[KAFKA-5415] TransactionCoordinator doesn't complete transition to PrepareCommit state

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 0.11.0.0
• Labels: exactly-once
• Assignee: Apurva Mehta
• Reporter: Apurva Mehta
• Created: 09/Jun/17 00:34
• Updated: 10/Jun/17 00:09
• Resolved: 10/Jun/17 00:09

Description

This has been revealed by the system test failures on jenkins.

The transaction coordinator seems to get into a path during the handling of the EndTxnRequest where it returns an error (possibly a NOT_COORDINATOR or COORDINATOR_NOT_AVAILABLE error, to be revealed by https://github.com/apache/kafka/pull/3278) to the client. However, due to network instability, the producer is disconnected before it receives this error.

As a result, the transaction remains in a `PrepareXX` state, and future `EndTxn` requests sent by the client after reconnecting result in a `CONCURRENT_TRANSACTION` error code. Hence the client gets stuck and the transaction never finishes, as expiration isn't done from a PrepareXX state.

Issue Links

• links to: GitHub Pull Request #3286