作为一个golang coder，使用golang编写代码是基本的要求。
能够写出代码，并能够熟悉程序执行过程中各方面的性能指标，则是更上一层楼。

如果在程序出现性能问题的时候，可以快速定位和解决问题，那么写起代码来，会更加自信。

本文介绍的pprof，是golang 自带性能剖析工具，可以帮助定位程序中可能存在的问题。

1.引入pprof

例子代码如下：

package main

import (
        "log"
        _ "net/http/pprof"
        "net/http"
        "time"
)

func main() {

        go func() {
                log.Println(http.ListenAndServe("localhost:6060",nil))
        }()

        go worker()

        select{}
}

// simple worker
func worker(){

        strSlice := []string{}
        for {
                str := "hello world "
                strSlice = append(strSlice,str)

                time.Sleep(time.Second)
        }

}
net/http/pprof

启动应用程序

go build simple.go

./simpe

1.1 查看内存使用情况

使用heap profile查看内存使用情况。

go tool pprof http://localhost:6060/debug/pprof/heap
Fetching profile over HTTP from http://localhost:6060/debug/pprof/heap
Saved profile in /Users/lanyang/pprof/pprof.alloc_objects.alloc_space.inuse_objects.inuse_space.001.pb.gz
Type: inuse_space
Time: Sep 21,2019 at 1:56pm (CST)
Entering interactive mode (type "help" for commands,"o" for options)
(pprof)
(pprof) top10
Showing nodes accounting for 514kB,100% of 514kB total
      flat  flat%   sum%        cum   cum%
     514kB   100%   100%      514kB   100%  unicode.init
         0     0%   100%      514kB   100%  runtime.doInit
         0     0%   100%      514kB   100%  runtime.main
(pprof)
inuse_spacealloc_objects

列出top10的内存占用。

1.2 查看cpu使用情况

使用cpu profile查看cpu使用情况。

例如查看过去30s的cpu profile

go tool pprof http://localhost:6060/debug/pprof/profile?seconds=30
Fetching profile over HTTP from http://localhost:6060/debug/pprof/profile?seconds=30
Saved profile in /Users/lanyang/pprof/pprof.samples.cpu.001.pb.gz
Type: cpu
Time: Sep 21,2019 at 2:19pm (CST)
Duration: 30s,Total samples = 0
No samples were found with the default sample value type.
Try "sample_index" command to analyze different sample values.
Entering interactive mode (type "help" for commands,"o" for options)
(pprof)

1.3 浏览器打开pprof页面

http://localhost:6060/debug/pprof/

在这里插入图片描述

Profile Descriptions:

allocs:
A sampling of all past memory allocations

block:
Stack traces that led to blocking on synchronization primitives

cmdline:
The command line invocation of the current program

goroutine:
Stack traces of all current goroutines

heap:
A sampling of memory allocations of live objects. You can specify the gc GET parameter to run GC before taking the heap sample.

mutex:
Stack traces of holders of contended mutexes

profile:
cpu profile. You can specify the duration in the seconds GET parameter. After you get the profile file,use the go tool pprof command to investigate the profile.

threadcreate:
Stack traces that led to the creation of new OS threads

trace:
A trace of execution of the current program. You can specify the duration in the seconds GET parameter. After you get the trace file,use the go tool trace command to investigate the trace.

可以通过链接跳转到对应界面。

1.4 保存profile文件

从pprof使用上看，是首先保存profile文件，再进行分析的。

在一些场景，例如在线上环境，最好保存profile，拿到线下做分析。

将profile文件保存下来：

wget  http://localhost:6060/debug/pprof/heap
--2019-09-21 15:20:17--  http://localhost:6060/debug/pprof/heap
正在解析主机 localhost (localhost)... ::1,127.0.0.1
正在连接 localhost (localhost)|::1|:6060... 失败：Connection refused。
正在连接 localhost (localhost)|127.0.0.1|:6060... 已连接。
已发出 HTTP 请求，正在等待回应... 200 OK
长度：1162 (1.1K) [application/octet-stream]
正在保存至: “heap”

heap                                         100%[============================================================================================>]   1.13K  --.-KB/s  用时 0s

2019-09-21 15:20:17 (111 MB/s) - 已保存 “heap” [1162/1162])

ll
-rw-r--r--  1 lanyang  staff   1.1K  9 21 15:20 heap
./simple./heap
go tool pprof ./simple ./heap
Type: inuse_space
Time: Sep 21,2019 at 3:20pm (CST)
No samples were found with the default sample value type.
Try "sample_index" command to analyze different sample values.
Entering interactive mode (type "help" for commands,"o" for options)
(pprof)
2.火焰图

go 1.11已经可以查看火焰图了，直接使用如下命令：

$ go tool pprof -http=":8081" [binary] [profile]
binaryprofile

例如，使用以保存的profile文件：

$ go tool pprof -http=":8081" ./simple ./heap

或者，通过http 的profile:

go tool pprof -http=":8081" ./simple  http://localhost:6060/debug/pprof/heap
Fetching profile over HTTP from http://localhost:6060/debug/pprof/heap
Saved profile in /Users/zhangyunyang/pprof/pprof.simple.alloc_objects.alloc_space.inuse_objects.inuse_space.001.pb.gz
Serving web UI on http://localhost:8081

火焰图如图所示，示例代码比较简单，所以火焰图不是很明显。

在这里插入图片描述

如果不能使用go1.11，则可以使用最新的pprof工具：

# Get the pprof tool directly
$ go get -u github.com/google/pprof

$ pprof -http=":8081" [binary] [profile]
参考