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https://issues.apache.org/jira/browse/KAFKA-2042?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14378986#comment-14378986
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Jiangjie Qin commented on KAFKA-2042:
-------------------------------------
Yes, it depends on whether the topic list is empty or not when we send the
first TMR.
I might miss something but I think the TMR will be sent very soon after the
producer is instantiated.
In the first NetworkClient.poll(), it checks if metadata needs update by
getting the max of
timeToNextMeatadataUpdate
timeToNextReconnectAttempt
waitForMetadataFetch
All of them will be 0 on starting up. That means the TMR will be sent at the
first poll().
> New producer metadata update always get all topics.
> ---------------------------------------------------
>
> Key: KAFKA-2042
> URL: https://issues.apache.org/jira/browse/KAFKA-2042
> Project: Kafka
> Issue Type: Bug
> Reporter: Jiangjie Qin
> Assignee: Jiangjie Qin
> Priority: Blocker
> Fix For: 0.8.3
>
> Attachments: KAFKA-2042.patch, KAFKA-2042_2015-03-24_13:37:49.patch,
> KAFKA-2042_2015-03-24_13:57:23.patch
>
>
> The new java producer metadata.topics is initially empty so the producer
> sends TMR with empty topic set. The broker takes the empty requested topic
> set as all topics, so metadata.cluster contains all topic metadata. Later on,
> when a new topic was produced, it gets added into the metadata.topics. The
> next metadata update will only contain the meta data for this new topic, so
> the metadata.cluster will only have this topic. Since there are a lot of
> messages are still in the accumulator but has no metadata in
> metadata.cluster, if a caller thread do a flush(), the caller thread will
> block forever because the messages sitting in accumulator without metadata
> will never be ready to send.
> We should add check for the metadata.topics, if it is empty, no TMR should be
> sent.
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