private static SynchronousQueue<Runnable> getSynchronousQueue(
      BlockingQueue<Runnable> blockingQueue) {
    if (blockingQueue instanceof SynchronousQueue) {
      return (SynchronousQueue<Runnable>) blockingQueue;
    }
    return new SynchronousQueue<>();
  }
Is the current thread used for executing Functions?
geode-core/src/main/java/org/apache/geode/distributed/internal/FunctionExecutionPooledExecutor.java