[racket] Stuttering problems with big-bang

From: Carl Eastlund (cce at ccs.neu.edu)
Date: Wed Aug 7 18:16:10 EDT 2013

For reference, I was on IRC with Jack when he first ran into this, and
reproduced the jittery behavior on my own machine with a freshly started
DrRacket.  The first time I ran the program, and perhaps every 10th time I
ran it, it would hiccup briefly within a second of hitting run, then run
smoothly.  This is on a relatively recent Mac Mini with 16 GB RAM, 4
physical / 8 virtual cores, and little else running at the time.

Carl Eastlund

On Wed, Aug 7, 2013 at 5:22 PM, Robby Findler
<robby at eecs.northwestern.edu>wrote:

> I just tried this on my mac (a fairly recent machine but not a super-duper
> powerhouse) and it didn't seem jittery.
> What happens if you save it in "file.rkt" and, from a terminal window, run
> "racket file.rkt"? Here's the precise command I ran (on a mac):
>     /Applications/Racket\ v5.3.5/bin/racket -W debug at GC  ~/file.rkt
> I didn't see too many GCs once the game started and the ones I saw were
> unlikely to be noticeable (they were 3-5 msec; well below the 16 msec
> screen refresh rate).
> If that makes a difference on your machine, perhaps that means it is time
> to restart DrRacket (as GCs can take significantly longer for programs
> running inside DrRacket, esp. if there is a leak somewhere).
> Robby
> On Wed, Aug 7, 2013 at 2:58 AM, Robby Findler <robby at eecs.northwestern.edu
> > wrote:
>> Well, allocation is what triggers GC and there appears to be a fair
>> amount of that in your program. I am not in a good position to run your
>> code and nothing jumps out at me from a first glance at the gist but
>> probably it is allocation that originates there (not that that
>> means your code is necc. buggy).
>> Fundamentally, functional image construction (and lists) requires
>> allocation and allocation requires GC. That said there is probably
>> something's we can fix here. I will try to take a closer look in the coming
>> days of no one beats me to it.
>> Robby
>> On Wednesday, August 7, 2013, Jack Firth wrote:
>>> Hey users, I'm experimenting with some simple games using big-bang from
>>> 2htdp/universe and I keep running into stuttering problems. It seems to be
>>> the garbage collector slowing things down (green recycle symbol in drracket
>>> is on whenever the program is frozen).
>>> Increasing the memory limit or removing the limit altogether doesn't
>>> seem to affect the problem, and I've checked in the IRC and it occurs on
>>> other machines as well, all of which have the specs that it shouldn't have
>>> any problems with slowdown. Are there issues with big-bang and it's event
>>> handling?
>>> Source - https://gist.github.com/Universalist235/6171371
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