[jira] [Created] (BEAM-12915) No parallelism when using SDFBoundedSourceReader with Flink

["Rogan Morrow (Jira)" <ji...@apache.org>]

Rogan Morrow created BEAM-12915:
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             Summary: No parallelism when using SDFBoundedSourceReader with Flink
                 Key: BEAM-12915
                 URL: https://issues.apache.org/jira/browse/BEAM-12915
             Project: Beam
          Issue Type: Bug
          Components: runner-flink
    Affects Versions: 2.32.0
            Reporter: Rogan Morrow


Background: I am using TFX pipelines with Flink as the runner for Beam (flink session cluster using [flink-on-k8s-operator|https://github.com/GoogleCloudPlatform/flink-on-k8s-operator]). The Flink cluster has 2 taskmanagers with 16 cores each, and parallelism is set to 32. TFX components call {{beam.io.ReadFromTFRecord}} to load data. I have a dataset of TFRecords split across 160 files. When I try to run the component, processing for all 160 files ends up in a single subtask in Flink, i.e. the parallelism is effectively 1. See below images:

!https://i.imgur.com/ppba0AL.png!

!https://i.imgur.com/rSTFATn.png!

 
I have tried all manner of Beam/Flink options and different versions of Beam/Flink but the behaviour remains the same.

Furthermore, the behaviour affects anything that uses {{apache_beam.io.iobase.SDFBoundedSourceReader}}, e.g. {{apache_beam.io.parquetio.ReadFromParquet}} also has the same issue. Either I'm missing some obscure setting in my configuration, or this is a bug with the Flink runner.
 



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