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From Bikas Saha <>
Subject RE: Task count
Date Thu, 24 Jul 2014 18:38:57 GMT
The patch should work for all types of vertices because it gives each task
the total number of tasks for its vertex. Do you have any other use case?


-----Original Message-----
From: Johannes Zillmann []
Sent: Thursday, July 24, 2014 6:58 AM
To: Gopal V
Subject: Re: Task count

Hey Gopal,

using the task count basically for 2 things (in mr for both the map stage
and the reduce stage):
- each task samples its output-data up to a certain number. This number is
the desired sample count divided by the number of tasks
- also we use the task count in some scenarios to let the last task (of a
stage or a vertex) do some extra logic. That plays in combination of the

Looking at your patch it looks like it will do the job for kind of the
map-like vertex but not for the aggregation vertex, right ?
Also what jira issue is that ?


On 24 Jul 2014, at 07:40, Gopal V <> wrote:

> On 7/23/14, 6:07 PM, Johannes Zillmann wrote:
>> Hey Tez team,
>> is there some way to get the task count within a vertex from within a
task ?
>> Some equivalent to and mapred.reduce.tasks for
map-reduce ?
> Could you explain the use-case for this particular requirement?
> I intend to add the vertex parallelism to the task context as part of
one of my WIP branches.
> I uploaded my base patch-set as is (including the TODO markers).
> If you can explain what you are actually looking to do with this
information, perhaps I can roll the two feature reqs together.
> Cheers,
> Gopal

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