code: public void processEventsUntilIdle() {
          boolean idle;
          do {
              idle = true;
              for (MessageProcessor actorThread : actorThreads) {
                  if (actorThread.processNextMessageIfAny()) {
                      idle = false;
                  }
                  if (Thread.interrupted()) {
                      actorThreads.remove(actorThread);
                  }
              }
          } while (!idle);
      }
docs: Processes in the current thread all messages which were sent to actors. The order of processing messages is
  deterministic. Will block until all messages have been processed and nobody is sending more messages.
  <p>
  When using {@link CrashEarlyFailureHandler}, will rethrow uncaught exceptions from actors to the caller of this
  method.