public static Map getClientQueueSizes(final InternalCache cache) {
    if (cache == null) {
      return Collections.emptyMap();
    }

    Map clientQueueSizes = new HashMap();
    for (CacheServer cacheServer : cache.getCacheServers()) {
      InternalCacheServer internalCacheServer = (InternalCacheServer) cacheServer;
      Acceptor acceptor = internalCacheServer.getAcceptor();
      if (acceptor != null && acceptor.getCacheClientNotifier() != null) {
        clientQueueSizes.putAll(acceptor.getCacheClientNotifier().getClientQueueSizes());
      }
    }
    return clientQueueSizes;
  }
Caller must synchronize on cache.allClientServersLock

@return all the clients
geode-core/src/main/java/org/apache/geode/internal/cache/tier/InternalClientMembership.java