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https://issues.apache.org/jira/browse/HADOOP-14599?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16113082#comment-16113082
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Daryn Sharp commented on HADOOP-14599:
--------------------------------------

General implementation issues:
# No need to change UGI.  Revert them.
# Don't change {{RpcProtobufRequest#getRequestHeader}} to convert IOE to an 
illegal arg.
# In {{NamenodeWebHdfsMethods#doAsExternalCall}}, the changed indentation of 
methods like {{getHostInetAddress}} and {{getDeclaringClassProtocolName}} 
violate style guidelines.
# {{WritableRpcEngine#call}} doesn't appear to need the finally clause anymore?
# Is the change in {{Server}} to the deferred response handling is necessary?  
It's subtlety changing the behavior.
# In the finally block that updates the metrics, please update _after_ clearing 
the call and closing the scope.  If for some reason the metrics update blow up, 
the handler will be left in an inconsistent state.

Most importantly: The queue time for skipped calls is recorded = great!; _but 
with a processing time of 0_ = bad.  As the call queue becomes congested with 
timing out clients, the average processing time will plummet and artificially 
make performance appear great when it's not.  The updates to queue time and 
processing time need to be independent.

> RPC queue time metrics omit timed out clients
> ---------------------------------------------
>
>                 Key: HADOOP-14599
>                 URL: https://issues.apache.org/jira/browse/HADOOP-14599
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: metrics, rpc-server
>    Affects Versions: 2.7.0
>            Reporter: Ashwin Ramesh
>            Assignee: Ashwin Ramesh
>         Attachments: HADOOP-14599.001.patch, HADOOP-14599-002.patch, 
> HADOOP-14599-003.patch, HADOOP-14599-004.patch
>
>
> RPC average queue time metrics will now update even if the client who made 
> the call timed out while the call was in the call queue.



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