What happens when a map task crashes while running a mapreduce job?

Question

Options

• AThe job immediately fails
• BThe tasktracker closes the JVM instance and restarts
• CThe jobtracker attempts to re-run the task on the same node
• Dthe jobtracket attempts to re-run the task on a different node

• A
  9% (5)
• B
  7% (4)
• C
  3% (2)
• D
  81% (47)

Explanation

When the jobtracker is notified of a task attempt that has failed (by the tasktracker's heartbeat call), it will reschedule execution of the task. The jobtracker will try to avoid rescheduling the task on a tasktracker where it has previously failed. Consider first the case of the child task failing. The most common way that this happens is when user code in the map or reduce task throws a runtime exception. If this happens, the child JVM reports the error back to its parent tasktracker, before it exits. The error ultimately makes it into the user logs. The tasktracker marks the task attempt as failed, freeing up a slot to run another

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