[jira] [Commented] (KAFKA-7318) Should introduce a offset reset policy to consume only the messages after subscribing

["Matthias J. Sax (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-7318?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16587689#comment-16587689 ] 

Matthias J. Sax commented on KAFKA-7318:
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> {{latest}} (the default) , if a consumer subscribe a new topic and then close, during these times, there are some message was produced,  the consumer can not poll these messages.

If you commit offsets, as you describe later, you get the behavior you want. Committing offsets is the right thing to do, to pick up where you left off. Note, that `auto.offset.reset` only triggers if there is no committed offsets. Thus, a now policy would not resolve the issue.

You are right, that `poll()` semantics were changed – for a good reason. Also note, that you example code above might miss records, as `poll(0)` could return data that you would not process.

What you could do is, to use `endOffsets(...)` API (after you subscribed) to get the current end-offsets, commit those, call seekToEnd() and start processing.

> Should introduce a offset reset policy to consume only the messages after subscribing
> -------------------------------------------------------------------------------------
>
>                 Key: KAFKA-7318
>                 URL: https://issues.apache.org/jira/browse/KAFKA-7318
>             Project: Kafka
>          Issue Type: Improvement
>          Components: consumer
>    Affects Versions: 1.1.0, 1.1.1, 2.0.0
>            Reporter: joechen8310@gmail.com
>            Priority: Major
>
> On our situation, we want the consumers only consume the messages which was produced after subscribing.   
> Currently, kafka support 3 stategies with auto.offset.reset, but seems both of them can not support the feature we want.
>  * {{latest}} (the default) , if a consumer subscribe a new topic and then close, during these times, there are some message was produced,  the consumer can not poll these messages.
>  * earliest , consumer may consume all the messages on the topic  before subscribing.
>  * none, not in this scope.
> Before version 1.1.0, we make the consumer poll and commit  after subscribe as below, this can mark the offset to 0 and works (enable.auto.commit is false) .
>  
> {code:java}
> consumer.subscribe(topics, consumerRebalanceListener);
> if(consumer.assignment().isEmpty()) {
>    consumer.poll(0);
>    consumer.commitSync();
> }
> {code}
> After upgrade the clients to >=1.1.0,  it is broke. Seems it was broke by the fix [KAFKA-6397|https://github.com/apache/kafka/commit/677881afc52485aef94150be50d6258d7a340071#diff-267b7c1e68156c1301c56be63ae41dd0], but I am not sure about that.  Then I try to invoke the consumer.position(partitions) in onPartitionsAssigned of ConsumerRebalanceListener,  it works again. but it looks strangely that get the position but do nothing.  
>  
> so we want to know whether there is a formal way to do this, maybe introduce another stategy for auto.offset.reset to only consume the message after  the consumer subscribing is perfect.
>  
>  



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