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https://issues.apache.org/jira/browse/KAFKA-5482?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Apurva Mehta updated KAFKA-5482:
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Fix Version/s: (was: 0.11.0.2)
1.0.0
> A CONCURRENT_TRANASCTIONS error for the first AddPartitionsToTxn request
> slows down transactions significantly
> --------------------------------------------------------------------------------------------------------------
>
> Key: KAFKA-5482
> URL: https://issues.apache.org/jira/browse/KAFKA-5482
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 0.11.0.0
> Reporter: Apurva Mehta
> Assignee: Apurva Mehta
> Fix For: 1.0.0
>
>
> Here is the issue.
> # When we do a commit transaction, the producer sends an `EndTxn` request to
> the coordinator. The coordinator writes the `PrepareCommit` message to the
> transaction log and then returns the response the client. It writes the
> transaction markers and the final 'CompleteCommit' message asynchronously.
> # In the mean time, if the client starts another transaction, it will send an
> `AddPartitions` request on the next `Sender.run` loop. If the markers haven't
> been written yet, then the coordinator will return a retriable
> `CONCURRENT_TRANSACTIONS` error to the client.
> # The current behavior in the producer is to sleep for `retryBackoffMs`
> before retrying the request. The current default for this is 100ms. So the
> producer will sleep for 100ms before sending the `AddPartitions` again. This
> puts a floor on the latency for back to back transactions.
> This has been worked around in
> https://issues.apache.org/jira/browse/KAFKA-5477 by reducing the retryBackoff
> for the first AddPartitions request. But we need a stronger solution: like
> having the commit block until the transaction is complete, or delaying the
> addPartitions until batches are actually ready to be sent to the transaction.
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