// runtime_pprof/os.args.go
package main

import (
	"flag"
	"fmt"
	"os"
	"runtime/pprof"
	"time"
)

// 一段有问题的代码
func logicCode() {
	var c chan int //nil 未初始化
	for {
		select {
		case v := <-c: //阻塞
			fmt.Printf("recv from chan, value:%v\n", v)
		default:
			//time.Sleep(time.Millisecond * 500) //优化

		}
	}
}

func main() {
	var isCPUPprof bool //是否开启内存profile的标志位
	var isMemPprof bool //是否开启内存profile的标志位

	flag.BoolVar(&isCPUPprof, "cpu", false, "turn cpu pprof on")
	flag.BoolVar(&isMemPprof, "mem", false, "turn mem pprof on")
	flag.Parse()

	if isCPUPprof {
		f1, err := os.Create("./cpu.pprof") //在当前目录创建cpu.pprof文件
		if err != nil {
			fmt.Printf("create cpu pprof failed, err:%v\n", err)
			return
		}
		pprof.StartCPUProfile(f1) //往文件中记录cpu的信息
		defer func() {
			pprof.StopCPUProfile()
			f1.Close()
		}() //main函数退出之后结束
	}
	for i := 0; i < 8; i++ {
		go logicCode()
	}
	time.Sleep(20 * time.Second)
	if isMemPprof {
		f2, err := os.Create("./mem.pprof")
		if err != nil {
			fmt.Printf("create mem pprof failed, err:%v\n", err)
			return
		}
		pprof.WriteHeapProfile(f2)
		f2.Close()
	}
}

//生成文件之后用 go tool pprof cpu.pprof
//list logicCode 查看哪一行执行时间长