corosio produces much bigger binaries than asio

[pfeatherstone]

I'm comparing a simple echo server written in corosio and asio. I'm using the example echo server on the corosio webpage. I've attached the code. On my machine, compiling with gcc 14.2.0 i get the following binary sizes:

• echo_corosio: 683280 bytes
• echo_asio: 108952 bytes

CMakeLists.txt

main_asio.cpp

main_corosio.cpp

[pfeatherstone]

Could you open the "discussions" tab on the corosio project?

[pfeatherstone]

when i compile with clang18 i get:

• echo_corosio: 692496 bytes
• echo_asio: 101664 bytes

[pfeatherstone]

so i'm not convinced of the promise of "smaller binaries" due to less template bloat.

[InternalHigh]

What could be the reason for this?

[pfeatherstone]

I was surprised by how little difference LTO made for corosio.

[pfeatherstone]

In that simple corosio echo server, it's building ALL of corosio, including UDP, DNS resolution, thread pools, absolutely everything, and the linker can't get rid of it. ChatGPT is saying that corosio's io_context on Linux is constructing the epoll backend like so:

auto& sched = ctx.make_service<detail::epoll_scheduler>(
    static_cast<int>(concurrency_hint));

ctx.make_service<detail::epoll_tcp_service>();
ctx.make_service<detail::epoll_tcp_acceptor_service>();
ctx.make_service<detail::epoll_udp_service>();
ctx.make_service<detail::epoll_local_stream_service>();
ctx.make_service<detail::epoll_local_stream_acceptor_service>();
ctx.make_service<detail::epoll_local_datagram_service>();

So it's bringing in a lot of logic. Asio's io_context doesn't do this. So it's no wonder LTO won't achieve much here.