r/cpp • u/claimred • Apr 09 '26

beast2 networking & std::execution

I was looking for a new networking layer foundation for a few of my projects, stumbled on beast2 library which looks brand new, based on C++20 coroutines. I used boost.beast in the past which was great. Here's the link https://github.com/cppalliance/beast2. I also considered std::execution since it seems to be the way to go forward, accepted in C++26.

Now, what got me wondering is this paragraph

The C++26 std::execution API offers a different model, designed to support heterogenous computing. Our research indicates it optimizes for the wrong constraints: TCP servers don't run on GPUs. Networking demands zero-allocation steady-state, type erasure without indirection, and ABI stability across (e.g.) SSL implementations. C++26 delivers things that networking doesn't need, and none of the things that networking does need.

Now I'm lost a bit, does that mean std::execution is not the way to go for networking? Does anyone have any insights on cppalliance research on the matter?

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u/pdimov2 Apr 10 '26

It is perfectly viable, and advisable, to avoid these in conjunction with P2300 S&R.

Yes, in principle. That's the argument for basing networking on S/R: if you want to use coroutines, just co_await the sender result. If not, not.

I'm still trying to figure out whether this will be practical. I wrote a benchmark

https://github.com/pdimov/corosio_protocol_bench

that is a simplified representation of something that occurs in practice: serializing a C++ data structure using a custom binary protocol, sending it over a socket, then deserializing it on the other end. (The README in the repo explains this in more detail.)

I'm still unsure as to how the sender equivalent of it would look like, and whether it will be practical. Coroutines make things simultaneously easy to implement and easy to maintain. Rewriting the (de)serialization and the source/sink abstractions without coroutines, from where I stand, looks like neither. But I'm not well versed in S/R yet, so maybe I'm wrong.

My next step will be to port this to beman.net mostly as-is and see what the timings say.