We have an ISPN 5.1.6 data grid (that executes on top of JGroups) that includes the following topology: 2 x Linux host(s) Each with 30 x Java VM Nodes TOTAL = 60 Nodes On this 60 Node grid we use the org.infinispan.distexec.DistributedExecutorService and org.inifinispan.util.concurrent.NotifyingFuture APIs to manage the dispatch of a MapReduce TASK that originates from a dedicated TASK SENDER Node and targets the full set of 60 TASK RECEIVER Nodes to complete the computation. The exact API invoke (from the Task SENDER) – of course – looks like //build the DistributedExecutorService and Callable instance references * List<Future&lt;T>> futureList = distExecSvc.submitEverywhere(ourCallableTask);* Now, as expected, 99+% of the time we are able to realize exactly 1 Task being distributed to all 60 RECEIVER Nodes and we see exactly 1 Future List entry being returned per Node submitted. However, under very rare circumstances … (and *only* when a certain subset of RECEIVER Nodes are enduring a major GC event) we are able to see undeniable evidence that the callableTask is being submitted /multiple times/ to a certain subset of the RECEIVER Nodes. Is there any ISPN/JGroups API or configuration mechanism by which we can be assured of being able to prevent the callableTask being submitted multiple times to a certain subset of the RECEIVER Nodes? Thanks for any insights, Ben Ben D. Cotton III J.P.Morgan Liquidity Risk Technology 277 Park Ave Desk 08-GG64 New York, NY 10172-0003 212.622.5010 ben.cotton(a)jpmorgan.com -- View this message in context: http://infinispan-developer-list.980875.n3.nabble.com/DistributedExecutor... Sent from the Infinispan Developer List mailing list archive at Nabble.com. _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev