Apple Open Sources Snow Leopard's Grand Central Dispatch (Apple Insider)

I'm not suggesting any kind of rich management API - just a scheduling class that runs threads one at a time and never pre-empts one thread to run another. If they are all batch jobs and all of the same priority, there is no need for preemption.

You're right, the choice to start 500 threads is itself a bit arbitrary. What I mean is if you know that (for whatever reason) you want to start 500, why hold back for fear of overwhelming the poor kernel with too many at once? Surely you should just be able to create them, and the kernel will decide for itself when to schedule each one.