[jira] [Comment Edited] (STORM-3279) Kafka trident spout could loose its position with EARLIEST or LATEST FirstPollOffsetStrategy

["Janith Kaiprath Valiyalappil (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/STORM-3279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16687429#comment-16687429 ] 

Janith Kaiprath Valiyalappil edited comment on STORM-3279 at 11/15/18 3:08 AM:
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[~Srdo], I think your solution is better than what I had working. Just a small comment.

I was trying to pass a signal back from seek. But I guess I should have thought about reading straight from consumer. 

https://gist.github.com/janithkv/a5b5e90db9e35d0e370408de0d7f2a72


was (Author: janithkv):
[~Srdo], I think your solution is better than what I had working. Just a small comment.

I was trying to pass a signal back from seek. But I guess I should have thought to read straight from consume. But this works too. I tested.

https://gist.github.com/janithkv/a5b5e90db9e35d0e370408de0d7f2a72

> Kafka trident spout could loose its position with EARLIEST or LATEST FirstPollOffsetStrategy
> --------------------------------------------------------------------------------------------
>
>                 Key: STORM-3279
>                 URL: https://issues.apache.org/jira/browse/STORM-3279
>             Project: Apache Storm
>          Issue Type: Bug
>          Components: trident
>    Affects Versions: 2.0.1
>            Reporter: Janith Kaiprath Valiyalappil
>            Assignee: Janith Kaiprath Valiyalappil
>            Priority: Major
>              Labels: kafka, trident
>
> In KafkaTridentSpoutEmitter emitPartitionBatch() function, when kafkaConsumer.poll(pollTimeoutMs) returns 0 records for the very first transaction where FirstPollOffsetStrategy is set to EARLIEST or LATEST, the spout fails to move to EARLIEST or LATEST, and continues from the last metadata position.
>  
> The flow of events which would cause this bug :
>  
> 1. FirstPollOffsetStrategy set to EARLIEST or LATEST
> 2. For first transaction after restart txid1 Based on [link L164|https://github.com/apache/storm/blob/master/external/storm-kafka-client/src/main/java/org/apache/storm/kafka/spout/trident/KafkaTridentSpoutEmitter.java#L164] ,
> The currentBatch is initialized to lastBatchMeta (which need not be null);
> 3. Later in L171, the consumer seeks to "start" OR "end"
> 4. Then consumer.poll(pollTimeoutMs) is called.
> 5. If poll returns non 0 records , currentBatch is set to a new metadata . *If poll returns 0 records,*
> *currentBatch is not reset ie, currentBatch is still lastBatchMeta (which need not be null)*
>  
> So now in transaction txid2 after txid1, isFirstPoll() returns false, and the spout continues from lastBatchMeta.
>  
>  



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