[infinispan-dev] DistributedExecutorSVC.submitEverywhere(callableTask) -- dispatching task > 1x (??)

[ben.cotton]

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 at jpmorgan.com



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