dieter <die...@handshake.de>: > Every system you use has its advantages and its drawbacks. > Depending on the specific context (problem, resources, knowledge, ...), > you must choose an appropriate one.
Yep. I use Python for numerous tasks professionally and at home. Just this past week I used it to plan a junior soccer winter tournament. Python is used to verify various team and match constraints and Sudoku-solver-type match order generation. > Python uses the GIL mainly because it uses reference counting (with > almost constant changes to potentially concurrently used objects) for > memory management. Dropping the GIL would mean dropping reference > counting likely in favour of garbage collection. Reference counting was likely a bad idea to begin with. > I work in the domain of web applications. And I made there a nasty > experience with garbage collection: occasionally, the web application > stopped to respond for about a minute. A (quite difficult) analysis > revealed that some (stupid) component created in some situations (a > search) hundreds of thousands of temporary objects and thereby > triggered a complete garbage collection. The garbage collector started > its mark and sweep phase to detect unreachable objects - traversing a > graph of millions of objects. > > As garbage collection becomes drastically more complex if the object > graph can change during this phase (and this was Python), a global > look prevented any other activity -- leading to the observed > latencies. Yes. The occasional global freeze is unavoidable in any garbage-collected runtime environment regardless of the programming language. However, I challenge the notion that creating hundreds of thousands of temporary objects is stupid. I suspect that the root cause of the lengthy pauses is that the program maintains millions of *nongarbage* objects in RAM (a cache, maybe?). > When I remember right, there are garbage collection schemes that > can operate safely without stopping other concurrent work. There are heuristics, but I believe the worst case is the same. > Nevertheless, even those garbage collectors have a significant impact > on performance when they become active (at apparently > non-deterministic times) and that may be inacceptable for some > applications. If performance is key, Python is probably not the answer. Python's dynamism make it necessarily much slower than, say, Java or Go. Marko -- https://mail.python.org/mailman/listinfo/python-list
