package main

func fakeBurn() {
 for {

 }
}

package main

import (
 "flag"
 "fmt"
 "runtime"
 "time"
)

var (
 numBurn        int
 updateInterval int
)

func cpuBurn() {
 for {
  for i := 0; i < 2147483647; i++ {
  }

  // Gosched yields the processor, allowing other goroutines to run. It does not suspend the current goroutine, so execution resumes automatically.
  // Gosched让当前goroutine让出处理器，从而使得其它goroutine可以运行。它不会挂起/暂停当前的goroutine，它会自动恢复执行。
  runtime.Gosched()
 }
}

func init() {
 flag.IntVar(&numBurn, "n", 0, "number of cores to burn (0 = all)")
 flag.IntVar(&updateInterval, "u", 10, "seconds between updates (0 = don't update)")
 flag.Parse()
 if numBurn <= 0 {
  numBurn = runtime.NumCPU()
 }
}

func main() {
 runtime.GOMAXPROCS(numBurn)
 fmt.Printf("Burning %d CPUs/cores\n", numBurn)
 for i := 0; i < numBurn; i++ {
  go cpuBurn()
 }

 // 一直执行，区别是其中一个会定期打印，另一个不会打印
 if updateInterval > 0 {
  t := time.Tick(time.Duration(updateInterval) * time.Second)
  for secs := updateInterval; ; secs += updateInterval {
   <-t
   fmt.Printf("%d seconds\n", secs)
  }
 } else {
  select {} // wait forever
 }
}