在Golang的FAQ中，解释了为什么goroutine是匿名的，没有暴露出ID等状态信息，主要是因为如果一个特定的goroutine有了名字(ID)，开发者就会忽略使用多个goroutine来处理信息的可能，从而限制库的使用。
但是，有时候开发者也需要获取goroutine来进行特定的操作。本文介绍如何从堆栈信息中获取goroutine信息。
panic获取堆栈信息
当go程序panic的时候，会打印出goroutine的ID, 状态，函数，调用栈的信息。
func TestPanic(t *testing.T){
panic("get stack info")
}
堆栈信息
goroutine 18 [running]:
testing.tRunner.func1.1(0x111b7e0, 0x116c710)
/usr/local/go/src/testing/testing.go:1076 +0x30d
testing.tRunner.func1(0xc000082600)
/usr/local/go/src/testing/testing.go:1079 +0x41a
panic(0x111b7e0, 0x116c710)
/usr/local/go/src/runtime/panic.go:969 +0x175
awesomeProject/goid.TestPanic(0xc000082600)
/Users/liangyaopei/go/src/awesomeProject/goid/goid_test.go:6 +0x39
testing.tRunner(0xc000082600, 0x114d490)
/usr/local/go/src/testing/testing.go:1127 +0xef
created by testing.(*T).Run
/usr/local/go/src/testing/testing.go:1178 +0x38
可以看到，goroutine的ID是18，当前状态是running，调用的函数是testing.tRunner.func1。
goroutine的状态
在/runtime/traceback.go中，可以看到goroutine一共有以下的状态:
var gStatusStrings = [...]string{
_Gidle: "idle",
_Grunnable: "runnable",
_Grunning: "running",
_Gsyscall: "syscall",
_Gwaiting: "waiting",
_Gdead: "dead",
_Gcopystack: "copystack",
_Gpreempted: "preempted",
}
runtime.Stack获取堆栈信息
package runtime
// Stack formats a stack trace of the calling goroutine into buf
// and returns the number of bytes written to buf.
// If all is true, Stack formats stack traces of all other goroutines
// into buf after the trace for the current goroutine.
func Stack(buf []byte, all bool) int {
if all {
stopTheWorld("stack trace")
}
...
if all {
startTheWorld()
}
}
runtime.Stack(),接受2个参数，一个是保存信息的字符串数字，另一个all表示是否要打印全部的堆栈信息。如果all为true，就会先调用stopTheWorld
看下面的测试:
func TestGetStackInfo(t *testing.T) {
var (
size = 64 * 1024
all = false
)
buf := make([]byte, size)
runtime.Stack(buf, all)
t.Logf("%s", string(buf))
}
输入结果:
goid_test.go:19: goroutine 18 [running]:
awesomeProject/goid.TestGetStackInfo(0xc000082600)
/Users/liangyaopei/go/src/awesomeProject/goid/goid_test.go:18 +0x6f
testing.tRunner(0xc000082600, 0x114d5c0)
/usr/local/go/src/testing/testing.go:1127 +0xef
created by testing.(*T).Run
/usr/local/go/src/testing/testing.go:1178 +0x386
可以看到，输入的结果都是有格式的。
解析堆栈信息，获取goroutine ID
在stack.go中，通过调用runtime.Stack函数，获取当前的堆栈信息，然后解析。
// GetInfo returns goroutine stack information.
// Stack information includes id, state, firstFunction,fullStack and timestamp.
func GetInfo(all bool) []Stack {
var stacks []Stack
var curStack *Stack
stackReader := bufio.NewReader(bytes.NewReader(getStackBuffer(all)))
for {
line, err := stackReader.ReadString('\n')
if err == io.EOF {
break
}
if err != nil {
panic("bufio.NewReader failed on a fixed string")
}
// If we see the goroutine header, start a new stack.
isFirstLine := false
if strings.HasPrefix(line, "goroutine ") {
// flush any previous stack
if curStack != nil {
stacks = append(stacks, *curStack)
}
id, goState := parseGoStackHeader(line)
curStack = &Stack{
id: id,
state: goState,
fullStack: &bytes.Buffer{},
timeStamp: time.Now().UnixNano(),
}
isFirstLine = true
}
curStack.fullStack.WriteString(line)
if !isFirstLine && curStack.firstFunction == "" {
curStack.firstFunction = parseFirstFunc(line)
}
}
if curStack != nil {
stacks = append(stacks, *curStack)
}
return stacks
}
通过解析以下的信息格式，获取对于的id。
xxx.go:19: goroutine xx [xx]:
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