Rinat Sharipov created FLINK-9558:
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Summary: Memory leaks during usage 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
Hi mates, we got 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 opened 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.
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