[Haskell-cafe] GHC 7.0.1 developer challenges

Peter Simons simons at cryp.to
Wed Dec 15 16:50:56 CET 2010

Hi John,

 > I think the previous responder was asserting the 32M limit, not you.

I believe the previous poster suggested that you use ulimit to provide a
hard upper bound for run-time memory use. That 32M figure seemed to be made
up out of thin air just as an example to illustrate the syntax of the ulimit
command. I don't have the impression that it was meant be any significant.

 > [My program allows] users to set a step count bound, after which the
 > program aborts. But guess what users do. They keep increasing the step
 > count bound to see if just a few more steps will allow termination on
 > their problem. Of course, some end up setting the bound so high, that
 > thrashing occurs.

I see. I must have misunderstood the situation. From your original posting,
I got the impression that the program would depend on an externally enforced
memory limit just to terminate at all!

 > So for implementations of undecidable algorithms, you really need an
 > intelligent memory bound on the GHC runtime.

Well, some sort of externally enforced memory limit is useful, yes, but you
don't strictly need that functionality in GHC. You can just as well use the
operating system to enforce that limit, i.e. by means of 'ulimit'.

Take care,

More information about the Haskell-Cafe mailing list