[SOLR-9365] Reduce noise in solr logs during graceful shutdown

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 6.3, 7.0
• Component/s: SolrCloud
• Labels: difficulty-easy impact-low newdev
• Assignee: Cao Manh Dat
• Reporter: Shalin Shekhar Mangar
• Created: 01/Aug/16 16:22
• Updated: 02/Oct/19 17:23
• Resolved: 12/Sep/16 19:07

Description

There is too much unnecessary logging of exceptions during a graceful shutdown. This is mostly due to:

1. Watcher invocations fired after the zk callback executor is shutdown, and
2. Session expiry because of zkclient or embedded zk server shutdown

We should add a simple check for such conditions to reduce noise in our logs.