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From "Jinglun (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-16403) Start a new statistical rpc queue and make the Reader's pendingConnection queue runtime-replaceable
Date Mon, 12 Aug 2019 11:01:00 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-16403?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Jinglun updated HADOOP-16403:
    Attachment: HADOOP-16403.007.patch

> Start a new statistical rpc queue and make the Reader's pendingConnection queue runtime-replaceable
> ---------------------------------------------------------------------------------------------------
>                 Key: HADOOP-16403
>                 URL: https://issues.apache.org/jira/browse/HADOOP-16403
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Jinglun
>            Assignee: Jinglun
>            Priority: Major
>         Attachments: HADOOP-16403-How_MetricLinkedBlockingQueue_Works.pdf, HADOOP-16403.001.patch,
HADOOP-16403.002.patch, HADOOP-16403.003.patch, HADOOP-16403.004.patch, HADOOP-16403.005.patch,
HADOOP-16403.006.patch, HADOOP-16403.007.patch, MetricLinkedBlockingQueueTest.pdf
> I have an HA cluster with 2 NameNodes. The NameNode's meta is quite big so after the
active dead, it takes the standby more than 40s to become active. Many requests(tcp connect
request and rpc request) from Datanodes, clients and zkfc timed out and start retrying. The
suddenly request flood lasts for the next 2 minutes and finally all requests are either handled
or run out of retry times. 
>  Adjusting the rpc related settings might power the NameNode and solve this problem and
the key point is finding the bottle neck. The rpc server can be described as below:
> {noformat}
> Listener -> Readers' queues -> Readers -> callQueue -> Handlers{noformat}
> By sampling some failed clients, I find many of them got ConnectTimeoutException. It's
caused by a 20s un-responded tcp connect request. I think may be the reader queue is full
and block the listener from handling new connections. Both slow handlers and slow readers
can block the whole processing progress, and I need to know who it is. I think *a queue that
computes the qps, write log when the queue is full and could be replaced easily* will help.

>  I find the nice work HADOOP-10302 implementing a runtime-swapped queue. Using it at
Reader's queue makes the reader queue runtime-swapped automatically. The qps computing job
could be done by implementing a subclass of LinkedBlockQueue that does the computing job while
put/take/... happens. The qps data will show on jmx.

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