Will S added the comment:
Documentation would be appreciated. I have a project that uses BaseManager,
Client, and Listener to create some servers and clients. I would like to update
the project to work with Python 3 and would prefer to update the clients and
the servers separately (i.e. switch the client to Python 3 while the server is
run with Python 2.7). However, BaseManager uses connection.Client which uses
connection._ConnectionBase which uses reduction.ForkingPickler without a
protocol argument. It seems the default protocol is 3 on Python 3.6 and 2 on
Python 2.7 (contrary to the comment above about v2 being used). I just want to
set the protocol version to 2 in Python 3.6. Can I do that with the changes
added by this patch?
I tried creating pickle2reducer.py like this:
from multiprocessing.reduction import ForkingPickler, AbstractReducer
class ForkingPickler2(ForkingPickler):
def __init__(self, *args):
if len(args) > 1:
args[1] = 2
else:
args.append(2)
super().__init__(*args)
@classmethod
def dumps(cls, obj, protocol=2):
return ForkingPickler.dumps(obj, protocol)
def dump(obj, file, protocol=2):
ForkingPickler2(file, protocol).dump(obj)
class Pickle2Reducer(AbstractReducer):
ForkingPickler = ForkingPickler2
register = ForkingPickler2.register
dump = dump
and then putting
import pickle2reducer
multiprocessing.reducer = pickle2reducer.Pickle2Reducer()
at the top of my module before
import multiprocessing.connection
but I still see "ValueError: unsupported pickle protocol: 3" on the server when
I connect with a Python 3.6 client.
--
nosy: +Will S
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