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https://issues.apache.org/jira/browse/HADOOP-12916?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15217939#comment-15217939
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Tsz Wo Nicholas Sze commented on HADOOP-12916:
----------------------------------------------

{code}
+        double decayedAvgRespTime = (responseTimeAvgInLastWindow.get(i) > 0.0) 
?
+            decayFactor * responseTimeAvgInLastWindow.get(i) +
+            (1 - decayFactor) * averageResponseTime : averageResponseTime;
{code}
For the decayed case, should the formula be 
{{decayFactor*responseTimeAvgInLastWindow.get( i) + averageResponseTime}}, i.e. 
no {{(1 - decayFactor)}} in the second term?

BTW, the if-statement can be rewritten as below to make it shorter.
{code}
      final double lastAvg = responseTimeAvgInLastWindow.get(i);
      if (enableDecay && lastAvg > 0) {
        final double decayed =  decayFactor * lastAvg + averageResponseTime;
        responseTimeAvgInLastWindow.set(i, decayed);
      } else {
        responseTimeAvgInLastWindow.set(i, averageResponseTime);
      }
{code}


> Allow different Hadoop IPC Call Queue throttling policies with FCQ/BackOff
> --------------------------------------------------------------------------
>
>                 Key: HADOOP-12916
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12916
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: ipc
>            Reporter: Xiaoyu Yao
>            Assignee: Xiaoyu Yao
>         Attachments: HADOOP-12916.00.patch, HADOOP-12916.01.patch, 
> HADOOP-12916.02.patch, HADOOP-12916.03.patch, HADOOP-12916.04.patch, 
> HADOOP-12916.05.patch
>
>
> Currently back off policy from HADOOP-10597 is hard coded to base on whether 
> call queue is full. This ticket is open to allow flexible back off policies 
> such as moving average of response time in RPC calls of different priorities. 



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