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
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
mailto:eric@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-leave@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/QVQWSN... Code of Conduct: http://python.org/psf/codeofconduct/