nicolas_riesch wrote: > Does someone know if the module pytz > (http://sourceforge.net/projects/pytz/) is thread-safe ?
On that, I don't know. > That's because in the file pytz/tzinfo.py, I see global variables > _timedelta_cache, _datetime_cache, _ttinfo_cache, which are > dictionnaries and are used as cache. > I always thought that you must protect shared data with locks when > multithreading, but I don't see any lock anywhere in pytz. Definitely stick with what you always thought. > However, pytz seems to work well with multiple threads creating various > timezone objects at the same time. Buggy threading can seem to work well for along time. It may be a billion-to-one shot that a thread switch happens at just the wrong time. > I don't understand where the trick is, that allows multiple threads to > access this module without any locking and that all this seems to work > without any problem... > > Does this mean that there is a means to write a module that is > thread-safe, without importing the threading module and creating locks > ? > > Or have I not understood something ...? > > Can someone give me a hint ? In the current Python implementation, more things are atomic than the language guarantees to be atomic. Programmers should not depend on that behavior. Again, I don't know anything about pytz, but we wouldn't bother with locks and semaphores and such if we could make the problems go away just by ignoring them. -- --Bryan -- http://mail.python.org/mailman/listinfo/python-list
