[jira] [Assigned] (FLINK-9558) Memory leaks during usage of bucketing-sink with disabled checkpointing

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

     [ https://issues.apache.org/jira/browse/FLINK-9558?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

vinoyang reassigned FLINK-9558:
-------------------------------

    Assignee: vinoyang

> Memory leaks during usage of bucketing-sink with disabled checkpointing
> -----------------------------------------------------------------------
>
>                 Key: FLINK-9558
>                 URL: https://issues.apache.org/jira/browse/FLINK-9558
>             Project: Flink
>          Issue Type: Bug
>          Components: filesystem-connector
>    Affects Versions: 1.3.0
>            Reporter: Rinat Sharipov
>            Assignee: vinoyang
>            Priority: Major
>
> Hi mates, we have some Flink jobs, that are writing data from kafka into hdfs, using Bucketing-Sink.
>  For some reasons, those jobs are running without checkpointing. For now, it not a big problem for us, if some files are remained open in case of job reloading.
>   
>  Periodically, those jobs fail with *OutOfMemory* exception, and seems, that I found a strange thing in the implementation of BucketingSink.
>   
>  During the sink lifecycle, we have a state object, implemented as a map, where key is a bucket path, and value is a state, that contains information about opened files and list of pending files.
>  After researching of the heap dump, I found, that those state stores information about ~ 1_000 buckets and their state, all this stuff weights ~ 120 Mb.
>   
>  I’ve looked through the code, and found, that we removing the buckets from the state, in *notifyCheckpointComplete* method. 
> {code:java}
> @Override
> public void notifyCheckpointComplete(long checkpointId) throws Exception {
>   Iterator<Map.Entry<String, BucketState<T>>> bucketStatesIt = state.bucketStates.entrySet().iterator();
>   while (bucketStatesIt.hasNext()) {
>        if (!bucketState.isWriterOpen &&
>        bucketState.pendingFiles.isEmpty() &&
>        bucketState.pendingFilesPerCheckpoint.isEmpty()) {
>        // We've dealt with all the pending files and the writer for this bucket is not currently open.
>        // Therefore this bucket is currently inactive and we can remove it from our state.
>        bucketStatesIt.remove();
>     }
>     }
> }
> {code}
> So, this looks like an issue, when you are using this sink in checkpointless environment, because the data always added to the state, but never removed.
>   
>  Of course, we could enable checkpointing, and use one of available backends, but as for me, it seems like a non expected behaviour, like I have an opportunity to run the job without checkpointing, but really, if I do so, I got an exception in sink component.
> As for me, it seems, that we should at least document such behaviour, or implement any fail-fast implementation, that wouldn't work in env with disabled checkpointing
>  



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