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From Rakesh Radhakrishnan <rakeshr.apa...@gmail.com>
Subject Re: Latency in asynchronous mode
Date Thu, 23 Oct 2014 14:57:54 GMT
Hi Ibrahim,

In async tests, could you give the details like:

* number of clients
* number of threads
* data size storing in each znode

Also, it would be good to monitor :

1) JVM stats(one way is through JMX) like heap, gc activities. This is to
see if latency spike corresponds to gc activity or not.

2) Since you are doubting fsync, I think $ iostat would be helpful to see
disk statistics. For example, $ iostat -d -x 2 10 and collects the disk
latency.

3) CPU usage through top or sar unix commands. I didn't use sar , but I
could see it gives more details like percent of CPU running idle with a
process waiting for block I/O etc.


-Rakesh


On Thu, Oct 23, 2014 at 6:44 PM, Alexander Shraer <shralex@gmail.com> wrote:

> Maybe due to queueing at the leader in asynchronous mode - if in your
> experiment you have one client in sync mode the leader has just one op in
> the queue at a time
> On Oct 23, 2014 1:57 PM, "Ibrahim" <i.s.el-sanosi@newcastle.ac.uk> wrote:
>
> > Hi folks,
> >
> > I am testing ZooKeeper latency in Asynchronous mode. I am sending update
> > (write) requests to Zookeeper cluster that consists of 5 physical
> > Zookeeper.
> >
> > So, when I run the stat command I get high latency like:
> > Latency min/avg/max: 7/339/392
> > Latency min/avg/max: 1/371/627
> > Latency min/avg/max: 1/371/627
> > Latency min/avg/max: 1/364/674
> > I guess such high latency correspond to fsync (batch requests). But I
> wish
> > if someone could help me and explain this behaviour.
> >
> > However, testing Zookeeper using Synchronous mode, it gives me reasonable
> > result like:
> > Latency min/avg/max: 6/24/55
> > Latency min/avg/max: 7/22/61
> > Latency min/avg/max: 7/30/65
> >
> > Note that the latency measures in milliseconds.
> >
> > I look forward to hearing from you.
> >
> > Ibrahim
> >
> >
> >
> >
> >
> >
> >
> > --
> > View this message in context:
> >
> http://zookeeper-user.578899.n2.nabble.com/Latency-in-asynchronous-mode-tp7580446.html
> > Sent from the zookeeper-user mailing list archive at Nabble.com.
> >
>

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