How to change the JVM Threads of SolrCloud

[Issei Nishigata <du...@gmail.com>]

Hello All,

I'm running SolrCloud(1 shard,9 replicas) on Amazon EKS.

The other day, when I accidentally stopped CoreDNS of EKS,
the entire Solr cluster went down due to the inability to resolve names of
each node.
I restarted CoreDNS shortly afterwards, but the Solr node just repeated
down and recovering,
and it did not return to the normal state automatically.

During this time Solr was in a state of accepting search requests all the
time,
so I stopped the search request completely.
After that, I executed DELETEREPLICA to reduce the number of Solr nodes to
one.
I increased the number of replicas little by little, and after returning to
the original cluster state completely,
I restarted the search request, and after that, no particular problem
occurred.

At the time of this failure, the JVM Threads on each node were stuck at
10000.
Since the load was very high, it is probable that each node repeated down
and recovering.
If I reduced(or increased) this JVM Threads, would the Solr cluster
automatically return to normal state?
If so, what setting in sorlconfig.xml should I change to reduce(or
increase) this JVM Threads?
I think "maxConnectionsPerHost" and "maximumPoolSize" are related to this
issue,
but I'm not sure about the difference between the two.

Any help would be appreciated.

Thanks, Issei