[infinispan-issues] [JBoss JIRA] (ISPN-2067) The ConsistentHash implementation on the hotrod client is very inefficient

The ConsistentHash implementation on the hotrod client is very inefficient -------------------------------------------------------------------------- Key: ISPN-2067 URL: https://issues.jboss.org/browse/ISPN-2067 Project: Infinispan Issue Type: Feature Request Affects Versions: 5.1.4.FINAL Reporter: Mircea Markus Assignee: Mircea Markus Fix For: 5.1.5.FINAL Profiler snapshots show that a large amount of time is spent in the {{org.infinispan.client.hotrod.impl.consistenthash.ConsistentHashV1#getServer}} method (about 13%). The root cause of this is the fact that the size method invoked on an object returned by TreeMap.tail() is very expensive: TreeMap.tail() returns an instance of TreeMap.AscendingSubMap class for which the size method, in order to calculates the number of elements, iterates over the entire collection(O(n)). This is highly inefficient and not scalable especially since the number of virtual nodes was set to 50 by default, as not the size of the collection is quite high: e.g. 32 nodes with 50 virtual nodes each, size()'s iterates an average of ~750 elements.