Re: Garbage collection bug

[Andreas Røsdal]

Hello Rob,


On Sat, 29 Jul 2006, Rob Browning wrote:
> 
> It might be helpful to describe the Guile version involved,

Guile 1.6.7

> the
> machine architecture,

Intel Pentium x86, running on OpenSuSE 10.1.

> and roughly where you think the bug might be
> occurring.  

I think the bug is occuring in /aisleriot/sol.scm, where the garbage 
collector prematurely gabage collects the list of cards.
Here is a patch we tried to create, to fix the bug:
http://bugzilla.gnome.org/attachment.cgi?id=69406&action=view
(The patch didn't solve the problem.)

> In particular is there some specific bit of the C code
> that you're concerned about?

As described here, http://bugzilla.gnome.org/show_bug.cgi?id=342038
we think the bug is caused by premature garbage collection. 
When the cards get dragged the list of cards is kept purely on the C side 
of the code - hence there is an opportunity for them to get garbage 
collected. guile has some mechanisms for tracking its objects on the C 
side, but our code doesn't fall into that category (since 
the objects aren't kept on the stack, they're put in a list).

 - Andreas