多线程-两个线程交替打印数字

两个线程交替打印奇偶数

方案一:使用 channel 控制交替

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package main

import (
	"fmt"
	"sync"
)

func main() {
	oddChan := make(chan bool, 1)  // 奇数
	evenChan := make(chan bool, 1) // 偶数

	var wg sync.WaitGroup
	wg.Add(2)

	go func() {
		defer wg.Done()

		for i := 1; i <= 10; i += 2 {
			<-oddChan
			fmt.Println("odd(奇数): ", i)
			evenChan <- true
		}
	}()

	go func() {
		defer wg.Done()

		for i := 2; i <= 10; i += 2 {
			<-evenChan
			fmt.Println("even(偶数): ", i)
			oddChan <- true
		}
	}()

	oddChan <- true

	wg.Wait()
}

image-20250613172414067

方案二:sync.Cond 条件变量实现

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package main

import (
	"fmt"
	"sync"
)

func main() {
	var mu sync.Mutex
	cond := sync.NewCond(&mu)

	var wg sync.WaitGroup
	wg.Add(2)

	turn := "A"
	n := 5

	go func() {
		defer wg.Done()

		for i := 0; i < n; i++ {
			mu.Lock()
			for turn != "A" {
				cond.Wait() // 等待轮到 A
			}

			fmt.Println("odd: A")

			turn = "B"
			cond.Signal() // 通知 B
			mu.Unlock()
		}
	}()

	go func() {
		defer wg.Done()

		for i := 0; i < n; i++ {
			mu.Lock()
			for turn != "B" {
				cond.Wait() // 等待轮到 B
			}

			fmt.Println("even: B")

			turn = "A"
			cond.Signal() // 通知 A
			mu.Unlock()
		}
	}()

	wg.Wait()
}

image-20250613175253718

本文作者:
本文链接: https://hgnulb.github.io/blog/2025/58202529
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