Boost.Redis will coalesce requests into a single one when it can. When a request is issued using async_exec, the following happens:

• If no request is in the process of being written, the request is written to the socket.

• Otherwise, the request will wait until the socket is idle. Any subsequent incoming requests will be merged with it, until the socket is idle again.

I still advise to pipeline explicitly as much as you can when building the requests to be used with async_exec. The request class has native pipeline support - just call request::push several times to create a pipeline.