概要
よく忘れるので、ここにメモメモ。。。
たまにスタックトレースを取りたいときがあったりします。
Goだと debug.PrintStack() とか debug.Stack() とか何個かやり方があるので
ついでに以下にメモしておきます。
debug.PrintStack()
package stacktrace import ( "context" "runtime/debug" "time" "github.com/devlights/gomy/output" ) // DebugPrintStack -- runtime/debug.PrintStack のサンプルです. // // REFERENCES // - https://pkg.go.dev/runtime/debug#PrintStack // - https://stackoverflow.com/questions/19094099/how-to-dump-goroutine-stacktraces func DebugPrintStack() error { var ( third = func(pCtx context.Context) context.Context { ctx, cxl := context.WithTimeout(pCtx, 100*time.Millisecond) defer cxl() // この処理が走っているgoroutineのスタックトレースを出力 (全部ではない) output.StderrHr() debug.PrintStack() <-ctx.Done() return ctx } second = func(pCtx context.Context) context.Context { ctx, cxl := context.WithCancel(pCtx) go func() { defer cxl() <-third(ctx).Done() }() return ctx } first = func(pCtx context.Context) context.Context { ctx, cxl := context.WithCancel(pCtx) go func() { defer cxl() <-second(ctx).Done() }() return ctx } ) <-first(context.Background()).Done() return nil }
実行すると以下のようになります。
gitpod /workspace/try-golang (master) $ make run go run github.com/devlights/try-golang/cmd/trygolang -onetime -example "" ENTER EXAMPLE NAME: stacktrace_debug_printstack [Name] "stacktrace_debug_printstack" -------------------------------------------------- goroutine 20 [running]: runtime/debug.Stack() /home/gitpod/go/src/runtime/debug/stack.go:24 +0x65 runtime/debug.PrintStack() /home/gitpod/go/src/runtime/debug/stack.go:16 +0x19 github.com/devlights/try-golang/examples/basic/stacktrace.DebugPrintStack.func1({0xaedc18, 0xc0001bf9c0}) /workspace/try-golang/examples/basic/stacktrace/debug_printstack.go:24 +0x8d github.com/devlights/try-golang/examples/basic/stacktrace.DebugPrintStack.func2.1() /workspace/try-golang/examples/basic/stacktrace/debug_printstack.go:34 +0x47 created by github.com/devlights/try-golang/examples/basic/stacktrace.DebugPrintStack.func2 /workspace/try-golang/examples/basic/stacktrace/debug_printstack.go:32 +0xc8 [Elapsed] 100.315646ms
C# とか Java やってる人からすると、Goのスタックトレースは逆になって出力されてるように見えるはずです。
debug.Stack()
package stacktrace import ( "context" "runtime/debug" "time" "github.com/devlights/gomy/output" ) // DebugStack -- debug.Stack() の サンプルです。 // // REFERENCES // - https://pkg.go.dev/runtime/debug#Stack // - https://stackoverflow.com/questions/19094099/how-to-dump-goroutine-stacktraces func DebugStack() error { // channels var ( ch = make(chan []byte, 1) ) defer close(ch) // funcs var ( third = func(pCtx context.Context) context.Context { ctx, cxl := context.WithTimeout(pCtx, 100*time.Millisecond) defer cxl() // この処理が走っているgoroutineのスタックトレースを取得 (全部ではない) ch <- debug.Stack() <-ctx.Done() return ctx } second = func(pCtx context.Context) context.Context { ctx, cxl := context.WithCancel(pCtx) go func() { defer cxl() <-third(ctx).Done() }() return ctx } first = func(pCtx context.Context) context.Context { ctx, cxl := context.WithCancel(pCtx) go func() { defer cxl() <-second(ctx).Done() }() return ctx } ) // contexts var ( ctx = first(context.Background()) ) LOOP: for { select { case <-ctx.Done(): break LOOP case buf := <-ch: output.Stdoutl("stack", string(buf)) } } output.Stdoutl("done") return nil }
実行すると以下のようになります。
