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https://issues.apache.org/jira/browse/YARN-4712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15168524#comment-15168524
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Varun Saxena commented on YARN-4712:
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[~Naganarasimha],
We had decided in YARN-4053 that we wont support doubles/floats as of now
because of the complexities involved due to its implementation.
Moreover, we found that most of the times floats would come for some metric
which is represented as a percentage(%) or a ratio.
In this case the denominator is fixed so you can easily normalize the value and
store it as an integer. And divide it by 100(if its a %) when you read it back.
Moreover, in case of percentages a precision higher than 2 decimal places, wont
be mighty important.
We thought if user/client wanted to store a value/ratio where denominator is
not fixed, he can merely store numerator and denominator separately and do the
necessary computation after reading it back.
We had decided until and unless there was a strong use case, we will go with
only longs for now.
And we could not think of any use cases for current metrics as of now.
And there is a way around it as well if somebody wants to store a float by
normalizing the value and storing numerator and denominator separately.
> CPU Usage Metric is not captured properly in YARN-2928
> ------------------------------------------------------
>
> Key: YARN-4712
> URL: https://issues.apache.org/jira/browse/YARN-4712
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: timelineserver
> Reporter: Naganarasimha G R
> Assignee: Naganarasimha G R
> Labels: yarn-2928-1st-milestone
>
> There are 2 issues with CPU usage collection
> * I was able to observe that that many times CPU usage got from
> {{pTree.getCpuUsagePercent()}} is
> ResourceCalculatorProcessTree.UNAVAILABLE(i.e. -1) but ContainersMonitor do
> the calculation i.e. {{cpuUsageTotalCoresPercentage = cpuUsagePercentPerCore
> /resourceCalculatorPlugin.getNumProcessors()}} because of which UNAVAILABLE
> check in {{NMTimelinePublisher.reportContainerResourceUsage}} is not
> encountered. so proper checks needs to be handled
> * {{EntityColumnPrefix.METRIC}} uses always LongConverter but
> ContainerMonitor is publishing decimal values for the CPU usage.
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