previously? If yes, please let me know.

I have tested on a cluster with *3 Solr nodes* and *3 Zookeeper nodes*
Logs for one of the Zookeeper nodes
*Column Description:[Date, time interval(hourly), number of connection from
Solr, Number of connections from Zookeeper]*

Oct 09 16-17 180 connections from solr nodes.240 connections from zk nodes

Oct 09 17-18 180 connections from solr nodes.240 connections from zk nodes

Oct 09 18-19 69 connections from solr nodes.93 connections from zk nodes

Oct 08 10-11 120 connections from solr nodes.174 connections from zk nodes

Oct 08 11-12 180 connections from solr nodes.240 connections from zk nodes

Oct 08 12-13 180 connections from solr nodes.240 connections from zk nodes

Oct 08 13-14 180 connections from solr nodes.240 connections from zk nodes

Oct 08 14-15 180 connections from solr nodes.240 connections from zk nodes

Oct 08 15-16 180 connections from solr nodes.240 connections from zk nodes

Oct 08 16-17 180 connections from solr nodes.240 connections from zk nodes

Oct 08 17-18 180 connections from solr nodes.240 connections from zk nodes

Oct 08 18-19 180 connections from solr nodes.240 connections from zk nodes

Oct 08 19-20 180 connections from solr nodes.240 connections from zk nodes

Oct 08 20-21 180 connections from solr nodes.240 connections from zk nodes

Oct 08 21-22 180 connections from solr nodes.240 connections from zk nodes

Oct 08 22-23 180 connections from solr nodes.240 connections from zk nodes

Oct 08 23-24 180 connections from solr nodes.240 connections from zk nodes

Thank you,
Karthik

Re: Does mentioning port number with FQDN resolve multiple connections

[Shawn Heisey <ap...@elyograg.org>]

On 10/9/2018 12:54 PM, Karthik K G wrote:
> We have a scenario where we give the Zookeeper FQDN to our Solr Application.
> When we use this we are seeing that zookeeper is accepting connections from
> all Solr nodes every minute.

I'm more familiar with the Solr side than the ZK side. Here's a ZKHOST 
string that might be given to Solr, to connect to a three-node ensemble:

zoo1.example.com:2181,zoo2.example.com:2181,zoo3.example.com:2181/solr

The way I understand things, the ZK client (which is embedded in Solr) 
should open one TCP connection to each server listed, and leave those 
connections open indefinitely.  I have not examined network traffic to 
verify this, but that is my understanding.  So if my understanding is 
correct, then the following statement should be true:

If you're seeing lots of connections, then you may have some kind of 
problem, where services are being restarted frequently, or where 
connections are getting terminated prematurely outside the control of 
either ZK or Solr.

Thanks,
Shawn