Thread safety is very complex and has an impact on performance. I dislike the idea of providing such property to generators which can have a complex next method.
IMHO it's better to put a generator in wrapper which adds thread safety. What do you think? Victor Le 14 avr. 2017 18:48, "Serhiy Storchaka" <storch...@gmail.com> a écrit : > When use a generator from different threads you can get a ValueError > "generator already executing". Getting this exception with the single > thread is a programming error, it in case of different threads it could be > possible to wait until other thread finish executing the generator. The > generator can be made thread-safe after wrapping it in a class that acquire > a lock before calling the generator's __next__ method (for example see > [1]). But this is not very efficient of course. > > I wondering if it is worth to add support of thread-safe generators in the > stdlib. Either by providing standard decorator (written in C for > efficiency), or adding threading support just in the generator object. The > latter may need increasing the size of the generator object for a lock and > thread identifier (but may be GIL is enough), but should not affect > performance since locking is used only when you faced with a generator > running in other thread. > > This topic already was raised on Python-Dev [2] but didn't moved too much. > There are a number of StackOverflow questions about threads and generators. > We have already encountered this issue in the stdlib. Once in regrtest with > the -j option ([3], [4]), other time after reimplementing > tempfile._RandomNameSequence as a generator [5]. > > [1] http://anandology.com/blog/using-iterators-and-generators/ > [2] https://mail.python.org/pipermail/python-dev/2004-February/042390.html > [3] https://bugs.python.org/issue7996 > [4] https://bugs.python.org/issue15320 > [5] https://bugs.python.org/issue30030 > > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ >
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