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Posted to issues@beam.apache.org by "Beam JIRA Bot (Jira)" <ji...@apache.org> on 2022/03/03 17:29:00 UTC
[jira] [Assigned] (BEAM-13667) Users cannot provide their own sharding function when using FileIO
[ https://issues.apache.org/jira/browse/BEAM-13667?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Beam JIRA Bot reassigned BEAM-13667:
------------------------------------
Assignee: (was: Sandeep Kathula)
> Users cannot provide their own sharding function when using FileIO
> ------------------------------------------------------------------
>
> Key: BEAM-13667
> URL: https://issues.apache.org/jira/browse/BEAM-13667
> Project: Beam
> Issue Type: Improvement
> Components: sdk-java-core
> Affects Versions: 2.35.0
> Reporter: Sandeep Kathula
> Priority: P2
> Labels: stale-assigned
>
> Beam uses RandomShardingFunction ([https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/io/WriteFiles.java#L834]) by default for sharding when using FileIO.write().
>
> RandomShardingFuncction doesn’t work well with Flink Runner. Its assigning same key (hashDestination(destination, destinationCoder)) along with the shard number. ([https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/io/WriteFiles.java#L863])
> This is causing different ShardedKeys going to same task slot. As a result, there is no equal distribution of files written from different task slots.
> E.g. 2 files are written by task slot 1, 3 files written by task slot 2, 0 files written by other task slots.
>
> As a result, we are seeing Out of Memory from the pods writing more files.
>
> At [https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/io/WriteFiles.java#L695-L698]
> There is an option to give a different sharding function. But there is no way for the user to mention different sharding function when using FileIO class.
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