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From Hongchao Deng <fengjingc...@hotmail.com>
Subject RE: Why sessionTimeout is restricted by tickTime
Date Thu, 28 Aug 2014 04:35:26 GMT
My understanding is that large session timeout limits scalability of client numbers. Theoretically
speaking, it is possible to increase the maximum session timeout in your case.

- Hongchao Deng

> Date: Thu, 28 Aug 2014 12:22:52 +0800
> Subject: Re: Why sessionTimeout is restricted by tickTime
> From: tobeg3oogle@gmail.com
> To: user@zookeeper.apache.org
> CC: dev@zookeeper.apache.org
> 
> By the way, it comes down to a conflict if one ZooKeeper client set timeout
> as 10 and one client set timeout as 110. The tickTime can't satisfy all.
> 
> 
> On Thu, Aug 28, 2014 at 11:53 AM, tobe <tobeg3oogle@gmail.com> wrote:
> 
> > Refer to the official guide, we know that the negotiationTimeout must be
> > greater than twice tickTime and smaller than 20 times of tickTime.
> >
> > I know the tickTime should not be too large or even larger than
> > sessionTimeout, or the session will time out all the time. This limitation
> > is reasonable, but why the sessionTimeout must be smaller than 20 times of
> > tickTime?
> >
> > The problem happens in our production environment. We share a ZooKeeper
> > cluster for a few HBase cluster. By default, the tickTime is 2s and the
> > sessionTimeout is 30s. It's ok. But now one of our HBase clusters need to
> > increase the sessionTimeout to 90s because of long time  gc. After updating
> > the sessionTimout in HBase, we have to update the tickTime in ZooKeeper.
> > And this setting may have an effect on other HBase clusters.
> >
> > So I wonder why ZooKeeper has this limitation. Can anyone explain to me?
> >
 		 	   		  
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