[KAFKA-8831] Joining a new instance sometimes does not cause rebalancing

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Component/s: streams
• Assignee: Chris Pettitt
• Reporter: Chris Pettitt
• Created: 23/Aug/19 23:21
• Updated: 26/Aug/19 23:52
• Resolved: 26/Aug/19 22:48

Description

See attached log. The application is in a REBALANCING state. The second instance joins a bit after the first instance (~250ms). The group coordinator says it is going to rebalance but nothing happens. The first instance gets all partitions (2). The application transitions to RUNNING.

See attached test, which starts one client and then starts another about 250ms later. This seems to consistently repro the issue for me.

This is blocking my work on KAFKA-8755, so I'm inclined to pick it up