https://github.com/google/gops
一个用于列出和诊断分析系统中正在运行的 Go 程序的命令行工具,Google 自己出品的

java 的开发者没有不知道或者没用过 jps 这个命令的，这个命令是用来在主机上查看有哪些 Java 程序在运行的。

安装
go get -u github.com/google/gops
命令帮助
执行 gops help 查看帮助文档：
gops is a tool to list and diagnose Go processes.

gops <cmd> <pid|addr> ...

gops <pid> # displays process info

Commands:
stack Prints the stack trace.
gc Runs the garbage collector and blocks until successful.
setgc Sets the garbage collection target percentage.
memstats Prints the allocation and garbage collection stats.
version Prints the Go version used to build the program.
stats Prints the vital runtime stats.
help Prints this help text.

Profiling commands:
trace Runs the runtime tracer for 5 secs and launches “go tool trace”.
pprof-heap Reads the heap profile and launches “go tool pprof”.
pprof-cpu Reads the CPU profile and launches “go tool pprof”.

All commands require the agent running on the Go process.
Symbol “*” indicates the process runs the agent.
使用详解
为了能更好的分析程序，需要在我们的项目中加一行 agent 诊断分析代码，用于统计分析程序问题。
package main

import (
“log”
“time”

"github.com/google/gops/agent" )

func main() {
if err := agent.Listen(agent.Options{}); err != nil {
log.Fatal(err)
}

time.Sleep(time.Hour) } 其中，agent. 支持更多的参数： // Code reference: github.com/google/gops/agent/agent.go:42

// Options allows configuring the started agent.
type Options struct {
// Addr is the host:port the agent will be listening at.
// Optional.
Addr string

// ConfigDir is the directory to store the configuration file,

// PID of the gops process, filename, port as well as content.

// Optional.

ConfigDir string



// ShutdownCleanup automatically cleans up resources if the

// running process receives an interrupt. Otherwise, users

// can call Close before shutting down.

// Optional.

ShutdownCleanup bool } Addr

可选。为远程分析服务提供监听地址，例如: :9119。配置了该项，那我们可以在本机查看分析远程服务器上的 Go 程序，非常有帮助。

ConfigDir

可选。用于存放统计数据和配置的目录，默认为当前用户的主目录。也可以通过环境变量GOPS_CONFIG_DIR设置。具体参考代码：
const gopsConfigDirEnvKey = “GOPS_CONFIG_DIR”

func ConfigDir() (string, error) {
if configDir := os.Getenv(gopsConfigDirEnvKey); configDir != “” {
return configDir, nil
}

if runtime.GOOS == "windows" {

	return filepath.Join(os.Getenv("APPDATA"), "gops"), nil

}

homeDir := guessUnixHomeDir()

if homeDir == "" {

	return "", errors.New("unable to get current user home directory: os/user lookup failed; $HOME is empty")

}

return filepath.Join(homeDir, ".config", "gops"), nil }

func guessUnixHomeDir() string {
usr, err := user.Current()
if err == nil {
return usr.HomeDir
}
return os.Getenv(“HOME”)
}
ShutdownCleanup

可选。设置为 true，则在程序关闭时会自动清理数据。

NOTE: 如果不加 agent 代码，那我们无法更深入的诊断程序，也就是说无法执行gops memstats、gops pprof-heap等所有类似于 gops <pid|addr> ... 的子命令。

gops
直接执行 gops 命令会列出本机所有正在运行的 Go 程序。
$ gops

99288 47636 go go1.10.1 /usr/local/Cellar/go/1.10.1/libexec/bin/go
99300 99288 main* go1.10.1 /private/var/folders/cs/mfl4k8t54_g1thdzvzkdxbbr0000gn/T/go-build375822490/b001/exe/main
99570 2899 gops go1.10.1 /Users/shocker/gowork/bin/gops
99154 14655 hugo go1.11.1 /usr/local/Cellar/hugo/0.49.1/bin/hugo
该命令会显示以下内容：

PID
PPID
程序名称
构建该程序的 Go 版本号
程序所在绝对路径
注意，列表中有个程序名称后面带了个 *，表示该程序加入了 gops 的诊断分析代码。

gops
用法: gops 查看本机指定 PID Go 程序的基本信息
$ gops 99300

parent PID: 99288
threads: 11
memory usage: 0.157%
cpu usage: 0.013%
username: shocker
cmd+args: /var/folders/cs/mfl4k8t54_g1thdzvzkdxbbr0000gn/T/go-build375822490/b001/exe/main
local/remote: *:9105 <-> :0 (LISTEN)
local/remote: 127.0.0.1:57109 <-> 127.0.0.1:3306 (ESTABLISHED)
local/remote: *:8000 <-> :0 (LISTEN)
local/remote 表示本机建立的监听(LISTEN)，或者与远程服务器建立的链接(ESTABLISHED)

local/remote: *:9105 <-> :0 (LISTEN) 中的 *:9105 是 gops/agent 提供的服务，

gops tree
用法: gops tree 以目录树的形式展示所有 Go 程序。
$ gops tree

…
├── 2899
│ └── 99996 (gops) {go1.10.1}
├── 47636
│ └── 99288 (go) {go1.10.1}
│ └── [*] 99300 (main) {go1.10.1}
└── 14655
└── 99154 (hugo) {go1.11.1}
gops stack (|)
用法: gops stack (|) 用于显示程序所有堆栈信息，包括每个 goroutine 的堆栈信息、运行状态、运行时长等。
$ gops stack 99300

