sharedctypes can only be used with related processes. There is no way that you can pass a sharedctype to an unrelated process. multiprocessing.shared_memory was created to handle this i.e. allow usage of shared memory IPC across unrelated processes.
> On 02-Aug-2020, at 9:42 PM, Marco Sulla <marco.sulla.pyt...@gmail.com> wrote: > > There's also the possibility to use shared ctypes: > https://docs.python.org/3/library/multiprocessing.html#shared-ctypes-objects > <https://docs.python.org/3/library/multiprocessing.html#shared-ctypes-objects> > > Operations like += which involve a read and write are not atomic. So if, for > instance, you want to atomically increment a shared value it is insufficient > to just do > counter.value += 1 > > Assuming the associated lock is recursive (which it is by default) > you can instead do > > with counter.get_lock(): > counter.value += 1 > > Notice that they use a lock anyway. Maybe the solution of Wes Turner is > better. See also RLock: > https://docs.python.org/3/library/multiprocessing.html#multiprocessing.RLock > <https://docs.python.org/3/library/multiprocessing.html#multiprocessing.RLock> > On Sat, 1 Aug 2020 at 22:42, Eric V. Smith <e...@trueblade.com > <mailto:e...@trueblade.com>> wrote: > While they're immutable at the Python level, strings (and all other > objects) are mutated at the C level, due to reference count updates. You > need to consider this if you're sharing objects without locking or other > synchronization. > > > This is interesting. What if you want to have a language that uses only > immutable objects and garbage collection? Could smart pointers address this > problem? > _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/QVQWSNWJMMMRVFA6BTXDNJHIGAUBPWVX/ > Code of Conduct: http://python.org/psf/codeofconduct/
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