Go语言如何实现Benchmark函数_Golang

背景

go 必须要 test 才能跑benchmark，导致一些情况下想要在main函数中测试benchmark会麻烦一些，因此我实现了一个简单的且没有开销的benchmark函数，方便使用！其次也方便大家学习下如何实现一个零开销的benchmark框架!

benchamrk 实现

对于有timeout的benchamrk，每次都去比较 time.before(timeout) 开销非常的大，而且 benchmark 的对外函数也不能是一个空函数一定要带 count ，因为函数调用大概会劣化 ns 级别！

所以一般的benchmark算法都是梯度benchmark，即 1，10，100，1000，10000，100000，1000000 ... 的数量级去benchmark，好处就是避免了大量的time.since 计算开销，因为time.since单次在 30ns 左右（linux环境下），开销非常大的！

package pprof

import (
    "fmt"
    "sync"
    "sync/atomic"
    "time"
)

func parallelbenchmark(name string, thread int, duration time.duration, execute func(count int)) {
    wg := sync.waitgroup{}
    wg.add(thread)
    totalcount := uint64(0)
    totalspend := uint64(0)
    for i := 0; i < thread; i++ {
       go func() {
          defer wg.done()
          spend, count := benchmark(duration, execute)
          atomic.adduint64(&totalspend, uint64(spend))
          atomic.adduint64(&totalcount, uint64(count))
       }()
    }
    wg.wait()
    fmt.printf("name=%s thread=%d duration=%s total=%d avg=%s\n", name, thread, duration, totalcount, avg(time.duration(totalspend), int(totalcount)))
}

func avg(spend time.duration, count int) string {
    avg := float64(spend) / float64(count)
    if avg > 100 {
       return time.duration(avg).string()
    }
    return fmt.sprintf("%.4fns", avg)
}

func benchmark(duration time.duration, bench func(count int)) (time.duration, int) {
    const maxtotalcount = 1000000000 // 10e
    count := 1
    totalspend := time.duration(0)
    totalcount := 0
    for {
       start := time.now()
       bench(count)
       spend := time.since(start)

       totalspend = totalspend + spend
       totalcount = totalcount + count

       if totalcount >= maxtotalcount {
          break
       }
       subspend := duration - totalspend
       if subspend <= 0 {
          break
       }
       count = totalcount*10 - totalcount
       if subcount := int(float64(subspend) / (float64(totalspend) / float64(totalcount))); count > subcount {
          count = subcount
       }
    }
    return totalspend, totalcount
}

profile 实现

package pprof

import (
    "net/http"
    _ "net/http/pprof"
    "os"
    "runtime"
    "runtime/pprof"
)

// initpprof
// go initpprof()
func initpprof() {
    err := http.listenandserve(":12345", http.defaultservemux)
    if err != nil {
       panic(err)
    }
}

func startcpuprofile(filename string) (stop func()) {
    f, err := os.create(filename)
    if err != nil {
       panic(err)
    }
    if err := pprof.startcpuprofile(f); err != nil {
       if err := f.close(); err != nil {
          panic(err)
       }
       panic(err)
    }
    return func() {
       pprof.stopcpuprofile()
       if err := f.close(); err != nil {
          panic(err)
       }
    }
}

func startmemprofile(filename string) (stop func()) {
    f, err := os.create(filename)
    if err != nil {
       panic(err)
    }
    return func() {
       defer func() {
          if err := f.close(); err != nil {
             panic(err)
          }
       }()
       runtime.gc() // get up-to-date statistics
       if err := pprof.writeheapprofile(f); err != nil {
          panic(err)
       }
    }
}

例子

package main

import (
	"github.com/anthony-dong/golang/pkg/pprof"
	"sync"
	"time"
)

func main() {
	// 记录 cup pprof
	//stop := pprof.startcpuprofile("cpu.out")
	//defer stop()

	// 并发测试 sync map的性能
	mm := sync.map{}
	pprof.parallelbenchmark("test1", 64, time.second, func(count int) {
		for i := 0; i < count; i++ {
			mm.store(i%10000, 1)
		}
	})
	// name=test1 thread=32 duration=1s total=6708009 avg=4.772µs
	// name=test1 thread=64 duration=1s total=6883456 avg=9.3µs
}

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