code review 9778048: os/exec: fix test hang

os/exec: fix test hang
Currently the test closes random files descriptors,
which leads to hang (in particular if netpoll fd is closed).
Try to open only fd 3, since the parent process expects it to be fd 3 anyway.
Fixes issue 5571.

[dvyukov, 2013-05-28 15:23:44]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://dvyukov%40google.com@code.google.com/p/go/

[r, 2013-05-28 15:27:00]

https://codereview.appspot.com/9778048/diff/5001/src/pkg/os/exec/exec_test.go
File src/pkg/os/exec/exec_test.go (right):

https://codereview.appspot.com/9778048/diff/5001/src/pkg/os/exec/exec_test.go...
src/pkg/os/exec/exec_test.go:543: f := os.NewFile(3, fmt.Sprintf("fd-3"))
inconsistent: see line 495.

i'm ok with this but i'd like to understand why it was different in the first
place.

[dvyukov, 2013-05-28 15:36:49]

On 2013/05/28 15:27:00, r wrote:
> https://codereview.appspot.com/9778048/diff/5001/src/pkg/os/exec/exec_test.go
> File src/pkg/os/exec/exec_test.go (right):
> 
>
https://codereview.appspot.com/9778048/diff/5001/src/pkg/os/exec/exec_test.go...
> src/pkg/os/exec/exec_test.go:543: f := os.NewFile(3, fmt.Sprintf("fd-3"))
> inconsistent: see line 495.
> 
> i'm ok with this but i'd like to understand why it was different in the first
> place.

Dunno
I will fail if fd != 3 anyway. Probably if the child process with return "fd4",
it will give some information for debugging.

[dvyukov, 2013-05-28 15:36:57]

PTAL

https://codereview.appspot.com/9778048/diff/5001/src/pkg/os/exec/exec_test.go
File src/pkg/os/exec/exec_test.go (right):

https://codereview.appspot.com/9778048/diff/5001/src/pkg/os/exec/exec_test.go...
src/pkg/os/exec/exec_test.go:543: f := os.NewFile(3, fmt.Sprintf("fd-3"))
On 2013/05/28 15:27:00, r wrote:
> inconsistent: see line 495.

Done

[r, 2013-05-28 16:23:48]

LGTM
what a mess

[dvyukov, 2013-05-28 17:09:34]

*** Submitted as https://code.google.com/p/go/source/detail?r=9cc232c5d990 ***

os/exec: fix test hang
Currently the test closes random files descriptors,
which leads to hang (in particular if netpoll fd is closed).
Try to open only fd 3, since the parent process expects it to be fd 3 anyway.
Fixes issue 5571.

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/9778048