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https://issues.apache.org/jira/browse/KAFKA-3904?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15352555#comment-15352555
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Ismael Juma commented on KAFKA-3904:
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[~h...@pinterest.com], I didn't mean to suggest that `FileChannel.open` would
fix the issue. It's just a more direct way to get a file channel. The only
reason we have a bunch of code that uses `RandomAccessFile` for this is that we
previously could not use Java 7. The issue you saw with some implementations
that don't support it isn't really an issue when dealing with a normal file
system path. It's just for custom file system implementations (eg
ZipFileSystemProvider, etc.).
Using `RandomFileAccess` is also not great because it holds a reference to the
file descriptor, which can delay resource release.
> 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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