gdb调试

有人写的不错了，其实没难的，可能就是第一次不会使用。

总体就是先build，然后再操作了，windows我一般用的是dlv。具体进入gdb后help看下命令帮助即可。

http://lday.me/2017/02/27/0005_gdb-vs-dlv/

顺带简单分析下proc吧。

test.go

func counting(c chan<- int) {
    for i := 0; i < 10; i++ {
        time.Sleep(2 * time.Second)
        c <- i
    }
    close(c)
}


func main() {
    msg := "Starting main"
    fmt.Println(msg)
    bus := make(chan int)
    msg = "starting a gofunc"
    go counting(bus)
    for count := range bus {
        fmt.Println("count:", count)
    }
}

先编译一下

go build -gcflags “-N -l” test.go

再用dlv

dlv exec test.ext

打个breakpoint

b runtime.init

Breakpoint 1 set at 0x42ed4a for runtime.main() D:/program/Go/src/runtime/proc.go:113

我们即可跳转到proc.go

// The main goroutine.
func main() {
    g := getg()

    // Racectx of m0->g0 is used only as the parent of the main goroutine.
    // It must not be used for anything else.
    g.m.g0.racectx = 0

    // Max stack size is 1 GB on 64-bit, 250 MB on 32-bit.
    // Using decimal instead of binary GB and MB because
    // they look nicer in the stack overflow failure message.
    if sys.PtrSize == 8 {
        maxstacksize = 1000000000
    } else {
        maxstacksize = 250000000
    }
...

}

对于目前的1.4，我们发现在开启后台系统监控也就是sysmon这边多了对于GOOS编译的识别，主要是对于WebAssembly的支持。

    if GOARCH != "wasm" { // no threads on wasm yet, so no sysmon
        systemstack(func() {
            newm(sysmon, nil)
        })
    }

这边就是进入执行我们的业务逻辑代码了

    fn := main_main // make an indirect call, as the linker doesn't know the address of the main package when laying down the runtime
    fn()

总之分析还是看起来不复杂的，只是一小部分。可认真学习雨痕大神的go学习笔记。