Hi team,
I found a problem: ZkController.onReconnect is triggered unnecessarily.
Curator's RECONNECTED event is different from the previous RECONNECTED
event. Before Solr10, the OnReconnect is only triggered after a reconnection
from a zookeeper session expiration.
Please check the following
https://github.com/apache/solr/blob/fdb5314279657f7895a90123436d834e81ea3157/solr/solrj-zookeeper/src/java/org/apache/solr/common/cloud/ConnectionManager.java#L165
https://github.com/apache/solr/blob/fdb5314279657f7895a90123436d834e81ea3157/solr/solrj-zookeeper/src/java/org/apache/solr/common/cloud/ConnectionManager.java#L199
However Curator's RECONNECTED event is triggered every time a Solr node is
disconnected from a ZooKeeper instance and reconnected to another ZooKeeper
instance. As a result, currently ZkController.onReconnect is invoked every time
a Solr node reconnects to a ZooKeeper instance without a session expiration,
which is a huge overhead, especially when we need to rolling-restart a
ZooKeeper cluster for upgrade. It can take more than 10 minutes for a small
Solr cluster to stabilize.
Similarly, now ZkController.onDisconnect is triggered just after a
disconnection from a ZooKeeper instance. It should only be triggered after a
session expiration.
I created a PR in my fork: https://github.com/linxiaokun528/solr/pull/1.
Should I create an issue in Solr Jira and submit a PR to the official
repository?
Regards,
Jerry
