[CASSANDRA-9999] Improve usage of HashMap and HashSet in NetworkTopologyStrategy

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Won't Fix
• Assignee: Tommy Stendahl
• Reporter: Tommy Stendahl

Authors

Tommy Stendahl

Reviewers

Branimir Lambov

• Created: 06/Aug/15 11:17
• Updated: 16/Apr/19 09:31
• Resolved: 15/Jan/16 08:56

Description

In NetworkTopologyStrategy there are HashMaps and HashSets created with a specified initial size. I assume that this is done avoid having them re sized then when objects are inserted to them. Unfortunately they are created with the size of the expected number of object that will be inserted into them. Since the default load factor is 0.75 this will almost guarantee that HashMaps and HashSets are re sized, to avoid re size the initial size should be set to "no of objects / 0.75 +1".

Since this is done every time calculateNaturalEndpoints() is called this might have some performance impact.

Issue Links

• relates to: CASSANDRA-10200 NetworkTopologyStrategy.calculateNaturalEndpoints is rather inefficient