PyArrow Plasma object ids, "sealing" makes an object immutable, pyristent
https://arrow.apache.org/docs/python/plasma.html#object-ids https://arrow.apache.org/docs/python/plasma.html#creating-an-object-buffer > Objects are created in Plasma in two stages. First, they are created, which allocates a buffer for the object. At this point, the client can write to the buffer and construct the object within the allocated buffer. > > To create an object for Plasma, you need to create an object ID, as well as give the object’s maximum size in bytes. > ```python > # Create an object buffer. > object_id = plasma.ObjectID(20 * b"a") > object_size = 1000 > buffer = memoryview(client.create(object_id, object_size)) > > # Write to the buffer. > for i in range(1000): > buffer[i] = i % 128 > ``` > > When the client is done, the client seals the buffer, making the object immutable, and making it available to other Plasma clients. > > ```python > # Seal the object. This makes the object immutable and available to other clients. > client.seal(object_id) > ``` https://pypi.org/project/pyrsistent/ also supports immutable structures On Sat, Aug 1, 2020 at 4:44 PM Eric V. Smith <e...@trueblade.com> wrote: > On 8/1/2020 1:25 PM, Marco Sulla wrote: > > You don't need locks with immutable objects. Since they're immutable, > > any operation that usually will mutate the object, generate another > > immutable instead. The most common example is str: the sum of two > > strings in Python (and in many other languages) produces a new string. > > 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. > > Eric > > _______________________________________________ > 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/FEJEHFKBK7TMH6KIYJBPLBYBDU4IA4EB/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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