yes, it's always null. actually I checked the code that parameter was never set. https://github.com/apache/helix/blob/acd902e2433f65e9864ccf49fcd1a04c36b1f206/helix-core/src/main/java/org/apache/helix/controller/stages/BestPossibleStateCalcStage.java#L222
On Wed, Jun 24, 2015 at 10:41 PM, kishore g <[email protected]> wrote: > I see that you haven't subscribed to mailing list yet. Please do that my > sending an email to [email protected]. > > I am also available on #apachehelix irc if you have additional questions. > http://helix.apache.org/IRC.html > > > ---------- Forwarded message ---------- > From: kishore g <[email protected]> > Date: Wed, Jun 24, 2015 at 10:37 PM > Subject: Re: Customized rebalancer > To: "[email protected]" <[email protected]> > > > Hi Changgeng, > > I think the first invocation will always be null, subsequent invocations > should provide you the previous resource assignment. Are you saying its > always null?. > > thanks, > Kishore G > > On Wed, Jun 24, 2015 at 3:42 PM, Changgeng Li <[email protected]> > wrote: > >> Hello, >> >> We have a use case that when adding or removing a new node, we hope to >> minimize the shuffle of partitions between nodes. I'm trying to implement a >> customized rebalancer calculating the new resource assignment based on the >> previous resource assignment. When a new node is added, just move some >> partitions from existing node to the new node, and when a node is down, >> move the partitions on this node to the other nodes. Partitions would not >> move between two nodes if the both status are not changed. >> >> The documentation says: >> In rebalance(), ... the third is the output of the previous invocation >> of this method (if supported) ... >> >> During my testing I found the previous resource assignment passed in is >> always null. my question is what "if supported" means here? Does the >> rebalancer need to support something? >> >> >> Any other suggestions are also welcome. >> >> Thanks, >> Changgeng >> > > >
