I sort of skimmed ESR's post, and sort of skimmed this thread, so obviously I'm totally qualified to offer my observations on the post and follow ups. :-)
Eric makes a mistake, in my opinion, confusing his particular application with the mainstream, when in fact it seems pretty specialized to me. Consequently, he foresees the waning of Python, in my opinion, incorrectly. As to the problems posed by the GIL, I am aware of serious attempts to remove it at least as far back as Python ~ 1.4 (by Greg Smith, as I recall). His experience was what has been reported in this thread. While he could improve CPU utilization for multi-threaded applications, that came at an unacceptable performance cost for single-threaded applications, which I believe still dominate the application landscape today. Beyond performance, there is the issue that the GIL keeps extension authors from shooting themselves in the foot. When your code is called, the GIL insures that nobody else can stomp on your data when you are executing. Skip Montanaro -- https://mail.python.org/mailman/listinfo/python-list