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: https://issues.apache.org/jira/browse/HADOOP-7973.
On Fri, Jan 25, 2013 at 6:56 AM, Hemanth Yamijala <yhema...@thoughtworks.com> wrote: > 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
