Revisiting thread priorities and the new GIL

[gthank]

http://www.dabeaz.com/blog/2010/02/revisiting-thread-priorities-and-new.html

[viraptor]

Can anyone explain shortly, or point to a source describing why is the GIL actually needed? Lots of sources say "it would make GC very complicated otherwise", or "current design would need lots of changes", but I cannot find any detailed answers. The question is - why cannot python migrate to a Boehm-like GC with "stop the world" step and kill the GIL completely?

What is the biggest problem?

Update: actually the official wiki turned out to have some of the answers... http://wiki.python.org/moin/GlobalInterpreterLock - it seems that backwards compatibility (extensions, destruction timing) is the biggest problem

[ableal → viraptor]

You're asking a bit more than is answered directly here, but it may help, if you haven't seen it yet (skip to the middle of the page): http://jessenoller.com/2009/02/01/python-threads-and-the-glo...

[viraptor → ableal]

Yup - that link's got a lot more details missing elsewhere. Thanks a lot!