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https://issues.apache.org/jira/browse/HADOOP-4373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12637879#action_12637879
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Hemanth Yamijala commented on HADOOP-4373:
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BTW, I observed some odd behavior of java with the current code. I am sure
there are good explanations, but it was just counter intuitive.
For e.g.
{code}
if (slotsDiff != 0) {
qsi.guaranteedCapacity +=
qsi.guaranteedCapacityPercent*slotsDiff/100;
}
{code}
has the following type of expression: {{int += float*int/100}}. I expected this
to actually be a compile time error, because of the loss in precision. Indeed,
{{int = float*int/100}} does give a compile time error.
Also, in the {{QueueComparator}} class, we have the following expression:
{code}
double r1 = (double)q1.numRunningTasks/(double)q1.guaranteedCapacity;
double r2 = (double)q2.numRunningTasks/(double)q2.guaranteedCapacity;
{code}
I thought this would give a divide by zero somewhere. However, because of the
cast to double, this works fine, and the result is two NaN or Infinite numbers,
which when compared returned -1.
Because it is not fully explained, the simple fix I've proposed above may not
be complete. I will continue to see if there are more gotchas involving
guaranteed capacity.
> Guaranteed Capacity calculation is not calculated correctly
> -----------------------------------------------------------
>
> Key: HADOOP-4373
> URL: https://issues.apache.org/jira/browse/HADOOP-4373
> Project: Hadoop Core
> Issue Type: Bug
> Components: contrib/capacity-sched
> Affects Versions: 0.19.0
> Reporter: Karam Singh
> Assignee: Hemanth Yamijala
> Priority: Blocker
> Fix For: 0.19.0
>
>
> Guaranteed Capacity calculation is not calculated correctly.
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