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
