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Date:Mon Oct 26 12:59:44 1993 
Subject:Re: Threaded Interpreted Languages 
From:Helen McCall - PML Mast2 
Volume-ID:931029.01 

	To: pop-forum@uk.ac.bham.cs
	From: ianr <ianr@uk.ac.susx.cogs>
	Subject: Re: Threaded Interpreted Languages
	X-Relay-Info: Relayed through cs.bham.ac.uk NEWS->MAIL gateway
	Date: Sat, 16 Oct 1993 04:55:00 +0100
	Original-Sender: news@cs.bham.ac.uk
	Sender: pop-forum-request <pop-forum-request@uk.ac.bham.cs>
	Status: R

	hmc@uk.ac.nerc-pml.unixb (Helen McCall - PML Mast2) writes:
	> 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.

	This is obviously nonesense! Do you have a piece of code that does
	this? In 10 lines? In 100? I doubt it!

	It's easy to force Poplog to use a huge amount of heap for testing
	purposes:

	    false -> popmemlim;
	    vars whopper = initv(5e7); ;;; 50 million long words of store

	The above two lines will *not* effect the execution of *any*
	program! (except that garbage collections may take a few seconds ;)

	Ian.

Hello Ian.

Sorry I couldn't reply earlier, but I have been away at a conference.

Some of the replies I have recieved have suggested that the executable image of POPLOG might have been corrupted.

I have checked with the people at the University, whose equipment I have been using, and they agree that this is a very likely cause of the strange problems that I and others have been encountering.

As to the defaulting of conditional branches: This is not a whopper! It took some considerable testing by myself before I would believe what had been happening. There have also been a number of other equally strange pieces of behaviour experienced by myself and others at the University on that installation.

They say they are going to reinstall it!

Helen.