code review 902041: runtime: use explicit flag when finalizer goroutine is ...

runtime: use explicit flag when finalizer goroutine is waiting

Avoids spurious wakeups during other sleeping by that goroutine.
Fixes issue 711.

[rsc, 2010-04-08 01:27:58]

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

I'd like you to review this change.

[r2, 2010-04-08 02:00:39]

LGTM

On Apr 7, 2010, at 6:27 PM, rsc@golang.org wrote:

> Reviewers: r,
> 
> Message:
> Hello r (cc: golang-dev@googlegroups.com),
> 
> I'd like you to review this change.
> 
> 
> Description:
> runtime: use explicit flag when finalizer goroutine is waiting
> 
> Avoids spurious wakeups during other sleeping by that goroutine.
> Fixes issue 711.
> 
> Please review this at http://codereview.appspot.com/902041/show
> 
> Affected files:
>  M src/pkg/runtime/mgc0.c
> 
> 
> Index: src/pkg/runtime/mgc0.c
> ===================================================================
> --- a/src/pkg/runtime/mgc0.c
> +++ b/src/pkg/runtime/mgc0.c
> @@ -25,6 +25,8 @@
> 
> static G *fing;
> static Finalizer *finq;
> +static int32 fingwait;
> +
> static void sweepblock(byte*, int64, uint32*, int32);
> static void runfinq(void);
> 
> @@ -306,8 +308,10 @@
> 		// kick off or wake up goroutine to run queued finalizers
> 		if(fing == nil)
> 			fing = newproc1((byte*)runfinq, nil, 0, 0);
> -		else if(fing->status == Gwaiting)
> +		else if(fingwait) {
> 			ready(fing);
> +			fingwait = 0;
> +		}
> 	}
> 	m->locks--;
> 
> @@ -340,6 +344,7 @@
> 		f = finq;
> 		finq = nil;
> 		if(f == nil) {
> +			fingwait = 1;
> 			g->status = Gwaiting;
> 			gosched();
> 			continue;
> 
> 
> 
> 
> -- 
> To unsubscribe, reply using "remove me" as the subject.

[rsc, 2010-04-08 03:38:04]

*** Submitted as http://code.google.com/p/go/source/detail?r=9cf4bce3ad75 ***

runtime: use explicit flag when finalizer goroutine is waiting

Avoids spurious wakeups during other sleeping by that goroutine.
Fixes issue 711.

R=r
CC=golang-dev
http://codereview.appspot.com/902041