[jira] [Created] (APEXMALHAR-2493) KafkaSinglePortExactlyOnceOutputOperator going to the blocked state during recovery

["Chaitanya (JIRA)" <ji...@apache.org>]

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" operator(KO2).
- During recovery, the instance comes up and after some time, it goes to the blocked state. App master killed this instance.

Observation:
----------------
* 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 satisfy.
Operator is not checking the 2nd condition because of the below continue statement: 
          if (!doesKeyBelongsToThisInstance(operatorId, consumerRecord.key())) {
            continue;
          }

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




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