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Posted to issues@storm.apache.org by "Janith Kaiprath Valiyalappil (JIRA)" <ji...@apache.org> on 2018/11/04 21:16:00 UTC
[jira] [Assigned] (STORM-3279) Kafka trident spout could loose its
position with EARLIEST or LATEST FirstPollOffsetStrategy
[ https://issues.apache.org/jira/browse/STORM-3279?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Janith Kaiprath Valiyalappil reassigned STORM-3279:
---------------------------------------------------
Assignee: (was: Stig Rohde Døssing)
> 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
> 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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