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)
}
}
}
