基本的cpu和内存分析

在主程序中添加以下代码。

var cpuprofile = flag.String("cpuprofile", "", "write cpu profile `file`")
var memprofile = flag.String("memprofile", "", "write memory 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)
        }
        if err := pprof.StartCPUProfile(f); err != nil {
            log.Fatal("could not start CPU profile: ", err)
        }
        defer pprof.StopCPUProfile()
    }
    ...
    if *memprofile != "" {
        f, err := os.Create(*memprofile)
        if err != nil {
            log.Fatal("could not create memory profile: ", err)
        }
        runtime.GC() // get up-to-date statistics
        if err := pprof.WriteHeapProfile(f); err != nil {
            log.Fatal("could not write memory profile: ", err)
        }
        f.Close()
    }
}

之后构建go程序(如果添加到main go build main.go中)。 使用在代码main.exe -cpuprofile cpu.prof -memprof mem.prof中定义的标志运行主程序。 如果对测试用例进行了概要分析，请使用相同的标志运行测试，然后go test -cpuprofile cpu.prof -memprofile mem.prof

使用基准创建配置文件

对于非主要包和主要包，不要在代码内添加标志，而在测试包中编写基准，例如:

func BenchmarkHello(b *testing.B) {
    for i := 0; i < b.N; i++ {
        fmt.Sprintf("hello")
    }
}

然后使用配置文件标志运行测试

go test -cpuprofile cpu.prof -bench=.

And the benchmarks will be run and create a prof file with filename cpu.prof (in the above example).

基本内存配置

var memprofile = flag.String("memprofile", "", "write memory profile to `file`")

func main() {
    flag.Parse()
    if *memprofile != "" {
        f, err := os.Create(*memprofile)
        if err != nil {
            log.Fatal("could not create memory profile: ", err)
        }
        runtime.GC() // get up-to-date statistics
        if err := pprof.WriteHeapProfile(f); err != nil {
            log.Fatal("could not write memory profile: ", err)
        }
        f.Close()
    }
}

$ go build main.go
$ main.exe -memprofile mem.prof
$ go tool pprof main.exe mem.prof

设置CPU/块配置文件速率

// Sets the CPU profiling rate to hz samples per second
// If hz <= 0, SetCPUProfileRate turns off profiling
runtime.SetCPUProfileRate(hz)

// Controls the fraction of goroutine blocking events that are reported in the blocking profile
// Rate = 1 includes every blocking event in the profile
// Rate <= 0 turns off profiling
runtime.SetBlockProfileRate(rate)

访问配置文件

Once a prof file has been generated, one can access the prof file using go tools:

go tool pprof cpu.prof This will enter into a command line interface for exploring the profile

常用命令包括:

• (pprof) top Lists top processes in memory
• (pprof) peek Lists all processes, use regex to narrow search.
• (pprof) web Opens an graph (in svg format) of the process.

top命令的示例:

69.29s of 100.84s total (68.71%)
Dropped 176 nodes (cum <= 0.50s)
Showing top 10 nodes out of 73 (cum >= 12.03s)
        flat  flat%   sum%        cum   cum%
    12.44s 12.34% 12.34%     27.87s 27.64%  runtime.mapaccess1
    10.94s 10.85% 23.19%     10.94s 10.85%  runtime.duffcopy
        9.45s  9.37% 32.56%     54.61s 54.16%  github.com/tester/test.(*Circle).Draw
        8.88s  8.81% 41.36%      8.88s  8.81%  runtime.aeshashbody
        7.90s  7.83% 49.20%     11.04s 10.95%  runtime.mapaccess1_fast64
        5.86s  5.81% 55.01%      9.59s  9.51%  github.com/tester/test.(*Circle).isCircle
        5.03s  4.99% 60.00%      8.89s  8.82%  github.com/tester/test.(*Circle).openCircle
        3.14s  3.11% 63.11%      3.14s  3.11%  runtime.aeshash64
        3.08s  3.05% 66.16%      7.85s  7.78%  runtime.mallocgc
        2.57s  2.55% 68.71%     12.03s 11.93%  runtime.memhash