Re: GOP-PROP 8: issue priorities (probable decision)

[Trevor Daniels]

David Kastrup wrote Saturday, August 13, 2011 6:12 AM

> It crashes because the internal garbage collector data structures 
> have
> been clobbered.  Which is likely due to some Lilypond code problem 
> (like
> data available too early for collection).  So it is likely that we 
> are
> not "powerless to resolve the issue", but since the crash is 
> happening
> at a point rather remote from the likely bug and is quite 
> sensitive to
> the memory layout of the code, it is really hard to track down.

This type of problem used to occur quite frequently in 1970s
IBM operating systems, when all the code of the OS ran in the
same address space.  The hardest bugs to find and fix were
when something was clobbered in a way which caused a crash
much later.  In fact most of these were never resolved.  The only
way to make progress (when it was possible) was to identify a
signature of the crash which allowed a trap to be set so a core
dump could be obtained a little earlier, and repeat.  Often setting
the trap disturbed things in such a way that the crash no longer
occurred because something less critical was being clobbered.
Maybe that was a fix of some sort.

Even that approach doesn't seem possible here, as we don't
have access to the garbage collector.

Trevor




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