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https://issues.apache.org/jira/browse/KAFKA-3904?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15352126#comment-15352126
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Henry Cai commented on KAFKA-3904:
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I took a look at FileChannel.open, looks like it will still create a file
descriptor for that channel, so the underlying problem of creating too many
file descriptors are still there.
I am not hundred percent sure we can use this new FileChannel.open() since it
relies on underlying FileSystemProvider.newFileChannel() and some of the
implementations throws NotSupportedOperationException.
I think I will still use the traditional RandomAccessFile.getChannel and post a
PR for this.
> File descriptor leaking (Too many open files) for long running stream process
> -----------------------------------------------------------------------------
>
> Key: KAFKA-3904
> URL: https://issues.apache.org/jira/browse/KAFKA-3904
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Reporter: Henry Cai
> Assignee: Henry Cai
> Labels: architecture, newbie
>
> I noticed when my application was running long (> 1 day), I will get 'Too
> many open files' error.
> I used 'lsof' to list all the file descriptors used by the process, it's over
> 32K, but most of them belongs to the .lock file, e.g. this same lock file
> shows 2700 times.
> I looked at the code, I think the problem is in:
> File lockFile = new File(stateDir, ProcessorStateManager.LOCK_FILE_NAME);
> FileChannel channel = new RandomAccessFile(lockFile, "rw").getChannel();
> Each time new RandomAccessFile is called, a new fd will be created, we
> probably should either close or reuse this RandomAccessFile object.
> lsof result:
> java 14799 hcai *740u REG 9,0 0 2415928585
> /mnt/stream/join/rocksdb/ads-demo-30/0_16/.lock
> java 14799 hcai *743u REG 9,0 0 2415928585
> /mnt/stream/join/rocksdb/ads-demo-30/0_16/.lock
> java 14799 hcai *746u REG 9,0 0 2415928585
> /mnt/stream/join/rocksdb/ads-demo-30/0_16/.lock
> java 14799 hcai *755u REG 9,0 0 2415928585
> /mnt/stream/join/rocksdb/ads-demo-30/0_16/.lock
> hcai@teststream02001:~$ lsof -p 14799 | grep lock | grep 0_16 | wc
> 2709 24381 319662
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