[GitHub] [beam] damccorm opened a new issue, #20563: Bug in recovering from checkpoints

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damccorm opened a new issue, #20563:
URL: https://github.com/apache/beam/issues/20563

   There is a bug in the Kinesis connector which doesn't allow Beam to read from new shards if restored from an old enough checkpoint.
   
   When loading from an old checkpoint `ShardReadersPool` will identify that the old shard is closed and only attempts to read from successive shards. However when trying to find successive shards it will only look for shards that were children of the old shard, these shards may not exist if the checkpoint is old enough as expired shards are not returned when listing shards ([docs](https://docs.aws.amazon.com/streams/latest/dev/kinesis-using-sdk-java-after-resharding.html))
   
   Example 1:
   
   Checkpoint:
   
   (Alive)
    Shard 1
   
   At restoration:
   
                      (Alive)
                    \> Shard 2 \
    (Exp)     /                    \  (Alive)
    Shard 1                        -\> Shard 4
                \   (Alive)      / 
                  \> Shard 3 /
   
   In this example the connector will currently work correctly as Shard 2 and 3 will be identified as the successive shards and will continue reading from them.
   
   Example 2:
   
   Checkpoint:
   
   (Alive)
    Shard 1
   
   At restoration:
   
                       (Exp)
                    \> Shard 2 \
    (Exp)     /                    \  (Alive)
    Shard 1                        -\> Shard 4
                \    (Exp)       / 
                  \> Shard 3 /
   
   In this example the connector currently won't work correctly as it wont identify Shard 4 as a successive shard as its not a child of Shard 1 and thus stop reading from the stream when it should start reading from Shard 4.
   
    
   
   Imported from Jira [BEAM-11014](https://issues.apache.org/jira/browse/BEAM-11014). Original Jira may contain additional context.
   Reported by: usamj.


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