Multi threaded HTTP server using crossbeam

The Rust book has a section on multi threaded HTTP server, and I found the corresponding implementation on github.
https://github.com/richardknox/rust-webserver

This was actually published 2 years ago.
While the code is pretty neat, but it is intersting to implement this with crossbeam so that it can directly apply SPMC channel. basically this is typical situation for load balance server.

In fact, the straight forward modification did not work.
it seems better to use hyper.

there is an interesting github, that is quite close to my goal. but it is not using crossbeam.
So it would be better to use this for multi threaded http server imple with crossbeam.

https://github.com/hyperium/hyper/issues/1358

https://gist.github.com/klausi/93b57d3abe2c5bc4975b0b9921f2a3c2


Go program may be useful:
 https://github.com/dc0d/tcpserver/blob/master/tcpserver.go

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After trying to combine crossbeam and tokio, I found this is not simple.
In particular the latest approach of Tokio rely on async, and async and thread seems not easy to coexist.
Once process function includes async code, all code must be async.
And thread's parameter closure should not be async, and the free variable are not permitted because of the lifetime of variable.
 there have been some discussion over mpsc channel against mpmc like approach, and if we use these Tokio, hyper library, we may not have to use mpmc at least for http related application.
since it already supports multi threaded handlers.

Anyway I will investigate hyper now. (hyper uses tokio)

https://tokio.rs/

https://hyper.rs/

https://github.com/hyperium/hyper