[jira] [Commented] (FLINK-6873) Limit the number of open writers in file system connector

["Oscar Westra van Holthe - Kind (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-6873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16630562#comment-16630562 ] 

Oscar Westra van Holthe - Kind commented on FLINK-6873:
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What may also be an issue is that the BucketingSink and the newer StreamingFileSink seem to ignore event time..

Thus, if your output stream uses a buffer of some sorts and your job catches up quickly (processing multiple days worth of events in a few hours), the sink may end up having too many open files.

> Limit the number of open writers in file system connector
> ---------------------------------------------------------
>
>                 Key: FLINK-6873
>                 URL: https://issues.apache.org/jira/browse/FLINK-6873
>             Project: Flink
>          Issue Type: Improvement
>          Components: filesystem-connector, Local Runtime, Streaming Connectors
>            Reporter: Mu Kong
>            Priority: Major
>
> Mail list discuss:
> https://mail.google.com/mail/u/1/#label/MailList%2Fflink-dev/15c869b2a5b20d43
> Following exception will occur when Flink is writing to too many files:
> {code}
> java.lang.OutOfMemoryError: unable to create new native thread
> at java.lang.Thread.start0(Native Method)
> at java.lang.Thread.start(Thread.java:714)
> at org.apache.hadoop.hdfs.DFSOutputStream.start(DFSOutputStream.java:2170)
> at org.apache.hadoop.hdfs.DFSOutputStream.newStreamForCreate(DFSOutputStream.java:1685)
> at org.apache.hadoop.hdfs.DFSClient.create(DFSClient.java:1689)
> at org.apache.hadoop.hdfs.DFSClient.create(DFSClient.java:1624)
> at org.apache.hadoop.hdfs.DistributedFileSystem$7.doCall(DistributedFileSystem.java:448)
> at org.apache.hadoop.hdfs.DistributedFileSystem$7.doCall(DistributedFileSystem.java:444)
> at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
> at org.apache.hadoop.hdfs.DistributedFileSystem.create(DistributedFileSystem.java:459)
> at org.apache.hadoop.hdfs.DistributedFileSystem.create(DistributedFileSystem.java:387)
> at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:909)
> at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:890)
> at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:787)
> at org.apache.flink.streaming.connectors.fs.StreamWriterBase.open(StreamWriterBase.java:120)
> at org.apache.flink.streaming.connectors.fs.StringWriter.open(StringWriter.java:62)
> at org.apache.flink.streaming.connectors.fs.bucketing.BucketingSink.openNewPartFile(BucketingSink.java:545)
> at org.apache.flink.streaming.connectors.fs.bucketing.BucketingSink.invoke(BucketingSink.java:440)
> at org.apache.flink.streaming.api.operators.StreamSink.processElement(StreamSink.java:41)
> at org.apache.flink.streaming.runtime.tasks.OperatorChain$CopyingChainingOutput.pushToOperator(OperatorChain.java:528)
> at org.apache.flink.streaming.runtime.tasks.OperatorChain$CopyingChainingOutput.collect(OperatorChain.java:503)
> at org.apache.flink.streaming.runtime.tasks.OperatorChain$CopyingChainingOutput.collect(OperatorChain.java:483)
> at org.apache.flink.streaming.api.operators.AbstractStreamOperator$CountingOutput.collect(AbstractStreamOperator.java:891)
> at org.apache.flink.streaming.api.operators.AbstractStreamOperator$CountingOutput.collect(AbstractStreamOperator.java:869)
> at org.apache.flink.streaming.api.operators.StreamSourceContexts$NonTimestampContext.collect(StreamSourceContexts.java:103)
> at org.apache.flink.streaming.connectors.kafka.internals.AbstractFetcher.emitRecord(AbstractFetcher.java:230)
> at org.apache.flink.streaming.connectors.kafka.internals.SimpleConsumerThread.run(SimpleConsumerThread.java:379)
> {code}
> Letting developers decide the max open connections to the open files would be great.



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