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MapReduce, mail # user - map tasks vs launched map tasks


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Re: map tasks vs launched map tasks
Allen Wittenauer 2011-03-25, 21:04

On Mar 25, 2011, at 10:09 AM, Pedro Costa wrote:

> Hi,
>
> during the setup phase and the cleanup phase of the tasks, the Hadoop
> MR uses map tasks to do it. These tasks appears in the counters shown
> at the end of an example?
> For example, the counter below shows that my example ran 9 map tasks
> and 2 reduce tasks, but the Launched map task has the value 13. The 4
> more tasks are the one used at setup and cleanup phase?

Probably speculative execution