Go性能调优

// runtime_pprof/main.go
package main

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

// 一段有问题的代码
func logicCode() {
    var c chan int
    for {
        select {
        case v := <-c:
            fmt.Printf("recv from chan, value:%v\n", v)
        default:

        }
    }
}

func main() {
    var isCPUPprof bool
    var isMemPprof bool

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

    if isCPUPprof {
        file, err := os.Create("./cpu.pprof")
        if err != nil {
            fmt.Printf("create cpu pprof failed, err:%v\n", err)
            return
        }
        pprof.StartCPUProfile(file)
        defer pprof.StopCPUProfile()
    }
    for i := 0; i < 6; i++ {
        go logicCode()
    }
    time.Sleep(20 * time.Second)
    if isMemPprof {
        file, err := os.Create("./mem.pprof")
        if err != nil {
            fmt.Printf("create mem pprof failed, err:%v\n", err)
            return
        }
        pprof.WriteHeapProfile(file)
        file.Close()
    }
}

上课笔记

• go run main.go -cpu=true 先让cpu调试，并在当前目录下生成cpu.pprof
• go tool pprof cpu.pprof 然后利用工具 进入交互式状态

Type: cpu
Time: Mar 2, 2021 at 7:41pm (CST)
Duration: 20.15s, Total samples = 56.16s (278.69%)
Entering interactive mode (type "help" for commands, "o" for options)
(pprof) 

• 输入top4返回

top4
Showing nodes accounting for 56.05s, 99.80% of 56.16s total
Dropped 19 nodes (cum <= 0.28s)
      flat  flat%   sum%        cum   cum%
    23.30s 41.49% 41.49%     43.52s 77.49%  runtime.selectnbrecv
    17.94s 31.94% 73.43%     18.58s 33.08%  runtime.chanrecv
    12.53s 22.31% 95.74%     56.10s 99.89%  main.logicCode
     2.28s  4.06% 99.80%      2.29s  4.08%  runtime.newstack
(pprof)

• 输入list logicCode 则返回

list logicCode
Total: 56.16s
ROUTINE ======================== main.logicCode in /Users/zhao/GolangProjects/Test/src/day_03_02/Runtime_pprof/main.go
    12.53s     56.10s (flat, cum) 99.89% of Total
         .          .      8:   "runtime/pprof"
         .          .      9:   "time"
         .          .     10:)
         .          .     11:
         .          .     12:// 一段有问题的代码
         .       10ms     13:func logicCode() {
         .          .     14:   var c chan int
         .          .     15:   for {
         .          .     16:           select {
    12.53s     56.09s     17:           case v := <-c:
         .          .     18:                   fmt.Printf("recv from chan, value:%v\n", v)
         .          .     19:           default:
         .          .     20:
         .          .     21:           }
         .          .     22:   }
(pprof) 

```