Threads

Rust threads work similarly to threads in other languages:

1. use std::thread;
2. use std::time::Duration;

4. fn main() {
5. thread::spawn(|| {
6. for i in 1..10 {
7. println!("Count in thread: {i}!");
8. thread::sleep(Duration::from_millis(5));
9. }
10. });

12. for i in 1..5 {
13. println!("Main thread: {i}");
14. thread::sleep(Duration::from_millis(5));
15. }
16. }

• Threads are all daemon threads, the main thread does not wait for them.
• Thread panics are independent of each other.
• Panics can carry a payload, which can be unpacked with downcast_ref.

Key points:

• Notice that the thread is stopped before it reaches 10 — the main thread is not waiting.
• Use let handle = thread::spawn(...) and later handle.join() to wait for the thread to finish.
• Trigger a panic in the thread, notice how this doesn’t affect main.
• Use the Result return value from handle.join() to get access to the panic payload. This is a good time to talk about Any.