public long estimateMemoryFootprint(SingleObjectSizer sizer) {
    return sizer.sizeof(this) + sizer.sizeof(regionToDispatchedKeysMap)
        + sizer.sizeof(userRegionNameToShadowPRMap) + sizer.sizeof(bucketToTempQueueMap)
        + sizer.sizeof(peekedEvents) + sizer.sizeof(conflationExecutor);
  }
shutdown this thread and the caller thread will join this thread
geode-core/src/main/java/org/apache/geode/internal/cache/wan/parallel/ParallelGatewaySenderQueue.java