TLDR: If you don't use C++ async client unary calls (ClientAsyncResponseReader), you can ignore this message. Even if you do, it is very unlikely that the behavior change described will affect your code.
Dear gRPC users, The C++ async API doesn't guarantee forward progress for an RPC unless that RPC has an operation with a tag associated with it and the RPC is bound to a completion queue that will be Next'ed at some point. For client async unary calls in the common case, this means when the "ClientAsyncResponseReader::Finish" method is invoked. However, our system _has_ been making progress on such calls anyway. A recently-merged PR (https://github.com/grpc/grpc/pull/14759) changes that behavior so as to allow all of the operations of a client async unary call to be processed as a single batch. This is only a change of behaviors, not a change of API guarantees. Additionally, it is unlikely to have any visible impact unless the client-side and server-side of an RPC were already in the same thread (a case that typically only arises in testing) or if the client-side uses some sort of backchannel to monitor the server's internal behavior (e.g., seeing if the servers' internal threads are busy, which is again a behavior that makes more sense in testing). The net effect of this change is a substantial reduction in the number of locks taken and atomic operations invoked during C++ client async unary RPC processing. Please feel free to followup here or on the PR if you would like any further discussions about this topic. Best regards, vjpai -- You received this message because you are subscribed to the Google Groups "grpc.io" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/grpc-io. To view this discussion on the web visit https://groups.google.com/d/msgid/grpc-io/1a4414c6-d742-4143-8d90-cdd70d71a173%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
