Details
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Bug
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Status: Open
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Minor
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Resolution: Unresolved
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3.0.0
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None
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openjdk version "11.0.13" 2021-10-19
Description
With org.apache.kafka/kafka-clients 3.0.0, under rare circumstances involving multiple node and network failures, I've observed a call to `producer.send()` throw `NotLeaderOrFollowerException` for a message which later appears in `consumer.poll()` return values.
I don't have a reliable repro case for this yet, but the case I hit involved retries=1000, acks=all, and idempotence enabled. I suspect what might be happening here is that an initial attempt to send the message makes it to the server and is committed, but the acknowledgement is lost e.g. due to timeout; the Kafka producer then automatically retries the send attempt, and on that retry hits a NotLeaderOrFollowerException, which is thrown back to the caller. If we interpret NotLeaderOrFollowerException as a definite failure, then this would constitute an aborted read.
I've seen issues like this in a number of databases around client or server-internal retry mechanisms, and I think the thing to do is: rather than throwing the most recent error, throw the most indefinite. That way clients know that their request may have actually succeeded, and they won't (e.g.) attempt to re-submit a non-idempotent request again.
As a side note: is there... perhaps documentation on which errors in Kafka are supposed to be definite vs indefinite? NotLeaderOrFollowerException is a subclass of RetriableException, but it looks like RetriableException is more about transient vs permanent errors than whether it's safe to retry.