private MemcachedCache initializeClient(String poolName) {
		MemcachedCache cache = clientPool.get(poolName);
		if (cache == null) {
			// I don't know why binary protocol is invalid in my pc, so just
			// use tcp ascii;
			MemCachedClient client = new MemCachedClient(poolName, true, false);
			cache = new MemcachedCache(client);
		}
		return cache;
	}