goroutine 7 [running]:
runtime/pprof.writeGoroutineStacks(0x1882720, 0xc4202b8010, 0xd0, 0xd0)
/usr/local/Cellar/go/1.10.1/libexec/src/runtime/pprof/pprof.go:650 +0xa7
runtime/pprof.writeGoroutine(0x1882720, 0xc4202b8010, 0x2, 0x30, 0xc420068248)
/usr/local/Cellar/go/1.10.1/libexec/src/runtime/pprof/pprof.go:639 +0x44

goroutine 1 [IO wait, 9 minutes]:
internal/poll.runtime_pollWait(0x1db4da0, 0x72, 0x0)
/usr/local/Cellar/go/1.10.1/libexec/src/runtime/netpoll.go:173 +0x57
internal/poll.(*pollDesc).wait(0xc4201e7318, 0x72, 0x0, 0x0, 0x0)

more …

gops memstats (|)
用法: gops memstats (|) 查看程序的内存统计信息
$ gops memstats 127.0.0.1:9105

alloc: 1.36MB (1428632 bytes)
total-alloc: 10.21MB (10709376 bytes)
sys: 9.07MB (9509112 bytes)
lookups: 91
mallocs: 102818
frees: 91896
heap-alloc: 1.36MB (1428632 bytes)
heap-sys: 5.22MB (5472256 bytes)
heap-idle: 2.34MB (2457600 bytes)
heap-in-use: 2.88MB (3014656 bytes)
heap-released: 0 bytes
heap-objects: 10922
stack-in-use: 704.00KB (720896 bytes)
stack-sys: 704.00KB (720896 bytes)
stack-mspan-inuse: 47.95KB (49096 bytes)
stack-mspan-sys: 80.00KB (81920 bytes)
stack-mcache-inuse: 6.78KB (6944 bytes)
stack-mcache-sys: 16.00KB (16384 bytes)
other-sys: 1.21MB (1266624 bytes)
gc-sys: 492.00KB (503808 bytes)
next-gc: when heap-alloc >= 4.00MB (4194304 bytes)
last-gc: 2018-10-18 13:37:04.37511973 +0800 CST
gc-pause-total: 9.209158ms
gc-pause: 52831
num-gc: 60
enable-gc: true
debug-gc: false
gops gc (|)
用法: gops gc (|) 查看指定程序的垃圾回收(GC)信息

gops setgc (|)
用法: gops setgc (|) 设定指定程序的 GC 目标百分比

gops version (|)
用法: gops version (|) 查看指定程序构建时的 Go 版本号

gops stats (|)
用法: gops stats (|) 查看指定程序的 goroutine 数量、GOMAXPROCS 值等信息
$ gops stats 127.0.0.1:9105

goroutines: 11
OS threads: 14
GOMAXPROCS: 4
num CPU: 4
gops pprof-cpu (|)
用法: gops pprof-cpu (|) 调用并展示 go tool pprof 工具中关于 CPU 的性能分析数据，操作与 pprof 一致。
$ gops pprof-cpu 99300

Profiling CPU now, will take 30 secs…
Profile dump saved to: /var/folders/cs/mfl4k8t54_g1thdzvzkdxbbr0000gn/T/profile881383738
Profiling dump saved to: /var/folders/cs/mfl4k8t54_g1thdzvzkdxbbr0000gn/T/profile881383738
Binary file saved to: /var/folders/cs/mfl4k8t54_g1thdzvzkdxbbr0000gn/T/binary970030929
File: binary970030929
Type: cpu
Time: Oct 18, 2018 at 2:43pm (CST)
Duration: 30s, Total samples = 0
Entering interactive mode (type “help” for commands, “o” for options)
(pprof)
gops pprof-heap (|)
用法: gops pprof-heap (|) 调用并展示 go tool pprof 工具中关于 heap 的性能分析数据，操作与 pprof 一致。
$ gops pprof-heap 99300

Profile dump saved to: /var/folders/cs/mfl4k8t54_g1thdzvzkdxbbr0000gn/T/profile045800436
Profiling dump saved to: /var/folders/cs/mfl4k8t54_g1thdzvzkdxbbr0000gn/T/profile045800436
Binary file saved to: /var/folders/cs/mfl4k8t54_g1thdzvzkdxbbr0000gn/T/binary315133123
File: binary315133123
Type: inuse_space
Time: Oct 18, 2018 at 2:46pm (CST)
Entering interactive mode (type “help” for commands, “o” for options)
(pprof)
gops trace (|)
用法: gops trace (|) 追踪程序运行5秒，生成可视化报告，并可在浏览器中查看: http://127.0.0.1:61380
$ gops trace 99300

Tracing now, will take 5 secs…
Trace dump saved to: /var/folders/cs/mfl4k8t54_g1thdzvzkdxbbr0000gn/T/trace136310737
2018/10/18 14:49:06 Parsing trace…
2018/10/18 14:49:06 Serializing trace…
2018/10/18 14:49:06 Splitting trace…
2018/10/18 14:49:06 Opening browser. Trace viewer is listening on http://127.0.0.1:61380

诊断
可能有人注意到了上面我的 memory-test 程序后面有个 * 号。这是因为程序中我加入了 gops 用的诊断支持代码：

if err := agent.Listen(agent.Options{ShutdownCleanup:true}); err != nil {
log.Fatalln(err)
}
对于这样的程序，我们才能进行 gops pprof-cpu 和 gops pprof-heap 等命令。（stack, gc, setgc, memstats, version, stats, trace 等命令运行同样需要加入上面的代码）。

https://github.com/XanthusL/blog-gen/blob/master/content/post/gops.md