使用gdb调试go项目

原始文档：https://golang.org/doc/gdb，本文以docker的libnetwork库为例，说明如何用gdb调试。

首先安装golang和gdb(版本7.0以上)，在FreeBSD上，请用gdb7121。设置GOPATH=$HOME/go。

下载libnetwork：go get github.com/docker/libnetwork

在$GOPATH/github.com/clovertrail/testlibnetwork目录，创建测试程序，此处直接使用libnetwork的示例，稍作修改：

package mainimport (        "fmt"        "github.com/docker/libnetwork"        "github.com/docker/libnetwork/options"        "github.com/docker/libnetwork/netlabel"        "github.com/docker/libnetwork/config")func main() {        networkType := "bridge"        // Create a new controller instance        driverOptions := options.Generic{}        genericOption := make(map[string]interface{})        genericOption[netlabel.GenericData] = driverOptions        controller, err := libnetwork.New(config.OptionDriverConfig(networkType, genericOption))        if err != nil {                fmt.Println(err)                return        }        fmt.Println(controller)        // Create a network for containers to join.        // NewNetwork accepts Variadic optional arguments that libnetwork and Drivers can make use of        network, err := controller.NewNetwork(networkType, "network1", "")        if err != nil {                fmt.Println(err)                return        }        fmt.Println(network)        // For each new container: allocate IP and interfaces. The returned network        // settings will be used for container infos (inspect and such), as well as        // iptables rules for port publishing. This info is contained or accessible        // from the returned endpoint.        ep, err := network.CreateEndpoint("Endpoint1")        if err != nil {                fmt.Println(err)                return        }        fmt.Println(ep)        // Create the sandbox for the container.        // NewSandbox accepts Variadic optional arguments which libnetwork can use.        sbx, err := controller.NewSandbox("container1",                libnetwork.OptionHostname("test"),                libnetwork.OptionDomainname("docker.io"))        fmt.Println(sbx)        // A sandbox can join the endpoint via the join api.        err = ep.Join(sbx)        if err != nil {                fmt.Println(err)                return        }}

项目的目录结构如下：

.
`-- testlibnetwork
    |-- bingo.go
    `-- vendor
        `-- github.com
            `-- docker
                `-- libnetwork -> $GOPATH/src/github.com/docker/libnetwork

重新编译libnetwork，打印编译的命令细节，并关闭内联优化：

go build -a -x -gcflags "-N -l" github.com/docker/libnetwork

编译测试用例，同时关闭内联优化：

go build -gcflags "-N -l" -o ~/go/bin/bingo bingo.go

好了，启动gdb，开始调试：

gdb ~/go/bin/bingo -d $GOROOT

正常情况，gdb会自动load $GOROOT/src/runtime/runtime-gdb.py，如果没有load，请手动load：

(gdb) source $GOROOT/src/runtime/runtime-gdb.py

开始调试，设置断点。go里面的第三方源代码的路径和import里面是一致的，比如我们想在controller.go:180行设断点：

(gdb) b github.com/docker/libnetwork/controller.go:180
Breakpoint 1 at 0x481397: file /home/honzhan/go/src/github.com/clovertrail/testlibnetwork/vendor/github.com/docker/libnetwork/controller.go, line 180.

(gdb) r
Starting program: /usr/home/honzhan/go/bin/bingo
[New LWP 100134 of process 16801]
[New LWP 100260 of process 16801]
[New LWP 100283 of process 16801]
[New LWP 100294 of process 16801]
[New LWP 100470 of process 16801]


Thread 1 hit Breakpoint 1, github.com/clovertrail/testlibnetwork/vendor/github.com/docker/libnetwork.New (
    cfgOptions= []github.com/clovertrail/testlibnetwork/vendor/github.com/docker/libnetwork/config.Option = {...}, ~r1=..., ~r2=...)
    at /home/honzhan/go/src/github.com/clovertrail/testlibnetwork/vendor/github.com/docker/libnetwork/controller.go:180
180             c := &controller{

更多调试命令请参考https://golang.org/doc/gdb