p-h-c-s/rust-threadpool

Toy Threadpool implementation

A custom thread pool implementation in rust

This repo contains a custom thread pool implementation in Rust. It was created in order to learn the quirks of the language. It allows the submission of closures that capture non 'static lifetime references.

Usage

let num_threads = 5
let unscoped = String::from("123");
scoped_tpool::thread_pool::with_pool(num_threads, |t_pool| {
    t_pool.submit(|| {
        let x = 2 * 2;
        let z = &unscoped;
    })
})

Small quirk

Standard library's thread::scope can be a bit finicky to use. If you create a variable inside the scope you might not borrow it to the spawned threads. You must move it.

thread::scope(|s| {
    let val = &String::from("123");
    s.spawn(move || {
        let z = val;
    });
});

This same behaviour exists for the pool, as it uses a thread::Scope:

thread_pool::with_pool(num_threads, |t_pool| {
    let val = String::from("1234");
    t_pool.submit(move || {
        let z = &val;
    });
}

Self-imposed challenges

I challenged myself to avoid using the simple thread::spawn as it only allowed the closures to capture 'static lifetime references. This made everything a little bit harder as we then had to worry about the thread::Scope lifetimes carefully.

I also avoided channels as they're a (too) useful abstraction. I wanted to learn what it would take to implement a synchronized queue in rust. Channels basically abstract that away.