Go库性能分析工具pprof

// 处理某些业务，真实的代码中这个死循环很隐蔽
func retrieveSomeThing() {
	for {}
}
// 处理其他的一些业务，无意义，用于后续做例子
func doSomeThing() {
	do1()
	for i := 0; i < 200000000; i++ {}
	do2()
}
// 无意义
func do1() {
	for i := 0; i < 200000000; i++ {}
}
// 无意义
func do2() {
	for i := 0; i < 200000000; i++ {}
}
func main() {
	go retrieveSomeThing()
  go doSomeThing()
	// 阻塞一下
	time.Sleep(3 * time.Second)
}

// 输出到标准输出，一般是指定文件
if err := pprof.StartCPUProfile(os.Stdout); err != nil {
    log.Fatal("could not start CPU profile: ", err)
}
defer pprof.StopCPUProfile()

// 输出到标准输出，一般是指定文件
if err := pprof.WriteHeapProfile(os.Stdout); err != nil {
    log.Fatal("could not write memory profile: ", err)
}
}

// 通过参数指定 cpu profile 输出的文件
var cpuprofile = flag.String("cpuprofile", "", "write cpu profile to `file`")
func main() {
	flag.Parse()
	if *cpuprofile != "" {
		f, err := os.Create(*cpuprofile)
		if err != nil {
			log.Fatal("could not create CPU profile: ", err)
		}
		// 开启 CPU 分析
		if err := pprof.StartCPUProfile(f); err != nil {
			log.Fatal("could not start CPU profile: ", err)
		}
		defer pprof.StopCPUProfile()
	}
	// 业务代码
	go retrieveSomeThing()
  go doSomeThing()
	// 模拟阻塞
	time.Sleep(5 * time.Second)
}

go run main.go -cpuprofile cpu.prof

> go tool pprof cpu.prof 
Type: cpu
Time: Nov 16, 2022 at 1:40pm (CST)
Duration: 5.17s, Total samples = 4.54s (87.75%)
Entering interactive mode (type "help" for commands, "o" for options)
(pprof) 

(pprof) top10
Showing nodes accounting for 4650ms, 100% of 4650ms total
      flat  flat%   sum%        cum   cum%
    4220ms 90.75% 90.75%     4450ms 95.70%  main.retrieveSomeThing
     230ms  4.95% 95.70%      230ms  4.95%  runtime.asyncPreempt
      80ms  1.72% 97.42%      200ms  4.30%  main.doSomeThing
      70ms  1.51% 98.92%       70ms  1.51%  main.do2 (inline)
      50ms  1.08%   100%       50ms  1.08%  main.do1 (inline)

func doSomeThing() {                   // flat: 80ms  cum: 200ms
	do1()                                // 执行时间 50ms
	for i := 0; i < 200000000; i++ {}    // 执行时间 80ms
	do2()                                // 执行时间 70ms
}

(pprof) list retrieveSomeThing
Total: 4.65s
ROUTINE ======================== main.retrieveSomeThing in /xxxx/pprof_note/pprof/main.go
     4.22s      4.45s (flat, cum) 95.70% of Total
      10ms       10ms      1:package main
         .          .      2:
         .          .      3:import (
         .          .      4:   "flag"
         .          .      5:   "log"
         .          .      6:   "os"
         .          .      7:   "runtime/pprof"
         .          .      8:   "time"
         .          .      9:)
         .          .     10:
         .          .     11:// 处理某些业务，真实的代码中这个死循环很隐蔽
         .          .     12:func retrieveSomeThing() {
     4.21s      4.44s     13:   for {
         .          .     14:   }
         .          .     15:}
         .          .     16:
         .          .     17:// 处理其他的一些业务，无意义，用于后续做例子
         .          .     18:func doSomeThing() {