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MapReduce >> mail # user >> Filesystem closed exception

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Re: Filesystem closed exception
It is pretty much the same in 0.20.x as well, IIRC. Your two points
are also correct (for a fix to this). Also see:

On Fri, Jan 25, 2013 at 6:56 AM, Hemanth Yamijala
> Hi,
> We are noticing a problem where we get a filesystem closed exception when a
> map task is done and is finishing execution. By map task, I literally mean
> the MapTask class of the map reduce code. Debugging this we found that the
> mapper is getting a handle to the filesystem object and itself calling a
> close on it. Because filesystem objects are cached, I believe the behaviour
> is as expected in terms of the exception.
> I just wanted to confirm that:
> - if we do have a requirement to use a filesystem object in a mapper or
> reducer, we should either not close it ourselves
> - or (seems better to me) ask for a new version of the filesystem instance
> by setting the fs.hdfs.impl.disable.cache property to true in job
> configuration.
> Also, does anyone know if this behaviour was any different in Hadoop 0.20 ?
> For some context, this behaviour is actually seen in Oozie, which runs a
> launcher mapper for a simple java action. Hence, the java action could very
> well interact with a file system. I know this is probably better addressed
> in Oozie context, but wanted to get the map reduce view of things.
> Thanks,
> Hemanth

Harsh J