code review 4767041: runtime: track running goroutine count

runtime: track running goroutine count

Used to use mcpu+msyscall but that's
problematic for packing into a single
atomic word.  The running goroutine count
(where running == Go code or syscall)
can be maintained separately, always
manipulated under lock.

[rsc, 2011-07-18 19:44:05]

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

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

[bradfitz, 2011-07-18 19:49:47]

LGTM

On Mon, Jul 18, 2011 at 12:44 PM, <rsc@golang.org> wrote:

> Reviewers: golang-dev_googlegroups.com,
>
> Message:
> Hello golang-dev (cc: golang-dev@googlegroups.com),
>
> I'd like you to review this change to
> https://go.googlecode.com/hg
>
>
> Description:
> runtime: track running goroutine count
>
> Used to use mcpu+msyscall but that's
> problematic for packing into a single
> atomic word.  The running goroutine count
> (where running == Go code or syscall)
> can be maintained separately, always
> manipulated under lock.
>
> Please review this at
http://codereview.appspot.com/**4767041/<http://codereview.appspot.com/4767041/>
>
> Affected files:
>  M src/pkg/runtime/proc.c
>
>
> Index: src/pkg/runtime/proc.c
> ==============================**==============================**=======
> --- a/src/pkg/runtime/proc.c
> +++ b/src/pkg/runtime/proc.c
> @@ -62,13 +62,13 @@
>        G *gtail;
>        int32 gwait;    // number of gs waiting to run
>        int32 gcount;   // number of gs that are alive
> +       int32 grunning; // number of gs running on cpu or in syscall
>
>        M *mhead;       // ms waiting for work
>        int32 mwait;    // number of ms waiting for work
>        int32 mcount;   // number of ms that have been created
>        int32 mcpu;     // number of ms executing on cpu
>        int32 mcpumax;  // max number of ms allowed on cpu
> -       int32 msyscall; // number of ms in system calls
>
>        int32 predawn;  // running initialization, don't run new gs.
>        int32 profilehz;        // cpu profiling rate
> @@ -353,6 +353,7 @@
>  static void
>  mnextg(M *m, G *g)
>  {
> +       runtime·sched.grunning++;
>        runtime·sched.mcpu++;
>        m->nextg = g;
>        if(m->waitnextg) {
> @@ -397,6 +398,7 @@
>                                mnextg(gp->lockedm, gp);
>                                continue;
>                        }
> +                       runtime·sched.grunning++;
>                        runtime·sched.mcpu++;           // this m will run
> gp
>                        schedunlock();
>                        return gp;
> @@ -404,7 +406,7 @@
>                // Otherwise, wait on global m queue.
>                mput(m);
>        }
> -       if(runtime·sched.mcpu == 0 && runtime·sched.msyscall == 0)
> +       if(runtime·sched.grunning == 0)
>                runtime·throw("all goroutines are asleep - deadlock!");
>        m->nextg = nil;
>        m->waitnextg = 1;
> @@ -548,6 +550,7 @@
>                // Just finished running gp.
>                gp->m = nil;
>                runtime·sched.mcpu--;
> +               runtime·sched.grunning--;
>
>                if(runtime·sched.mcpu < 0)
>                        runtime·throw("runtime·sched.**mcpu < 0 in
> scheduler");
> @@ -634,7 +637,6 @@
>        schedlock();
>        g->status = Gsyscall;
>        runtime·sched.mcpu--;
> -       runtime·sched.msyscall++;
>        if(runtime·sched.gwait != 0)
>                matchmg();
>
> @@ -668,7 +670,6 @@
>                return;
>
>        schedlock();
> -       runtime·sched.msyscall--;
>        runtime·sched.mcpu++;
>        // Fast path - if there's room for this m, we're done.
>        if(m->profilehz == runtime·sched.profilehz && runtime·sched.mcpu <=
> runtime·sched.mcpumax) {
>
>
>

[rsc, 2011-07-18 19:50:59]

*** Submitted as http://code.google.com/p/go/source/detail?r=90a2e9f79fdc ***

runtime: track running goroutine count

Used to use mcpu+msyscall but that's
problematic for packing into a single
atomic word.  The running goroutine count
(where running == Go code or syscall)
can be maintained separately, always
manipulated under lock.

R=golang-dev, bradfitz
CC=golang-dev
http://codereview.appspot.com/4767041