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From: Rakesh Radhakrishnan <rakeshr@apache.org>
Date: Fri, 2 Dec 2016 11:23:37 +0530
Message-ID: <CAHB_t6p-QFu0wNzYkXjzLJnxhNs_wE9XCOj_GeWecssacy0+AA@mail.gmail.com>
Subject: Re: AvgRequestLatency metric always zero
To: "user@zookeeper.apache.org" <user@zookeeper.apache.org>
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archived-at: Fri, 02 Dec 2016 05:53:41 -0000

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Thanks Arshad for the good analysis.

>>>> How can we go about getting these fixes?

Please feel free to raise an improvement task under ZK project issue
tracker, URL: https://issues.apache.org/jira/browse/ZOOKEEPER
Also, I'd appreciate if you can put a patch to fix it. Probably you can
refer how to contribute to the project section,
https://cwiki.apache.org/confluence/display/ZOOKEEPER/HowToContribute

On Fri, Dec 2, 2016 at 3:25 AM, allen chan <allen.michael.chan@gmail.com>
wrote:

> Arshad,
> How can we go about getting these fixes?
>
>
> On Thu, Dec 1, 2016 at 12:01 PM, Arshad Mohammad <
> arshad.mohammad.k@gmail.com> wrote:
>
> > Hi Alen
> >
> > AvgRequestLatency 0 implies that on an average time taken by the server
> to
> > serve a request is less than one milli second. May be it is really 0 or
> it
> > may be 0.99 ms.
> >
> > This behaviour is not specific to 3.4.7 and 3.4.9 version but the same
> > behaviour is there in all versions
> >
> > I find two reason whys AvgRequestLatency is almost all the time 0
> >
> > 1) Ping requests are counted the most:
> >
> > AvgRequestLatency is calculated as
> >
> > AvgRequestLatency=totalLatency/count
> >
> > Ping requests come very often and complete very fast, these request add
> > nothing to totalLatency but add one to count.
> >
> > 2) Wrong data type is chosen to store AvgRequestLatency:
> >
> > AvgRequestLatency is calculated and store as the long value instead of
> > double vlaue.
> >
> >
> >
> > In my opinion ZooKeeper code should be modified to improve this metrics
> >
> > i) Ping request should be ignored while recording the statistics or at
> > least should be configurable whether to ignore or not. If ping request is
> > not counted even other metrics will be more meaningful.
> >
> > ii)  AvgRequestLatency should be of double type.
> >
> >
> >
> > -Arshad
> >
> > On Thu, Dec 1, 2016 at 4:50 AM, allen chan <allen.michael.chan@gmail.com
> >
> > wrote:
> >
> > > Anyone seeing this issue? I am experiencing it on 3.4.7 and 3.4.9
> > >
> > > JMX metric name: AvgRequestLatency
> > > JMX Location:
> > > org.apache.ZooKeeperService:name0=ReplicatedServer_id#,
> > > name1=replica.#,name2=[Leader|Follower]:AvgRequestLatency
> > >
> > > It always has a value of zero. The MaxRequestLatency is non-zero and
> > > changes while the AvgRequestLatency always is zero.
> > >
> > > The zk_avg_latency metric in mntr is also zero. Is this metric not
> > tracked
> > > anymore?
> > >
> > > Thanks
> > > --
> > > Allen Michael Chan
> > >
> >
>
>
>
> --
> Allen Michael Chan
>

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