[BOOKKEEPER-140] Hub server doesn't subscribe remote region correctly when a region is down.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0.0
• Fix Version/s: 4.1.0
• Component/s: hedwig-server
• Assignee: Sijie Guo
• Reporter: Sijie Guo
• Created: 06/Dec/11 11:31
• Updated: 22/Oct/12 14:50
• Resolved: 21/Dec/11 16:43

Description

Hub server doesn't subscribe remote region correctly in following cases: (assume there is 3 regions, A, B, C)

1. region shuts down before first subscribe.

1) region C is down.
2) subscribe-a subscribe a topic in region A. a subscription state is created in region A's zookeeper. but remote subscribe to region C would fail since region C is down. hub server will respond client that subscribe failed without deleting subscription state. The following subscriptions using same subscribe id and same topic would failed due to NodeExists.

2. region shuts down when attaches existing subscriptions.

1) In region A, there is a local subscriber a for topic T. in region B, subscriber b for topic T. in region B, subscribe c for topic T.
2) servers are all restarted in all three regions. But region C is network-partitioned (or shuts down) from region A and region B.
3) subscriber b and subscribe c try to subscribe T again. hub servers in region B, C will try to remote subscribe region A, but should failed. There is no mechanism to retry remote subscribe. so if messages are published to topic T in region A, subscribe b and subscribe c would receive any message.