@Override
  public int eventQueueSize() {
    ParallelGatewaySenderQueue queue = (ParallelGatewaySenderQueue) getQueue();
    return queue == null ? 0 : queue.localSize();
  }
use in concurrent scenario where queue is to be shared among all the processors.
geode-core/src/main/java/org/apache/geode/internal/cache/wan/parallel/ParallelGatewaySenderEventProcessor.java