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https://issues.apache.org/jira/browse/FLINK-9558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18057739#comment-18057739
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Natea Eshetu Beshada commented on FLINK-9558:
---------------------------------------------
The original BucketingSink was removed from the codebase in FLINK-19993. Its
replacement StreamingFileSink is also deprecated in favor of the newer FileSink
(connector-based, Sink V2 API).
All three generations of file sinks share the same design: inactive bucket
cleanup is tied to the checkpoint completion lifecycle
(notifyCheckpointComplete / commitUpToCheckpoint / prepareCommit). Without
checkpointing enabled, inactive buckets accumulate in the activeBuckets map
indefinitely.
However, running any of these file sinks without checkpointing is fundamentally
unsupported — files never transition from pending/in-progress to finished
state, so the output is broken regardless of the memory leak. The memory leak
is a secondary symptom.
Given that the original class no longer exists and the file sinks require
checkpointing to produce correct output, I think this issue can be closed as
Won't Fix.
> 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: Connectors / FileSystem
> Affects Versions: 1.3.0
> Reporter: Rinat Sharipov
> Priority: Not a Priority
> Labels: auto-deprioritized-major, auto-deprioritized-minor,
> auto-unassigned
>
> 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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