There are two ways to write your own rebalancer #1. Using CustomCode Runner. This is regsistered in any of the participants and can be invoked on any node in the cluster starts/stops. Kanak's email points to this option.
#2. Implement the rebalancer interface. This is one you have specified in your email. This is run in controller and is invoked on each and every change in the cluster such as node added/removed, start/stop, resource add/remove etc. Let me know which mode you are planning to use, we can provide additional details. On Sat, Sep 19, 2015 at 11:19 AM, Kanak Biscuitwala <[email protected]> wrote: > 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 >
