数据是以非阻塞方式从通道中读取的，并被写到Client对象中。
Data is read from the channel in a nonblocking fashion and written to the Client object.
mbox 和 ibox 用来读取那些被写入 SPU 邮箱写通道的数据，不过语义稍有不同。
mbox and ibox are used to read data written to the SPU mailbox write channels and have slightly different semantics.
主线程把从通道读取的数据写到管道中。
The main thread writes bytes read from the channel into the pipe.
应用推荐