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Date:Mon Oct 13 11:52:31 1993 
Subject:Re: Threaded Interpreted Languages 
From:Helen McCall - PML Mast2 
Volume-ID:931013.02 


Richard Hartman, hartman@uLogic.COM writes:


> Actually, no.  I am interested in finding out just what advantages
> GC actually might give me (who have so far had no problems keeping
> track of such things myself) for the performance penalty that is
> usually paid for such systems.  I have not said "GC is worthless",
> I have asked "what is it's worth?".  So far the only answer I have
> ever gotten to this question is "you don't have to keep track of
> your dynamically allocated objects".  I have never found this to
> be problematic -- thus never seen any actual ADVANTAGE to be had
> from using GC.  I'm just trying to see if someone else can give
> me a good reason why GC would be better (and worth the performance
> hit) than doing it myself.

My experience is that the performance penalty is not all one suffers with automatic garbage collection in POPLOG.

POPLOG may well collect up garbage and free the memory for it's own use, but it does not appear to be very altruistic with respect to other processes running on the machine. When making a garbage collection, POPLOG actually INCREASES the total amount of memory it is using, so forcing other processes running on the machine into an "out of swap space" situation and crashing them.

Further to this; I have found that POPLOG's own behaviour becomes somewhat unpredictable and irrational when swap space runs low, with a distinct tendency for conditional branches to default to the else path regardless of the evaluation performed, and without signalling any error.

Allowing the programmer to manage the utilisation of resources herself, can save an awful lot of heartache!

Helen.