qqu0127 opened a new issue, #2468: URL: https://github.com/apache/helix/issues/2468
**Is your feature request related to a problem? Please describe.** The WAGED rebalancer assigns partitions to instance only if all the hard constraints are satisfied. However, the calculation doesn't account for the temporary state during state transition. The result is measured at the eventual state after all state transitions complete. The "N+1" scenario is when on one `instance_0`, p1 is moving out while p3 is moving in, p2 stays at instance_0. The beginning state `[p1, p2]`, and ending state `[p2, p3]` all satisfies the hard constraint, while the temporary state [p1, p2, p3] may not. Note that this will expand the definition of hard constraint in WAGED. **Describe the solution you'd like** An ideal implementation should account for the "limit" during state transition so that a set of configurable limits or constraints are always honored. The feature doesn't need to and should not be tied to WAGED, it should be made as a universal feature that applies to any rebalancer. (The issue is raised from WAGED applications because it's the only place such constraints are defined, but the underlying causes would apply to all) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
