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From "Chaitanya (JIRA)" <j...@apache.org>
Subject [jira] [Created] (APEXMALHAR-2493) KafkaSinglePortExactlyOnceOutputOperator going to the blocked state during recovery
Date Thu, 18 May 2017 09:44:04 GMT
Chaitanya created APEXMALHAR-2493:

             Summary: KafkaSinglePortExactlyOnceOutputOperator going to the blocked state
during recovery
                 Key: APEXMALHAR-2493
                 URL: https://issues.apache.org/jira/browse/APEXMALHAR-2493
             Project: Apache Apex Malhar
          Issue Type: Bug
            Reporter: Chaitanya
            Assignee: Chaitanya

Steps to reproduce the issue: 
- Created the Kafka topic with single partition.
- Created the application with the following DAG:
BatchSequenceGenerator -> KafkaSinglePortExactlyOnceOutputOperator
      # of partitions of  KafkaSinglePortExactlyOnceOutputOperator =  2. Let's say KO1, KO2
are the two instances.
- Launched the app, after some time, manually killed the one of the instance of "KafkaSinglePortExactlyOnceOutputOperator"
- During recovery, the instance comes up and after some time, it goes to the blocked state.
App master killed this instance.

* There is an infinite while loop in rebuildPartialWindow() method.
* While loop will break on the below 2 conditions:
       a) # of trails for "polled records from Kafka is empty" = 10
       b) Crossed boundary (consumerRecord.offset() >= currentOffset)

In this scenario, KO1 keeps on writing the data to Kafka. So, the first condition will not
Operator is not checking the 2nd condition because of the below continue statement: 
          if (!doesKeyBelongsToThisInstance(operatorId, consumerRecord.key())) {

Solution: First check the cross boundary condition and then check the doesKeyBelongsToThisInstance(..).

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