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https://issues.apache.org/jira/browse/MAPREDUCE-3683?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13189306#comment-13189306
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Thomas Graves commented on MAPREDUCE-3683:
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{quote}
However, if the parent's max-capacity is undefined i.e. UNLIMITED (-1), we have
two choices:
1. Use the parent's 'current' capacity to compute the max-capacity of the
child at runtime
2. Set the child's max-capacity to be UNLIMITED too.
I'm leaning towards (2) since it's simpler and easier to explain to users i.e.
it's more consistent. Otherwise, we run the risk of differing max-capacity (due
to parent's capacity changing) which seems unpredictable and hard to explain to
users/admins.
Thoughts?
{quote}
I guess I expected if the parent wasn't set (its max-capacity defaults to -1),
which I thought implies a queue can use complete capacity of the cluster, so if
a childs max-capacity was set, then it would just use that childs max-capacity
- which would be % of the entire cluster. If you go with option 2 that means
that if I set my max-capacity for my child queue it basically does nothing,
which isn't what I would expect either.
{quote}
That isn't true. It just means there is no max-cap for the child and it can use
as much capacity as the parent queue gets, which might be capped by the
parent/grandparent capacity/max-capacity and so on. This seems like the correct
behaviour. Right?
{quote}
Ok, sorry I was wrong, it does enforce it, what threw me off here was the web
UI shows the absolute maximum capacity as 100% for the leaf queue and I
expected this to be parents absolute max capacity. But I think that must be a
web UI bug. I will file separate issue for that.
> Capacity scheduler LeafQueues maximum capacity calculation issues
> -----------------------------------------------------------------
>
> Key: MAPREDUCE-3683
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-3683
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv2
> Affects Versions: 0.23.0
> Reporter: Thomas Graves
> Assignee: Arun C Murthy
> Priority: Blocker
> Attachments: MAPREDUCE-3683.patch
>
>
> In the Capacity scheduler if you configure the queues to be hierarchical
> where you have root -> parent queue -> leaf queue, the leaf queue doesn't
> take into account its parents maximum capacity when calculate its own maximum
> capacity, instead it seems to use the parents capacity. Looking at the code
> its using the parents absoluteCapacity and I think it should be using the
> parents absoluteMaximumCapacity.
> It also seems to only use the parents capacity in the leaf queues max
> capacity calculation when the leaf queue has a max capacity configured. If
> the leaf queues maximum-capacity is not configured, then it can use 100% of
> the cluster.
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