154 lines
3.4 KiB
Go
154 lines
3.4 KiB
Go
package main
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import (
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"fmt"
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"net/http"
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"os/exec"
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"runtime"
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"sync"
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"time"
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)
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// 验证Hand Off触发场景，覆盖所有核心触发类型
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func main() {
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// 限制P数量为1，放大Hand Off效果（若不触发，G2需等待G1完成）
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runtime.GOMAXPROCS(1)
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fmt.Printf("当前P的数量: %d\n", runtime.GOMAXPROCS(0))
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// 强制GC和调度器初始化
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runtime.GC()
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time.Sleep(10 * time.Millisecond)
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// 1. 阻塞式网络I/O触发Hand Off
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testBlockNetIO()
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fmt.Println("=== 分割线 ===")
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// 2. time.Sleep()触发Hand Off
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testTimeSleep()
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fmt.Println("=== 分割线 ===")
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// 3. os/exec执行外部命令触发Hand Off
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testExecCommand()
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}
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// 场景1：阻塞式网络I/O（HTTP请求）
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func testBlockNetIO() {
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var wg sync.WaitGroup
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// 控制执行顺序，避免调度随机性
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g1Start := make(chan struct{})
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g2Exec := make(chan struct{})
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// G1：执行阻塞式HTTP请求
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wg.Add(1)
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go func() {
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defer wg.Done()
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close(g1Start)
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fmt.Println("G1: 开始执行阻塞式HTTP请求")
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// 阻塞式网络I/O
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_, err := http.Get("https://www.baidu.com")
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if err != nil {
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fmt.Printf("G1: HTTP请求异常: %v\n", err)
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}
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fmt.Println("G1: HTTP请求完成")
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close(g2Exec)
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}()
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// 等待G1启动后，启动G2
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<-g1Start
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time.Sleep(50 * time.Millisecond)
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// G2：验证Hand Off生效（若触发则立即执行）
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wg.Add(1)
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go func() {
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defer wg.Done()
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fmt.Println("G2: 开始执行（验证网络I/O触发Hand Off）")
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<-g2Exec
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fmt.Println("G2: 执行完成")
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}()
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wg.Wait()
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}
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// 场景2：time.Sleep()触发Hand Off
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func testTimeSleep() {
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var wg sync.WaitGroup
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g1Sleep := make(chan struct{})
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// G1：执行time.Sleep()
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wg.Add(1)
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go func() {
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defer wg.Done()
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close(g1Sleep)
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fmt.Println("G1: 开始执行time.Sleep(1秒)")
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time.Sleep(1 * time.Second)
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fmt.Println("G1: sleep完成，恢复执行")
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}()
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// 等待G1进入sleep后，启动G2
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<-g1Sleep
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time.Sleep(50 * time.Millisecond)
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// G2：验证Hand Off生效
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wg.Add(1)
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go func() {
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defer wg.Done()
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fmt.Println("G2: 开始执行（验证time.Sleep触发Hand Off）")
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}()
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wg.Wait()
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}
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// 场景3：os/exec执行外部命令
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func testExecCommand() {
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var wg sync.WaitGroup
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g1Exec := make(chan struct{})
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g2Started := make(chan struct{})
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// G1：执行外部sleep命令
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wg.Add(1)
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go func() {
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defer wg.Done()
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close(g1Exec) // 通知G1已启动
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fmt.Println("G1: 执行外部命令 sleep 1s")
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// 关键：在阻塞前让出处理器，确保调度器有机会切换
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runtime.Gosched()
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// 跨平台命令执行
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var cmd *exec.Cmd
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if runtime.GOOS == "windows" {
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fmt.Println("检测到Windows系统，使用timeout命令")
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cmd = exec.Command("powershell", "-command", "Start-Sleep -Seconds 1")
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} else {
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cmd = exec.Command("sleep", "1")
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}
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err := cmd.Run()
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if err != nil {
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fmt.Printf("G1: 命令执行错误: %v\n", err)
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}
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fmt.Println("G1: 外部命令执行完成")
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}()
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// 等待G1启动
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<-g1Exec
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time.Sleep(10 * time.Millisecond) // 短暂等待确保G1进入阻塞
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// G2：验证Hand Off生效
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wg.Add(1)
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go func() {
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defer wg.Done()
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close(g2Started)
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fmt.Println("G2: 开始执行（验证os/exec触发Hand Off）")
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}()
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// 等待G2启动确认
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select {
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case <-g2Started:
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fmt.Println("验证成功: G2在G1阻塞期间执行")
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case <-time.After(500 * time.Millisecond):
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fmt.Println("警告: G2未及时执行，可能未触发Hand Off")
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}
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wg.Wait()
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}
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