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http://issues.apache.org/jira/browse/HADOOP-639?page=comments#action_12451988 ]
Owen O'Malley commented on HADOOP-639:
--------------------------------------
To clarify, the point of the type ids in the TaskTrackerActions is so that we
can serialize the list of actions efficiently.
I'd make TaskTrackerAction an abstract class like:
abstract class TaskTrackerAction implements Writable {
/** Get the type id for a type */
public abstract int getTypeId();
/** Create an instance of the appropriate child type. */
public static TaskTrackerAction newInstance(int typeId);
}
and then the children look like:
class StartTaskAction extends TaskTrackerAction {
int getTypeId() { return 1; }
Task newTask;
public void readFields(...) throws IOException {...}
public void write(...) throws IOException {...}
}
KillTaskAction has a jobid and taskid.
KillJobAction has a jobid.
We also need a action to reinitialize the task tracker
(ReinitializeSelfAction?).
"JTResponse" is too information free. How about "TaskTrackerActionList" instead.
I think we are better off using a boolean than a special value for ackNo. As a
side effect we can use short for ackNo because it is ok if it rolls around. And
taking a hint from linux, we are probably better starting at a -100 so that we
wrap pretty soon after start up. *smile*
> task cleanup messages can get lost, causing task trackers to keep tasks
> forever
> -------------------------------------------------------------------------------
>
> Key: HADOOP-639
> URL: http://issues.apache.org/jira/browse/HADOOP-639
> Project: Hadoop
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.7.2
> Reporter: Owen O'Malley
> Assigned To: Arun C Murthy
> Fix For: 0.9.0
>
>
> If the pollForTaskWithClosedJob call from a job tracker to a task tracker
> times out when a job completes, the tasks are never cleaned up. This can
> cause the mini m/r cluster to hang on shutdown, but also is a resource leak.
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