TaskRunner.prepare() and close() methods call only mapOutputFile.removeAll(). The removeAll() call is a always a no-op in prepare(), because the directory is always empty during start up of the task. The removeAll() call in close() is useless, because it is followed by a attempt directory cleanup. Since the map output files are in attempt directory, the call to close() is useless.
MAPREDUCE-842, these calls are under TaskTracker space, passing the wrong conf. Now, the calls do not make sense at all.
I think we can remove the methods.