[Vm-dev] Re: [ANN] 7061 = Squeak 3.9 final

Andreas Raab andreas.raab at gmx.de
Mon Sep 25 22:36:26 UTC 2006

Adrian Lienhard wrote:
> I think, the current VM issues would be a good reason to pospone the 
> release.

I disagree. The issue in question is nothing new and it's unlikely to be 
fixed any time soon. Mostly because we don't have a reliable way of 
recreating (and therefore debugging) the problem.

> Unfortunately, as it seems to me, the VM is quite poorly maintained. 

I don't think it's fair to draw this conclusion based on the sample size 
you are using in particular given that you don't seem understand the 
problem well enough to see why it's so hard to fix.

> Probably the main reason being that the maintainers don't have enough 
> time (or, in other words, because they are not paid to fix the 
> problems). Another difficulty is that there are only few people that 
> actually work on the VM (why?).

Because it's hard. In this case, the problem is largely that you can't 
debug this stuff in the simulator because the simulator still uses 
Squeak semantics (i.e., unlimited integer arithmetic). For example, if 
you have code saying "a + b < c ifTrue:[...]" then in C this may have 
some very odd results (depending on the types of a, b, and c, as well as 
their values) whereas in the simulator the result is always the same 
(since we don't type variables).

> Apart from the bug you mention 
> (http://bugs.impara.de/view.php?id=0005056) there are others. For example:
> - http://bugs.impara.de/view.php?id=4709 (VM blocks after memory 
> consumtion exceeds ~120MB)

John has answered that one already. There is a simple application-level 
workaround for it.

> - http://bugs.impara.de/view.php?id=4882 (VM lockup)

John has replied to that one as well (and not being a Unix guy I have 
nothing to add).

   - Andreas

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