使用 dlv 调试 core dump

在编写 Go 代码时很容易忘记判断 nil 从而发生 panic，当 panic 没有使用recover()捕获时，程序将没有任何征兆就退出了，这对追溯原因造成很大困难，而 core dump 可以解决这个问题。

测试

启用 core dump

shell
ulimit -c unlimited

准备一个会 panic 的 Go 程序

go
package main

import (
	"fmt"
	"math/rand"
	"runtime/debug"
	"time"
)

func main() {
	// 打印各种堆栈信息
	debug.SetTraceback("crash")

	go func() {
		arr := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
		for {
			index := rand.Intn(11)
			fmt.Println(arr[index])
		}
	}()

	time.Sleep(time.Second * 5)
}

编译与运行

shell
go build main.go
./main
3
2
3
3
6
10
6
5
1
2
9
3
9
10
panic: runtime error: index out of range [10] with length 10
...(省略各种栈信息)

使用 dlv 调试

shell
# dlv 调试 core 的命令格式
dlv core <executable> <core> [flags]

shell
# 生成的 core 文件就在当前目录，文件名也是 core
dlv core main core
Type 'help' for list of commands.
(dlv) bt # 看这儿，打印栈信息
 0  0x00000000004674e1 in runtime.raise
    at /data/software/go/src/runtime/sys_linux_amd64.s:154
 1  0x000000000044bb25 in runtime.dieFromSignal
    at /data/software/go/src/runtime/signal_unix.go:923
 2  0x000000000044c146 in runtime.sigfwdgo
    at /data/software/go/src/runtime/signal_unix.go:1128
 3  0x000000000044a745 in runtime.sigtrampgo
    at /data/software/go/src/runtime/signal_unix.go:432
 4  0x00000000004674e1 in runtime.raise
    at /data/software/go/src/runtime/sys_linux_amd64.s:153
 5  0x000000000044bb25 in runtime.dieFromSignal
    at /data/software/go/src/runtime/signal_unix.go:923
 6  0x0000000000435a25 in runtime.crash
    at /data/software/go/src/runtime/signal_unix.go:1005
 7  0x0000000000435a25 in runtime.fatalpanic
    at /data/software/go/src/runtime/panic.go:1244
 8  0x0000000000434998 in runtime.gopanic
    at /data/software/go/src/runtime/panic.go:779
 9  0x0000000000433a1c in runtime.goPanicIndex
    at /data/software/go/src/runtime/panic.go:114
10  0x0000000000488250 in main.main.func1
    at ./main.go:17 # 看这儿
11  0x0000000000465cc1 in runtime.goexit
    at /data/software/go/src/runtime/asm_amd64.s:1695

shell
(dlv) frame 10 # 看这儿，跳转到指定栈帧
> runtime.raise() /data/software/go/src/runtime/sys_linux_amd64.s:154 (PC: 0x4674e1)
Warning: debugging optimized function
Frame 10: ./main.go:17 (PC: 488250)
    12:
    13:         go func() {
    14:                 arr := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
    15:                 for {
    16:                         index := rand.Intn(11)
=>  17:                         fmt.Println(arr[index]) # panic 的位置
    18:                 }
    19:         }()
    20:
    21:         time.Sleep(time.Second * 5)
    22: }
(dlv) quit # 退出

目录

测试

参考