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https://issues.apache.org/jira/browse/KAFKA-14445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17643768#comment-17643768
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Haruki Okada commented on KAFKA-14445:
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If the suggestion makes sense, we're happy to send a patch.
> Producer doesn't request metadata update on REQUEST_TIMED_OUT
> -------------------------------------------------------------
>
> Key: KAFKA-14445
> URL: https://issues.apache.org/jira/browse/KAFKA-14445
> Project: Kafka
> Issue Type: Improvement
> Reporter: Haruki Okada
> Priority: Major
>
> Produce requests may fail with timeout by `request.timeout.ms` in below two
> cases:
> * Didn't receive produce response within `request.timeout.ms`
> * Produce response received, but it ended up with `REQUEST_TIMEOUT_MS` in
> the broker
> Former case usually happens when a broker-machine got failed or there's
> network glitch etc.
> In this case, the connection will be disconnected and metadata-update will be
> requested to discover new leader:
> [https://github.com/apache/kafka/blob/3.3.1/clients/src/main/java/org/apache/kafka/clients/producer/internals/Sender.java#L556]
>
> The problem is in latter case (REQUEST_TIMED_OUT on the broker).
> In this case, the produce request will be ended up with TimeoutException,
> which doesn't inherit InvalidMetadataException so it doesn't trigger metadata
> update.
>
> Typical cause of REQUEST_TIMED_OUT is replication delay due to follower-side
> problem, that metadata-update doesn't make much sense indeed.
>
> However, we found that in some cases, stale metadata on REQUEST_TIMED_OUT
> could cause produce requests to retry unnecessarily , which may end up with
> batch expiration due to delivery timeout.
> Below is the scenario we experienced:
> * Environment:
> ** Partition tp-0 has 3 replicas, 1, 2, 3. Leader is 1
> ** min.insync.replicas=2
> ** acks=all
> * Scenario:
> ** broker 1 "partially" failed
> *** It lost ZooKeeper connection and kicked out from the cluster
> **** There was controller log like:
> *****
> {code:java}
> [2022-12-04 08:01:04,013] INFO [Controller id=XX] Newly added brokers: ,
> deleted brokers: 1, bounced brokers: {code}
> *** However, somehow the broker was able continued to receive produce
> requests
> **** We're still working on investigating how this is possible though.
> **** Indeed, broker 1 was somewhat "alive" and keeps working according to
> server.log
> *** In other words, broker 1 became "zombie"
> ** broker 2 was elected as new leader
> *** broker 3 became follower of broker 2
> *** However, since broker 1 was still out of cluster, it didn't receive
> LeaderAndIsr so 1 kept thinking itself as the leader of tp-0
> ** Meanwhile, producer keeps sending produce requests to broker 1 and
> requests were failed due to REQUEST_TIMED_OUT because no brokers replicates
> from broker 1.
> *** REQUEST_TIMED_OUT doesn't trigger metadata update, so produce didn't
> have a change to update its stale metadata
>
> So I suggest to request metadata update even on REQUEST_TIMED_OUT exception,
> for the case that the old leader became "zombie"
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