Chris Angelico <ros...@gmail.com>: > On Sun, Jul 8, 2018 at 11:04 AM, Steven D'Aprano > <steve+comp.lang.pyt...@pearwood.info> wrote: >>> The only thing Python should guarantee is that the data structures stay >>> "coherent" under race conditions. In other words, there cannot be a >>> segmentation fault. For example, if two threads executed this code in >>> parallel: >>> >>> global i >>> i = 1 >>> i += 1 >>> >>> a legal end result could be that i contains the string "impossible". >> >> That wouldn't be coherent. The only coherent results are that i could >> equal either 2 or 3: > > Python threads don't switch only between lines of code, so the actual > interaction is a bit more complicated than you say. [...] > > But you're absolutely right that there are only a small handful of > plausible results, even with threading involved.
You are on the right track, Chris, but you are still deducing behavior from a particular implementation. For example Java's definition is approximately the one I give above: Without correct synchronization, very strange, confusing and counterintuitive behaviors are possible. <URL: https://docs.oracle.com/javase/specs/jls/se7/html/jls-17.htm l#jls-17.4.5> And we know that Python has been implemented using Java... Marko -- https://mail.python.org/mailman/listinfo/python-list
