Major Description
Work directory is not deleted in DistCache if Exception happen in downloadCacheObject. In downloadCacheObject, the cache file will be copied to temporarily work directory first, then the work directory will be renamed to the final directory. If IOException happens during the copy, the work directory will not be deleted. This will cause garbage data left in local disk cache. For example If the MR application use Distributed Cache to send a very large Archive/file(50G), if the disk is full during the copy, then the IOException will be triggered, the work directory will be not deleted or renamed and the work directory will occupy a big chunk of disk space.