[dangxiaopin]

To implement, no. To make a performant server- yes. Most systems have limited number of threads (low limit constant compiled with the kernel), and each thread is triggered by the scheduler, not by network events, which is very uneconomical.

You with application level concurrency you get 100x performance boost for network servers.

[pcwalton]

On extreme workloads, perhaps. But we have people happily running Rust code with thousands of threads per second in production.

M:N was experimentally found to be slower than 1:1 in Rust.