[infinispan-issues] [JBoss JIRA] (ISPN-11679) Bad uneven segment distributions can happen after the rebalancing with SyncConsistentHashFactory

Bad uneven segment distributions can happen after the rebalancing with SyncConsistentHashFactory ------------------------------------------------------------------------------------------------ Key: ISPN-11679 URL: https://issues.redhat.com/browse/ISPN-11679 Project: Infinispan Issue Type: Bug Components: Core Affects Versions: 9.4.19.Final, 10.1.6.Final Reporter: Masafumi Miura Assignee: Dan Berindei Priority: Major Fix For: 11.0.0.Final Uneven segment distribution can happen after rebalancing with SyncConsistentHashFactory. Even if a larger number of segments than "20 * number of nodes" is configured, some nodes have only around 50-60% number of segments than other nodes after the rebalance in the worst case. I understand the documentation (like the following) states about the possibility of slight uneven distribution as a potential drawback of SyncConsistentHashFactory. [Infinispan 10 configuration guide|https://infinispan.org/docs/stable/titles/configuring/configuring.h...] says: {quote} This implementation does have some negative points in that the load distribution is slightly uneven. It also moves more segments than strictly necessary on a join or leave. {quote} [JDG 7 Developer Guide|https://access.redhat.com/documentation/en-us/red_hat_data_grid/7.2...] says: {quote} It has a potential drawback in that it can move a greater number of segments than necessary during re-balancing. This can be mitigated by using a larger number of segments. Another potential drawback is that the segments are not distributed as evenly as possible, and actually using a very large number of segments can make the distribution of segments worse. {quote} However, only half segments than others is not a slight uneven.