https://kaisery.github.io/trpl-zh-cn/ch16-01-threads.html

 

use std::thread;
use std::time::Duration;

fn main() {
    thread::spawn(|| {
        for i in 1..10 {
            println!("hi number {} from the spawned thread!", i);
            thread::sleep(Duration::from_millis(1));
        }
    });

    for i in 1..5 {
        println!("hi number {} from the main thread!", i);
        thread::sleep(Duration::from_millis(1));
    }
}

 

 

   Compiling hello_world v0.1.0 (/data2/rust/thread)
    Finished dev [unoptimized + debuginfo] target(s) in 0.59s
[root@bogon thread]# cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/hello_world`
hi number 1 from the main thread!
hi number 1 from the spawned thread!
hi number 2 from the main thread!
hi number 2 from the spawned thread!
hi number 3 from the main thread!
hi number 3 from the spawned thread!
hi number 4 from the main thread!
hi number 4 from the spawned thread!

 

 

 

 

use std::thread;
use std::time::Duration;

fn main() {
    let handle = thread::spawn(|| {
        for i in 1..10 {
            println!("hi number {} from the spawned thread!", i);
            thread::sleep(Duration::from_millis(1));
        }
    });

    for i in 1..5 {
        println!("hi number {} from the main thread!", i);
        thread::sleep(Duration::from_millis(1));
    }

    handle.join().unwrap();
}

 

 

[root@bogon thread1]# cargo build
   Compiling hello_world v0.1.0 (/data2/rust/thread1)
    Finished dev [unoptimized + debuginfo] target(s) in 0.58s
[root@bogon thread1]# cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/hello_world`
hi number 1 from the main thread!
hi number 1 from the spawned thread!
hi number 2 from the main thread!
hi number 2 from the spawned thread!
hi number 3 from the main thread!
hi number 3 from the spawned thread!
hi number 4 from the main thread!
hi number 4 from the spawned thread!
hi number 5 from the spawned thread!
hi number 6 from the spawned thread!
hi number 7 from the spawned thread!
hi number 8 from the spawned thread!
hi number 9 from the spawned thread!

 

这两个线程仍然会交替执行，不过主线程会由于 handle.join() 调用会等待直到新建线程执行完毕。

不过让我们看看将 handle.join() 移动到 main 中 for 循环之前会发生什么，如下：

文件名: src/main.rs

 

use std::thread;
use std::time::Duration;

fn main() {
    let handle = thread::spawn(|| {
        for i in 1..10 {
            println!("hi number {} from the spawned thread!", i);
            thread::sleep(Duration::from_millis(1));
        }
    });

    handle.join().unwrap();

    for i in 1..5 {
        println!("hi number {} from the main thread!", i);
        thread::sleep(Duration::from_millis(1));
    }
}

主线程会等待直到新建线程执行完毕之后才开始执行 for 循环，所以输出将不会交替出现，如下所示：

 

hi number 1 from the spawned thread!
hi number 2 from the spawned thread!
hi number 3 from the spawned thread!
hi number 4 from the spawned thread!
hi number 5 from the spawned thread!
hi number 6 from the spawned thread!
hi number 7 from the spawned thread!
hi number 8 from the spawned thread!
hi number 9 from the spawned thread!
hi number 1 from the main thread!
hi number 2 from the main thread!
hi number 3 from the main thread!
hi number 4 from the main thread!

诸如将 join 放置于何处这样的小细节，会影响线程是否同时运行。