kafka-streams-exactly-once-support-eos.adoc

Exactly-Once Support (EOS)

Exactly-Once Support (EOS) (aka Exactly-Once Processing Guarantee) is…​FIXME

StreamsConfig defines eosEnabled internal flag that is enabled (true) when StreamsConfig.PROCESSING_GUARANTEE_CONFIG is StreamsConfig.EXACTLY_ONCE (exactly_once).

StreamsConfig.PROCESSING_GUARANTEE_CONFIG can be one of the two values:

• AT_LEAST_ONCE (default)

• EXACTLY_ONCE

With EOS enabled, the frequency with which to save the position of a processor (StreamsConfig.COMMIT_INTERVAL_MS_CONFIG) is always 100L.

Exactly-once processing requires a cluster of at least three brokers (by default) what is the recommended setting for production. For development you can change this, by adjusting broker setting transaction.state.log.replication.factor and transaction.state.log.min.isr.

Notes

• Committing and suspending StreamTasks are sensitive to EOS (per eosEnabled flag)

• With Exactly-once support enabled StreamTask uses StreamTask.initializeTransactions when created and requested to resume