Golang性能调优入门

如何利用golang自带的profile工具进行应用程序的性能调优，前一段时间我做的日志分析系统在线上遇到了一个问题，就是分任务的系统down机了，日志处理延迟了10几个小时，这个时候任务分发系统重启之后开始分发任务，但是一下子就承受了十几个并发任务，导致内存消耗过快，直接吃掉了16G的内存，这可急坏了我啊。所以赶紧开始做性能优化。

性能优化我主要从以下几个方面进行了测试和调优：

• CPU Profiling
• Mem Profiling
• GC & HEAP

我采用了如下的profile工具代码：

package main

import (

"fmt"

"log"

"os"

"runtime"

"runtime/debug"

"runtime/pprof"

"strconv"

"sync/atomic"

"syscall"

"time"

)

var heapProfileCounter int32

var startTime = time.Now()

var pid int

func init() {

pid = os.Getpid()

}

func StartCPUProfile() {

f, err := os.Create("cpu-" + strconv.Itoa(pid) + ".pprof")

if err != nil {

log.Fatal(err)

}

pprof.StartCPUProfile(f)

}

func StopCPUProfile() {

pprof.StopCPUProfile()

}

func StartBlockProfile(rate int) {

runtime.SetBlockProfileRate(rate)

}

func StopBlockProfile() {

filename := "block-" + strconv.Itoa(pid) + ".pprof"

f, err := os.Create(filename)

if err != nil {

log.Fatal(err)

}

if err = pprof.Lookup("block").WriteTo(f, 0); err != nil {

log.Fatalf(" can't write %s: %s", filename, err)

}

f.Close()

}

func SetMemProfileRate(rate int) {

runtime.MemProfileRate = rate

}

func GC() {

runtime.GC()

}

func DumpHeap() {

filename := "heap-" + strconv.Itoa(pid) + "-" + strconv.Itoa(int(atomic.AddInt32(&heapProfileCounter, 1))) + ".pprof"

f, err := os.Create(filename)

if err != nil {

fmt.Fprintf(os.Stderr, "testing: %s", err)

return

}

if err = pprof.WriteHeapProfile(f); err != nil {

fmt.Fprintf(os.Stderr, "testing: can't write %s: %s", filename, err)

}

f.Close()

}

func showSystemStat(interval time.Duration, count int) {

usage1 := &syscall.Rusage{}

var lastUtime int64

var lastStime int64

counter := 0

for {

//http://man7.org/linux/man-pages/man3/vtimes.3.html

syscall.Getrusage(syscall.RUSAGE_SELF, usage1)

utime := usage1.Utime.Sec*1000000000 + usage1.Utime.Usec

stime := usage1.Stime.Sec*1000000000 + usage1.Stime.Usec

userCPUUtil := float64(utime-lastUtime) * 100 / float64(interval)

sysCPUUtil := float64(stime-lastStime) * 100 / float64(interval)

memUtil := usage1.Maxrss * 1024

lastUtime = utime

lastStime = stime

if counter > 0 {

fmt.Printf("cpu: %3.2f%% us  %3.2f%% sy, mem:%s \n", userCPUUtil, sysCPUUtil, toH(uint64(memUtil)))

}

counter += 1

if count >= 1 && count < counter {

return

}

time.Sleep(interval)

}

}

func ShowSystemStat(seconds int) {

go func() {

interval := time.Duration(seconds) * time.Second

showSystemStat(interval, 0)

}()

}

func PrintSystemStats() {

interval := time.Duration(1) * time.Second

showSystemStat(interval, 1)

}

func ShowGCStat() {

go func() {

var numGC int64

interval := time.Duration(100) * time.Millisecond

gcstats := &debug.GCStats{PauseQuantiles: make([]time.Duration, 100)}

memStats := &runtime.MemStats{}

for {

debug.ReadGCStats(gcstats)

if gcstats.NumGC > numGC {

runtime.ReadMemStats(memStats)

printGC(memStats, gcstats)

numGC = gcstats.NumGC

}

time.Sleep(interval)

}

}()

}

func PrintGCSummary() {

memStats := &runtime.MemStats{}

runtime.ReadMemStats(memStats)

gcstats := &debug.GCStats{PauseQuantiles: make([]time.Duration, 100)}

debug.ReadGCStats(gcstats)

printGC(memStats, gcstats)

}

func printGC(memStats *runtime.MemStats, gcstats *debug.GCStats) {

if gcstats.NumGC > 0 {

lastPause := gcstats.Pause[0]

elapsed := time.Now().Sub(startTime)

overhead := float64(gcstats.PauseTotal) / float64(elapsed) * 100

allocatedRate := float64(memStats.TotalAlloc) / elapsed.Seconds()

fmt.Printf("NumGC:%d Pause:%s Pause(Avg):%s Overhead:%3.2f%% Alloc:%s Sys:%s Alloc(Rate):%s/s Histogram:%s %s %s \n",

gcstats.NumGC,

toS(lastPause),

toS(avg(gcstats.Pause)),

overhead,

toH(memStats.Alloc),

toH(memStats.Sys),

toH(uint64(allocatedRate)),

toS(gcstats.PauseQuantiles[94]),

toS(gcstats.PauseQuantiles[98]),

toS(gcstats.PauseQuantiles[99]))

} else {

// while GC has disabled

elapsed := time.Now().Sub(startTime)

allocatedRate := float64(memStats.TotalAlloc) / elapsed.Seconds()

fmt.Printf("Alloc:%s Sys:%s Alloc(Rate):%s/s\n",

toH(memStats.Alloc),

toH(memStats.Sys),

toH(uint64(allocatedRate)))

}

}

func avg(items []time.Duration) time.Duration {

var sum time.Duration

for _, item := range items {

sum += item

}

return time.Duration(int64(sum) / int64(len(items)))

}

// human readable format

func toH(bytes uint64) string {

switch {

case bytes < 1024:

return fmt.Sprintf("�", bytes)

case bytes < 1024*1024:

return fmt.Sprintf("%.2fK", float64(bytes)/1024)

case bytes < 1024*1024*1024:

return fmt.Sprintf("%.2fM", float64(bytes)/1024/1024)

default:

return fmt.Sprintf("%.2fG", float64(bytes)/1024/1024/1024)

}

}

// short string format

func toS(d time.Duration) string {

u := uint64(d)

if u < uint64(time.Second) {

switch {

case u == 0:

return "0"

case u < uint64(time.Microsecond):

return fmt.Sprintf("%.2fns", float64(u))

case u < uint64(time.Millisecond):

return fmt.Sprintf("%.2fus", float64(u)/1000)

default:

return fmt.Sprintf("%.2fms", float64(u)/1000/1000)

}

} else {

switch {

case u < uint64(time.Minute):

return fmt.Sprintf("%.2fs", float64(u)/1000/1000/1000)

case u < uint64(time.Hour):

return fmt.Sprintf("%.2fm", float64(u)/1000/1000/1000/60)

default:

return fmt.Sprintf("%.2fh", float64(u)/1000/1000/1000/60/60)

}

}

}