Hi,

Yeah, you need to register a custom code runner. Here is an example: 
https://github.com/apache/helix/blob/master/helix-core/src/test/java/org/apache/helix/integration/TestHelixCustomCodeRunner.java



Kanak

From: [email protected]
Date: Mon, 14 Sep 2015 23:04:21 -0700
Subject: Question regarding to CUSTOMIZED balance mode
To: [email protected]

Hi,

We are evaluating CUSTOMIZED balance mode in helix 0.6.4 currently, and I have 
one question regarding to it.

How do I handle cluster failure case, e.g. the initial ideal state as following:
"mapFields" : {
   "MyResource_0" : {
     "N1" : "MASTER",
     "N2" : "SLAVE",
   }
}
If N1 goes down, N2 will not become MASTER automatically, right? 

If so, how do I register the listener for cluster state change to update ideal 
state? The doc says "The application needs to implement a callback interface 
that Helix invokes when the cluster state changes. Within this callback, the 
application can recompute the idealstate.", is that interface Rebalancer?

Do we have an example for CUSTOMIZED balance?

Besides, when looking at the code, CustomRebalancer implements Rebalancer 
interface, and just returns currentIdealState when computeNewIdealState is 
called.

Thanks
Hang Qi                                           

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