[jira] [Commented] (HADOOP-16395) when CallQueueManager swap queues, we should remove metrics about FCQ

["Erik Krogen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-16395?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16874270#comment-16874270 ] 

Erik Krogen commented on HADOOP-16395:
--------------------------------------

Hi [~hfyang20071], thanks for reporting this. There is one thing I am confused about with your patch. The comment on {{FairCallQueue.MetricsProxy}} says:
{code}
  /**
   * MetricsProxy is a singleton because we may init multiple
   * FairCallQueues, but the metrics system cannot unregister beans cleanly.
   */
{code}
This claims that we can't unregister beans properly. Does the code in place for {{DecayRpcScheduler.MetricsProxy}} work properly? If so, do we need to update this comment on {{FairCallQueue.MetricsProxy}}?

Assuming that this is the right approach, I have some more specific comments on the patch:
* Why are we defining a new {{CloseableQueue}} interface? Can't we just say that {{FairCallQueue implements Closeable}}?
* You've added a {{close()}} method to {{FairCallQueue}}, but it is not called anywhere. I think in {{swapQueues}} you need to check if the queue is {{instanceof Closeable}}, and if so, close it.

> when CallQueueManager swap queues, we should remove metrics about FCQ
> ---------------------------------------------------------------------
>
>                 Key: HADOOP-16395
>                 URL: https://issues.apache.org/jira/browse/HADOOP-16395
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: common, ipc
>    Affects Versions: 3.2.0
>            Reporter: yanghuafeng
>            Priority: Minor
>         Attachments: HADOOP-16395.001.patch
>
>
> when we use "dfsadmin -refreshCallQueue" between FCQ and LBQ, we find that the metrics about FCQ still display by the JMX. Normally the metrics should disappear like what  DecayRpcScheduler did. 



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