Extremely long startup time for exactly_once kafka sink

[Bobby Richard <bo...@broadcom.com>]

When enabling exactly_once on my kafka sink, I am seeing extremely long
initialization times (over 1 hour), especially after restoring from a
savepoint. In the logs I see the job constantly initializing thousands of
kafka producers like this:

2023-01-31 14:39:58,150 INFO org.apache.kafka.clients.producer.internals.
TransactionManager [] - [Producer
clientId=producer-common-event-enrichment-mutable-enriched-events-5-1,
transactionalId=common-event-enrichment-mutable-enriched-events-5-1]
ProducerId set to 847642 with epoch 14
2023-01-31 14:39:58,150 INFO org.apache.kafka.clients.producer.internals.
TransactionManager [] - [Producer
clientId=producer-common-event-enrichment-mutable-enriched-events-5-1,
transactionalId=common-event-enrichment-mutable-enriched-events-5-1]
Invoking InitProducerId for the first time in order to acquire a producer ID
2023-01-31 14:39:58,151 INFO org.apache.kafka.clients.producer.internals.
TransactionManager [] - [Producer
clientId=producer-common-event-enrichment-common-enriched-events-5-1,
transactionalId=common-event-enrichment-common-enriched-events-5-1]
ProducerId set to 2496758 with epoch 25
2023-01-31 14:39:58,151 INFO org.apache.kafka.clients.producer.internals.
TransactionManager [] - [Producer
clientId=producer-common-event-enrichment-immutable-enriched-events-5-1,
transactionalId=common-event-enrichment-immutable-enriched-events-5-1]
ProducerId set to 886210 with epoch 16
2023-01-31 14:39:58,151 INFO org.apache.kafka.clients.producer.internals.
TransactionManager [] - [Producer
clientId=producer-common-event-enrichment-mutable-enriched-events-5-1,
transactionalId=common-event-enrichment-mutable-enriched-events-5-1]
Discovered transaction coordinator kafka-broker-2:9092 (id: 2 rack: null)
2023-01-31 14:39:58,151 INFO org.apache.kafka.clients.producer.internals.
TransactionManager [] - [Producer
clientId=producer-common-event-enrichment-immutable-enriched-events-5-1,
transactionalId=common-event-enrichment-immutable-enriched-events-5-1]
Invoking InitProducerId for the first time in order to acquire a producer ID
2023-01-31 14:39:58,151 INFO org.apache.kafka.clients.producer.internals.
TransactionManager [] - [Producer
clientId=producer-common-event-enrichment-common-enriched-events-5-1,
transactionalId=common-event-enrichment-common-enriched-events-5-1] Invoking
InitProducerId for the first time in order to acquire a producer ID
2023-01-31 14:39:58,152 INFO org.apache.kafka.clients.producer.internals.
TransactionManager [] - [Producer
clientId=producer-common-event-enrichment-immutable-enriched-events-5-1,
transactionalId=common-event-enrichment-immutable-enriched-events-5-1]
Discovered transaction coordinator kafka-broker-0:9092 (id: 0 rack: null)
2023-01-31 14:39:58,152 INFO org.apache.kafka.clients.producer.internals.
TransactionManager [] - [Producer
clientId=producer-common-event-enrichment-common-enriched-events-5-1,
transactionalId=common-event-enrichment-common-enriched-events-5-1]
Discovered transaction coordinator kafka-broker-2:9092 (id: 2 rack: null)

Does transaction timeout impact the startup time? How can I optimize the
initialization time? Without exactly_once the job starts up very quickly.

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