MRv1 Only: The Linux TaskController Program
The task-controller program, which is used on MRv1 only, allows the TaskTracker to run tasks under the Unix account of the user who submitted the job in the first place. It is a setuid binary that must have a very specific set of permissions and ownership in order to function correctly. In particular, it must:
- Be owned by root
- Be owned by a group that contains only the user running the MapReduce daemons
- Be setuid
- Be group readable and executable
This corresponds to the ownership root:mapred and the permissions 4754.
Here is the output of ls on a correctly-configured Task-controller:
-rwsr-xr-- 1 root mapred 30888 Mar 18 13:03 task-controller
The TaskTracker will check for this configuration on start up, and fail to start if the Task-controller is not configured correctly.
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