[racket] universe program using 100% cpu on Mac (also poor Raspberry Pi performance)

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Mon Dec 29 09:05:19 EST 2014

On Dec 28, 2014, at 9:51 PM, Darren Cruse wrote:

> One thing I can see is that on-draw is called for every on-tick on all three platforms btw.
> And even in cases where the program is idling and on-tick has simply returned the world state it was given unmodified.  
> Is that normal I wonder?  Part of me thought that since to-draw is a function of the world state, and the world state hasn't changed, that it would *not* call to-draw in that case.

I experimented with this 'optimization' and, if I recall correctly, it didn't make much of a difference and got in the way of imperative world programs. So I took it out. Mea culpa, I should have commented on this experiment inside the code. 

> (but it calls to-draw for every on-tick even on the Windows machine which is using only 6% cpu - so maybe I'm wrong to look to that as the problem)

My Mac-based experiments suggest that this call is not the cause of performance problems. 

;; --- 

Could you post the code somewhere so we can experiment with it? 

Thanks -- Matthias

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