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https://issues.apache.org/jira/browse/KAFKA-966?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13785291#comment-13785291
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Jason Rosenberg commented on KAFKA-966:
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I think a nice api would be to have an enhanced version of
'auto.commit.enable', which allows you to 'mark for commit' a message after you
are done processing it. So, you'd call 'markForCommit()' once you have
successfully processed a message (and this would imply of course, that you are
marking all previous messages up to that offset). So, when a subsequent
invocation of commitOffsets() runs, it will only commit up to the last offset
'markedForCommit'. This would apply both to auto-initiated commits (if
auto.commit.enable is on) and to manually invocations of commitOffsets().
So, this would be a change in the PartitionTopicInfo class, I'd expect. So, in
addition to tracking 'fetchedOffset' and 'consumedOffset', it could track
'markedForCommitOffset' (maybe a better name :))
Then, when commitOffsets() runs, if 'reliable.auto.commit.enable' (or whatever
we call it) is enabled, then it would use the 'markedForCommitOffset' rather
than the 'consumedOffset' when committing.
Thoughts?
> Allow high level consumer to 'nak' a message and force Kafka to close the
> KafkaStream without losing that message
> -----------------------------------------------------------------------------------------------------------------
>
> Key: KAFKA-966
> URL: https://issues.apache.org/jira/browse/KAFKA-966
> Project: Kafka
> Issue Type: Improvement
> Components: consumer
> Affects Versions: 0.8
> Reporter: Chris Curtin
> Assignee: Neha Narkhede
> Priority: Minor
>
> Enhancement request.
> The high level consumer is very close to handling a lot of situations a
> 'typical' client would need. Except for when the message received from Kafka
> is valid, but the business logic that wants to consume it has a problem.
> For example if I want to write the value to a MongoDB or Cassandra database
> and the database is not available. I won't know until I go to do the write
> that the database isn't available, but by then it is too late to NOT read the
> message from Kafka. Thus if I call shutdown() to stop reading, that message
> is lost since the offset Kafka writes to ZooKeeper is the next offset.
> Ideally I'd like to be able to tell Kafka: close the KafkaStream but set the
> next offset to read for this partition to this message when I start up again.
> And if there are any messages in the BlockingQueue for other partitions, find
> the lowest # and use it for that partitions offset since I haven't consumed
> them yet.
> Thus I can cleanly shutdown my processing, resolve whatever the issue is and
> restart the process.
> Another idea might be to allow a 'peek' into the next message and if I
> succeed in writing to the database call 'next' to remove it from the queue.
> I understand this won't deal with a 'kill -9' or hard failure of the JVM
> leading to the latest offsets not being written to ZooKeeper but it addresses
> a likely common scenario for consumers. Nor will it add true transactional
> support since the ZK update could fail.
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