[jira] [Resolved] (FLINK-4080) Kinesis consumer not exactly-once if stopped in the middle of processing aggregated records

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

     [ https://issues.apache.org/jira/browse/FLINK-4080?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Metzger resolved FLINK-4080.
-----------------------------------
    Resolution: Fixed

Resolved in http://git-wip-us.apache.org/repos/asf/flink/commit/fa42cdab

> Kinesis consumer not exactly-once if stopped in the middle of processing aggregated records
> -------------------------------------------------------------------------------------------
>
>                 Key: FLINK-4080
>                 URL: https://issues.apache.org/jira/browse/FLINK-4080
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Kinesis Connector, Streaming Connectors
>            Reporter: Tzu-Li (Gordon) Tai
>            Assignee: Tzu-Li (Gordon) Tai
>            Priority: Critical
>             Fix For: 1.1.0
>
>
> I've occasionally experienced unsuccessful ManualExactlyOnceTest after several tries.
> Kinesis records of the same aggregated batch will have the same sequence number, and different sub-sequence numbers (http://docs.aws.amazon.com/streams/latest/dev/kinesis-kpl-consumer-deaggregation.html). The current code of the consumer is committing state every time it finishes processing a record, even de-aggregated ones. This is a bug since this will incorrectly mark all remaining records of the de-aggregated batch as processed in the state.
> Proposed fix:
> 1. Use the extended `UserRecord` class in KCL to represent all records (either non- or de-aggregated) instead of the basic `Record` class. This gives access to whether or not the record was originally aggregated.
> 2. The sequence number state we are checkpointing needs to be able to indicate that the last seen sequence number of a shard may be a de-aggregated shard, i.e., {"shard0" -> "5:8", "shard1" -> "2"} meaning the 8th sub-record of the 5th record was last seen for shard 0. On restore, we start again from record 5 for shard 0 and skip the first 7 sub-records; however, for shard 1 we start from record 3 since record 2 is non-aggregated and already fully processed.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)