May is a high-performant library for programming stackful coroutines with which you can easily develop and maintain massive concurrent programs. It can be thought as the Rust version of the popular [Goroutine][go].
A naive echo server implemented with May: ```rust
extern crate may;
use may::net::TcpListener; use std::io::{Read, Write};
fn main() { let listener = TcpListener::bind("127.0.0.1:8000").unwrap(); while let Ok((mut stream, )) = listener.accept() { go!(move || { let mut buf = vec![0; 1024 * 16]; // alloc in heap! while let Ok(n) = stream.read(&mut buf) { if n == 0 { break; } stream.writeall(&buf[0..n]).unwrap(); } }); } }
```
Just a simple comparison with the Rust echo server implemented with tokio to get sense about May.
Note:
The Tokio-based version is not at it's maximum optimization. In theory,
futurescheduling is not evolving context switch which should be a little bit faster than the coroutine version. But I can't find a proper example for multi-threaded version comparison, so just put it here for you to get some sense about the performance of May. If you have a better implementation of s futures-based echo server, I will update it here.
The machine's specification: * Logical Cores: 4 (4 cores x 1 threads) * Memory: 4gb ECC DDR3 @ 1600mhz * Processor: CPU Intel(R) Core(TM) i7-3820QM CPU @ 2.70GHz * Operating System: Ubuntu VirtualBox guest
An echo server and client:
You can just compile it under this project:
sh
$ cargo build --example=echo_client --release
Tokio-based echo server:
Run the server by default with 2 threads in another terminal:
sh
$ cd tokio-core
$ cargo run --example=echo-threads --release
```sh $ target/release/examples/echo_client -t 2 -c 100 -l 100 -a 127.0.0.1:8080 ==================Benchmarking: 127.0.0.1:8080================== 100 clients, running 100 bytes, 10 sec.
Speed: 315698 request/sec, 315698 response/sec, 30829 kb/sec Requests: 3156989 Responses: 3156989 target/release/examples/echo_client -t 2 -c 100 -l 100 -a 127.0.0.1:8080 1.89s user 13.46s system 152% cpu 10.035 total ```
May-based echo server:
Run the server by default with 2 threads in another terminal:
sh
$ cd may
$ cargo run --example=echo --release -- -p 8000 -t 2
```sh $ target/release/examples/echo_client -t 2 -c 100 -l 100 -a 127.0.0.1:8000 ==================Benchmarking: 127.0.0.1:8000================== 100 clients, running 100 bytes, 10 sec.
Speed: 419094 request/sec, 419094 response/sec, 40927 kb/sec Requests: 4190944 Responses: 4190944 target/release/examples/echo_client -t 2 -c 100 -l 100 -a 127.0.0.1:8000 2.60s user 16.96s system 195% cpu 10.029 total ```
There is a detailed document that describes May's main restrictions. In general, there are four things you should follow when writing programs that use coroutines: * Don't call thread-blocking API (It will hurt the performance); * Carefully use Thread Local Storage (access TLS in coroutine might trigger undefined behavior).
It's considered unsafe with the following pattern:
rust set_tls(); // Or another coroutine's API that would cause scheduling: coroutine::yield_now(); use_tls();but it's safe if your code is not sensitive about the previous state of TLS. Or there is no coroutines scheduling between set TLS and use TLS.
Note:
The first three rules are common when using cooperative asynchronous libraries in Rust. Even using a futures-based system also have these limitations. So what you should really focus on is a coroutine's stack size, make sure it's big enough for your applications.
If you want to tune your coroutine's stack size, please check out this document.
May is licensed under either of the following, at your option: