package main

import (
	"fmt"
	"os"
	"runtime"
	"time"
)

func main() {
	runtime.GOMAXPROCS(1) // 限制为1个P，便于观察Hand-off效果

	ch := make(chan bool)

	go func() {
		fmt.Println("Goroutine: performing blocking syscall (file read)")
		_, err := os.ReadFile("dev/urandom") // 阻塞式文件I/O
		if err != nil {
			fmt.Println("Error:", err)
		}
		fmt.Println("Goroutine: syscall completed")
		ch <- true
	}()

	// 主Goroutine持续执行，证明调度未停滞
	for i := 0; i < 5; i++ {
		fmt.Printf("Main: iteration %d\n", i)
		time.Sleep(50 * time.Millisecond)
	}

	<-ch
}