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https://issues.apache.org/jira/browse/FLUME-1850?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13559419#comment-13559419
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Connor Woodson commented on FLUME-1850:
---------------------------------------
The maximum for maxOpenFiles is 5000 for no good reason I know of. Lowering
that will have no visible effect up to a certain point (if it's lower than the
number of files you write to at one time that's just silly). Based on your
config, you will have at least as many open files as you have hosts. Setting
maxOpenFiles to the number of hosts you have will be good, but there could
occasionally be some performance issues. I think you should set it at roughly 2
* the number of hosts you have, as around the turn of an hour, you might still
be getting log events from the previous hour, so you don't want to close those
files just yet (you would be opening/closing files very fast for a period of
seconds to minutes which would create many 1-event files and slow the
application down)
Lowering maxOpenFiles to that value would likely solve the memory problem, but
to be safe setting rollInterval to 0 and setting a good value for idleTimeout
should theoretically prevent all memory issues.
To speed up testing, you could try lowering the heap size, but I don't know by
how much. The best way is probably to enable JVM monitoring so that you can
watch the heap usage yourself.
> OutOfMemory Error
> -----------------
>
> Key: FLUME-1850
> URL: https://issues.apache.org/jira/browse/FLUME-1850
> Project: Flume
> Issue Type: Bug
> Components: Node
> Affects Versions: v1.3.0
> Environment: RHEL 6
> Reporter: Mohit Anchlia
> Attachments: flume-oo.docx, Screen Shot 2013-01-16 at 11.05.55 PM.png
>
>
> We are using flume-1.3.0. After flume is up for a while (30 days+) we get
> OutOfMemory error. Our heap is set to 2G and load on the system is very low.
> Around 50 request/minute. We use AvroClient and long lived connection.
> Below is the stack trace. I don't have the heap dump but I plan to enable
> that for next time.
> 13/01/16 09:09:38 ERROR hdfs.HDFSEventSink: process failed
> java.lang.OutOfMemoryError: Java heap space
> at java.util.Arrays.copyOf(Arrays.java:2786)
> at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:94)
> at java.io.DataOutputStream.write(DataOutputStream.java:90)
> at org.apache.hadoop.io.Text.write(Text.java:282)
> at
> org.apache.hadoop.io.serializer.WritableSerialization$WritableSerializer.serialize(WritableSerialization.java:90)
> at
> org.apache.hadoop.io.serializer.WritableSerialization$WritableSerializer.serialize(WritableSerialization.java:77)
> at
> org.apache.hadoop.io.SequenceFile$BlockCompressWriter.append(SequenceFile.java:1320)
> at
> org.apache.flume.sink.hdfs.HDFSSequenceFile.append(HDFSSequenceFile.java:72)
> at
> org.apache.flume.sink.hdfs.BucketWriter.append(BucketWriter.java:376)
> at
> org.apache.flume.sink.hdfs.HDFSEventSink$2.call(HDFSEventSink.java:729)
> at
> org.apache.flume.sink.hdfs.HDFSEventSink$2.call(HDFSEventSink.java:727)
> at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
> at java.util.concurrent.FutureTask.run(FutureTask.java:138)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> at java.lang.Thread.run(Thread.java:662)
> Exception in thread "SinkRunner-PollingRunner-DefaultSinkProcessor"
> java.lang.OutOfMemoryError: Java heap space
> at java.util.Arrays.copyOf(Arrays.java:2786)
> at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:94)
> at java.io.DataOutputStream.write(DataOutputStream.java:90)
> at org.apache.hadoop.io.Text.write(Text.java:282)
> at
> org.apache.hadoop.io.serializer.WritableSerialization$WritableSerializer.serialize(WritableSerialization.java:90)
> at
> org.apache.hadoop.io.serializer.WritableSerialization$WritableSerializer.serialize(WritableSerialization.java:77)
> at
> org.apache.hadoop.io.SequenceFile$BlockCompressWriter.append(SequenceFile.java:1320)
> at
> org.apache.flume.sink.hdfs.HDFSSequenceFile.append(HDFSSequenceFile.java:72)
> at
> org.apache.flume.sink.hdfs.BucketWriter.append(BucketWriter.java:376)
> at
> org.apache.flume.sink.hdfs.HDFSEventSink$2.call(HDFSEventSink.java:729)
> at
> org.apache.flume.sink.hdfs.HDFSEventSink$2.call(HDFSEventSink.java:727)
> at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
> at java.util.concurrent.FutureTask.run(FutureTask.java:138)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> at java.lang.Thread.run(Thread.java:662)
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