c++ async client unexpectly timeout if I don't call `CQ::Next()`

[Arthur Wang]

Hi all :

I observed a VERY strange behavior of the async c++ client, it seems that even if the server has returned the result to the async client within the timeout value, grpc will still report a timeout error just because of you don't fetch the result out from the CQ by calling cq_->Next() !

I can't believe the CompletionQueue is designed like this ! Hope someone could help, details are here:  https://github.com/grpc/grpc/issues/19573 

 Thanks.

- Regards

- Arthur

[Juanli Shen]

Hy Arthur, I replied in https://github.com/grpc/grpc/issues/19573.