[
https://issues.apache.org/jira/browse/MAPREDUCE-1764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12867300#action_12867300
]
Scott Chen commented on MAPREDUCE-1764:
---------------------------------------
Joydeep:
Matei and I had some discussion and we have also looked the code.
In JobInProgress, there is such a HashMap of node->[tasks] and rack->[tasks]
exists.
It is not clear to me why this is so slow.
I agree with your point that we should not leave the slots idle especially in
the case that cluster is full of jobs.
> FairScheduler locality delay may put heavy pressure on Jobtracker
> -----------------------------------------------------------------
>
> Key: MAPREDUCE-1764
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1764
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 0.22.0
> Reporter: Scott Chen
> Assignee: Dmytro Molkov
> Fix For: 0.22.0
>
>
> FairScheduler locality delay feature holds the scheduling of jobs until it
> gets good locality.
> This greatly improves the locality of the tasks. Reduce the cost of traffic.
> We have observed the following problem on FairScheduler locality delay:
> We have some machines have older data and some newly added machines do not
> have important data.
> When these machines send heartbeat, JT scans tasks to find jobs has the right
> locality.
> Often time, these machines will scan all of the tasks of all the jobs and do
> not get any tasks.
> Scanning all the tasks on the JT is very costly. This makes JT very slow.
> And these machines often time do not get scheduled. This hurts the cluster
> utilization.
> Any ideas?
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
