[racket] DrRacket never uses more than 1 GB?

From: Greg Hendershott (greghendershott at gmail.com)
Date: Mon Jul 12 16:55:17 EDT 2010

Hi, Noel.

Thanks for the quick reply.

Ah. If the GC needs 2X actual that would explain 2 GB --> 1 GB usable.
That's a shame but I understand.

Since I posted, my git bisect suggests it wasn't my code that changed,
instead there was some change from PLT 4 to Racket. But next I need to
install PLT 4 again to confirm.

FWIW, if you check the RAM graph in performance monitor on Windows you see

                                  ______ kablooey
                 /|      /|   / \/
              /   |   /   |/
            /      |/

Yeah I'll keep my day job rather than pursue a career in ASCII art.  What
I'm trying to convey is a gradually rising sawtooth ("normal"). Then it
enters a second phase of long slopes up to 1 GB followed by a reclaim
drop-off, then marching up again but of course recovering less each time.
And finally the third phase is this frantic flatline. During which lots of
little ~30 msec GCs (according to DrRacket log) alternating with long, 5000
msec ones. Fourth phase is the poor DrRacket GUI gets sluggish and then

I'll re-install last PLT 4 version and see if it behaves differently as I
expect or if there's more to the story.


On Mon, Jul 12, 2010 at 4:19 PM, Noel Welsh <noelwelsh at gmail.com> wrote:

> The copying collector needs about as much space to copy into as it
> allocates. Hence Racket keeps about 1GB free of the 2GB it is
> allocated. (This was certainly the old behaviour, but I thought it was
> made a bit less conservative so perhaps something else is going on.)
> HTH,
> N.
> On Mon, Jul 12, 2010 at 8:43 PM, Greg Hendershott
> <greghendershott at gmail.com> wrote:
> > Regardless, the DrRacket process never seems to exceed about 1,069,999
> > bytes (Windows 7 64-bit).
> >
> > My understanding is that 32 bit processes on Win64 should get 2 GB (I
> > have 4 GB physical). So why is it maxing out at just under 1 GB?
> >...
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