gitpod /workspace/try-golang (master) $ make run go run github.com/devlights/try-golang/cmd/trygolang -onetime -example "" ENTER EXAMPLE NAME: stacktrace_debug_stack [Name] "stacktrace_debug_stack" stack goroutine 20 [running]: runtime/debug.Stack() /home/gitpod/go/src/runtime/debug/stack.go:24 +0x65 github.com/devlights/try-golang/examples/basic/stacktrace.DebugStack.func1({0xaedc18, 0xc00022f9c0}) /workspace/try-golang/examples/basic/stacktrace/debug_stack.go:30 +0x68 github.com/devlights/try-golang/examples/basic/stacktrace.DebugStack.func2.1() /workspace/try-golang/examples/basic/stacktrace/debug_stack.go:40 +0x47 created by github.com/devlights/try-golang/examples/basic/stacktrace.DebugStack.func2 /workspace/try-golang/examples/basic/stacktrace/debug_stack.go:38 +0xc8 done [Elapsed] 100.320653ms
runtime.Stack()
debug.PrintStack() と debug.Stack() はどちらも内部で runtime.Stack() を呼び出しています。当然直接使うこともできます。
package stacktrace import ( "runtime" "github.com/devlights/gomy/output" ) // RuntimeStack -- runtime.Stack() についてのサンプルです。 // // REFERENCES // - https://pkg.go.dev/runtime#Stack // - https://stackoverflow.com/questions/19094099/how-to-dump-goroutine-stacktraces func RuntimeStack() error { // channels var ( chSingle = make(chan []byte, 1) chAll = make(chan []byte, 1) ) // funcs var ( getStack = func(all bool) []byte { // From src/runtime/debug/stack.go var ( buf = make([]byte, 1024) ) for { n := runtime.Stack(buf, all) if n < len(buf) { return buf[:n] } buf = make([]byte, 2*len(buf)) } } ) // runtime.Stack() の 第２引数 に false を渡すと、現在のgoroutineのみが対象 go func(ch chan<- []byte) { defer close(ch) ch <- getStack(false) }(chSingle) // runtime.Stack() の 第２引数 に true を渡すと、全てのgoroutineが対象 go func(ch chan<- []byte) { defer close(ch) ch <- getStack(true) }(chAll) // runtime.Stack(false) の 結果 for v := range chSingle { output.Stdoutl("=== stack-single", string(v)) } // runtime.Stack(true) の 結果 for v := range chAll { output.Stdoutl("=== stack-all ", string(v)) } return nil }
実行すると以下のようになります。
gitpod /workspace/try-golang (master) $ make run go run github.com/devlights/try-golang/cmd/trygolang -onetime -example "" ENTER EXAMPLE NAME: stacktrace_runtime_stack [Name] "stacktrace_runtime_stack" === stack-single goroutine 21 [running]: github.com/devlights/try-golang/examples/basic/stacktrace.RuntimeStack.func1(0x0) /workspace/try-golang/examples/basic/stacktrace/runtime_stack.go:30 +0x6a github.com/devlights/try-golang/examples/basic/stacktrace.RuntimeStack.func2(0xc000112480) /workspace/try-golang/examples/basic/stacktrace/runtime_stack.go:42 +0x5f created by github.com/devlights/try-golang/examples/basic/stacktrace.RuntimeStack /workspace/try-golang/examples/basic/stacktrace/runtime_stack.go:40 +0xd2 === stack-all goroutine 22 [running]: github.com/devlights/try-golang/examples/basic/stacktrace.RuntimeStack.func1(0x0) /workspace/try-golang/examples/basic/stacktrace/runtime_stack.go:30 +0x6a github.com/devlights/try-golang/examples/basic/stacktrace.RuntimeStack.func3(0xc0001124e0) /workspace/try-golang/examples/basic/stacktrace/runtime_stack.go:48 +0x62 created by github.com/devlights/try-golang/examples/basic/stacktrace.RuntimeStack /workspace/try-golang/examples/basic/stacktrace/runtime_stack.go:46 +0x152 goroutine 1 [runnable]: github.com/devlights/try-golang/examples/basic/stacktrace.RuntimeStack() /workspace/try-golang/examples/basic/stacktrace/runtime_stack.go:52 +0x1f0 github.com/devlights/try-golang/runner.(*Exec).Run(0x4060105) /workspace/try-golang/runner/exec.go:52 +0x14c github.com/devlights/try-golang/runner.(*Loop).exec(0xc0001580f0, {0xa18416, 0x18}, 0xc0001f8210) /workspace/try-golang/runner/loop.go:126 +0x8f github.com/devlights/try-golang/runner.(*Loop).Run(0xc0001345b8) /workspace/try-golang/runner/loop.go:79 +0x265 main.main() /workspace/try-golang/cmd/trygolang/main.go:67 +0x532 [Elapsed] 379.428µs
