Affects Version/s: None
Fix Version/s: 0.20.0
The race condition occurs in following sequence of events:
1. User issues a command-line kill for a RUNNING map-task. JT stores the task in tasksToKill mapping.
2. TT reports the task status as SUCCEEDED.
3. JT creates a TaskCompletionEvent as SUCCEEDED. Also sends a killTaskAction.
4. Reducers fail fetching the map output.
5. finally, the task would fail with Fetch failures. After
HADOOP-4759, the task is left as FAILED_UNCLEAN task, since the task is present in tasksToKill mapping.