code review 137050043: runtime: fix Stack

runtime: fix Stack

Fixes issue 8626.

[rsc, 2014-09-01 22:56:23]

Hello golang-codereviews@googlegroups.com (cc: bradfitz, iant, r),

I'd like you to review this change to
https://code.google.com/p/go/

[bradfitz, 2014-09-01 23:38:58]

LGTM

nit: no need for Errorf on second Error line; just Error is fine.




On Mon, Sep 1, 2014 at 3:56 PM, <rsc@golang.org> wrote:

> Reviewers: golang-codereviews,
>
> Message:
> Hello golang-codereviews@googlegroups.com (cc: bradfitz, iant, r),
>
> I'd like you to review this change to
> https://code.google.com/p/go/
>
>
> Description:
> runtime: fix Stack
>
> Fixes issue 8626.
>
> Please review this at https://codereview.appspot.com/137050043/
>
> Affected files (+12, -2 lines):
>   M src/pkg/runtime/mprof.go
>   M src/pkg/runtime/stack_test.go
>
>
> Index: src/pkg/runtime/mprof.go
> ===================================================================
> --- a/src/pkg/runtime/mprof.go
> +++ b/src/pkg/runtime/mprof.go
> @@ -584,13 +584,13 @@
>
>         n := 0
>         if len(buf) > 0 {
> -               gp.writebuf = buf
> +               gp.writebuf = buf[0:0:len(buf)]
>                 goroutineheader(gp)
>                 traceback(pc, sp, 0, gp)
>                 if all {
>                         tracebackothers(gp)
>                 }
> -               n = len(buf) - len(gp.writebuf)
> +               n = len(gp.writebuf)
>                 gp.writebuf = nil
>         }
>
> Index: src/pkg/runtime/stack_test.go
> ===================================================================
> --- a/src/pkg/runtime/stack_test.go
> +++ b/src/pkg/runtime/stack_test.go
> @@ -6,6 +6,7 @@
>
>  import (
>         . "runtime"
> +       "strings"
>         "sync"
>         "testing"
>         "time"
> @@ -331,3 +332,12 @@
>                 }
>         }
>  }
> +
> +func TestStackOutput(t *testing.T) {
> +       b := make([]byte, 1024)
> +       stk := string(b[:Stack(b, false)])
> +       if !strings.HasPrefix(stk, "goroutine ") {
> +               t.Errorf("Stack (len %d):\n%s", len(stk), stk)
> +               t.Errorf("Stack output should begin with \"goroutine \"")
> +       }
> +}
>
>
>

[rsc, 2014-09-01 23:41:58]

thanks. i tend to use Errorf always, which is also fine.

[rsc, 2014-09-01 23:42:23]

*** Submitted as https://code.google.com/p/go/source/detail?r=b3b50b28df8a ***

runtime: fix Stack

Fixes issue 8626.

LGTM=bradfitz
R=golang-codereviews
CC=bradfitz, golang-codereviews, iant, r
https://codereview.appspot.com/137050043

[gobot, 2014-09-03 05:10:11]

This CL appears to have broken the linux-amd64-race-temp builder.
See http://build.golang.org/log/b26bb8d86b2fa819e3d430a98bc1b29071b43c66