[SOLR-14928] Remove Overseer ClusterStateUpdater

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 9.0
• Component/s: SolrCloud
• Labels: cluster collection-api overseer
• Assignee: Ilan Ginzburg
• Reporter: Ilan Ginzburg
• Created: 13/Oct/20 10:20
• Updated: 12/May/22 00:26
• Resolved: 28/Mar/22 01:32

Description

Remove the Overseer ClusterStateUpdater thread and associated Zookeeper queue at <chroot>/overseer/queue.

Change cluster state updates so that each (Collection API) command execution does the update directly in Zookeeper using optimistic locking (Compare and Swap on the state.json Zookeeper files).

Following this change cluster state updates would still be happening only from the Overseer node (that's where Collection API commands are executing), but the code will be ready for distribution once such commands can be executed by any node (other work done in the context of parent task SOLR-14927).

See the Cluster State Updater section in the Removing Overseer doc.

Issue Links

• links to: GitHub Pull Request #2285
• links to: GitHub Pull Request #2364
• links to: GitHub Pull Request #2438