[FLINK-8132] FlinkKafkaProducer011 can commit incorrect transaction during recovery

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 1.4.0
• Component/s: Connectors / Kafka
• Assignee: Piotr Nowojski
• Reporter: Piotr Nowojski
• Created: 22/Nov/17 11:28
• Updated: 03/Aug/21 13:11
• Resolved: 23/Nov/17 13:46

Description

Faulty scenario with producer pool of 2.

1. started transaction 1 (txn1) with producerA, written record 42
2. checkpoint 1 triggered, pre committing txn1, started txn2 with producerB, written record 43
3. checkpoint 1 completed, committing txn1, returning producerA to the pool
4. checkpoint 2 triggered , pre-committing txn2, started txn3 with producerA, written record 44
5. crash....
6. recover to checkpoint 1, txn1 from producerA found to "pendingCommitTransactions", attempting to recoverAndCommit(txn1)
7. unfortunately txn1 and txn3 from the same producers are identical from KafkaBroker perspective and thus txn3 is being committed

result is that both records 42 and 44 are committed.

Issue Links

• relates to: FLINK-23410 Use a pool of KafkaProducers to commit Kafka Transactions
• links to: GitHub Pull Request #5053