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https://issues.apache.org/jira/browse/HADOOP-4421?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12698358#action_12698358
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Devaraj Das commented on HADOOP-4421:
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I am +1 for the enum for TaskTypes.
There are two approaches to having slots for the setup/cleanup tasks -
1) Have a special slot in the TT for all the special tasks - JobSetup,
JobCleanup and TaskCleanup. This special slot can run any of the special tasks.
With this setup, we have three types of slots in the TT - Map, Reduce, and
Setup/Cleanup slot.
2) Have the Map slots in the TT be floating between the actual maps and the
special tasks. In this model, one would configure #Reduce slots in the TT, and
"#other slots".
The other thing that I am thinking of removing is the reuse of taskattemptID
for the cleanup tasks (as implemented in HADOOP-4759). Made the code hard to
read/maintain.
Thoughts?
> Rework job-setup and job-cleanup tasks
> --------------------------------------
>
> Key: HADOOP-4421
> URL: https://issues.apache.org/jira/browse/HADOOP-4421
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.19.0
> Reporter: Arun C Murthy
> Fix For: 0.20.0
>
>
> Currently we have a notion of map-{setup|cleanup} TIP and
> reduce-{setup|cleanup} TIP of which only 1 setup and cleanup tasks are picked
> by the JobInProgress. Also a lot of state-maintenence of these TIPs are done
> by the JobInProgress itself, outside of the more logical place i.e.
> TaskInProgress.
> We really should rework this to have a single setup and cleanup task which
> isn't associated with a map or reduce task i.e. into separate task _types_.
> What we have currently is quite ungainly and hard to maintain.
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