zookeeper-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Daniel Peon Quiros <daniel.peon.qui...@ericsson.com>
Subject RE: Session timeout parameter question
Date Mon, 03 Nov 2014 15:01:56 GMT
Hi Ivan, all,

If I didn't understand wrong, then if there is no answer from the server in 2/3 of the session
timeout, the client will search another server to connect to it. But, does it mean that once
the client is looking for a different server, it will connect to it even though in the last
1/3 of the session timeout the server eventually answers?

As it is stated below, the client has 1/3 of the timeout to find another server, but my concern
is what would happen if the server answers in that last 1/3 of the session timeout: does the
client keep the connection to the same server? Or on the contrary does the client connect
to a different server anyway?

Kind regards,


-----Original Message-----
From: Ivan Kelly [mailto:ivan@ivankelly.net] 
Sent: jueves, 30 de octubre de 2014 13:43
To: zookeeper user list
Subject: Re: Session timeout parameter question

Yes, if the partition occurs 1/3 of the timeout past the last time the server has heard from
the client. If the partition happens just after the server has heard from the client and only
last 2/3 of the timeout, the session will probably not be timed out. The server will not timeout
a session until it hasn't heard from the client for the whole session timeout period.


On 30 October 2014 13:05, Alen Čaljkušić <scuderiaforever@gmail.com> wrote:
> Hi ZooKeeper community
> I have a question about session timeout parameter. Quote from 
> ZooKeeper book by Flavio Junqueira and Benjamin Reed:
> "One important parameter you should set when creating a session is the 
> session timeout, which is the amount of time the ZooKeeper service 
> allows a session before declaring it expired. If the service does not 
> see message associated to a given session during time t, it declares session expired.
> On the client side, if it has heard nothing from the server at 1/3 of 
> t, it sends a heartbeat message to the server. At 2/3 of t, the 
> ZooKeeper client starts looking for a different server, and it has 
> another 1/3 of t to find one."
> Does this imply that network failure between client and all servers 
> lasting
> 2/3 of session timeout parameter may cause session expired?
View raw message