[HBASE-25505] ZK watcher threads are daemonized; reconsider

• Type: Brainstorming
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Assignee: Unassigned
• Reporter: Andrew Kyle Purtell
• Created: 14/Jan/21 02:09
• Updated: 11/Jun/22 21:10
• Resolved: 11/Jun/22 21:10

Description

On HBASE-25279 there was some discussion and difference of opinion about having ZK watcher pool threads be daemonized. This is not necessarily a problem but should be reconsidered.

Daemon threads are subject to abrupt termination during JVM shutdown and therefore may be interrupted before state changes are complete or resources are released.

As long as ZK watchers are properly closed by shutdown logic the pool threads will be terminated in a controlled manner and the JVM will exit.

Issue Links

• relates to: HBASE-25279 Non-daemon thread in ZKWatcher