CCD-410 Free Dumps Study Materials
Question 8: On a cluster running MapReduce v1 (MRv1), a TaskTracker heartbeats into the JobTracker on
your cluster, and alerts the JobTracker it has an open map task slot.
What determines how the JobTracker assigns each map task to a TaskTracker?
A. The amount of RAM installed on the TaskTracker node.
B. The amount of free disk space on the TaskTracker node.
C. The number and speed of CPU cores on the TaskTracker node.
D. The average system load on the TaskTracker node over the past fifteen (15) minutes.
E. The location of the InsputSplit to be processed in relation to the location of the node.
Correct Answer: E
Explanation:
The TaskTrackers send out heartbeat messages to the JobTracker, usually every few minutes, to
reassure the JobTracker that it is still alive. These message also inform the JobTracker of the number
of available slots, so the JobTracker can stay up to date with where in the cluster work can be
delegated. When the JobTracker tries to find somewhere to schedule a task within the MapReduce
operations, it first looks for an empty slot on the same server that hosts the DataNode containing the
data, and if not, it looks for an empty slot on a machine in the same rack.
Reference: 24 Interview Questions & Answers for Hadoop MapReduce developers, How JobTracker
schedules a task?