[SOLR-7503] Recovery after ZK session expiration happens in a single thread for all cores in a node

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 5.1
• Fix Version/s: 5.2, 6.0
• Component/s: SolrCloud
• Labels: impact-high
• Assignee: Timothy Potter
• Reporter: Shalin Shekhar Mangar
• Created: 05/May/15 14:45
• Updated: 09/May/16 18:53
• Resolved: 28/May/15 16:40

Description

Currently cores are registered in parallel in an executor. However, when there's a ZK expiration, the recovery, which also happens in the register call, happens in a single thread:

https://github.com/apache/lucene-solr/blob/trunk/solr/core/src/java/org/apache/solr/cloud/ZkController.java#L300

We should make these happen in parallel as well so that recovery after ZK expiration doesn't take forever.

Thanks to mewmewball for catching this.