[infinispan-issues] [JBoss JIRA] (ISPN-4851) Make SyncConsistentHashFactory the default CH factory

[Dan Berindei (JIRA)]

Dan Berindei created ISPN-4851:
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             Summary: Make SyncConsistentHashFactory the default CH factory
                 Key: ISPN-4851
                 URL: https://issues.jboss.org/browse/ISPN-4851
             Project: Infinispan
          Issue Type: Feature Request
          Components: Configuration, Core
    Affects Versions: 7.0.0.CR1
            Reporter: Dan Berindei
             Fix For: 7.0.0.CR2, 7.0.0.Final


With ISPN-4682 fixed, SyncConsistentHashFactory should be good enough to be the default. It still allows for more variation in the number of owned segments per node (+/-10% owned segments and +/-20% for primary-owned segments), but that should be acceptable for most purposes. 

The major advantage of SCHF is that it depends only on the cache members and not on the order they joined. Users expect a key to map to the same node in all caches (as long as the caches have the same members).

One downside of SCHF, especially for testing, is that the segment ownership differs between test runs (being based on the random address assigned to each node). However, most tests that depend on key ownership should use {{ControlledConsistentHashFactory}} anyway.

We also need to verify that the number of segments moved by SCHF is comparable to the number of segments moved by DefaultConsistentHashFactory (ISPN-3729).



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