[jira] [Resolved] (FLINK-17820) Memory threshold is ignored for channel state

["Roman Khachatryan (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-17820?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Roman Khachatryan resolved FLINK-17820.
---------------------------------------
    Resolution: Fixed

> Memory threshold is ignored for channel state
> ---------------------------------------------
>
>                 Key: FLINK-17820
>                 URL: https://issues.apache.org/jira/browse/FLINK-17820
>             Project: Flink
>          Issue Type: Bug
>          Components: Runtime / Checkpointing, Runtime / Task
>    Affects Versions: 1.11.0
>            Reporter: Roman Khachatryan
>            Assignee: Roman Khachatryan
>            Priority: Critical
>              Labels: pull-request-available
>             Fix For: 1.11.0
>
>
> Config parameter state.backend.fs.memory-threshold is ignored for channel state. Causing each subtask to have a file per checkpoint. Regardless of the size of channel state (of this subtask).
> This also causes slow cleanup and delays the next checkpoint.
>  
> The problem is that {{ChannelStateCheckpointWriter.finishWriteAndResult}} calls flush(); which actually flushes the data on disk.
>  
> From FSDataOutputStream.flush Javadoc:
> A completed flush does not mean that the data is necessarily persistent. Data persistence can is only assumed after calls to close() or sync().
>  
> Possible solutions:
> 1. not to flush in {{ChannelStateCheckpointWriter.finishWriteAndResult (which can lead to data loss in a wrapping stream).}}
> {{2. change }}{{FsCheckpointStateOutputStream.flush behavior}}
> {{3. wrap }}{{FsCheckpointStateOutputStream to prevent flush}}{{}}{{}}



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