When to invoke Requestxxx API when use async server

[yihao yang]

In the example of async server (see https://github.com/grpc/grpc/blob/release-0_14/examples/cpp/helloworld/greeter_async_server.cc)

I am very confused when to invoke RequestSayHello in the code. It seems in the example, RequestSayHello cannot be invoked concurrently.

My questions are:

1. RequestSayHello is used to wait a new coming request from network, right?

2. How to invoke RequestSayHello can gain a good performance, seems in the example, the next RequestSayHello will be invoked only when last Request is handling.

Thanks,

yihao