On 18 July 2017 at 05:42, Raymond Hettinger <raymond.hettin...@gmail.com> wrote: > One minor grumble: I think we need to give careful cost/benefit > considerations to optimizations that complicate the implementation. Over the > last several years, the source for Python has grown increasingly complicated. > Fewer people understand it now. It is much harder to newcomers to on-ramp. > The old-timers (myself included) find that their knowledge is out of date. > And complexity leads to bugs (the C optimization of random number seeding > caused a major bug in the 3.6.0 release; the C optimization of the lru_cache > resulted in multiple releases having a hard to find threading bugs, etc.). > It is becoming increasingly difficult to look at code and tell whether it is > correct (I still don't fully understand the implications of the recursive > constant folding in the peephole optimizer for example). In the case of > this named tuple proposal, the complexity is manageable, but the overall > trend isn't good and I get the feeling the aggressive optimization is causing > us to forget key p ar > ts of the zen-of-python.
As another example of this: while trading the global import lock for per-module locks eliminated most of the old import deadlocks, it turns out that it *also* left us with some fairly messy race conditions and more fragile code (I still count that particular case as a win overall, but it definitely raises the barrier to entry for maintaining that code). Unfortunately, these are frequently cases where the benefits are immediately visible (e.g. faster benchmark results, removing longstanding limitations on user code), but the downsides can literally take years to make themselves felt (e.g. higher defect rates in the interpreter, subtle bugs in previously correct user code that are eventually traced back to interpreter changes). Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
