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From Ajay Srivastava <Ajay.Srivast...@guavus.com>
Subject Re: Query about Speculative Execution
Date Fri, 07 Dec 2012 04:40:28 GMT
Thanks Mahesh & Harsh.



On 07-Dec-2012, at 7:42 AM, Mahesh Balija wrote:

To simply, if you turn-off the speculative execution then the system will never bother about
slow running jobs unless they won't report beyond specified time (10 minutes).
If you have set speculative execution to true then the system may spawn another instance of
mapper and consider the output of the fast running once or early completing task.

Best,
Mahesh Balija,
Calsoft Labs.

On Thu, Dec 6, 2012 at 8:27 PM, Ajay Srivastava <Ajay.Srivastava@guavus.com<mailto:Ajay.Srivastava@guavus.com>>
wrote:
Hi,

What is the behavior of jobTracker if speculative execution is off and a task on data node
is running extremely slow?
Will the jobTracker simply wait till the slow running task finishes or it will try to heal
the situation? Assuming that heartbeat from the node running slow task are regular.



Regards,
Ajay Srivastava



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