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HBase, mail # dev - Calling o/s.flush() in HLog.sync()?


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Himanshu Vashishtha 2013-11-05, 05:11
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Haosong Huang 2013-11-05, 09:08
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Himanshu Vashishtha 2013-11-06, 01:22
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Haosong Huang 2013-11-08, 14:57
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Re: Calling o/s.flush() in HLog.sync()?
Ted Yu 2013-11-07, 22:56
Himanshu:
See
http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/io/DataOutputStream.java#DataOutputStream.flush%28%29
The flush() call results in OutputStream.flush().

Cheers
On Mon, Nov 4, 2013 at 9:11 PM, Himanshu Vashishtha <[EMAIL PROTECTED]>wrote:

> Looking at ProtobufLogWriter class, it looks like the call to flush() in
> the sync method is a noop.
>
>
> https://github.com/apache/hbase/blob/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/ProtobufLogWriter.java#L134
>
> The underlying output stream is DFSOutputStream, which doesn't implement
> flush().
>
> And, it calls sync() anyway, which ensures the data is written to DN's
> (cache).
>
> Previously with SequenceFile$Writer, it writes data to the outputstream
> (using Writables#write), and invoke sync/hflush.
>
> https://github.com/apache/hadoop-common/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/SequenceFile.java#L1314
>
> Is there a reason we have this call here? Please let me know if I miss any
> context.
>
> Thanks,
> Himanshu
>
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Jonathan Hsieh 2013-11-15, 07:37