[infinispan-issues] [JBoss JIRA] Created: (ISPN-1085) TopologyAwareConsistentHash can run in an endless loop when rehashing

[Jürgen Kellerer (JIRA)]

TopologyAwareConsistentHash can run in an endless loop when rehashing
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                 Key: ISPN-1085
                 URL: https://issues.jboss.org/browse/ISPN-1085
             Project: Infinispan
          Issue Type: Bug
          Components: Distributed Cache
    Affects Versions: 4.2.1.FINAL
         Environment: Infinispan 4.2.1 using distributed caches and 3 cluster nodes with siteId and machineId (siteId is the same on all nodes, machineId is different)
            Reporter: Jürgen Kellerer
            Assignee: Mircea Markus


I'm not exactly sure how to reproduce it and why it happened but at least the problem is a quality / error handling issue. 

TopologyAwareConsistentHash can run in an endless loop when rehashing runs and 'numOwners' is greater than the available addresses in 'processSequence'.

The endless loop is in the method _getOwners()_ and the reason for it is shown in the simplified snippet below. It would really be helpful if the method either throws an exception with an exact definition what went wrong (e.g. including the address list and numOwners count) or handle the case if it's normal that this can happen when the cluster is just about to be built up.

{code:java}
private List<Address> getOwners(Address address, int numOwners) {
   ...
   ArrayList<Address> processSequence = ...
   ...
   List<Address> result = new ArrayList<Address>();
   while (result.size() < numOwners) {
       Iterator<Address> addrIt = processSequence.iterator();
       while (addrIt.hasNext()) {
          result.add(addrIt.next());
          addrIt.remove();
       }
   }
   return result;
}
{code}

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