backlog - the maximum length of the queue The maximum queue length for incoming connection indications (a request to connect) is set to the backlog parameter. If a connection indication arrives when the queue is full, the connection is refused.通俗地说，就是最大连接字长度。Socket能监听端口上的队列消息，但是如果指定了backlog的话，就会对连接字的长度进行校验，长于最大长度的话，就拒绝该连接。
The maximum queue length for incoming connection indications (a request to connect) is set to the backlog parameter. If a connection indication arrives when the queue is full, the connection is refused.通俗地说，就是最大连接字长度。Socket能监听端口上的队列消息，但是如果指定了backlog的话，就会对连接字的长度进行校验，长于最大长度的话，就拒绝该连接。