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MapReduce >> mail # user >> Counters that track the max value


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Jeremy Lewi 2012-10-03, 15:17
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Harsh J 2012-10-03, 16:52
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Re: Counters that track the max value
HI Harsh,

Thank you very much that will work.

How come we can't simply create a modification of a regular mapreduce
counter which does this behind the scenes? It seems like we should just be
able to replace "+" with "max" and everything else should work?

J

On Wed, Oct 3, 2012 at 9:52 AM, Harsh J <[EMAIL PROTECTED]> wrote:

> Jeremy,
>
> Here's my shot at it (pardon the quick crappy code):
> https://gist.github.com/3828246
>
> Basically - you can achieve it in two ways:
>
> Requirement:  All tasks must increment the "max" designated counter
> only AFTER the max has been computed (i.e. in cleanup).
>
> 1. All tasks may use same counter name. Later, we pull per-task
> counters and determine the max at the client. (This is my quick and
> dirty implementation)
> 2. All tasks may use their own task ID (Number part) in the counter
> name, but use the same group. Later, we fetch all counters for that
> group and iterate over it to find the max. This is cleaner, and
> doesn't end up using deprecated APIs such as the above.
>
> Does this help?
>
> On Wed, Oct 3, 2012 at 8:47 PM, Jeremy Lewi <[EMAIL PROTECTED]> wrote:
> > HI hadoop-users,
> >
> > I'm curious if there is an implementation somewhere of a counter which
> > tracks the maximum of some value across all mappers or reducers?
> >
> > Thanks
> > J
>
>
>
> --
> Harsh J
>
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Harsh J 2012-10-05, 17:13
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Jeremy Lewi 2012-10-05, 17:40