@Override
          public void receivedStatus(OperationStatus s) {
            flushResult.set(s.isSuccess());
          }
Flush all caches from all servers with a delay of application.

@param delay the period of time to delay, in seconds
@return whether or not the operation was accepted
@throws IllegalStateException in the rare circumstance where queue is too
          full to accept any more requests
src/main/java/net/spy/memcached/MemcachedClient.java