Hi Aimee,
Thank you for your prompt reply.

Best regards,
Yu
On Oct 12, 2012, at 9:55 AM, Aimee Cheng <chengsj.luo@gmail.com> wrote:

I can answer your second question: no. In current S4 piper, when there are no standby nodes, if one node crushes, the remaining nodes will not pick up the task and still focus on their own tasks.

-Aimee
 
On Oct 12, 2012, at 9:36 AM, Frank Zheng wrote:

Hi,

Thanks for your reply.
So the dynamic load balancing is not implemented yet, right?
In case of static load balancing, if there are two working PE node without any standby nodes, 
when one fails, does the workload for the remaining working PE increase?

Besides, can zeno prototype do dynamic load balancing? 

Thanks.

On Thu, Oct 11, 2012 at 7:00 PM, Matthieu Morel <mmorel@apache.org> wrote:
On 10/11/12 12:35 PM, Daniel Gómez Ferro wrote:


On Thu Oct 11 05:52:01 2012, Frank Zheng wrote:
Hi All,

I want to figure out the mechanism of load balancing in S4.
In the paper and web site, it says ZooKeeper takes this
responsibility, but the description is not very clear.
I want to figure out that how ZooKeeper does load balancing.
For example, if there are two working PE nodes, and 120 messages per
second. The adapter distributes these messages evenly, 60 per PE node,
right?
When one PE node is added into the cluster, does it mean ZooKeeper
balances the messages, 40 per PE node?
And how does ZooKeeper decide which message to be distributed to which
node?

Hi,

Currently load balancing is static. When you define your cluster you
specify the number of tasks (say, 2) which won't change for this
cluster. If you have more than 2 nodes, the rest will be backup nodes.
In case one of the serving nodes fails, a backup node will pick up the
orphaned task and start serving requests, but the load will always be
spread among the 2 tasks that you defined at the beginning.

Having dynamic load balancing would be really cool, but I don't know if
there are currently any efforts in that direction.

There is the zeno prototype https://github.com/s4/zeno , which is actually independent of S4. It also relies on ZooKeeper for metadata about partitions.

Matthieu



--
Sincerely,
Zheng Yu
Mobile:  (852) 60670059