[racket-dev] [racket] Stuttering problems with big-bang

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Thu Aug 8 08:38:42 EDT 2013

Truth in advertising: 

big-bang skips frames in certain circumstances -- when handlers take too long -- so if the GC kicks in when a handler runs, it is possible that the eventual result is a skip. 

Robby: do you think Jack's program would benefit from a forced gc before big-bang runs? (I can't find Jack's code.) 

-- Matthias

On Aug 8, 2013, at 6:40 AM, Robby Findler wrote:

> Hi Jack: the entire system freezes when the GC happens and the numbers you report match up with what I'd expect to be very annoying stuttering. (And just for the record, it doesn't skip frames -- it just doesn't update anything or draw any new frames during the GC.)
> Can you tell us more about your machine? What OS and what processor?
> Robby
> On Wed, Aug 7, 2013 at 9:55 PM, Jack Firth <the.game.creator6 at gmail.com> wrote:
> I started up the program from the command line with the garbage collection debugging information, and saw some interesting stuff once the program was up and running. Every second or so I'd see a very very slight stutter, which would be followed by a garbage collection lasting either 16ms or 15ms, slightly longer stutters would report as GCs of 31ms, and long freezing stutters would be around 109ms. I think perhaps big-bang is doing something where it's skipping a frame or two as a result of some sort of garbage collection. All the on-tick etc. events are performed for the frame, it just doesn't seem to be drawn. I can't fathom what's going on here.
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