Steven D'Aprano <ste...@remove.this.cybersource.com.au> writes: >> min() and max() don't release the GIL, so yes, they are safe, and >> shouldn't see a list in an inconsistent state (with regard to the >> Python interpreter, but not necessarily to your application). But a >> threaded approach is somewhat silly, since the GIL ensures that they >> *won't* walk over the same list simultaneously (two separate lists, >> for that matter). > > Perhaps that's true for list contents which are built-ins like ints, > but with custom objects, I can demonstrate that the two threads > operate simultaneously at least sometimes. Unless I'm misinterpreting > what I'm seeing.
If min and max call into Python code, which can happen for custom objects, then the interpreter will occasionally release the GIL to give other threads a chance to run. That way min and max will operate interleaved (if not exactly in parallel). Even so, I see no reason for them to break. -- http://mail.python.org/mailman/listinfo/python-list
