private void cleanUpRequestAllocatorThread(ContainerPlacementRequestAllocator requestAllocator, Thread containerPlacementRequestAllocatorThread) {
    requestAllocator.stop();
    try {
      containerPlacementRequestAllocatorThread.join();
    } catch (InterruptedException ie) {
      Thread.currentThread().interrupt();
    }
  }
Inject a duplicate request and check it is not accepted
samza-core/src/test/java/org/apache/samza/clustermanager/TestContainerPlacementActions.java