[Python-Dev] Trial balloon: microthreads library in stdlib (original) (raw)

Steve Holden steve at holdenweb.com
Tue Feb 13 09:19:41 CET 2007

Martin v. Löwis wrote:

Richard Tew schrieb:

I can't point you to the posts, but I can point you to something Christian has written on the subject which may indicate why it was never actually submitted for inclusion.

See "A Bit Of History" http://svn.python.org/view/stackless/trunk/Stackless/readme.txt I have not talked to Christian about it but as the current maintainer of Stackless I was under the impression that there was a complete lack of interest in even considering it for integration. I think this comes from a major misunderstanding of how free software works. This is not commercial software, so there is no "company agenda" that drives it forward. There are various contributors, each having their own agenda; for most of us, it's "scratch your own itches". Surely, the voices of people have varying significance (in Python, Guido is the BDFL, for example), but "there was a complete lack of interest in even considering" just cannot be true: clearly, some contributors and users were interested. There were surely objections to the implementation strategy, and I also had objections to the specific execution of this implementation strategy, see http://tinyurl.com/27v23r Now, the question is whose "job" it would have been to integrate Stackless to Python. Apparently, Christian tried to make it happen (see http://tinyurl.com/3bqe5d), although I'm still uncertain whether he ever got to a point where he said: "this is a patch, please review it" (of that, I can find no archives, as I said). I find it understandable that nobody else took over to work on integrating it (although there is PEP 219, so apparently some people worked at some point on it). From my point of view, people suggesting to incorporate code as-is often misunderstand that it is not sufficient for the code to work in the applications were it is used. It must also be sound (i.e. work in some meaningful way also in cases for which it wasn't designed), and it must be maintainable. I can understand how discouraging it is when you see that your code "works" that then people object to incorporating it as-is. However, I believe the long-term quality of Python can only be guaranteed when careful review is applied to every change made, or else we will regret changes in the future (and indeed, Python 3000 would not have been necessary if no mistakes had been made). If addition of microthreading is being considered please consider Stackless. One reason why Stackless is not so popular is that as a fork people shy away from it because it is not the main version. It would benefit Stackless to be integrated and I would be willing to do any work involved to either integrate or maintain it afterwards. This is what I'm talking about: nothing "is" ever considered. Instead, individuals make contributions, individuals review them, and individuals support and object to changes. There is no abstract python-dev entity that likes or dislikes changes. Individuals have individual opinions. Now, where is the SF patch that makes Stackless part of Python ?-) (and if you are serious about it, try to break it down into multiple pieces, each individually correct and useful; start with one where the effort isn't too big in case it gets rejected by BDFL pronouncement) I haven't reviewed the Stackless code in a while; last I looked, I found it was possible to crash the interpreter if you use it "incorrectly". I personally object to changes where it is easy to crash the interpreter, unless there is a clear specification when this may happen, and there is a systematic way to avoid that (this is the ctypes clause). Well given that ctypes has now been incorporated I suspect that the objections to Stackless might be different should a further integration "effort" materialise. I know that there's work in progress (and indeed almost complete) to put Stackless into 2.5, so it seems as though it might be practical to follow the approach you suggest.

The only things that concern me are a) whether it could make sense to add Stackless in bits and pieces and b) whether the BDFL (or even the developer community en masse) would object in principle, thereby rendering such efforts useless.

My (limited) understanding is that with Stackless installed all existing programs that don't import stackless should continue to run unchanged. If that's true then it seems to me it would be a desirable addition as long as maintainability wasn't compromised. I suppose only the patches will allow a sensible judgment on that issue.

regards Steve

Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://del.icio.us/steve.holden Blog of Note: http://holdenweb.blogspot.com See you at PyCon? http://us.pycon.org/TX2007

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