Hi,

the issue is the following:

1. There is a simple callable, which throws an exception. The class is written so that, the exception throwing part is configurable. After the first time the exception is thrown, the attribute is set so that, during 2nd execution, the normal value is returned.

2. The callable is executed with DefaultExecutorService. During DistributedTask building, a custom newly created failoverPolicy is set to the task, which maxFailoverAttempts is set to 1.

3. When the test run, first execution throws exception, then as the maxFailoverAttempts is set to 1, system retries to execution the callable once more. On the retry, the callable should return normal value. But instead, the following exception is thrown:

"java.util.concurrent.ExecutionException: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.util.Map at org.infinispan.distexec.DefaultExecutorService$DistributedTaskPart.innerGet(DefaultExecutorService.java:914) at org.infinispan.distexec.DefaultExecutorService$DistributedTaskPart.get(DefaultExecutorService.java:874) at org.infinispan.distexec.BasicDistributedExecutorTest.testDistributedCallableCustomFailoverPolicySuccessfullRetry(BasicDistributedExecutorTest.java:353) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) at java.util.concurrent.FutureTask.run(FutureTask.java:166) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) Caused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.util.Map at org.infinispan.distexec.DefaultExecutorService$DistributedTaskPart.retrieveResult(DefaultExecutorService.java:981) at org.infinispan.distexec.DefaultExecutorService$DistributedTaskPart.innerGet(DefaultExecutorService.java:912) ... 23 more ... Removed 16 stack frames
java.util.concurrent.ExecutionException: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.util.Map at org.infinispan.distexec.DefaultExecutorService$DistributedTaskPart.innerGet(DefaultExecutorService.java:914) at org.infinispan.distexec.DefaultExecutorService$DistributedTaskPart.get(DefaultExecutorService.java:874) at org.infinispan.distexec.BasicDistributedExecutorTest.testDistributedCallableCustomFailoverPolicySuccessfullRetry(BasicDistributedExecutorTest.java:353) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:80) at org.testng.internal.Invoker.invokeMethod(Invoker.java:715) at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:907) at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1237) at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:127) at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:111) at org.testng.TestRunner.privateRun(TestRunner.java:767) at org.testng.TestRunner.run(TestRunner.java:617) at org.testng.SuiteRunner.runTest(SuiteRunner.java:334) at org.testng.SuiteRunner.access$000(SuiteRunner.java:37) at org.testng.SuiteRunner$SuiteWorker.run(SuiteRunner.java:368) at org.testng.internal.thread.ThreadUtil$2.call(ThreadUtil.java:64) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) at java.util.concurrent.FutureTask.run(FutureTask.java:166) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) Caused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.util.Map at org.infinispan.distexec.DefaultExecutorService$DistributedTaskPart.retrieveResult(DefaultExecutorService.java:981) at org.infinispan.distexec.DefaultExecutorService$DistributedTaskPart.innerGet(DefaultExecutorService.java:912) ... 23 more "

You can find the reproduction scenario here:
https://github.com/andyuk1986/infinispan/blob/DIST_EXEC_TESTS/core/src/test/java/org/infinispan/distexec/BasicDistributedExecutorTest.java (testDistributedCallableCustomFailoverPolicySuccessfullRetry test)