pprof.Lookup("goroutine").WriteTo()
これが一番フレキシブルにいろいろな情報が取れるので便利です。
package stacktrace import ( "bytes" "fmt" "io" "runtime/pprof" "github.com/devlights/gomy/output" ) // PprofGoroutineWriteTo -- pprof.Lookup("goroutine").WriteTo() のサンプルです. // REFERENCES // - https://pkg.go.dev/runtime/pprof#Lookup // - https://pkg.go.dev/runtime/pprof#Profile.WriteTo // - https://pkg.go.dev/runtime/pprof#Profile // - https://stackoverflow.com/questions/19094099/how-to-dump-goroutine-stacktraces func PprofGoroutineWriteTo() error { const ( profile = "goroutine" // https://pkg.go.dev/runtime/pprof#Profile に事前定義プロファイルが記載されている useGoroutineStyle = 2 // goroutineの場合 2 を指定すると debug.Stack() と同じフォーマットになる. ) var ( errCh = make(chan error, 1) buf = bytes.NewBuffer(nil) fn = func(w io.Writer) error { p := pprof.Lookup(profile) if p == nil { return fmt.Errorf("profile does not exists (%s)", profile) } return p.WriteTo(w, useGoroutineStyle) } ) go func() { defer close(errCh) if err := fn(buf); err != nil { errCh <- err } }() for e := range errCh { return e } output.Stdoutl("pprof", buf.String()) return nil }
実行すると以下のようになります。
gitpod /workspace/try-golang (master) $ make run go run github.com/devlights/try-golang/cmd/trygolang -onetime -example "" ENTER EXAMPLE NAME: stacktrace_pprof_writeto [Name] "stacktrace_pprof_writeto" pprof goroutine 6 [running]: runtime/pprof.writeGoroutineStacks({0xade4c0, 0xc0001e6240}) /home/gitpod/go/src/runtime/pprof/pprof.go:693 +0x70 runtime/pprof.writeGoroutine({0xade4c0, 0xc0001e6240}, 0xedd080) /home/gitpod/go/src/runtime/pprof/pprof.go:682 +0x2b runtime/pprof.(*Profile).WriteTo(0xa09359, {0xade4c0, 0xc0001e6240}, 0x0) /home/gitpod/go/src/runtime/pprof/pprof.go:331 +0x14b github.com/devlights/try-golang/examples/basic/stacktrace.PprofGoroutineWriteTo.func1({0xade4c0, 0xc0001e6240}) /workspace/try-golang/examples/basic/stacktrace/pprof_goroutine_writeto.go:33 +0x4c github.com/devlights/try-golang/examples/basic/stacktrace.PprofGoroutineWriteTo.func2() /workspace/try-golang/examples/basic/stacktrace/pprof_goroutine_writeto.go:39 +0x6f created by github.com/devlights/try-golang/examples/basic/stacktrace.PprofGoroutineWriteTo /workspace/try-golang/examples/basic/stacktrace/pprof_goroutine_writeto.go:37 +0xb6 goroutine 1 [chan receive]: github.com/devlights/try-golang/examples/basic/stacktrace.PprofGoroutineWriteTo() /workspace/try-golang/examples/basic/stacktrace/pprof_goroutine_writeto.go:44 +0xcb github.com/devlights/try-golang/runner.(*Exec).Run(0x7060102) /workspace/try-golang/runner/exec.go:52 +0x14c github.com/devlights/try-golang/runner.(*Loop).exec(0xc00002e210, {0xa183fe, 0x18}, 0xc0001e6210) /workspace/try-golang/runner/loop.go:126 +0x8f github.com/devlights/try-golang/runner.(*Loop).Run(0xc0000105c8) /workspace/try-golang/runner/loop.go:79 +0x265 main.main() /workspace/try-golang/cmd/trygolang/main.go:67 +0x532 [Elapsed] 262.114µs
参考情報
過去の記事については、以下のページからご参照下さい。
サンプルコードは、以下の場所で公開しています。
