code review 4675081: cgi: close stdout reader pipe when finished

cgi: close stdout reader pipe when finished

This causes the child, if still writing, to get an error or
SIGPIPE and most likely exit so our subsequent wait can
finish.

A more guaranteed fix would be putting a time limit on the
child's overall execution, but this fixes the problem
I was having.

Fixes issue 2059

[bradfitz, 2011-07-11 20:47:42]

Hello golang-dev@googlegroups.com (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://go.googlecode.com/hg/

[rsc, 2011-07-11 20:54:57]

i think it's a more general bug.
if we think the cgi is done we should kill it.

if this isn't right (maybe it's not) then the
output-only kill isn't right either.
the alternative is to close the pipe.

http://codereview.appspot.com/4675081/diff/5001/src/pkg/http/cgi/host.go
File src/pkg/http/cgi/host.go (right):

http://codereview.appspot.com/4675081/diff/5001/src/pkg/http/cgi/host.go#newc...
src/pkg/http/cgi/host.go:189: defer cmd.Wait()
defer cmd.Wait()
defer cmd.Process.Kill()

[bradfitz, 2011-07-11 21:22:07]

Hello rsc@golang.org (cc: golang-dev@googlegroups.com),

Please take another look.

[bradfitz, 2011-07-11 22:03:46]

Hello rsc@golang.org (cc: golang-dev@googlegroups.com),

Please take another look.

[rsc, 2011-07-11 22:53:44]

LGTM

http://codereview.appspot.com/4675081/diff/9002/src/pkg/exec/exec.go
File src/pkg/exec/exec.go (right):

http://codereview.appspot.com/4675081/diff/9002/src/pkg/exec/exec.go#newcode340
src/pkg/exec/exec.go:340: // standard output when the command starts.
add
// The pipe will be closed automatically after Wait sees the command exit.

same on next

[bradfitz, 2011-07-11 22:59:40]

*** Submitted as http://code.google.com/p/go/source/detail?r=bd12ee706335 ***

cgi: close stdout reader pipe when finished

This causes the child, if still writing, to get an error or
SIGPIPE and most likely exit so our subsequent wait can
finish.

A more guaranteed fix would be putting a time limit on the
child's overall execution, but this fixes the problem
I was having.

Fixes issue 2059

R=rsc
CC=golang-dev
http://codereview.appspot.com/4675081

[bradfitz, 2011-07-12 00:35:23]

You have to build + install the exec package too.

On Mon, Jul 11, 2011 at 5:34 PM, mattn <mattn.jp@gmail.com> wrote:

> This changes make build error.
>
> C:\go\src\pkg\http\cgi>gomake 2>&1 | tee log
> 8g  -o _go_.8 child.go host.go
> host.go:190: stdoutRead.Close undefined (type io.Reader has no field or
> method Close)
> mingw32-make: *** [_go_.8] Error 1
>
>