The GIL is mostly a problem for cpu bound programs. GC pauses in Python really aren't much of an issue, partly because Python uses refcounting (ironically the

The GIL is mostly a problem for cpu bound programs. GC pauses in Python really aren't much of an issue, partly because Python uses refcounting (ironically the cause of the GIL) so it usually frees stuff as it goes along, keeping pauses pretty short. Even with a real GC though, I think it's usually not much of a problem. I've written Python gui's in multi-threaded (but not too compute intensive) apps on quite slow processors by today's standards, and there wasn't much of a problem in UI responsiveness. I think it's important to remember the difference between parallelism (trying to compute faster by using multiple cpu's simultaneously) and concurrency (communicating on multiple communication channels that are sending stuff non-deterministically). The GIL gets in the way of parallelism but except in extreme cases, it doesn't interfere with concurrency.