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From "Ibrahim El-sanosi (PGR)" <i.s.el-san...@newcastle.ac.uk>
Subject RE: Latency in asynchronous mode
Date Thu, 23 Oct 2014 20:16:03 GMT
Ok, this makes sense.  So, we can see that in sync mode the latency will measure for just one
operation at the time (per fsync), because  the transaction log system will  log  (fsync)
one request at the time. Whereas, in Asyc mode, the latency will measure several operationa
per fsync, meaning that it is not possible to measure the latency per operation because the
transaction log will (fsync) batch multiple requests in one fsync. 


Can you correct me if the above is not true?

Thank you a lot

Ibrahim


-----Original Message-----
From: Alexander Shraer [mailto:shralex@gmail.com] 
Sent: Thursday, October 23, 2014 04:02 م
To: user@zookeeper.apache.org
Subject: RE: Latency in asynchronous mode

I still stay with my previous explanation :) in async mode each client invokes many ops concurrently
resulting in a longer queue at the leader On Oct 23, 2014 3:32 PM, "Ibrahim El-sanosi (PGR)"
< i.s.el-sanosi@newcastle.ac.uk> wrote:

> Thank you Alexander for  replay,
>
> In fact, I use more than one clients (one, two, three, four ......., 
> ten), in both modes (synchronous  and asynchronous). So, I found the latency in
> Asynchronous Mode is much higher than latency in synchronous   mode. I am
> really wondering why I am getting such a big different.
>
> In synchronous  mode, the latency vary between min/avr/max=5/20/50 and 
> min/avr/max=11/50/120, but it is never reach min/avg/max: 1/371/627 as 
> in asynchronous  mode.
>
> Any thought?
>
> Thank you
>
> -----Original Message-----
> From: Alexander Shraer [mailto:shralex@gmail.com]
> Sent: Thursday, October 23, 2014 02:14 م
> To: user@zookeeper.apache.org
> Subject: Re: Latency in asynchronous mode
>
> 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-m
> > od e-tp7580446.html Sent from the zookeeper-user mailing list 
> > archive at Nabble.com.
> >
>
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