Can't connect to memcached when it is restarted!

[然 安]

 Hi,all:
        I use libmemcached as the client and create a memcached_st instance to 
transfer datas. The problem is that the memcached_st instance can't connect to 
the memcached server after the server is stopped and restarted. How can I 
resolve this problem except restarting the client? Thank you for your reply.