[racket] debugging core dump - comments appreciated

At Mon, 23 May 2011 18:35:12 -0400, Neil Van Dyke wrote:
> Looks like that bug fix was after 4.2.5, and indeed we are on x86_64.  
> However, we happened to have JIT disabled for the stress-testing that 
> caused the core dump.  Two questions:
> 
> 1. Would that bug you mentioned (or perhaps a very similar bug elsewhere 
> in the code) affect us if JIT were disabled?  Or is that code only 
> called if JIT is enabled?

It's only if the JIT is enabled. (I should have noticed from the stack
trace that you must have the JIT disabled.)

> 2. In general, if we have JIT disabled, are we ever running code paths 
> that no one else does, because everyone else uses JIT?

That doesn't seem likely. The JIT only applies to code under `lambda',
and there's enough variation in module top levels that probably all
core forms get used in interpreted mode all the time. We also run some
tests with the JIT disabled as part of the nightly build.

> (Or, similarly, 
> is it reasonably possible that we would encounter bugs that no one else 
> does because everyone is running the probematic code but the JIT is 
> mitigating somehow and avoiding the error condition?)

It doesn't sound likely to me.