In the previous neural network example, we used a static data structure that was shared between threads without being wrapped in a counter or lock. It contained locks, but why was the outer data structure permitted to be shared?
To answer this question, let's first review the rules of ownership:
- Each value in Rust has a variable that's called its owner
- There can only be one owner at a time
- When the owner goes out of scope, the value will be dropped
With these rules in mind, let's try to share a variable across threads, as follows:
use std::thread;fn main() { let a = vec![1, 2, 3]; thread::spawn(|| { println!("a = {:?}", a); });}
If we try to compile this, then we will get an error complaining of the following: ...
