Queue between Python2 and Python3












1















I have a very simple queue which is used between Python3 modules in Raspberry Pi. I want to send messages to the same queue from one Python2 module. Does not work.



Server is running in Python3 as in this example:



from multiprocessing.managers import BaseManager
import Queue
queue = Queue.Queue()
class QueueManager(BaseManager): pass
QueueManager.register('get_queue', callable=lambda:queue)
m = QueueManager(address=('', 50000), authkey='abracadabra')
s = m.get_server()
s.serve_forever()


Sender is like this:



from multiprocessing.managers import BaseManager
class QueueManager(BaseManager): pass
QueueManager.register('get_queue')
m = QueueManager(address=('foo.bar.org', 50000), authkey='abracadabra')
m.connect()
queue = m.get_queue()
queue.put('hello')


With both only in Python3 or in Python2 everything runs perfectly. If server is in Python3 and sender is in Python2, result is the following error:




Blockquote



Traceback (most recent call last):
File "sender_V2.py", line 22, in m.connect()
File "/usr/lib/python2.7/multiprocessing/managers.py", line 501, in connect >dispatch(conn, None, 'dummy')
File "/usr/lib/python2.7/multiprocessing/managers.py", line 102, in dispatch >kind, result = c.recv()
ValueError: unsupported pickle protocol: 3











share|improve this question


















  • 2





    Python 2 can't deserialise data pickled by Python 3 using the latest protocol, see e.g. docs.python.org/3/library/pickle.html#data-stream-format. There's a workaround here, but you might be better using a proper external queue where you can control the serialisation format. See also stackoverflow.com/q/54135972/3001761

    – jonrsharpe
    Jan 20 at 15:30













  • It might be easier to just use language agnostic MQ like ZeroMQ, Protobufs, or even just simple JSON over UDP.

    – Gillespie
    Jan 20 at 18:54











  • Unfortunately changing the existing solution to something new is too much work. It is surprising that compatibility mode between between Python 2 and Python 3 is not available. Should not be too difficult, because the same code using queue works exactly the same way in both pythons. Naturally with the known syntax changes.

    – Juhani Miettunen
    Jan 21 at 6:55











  • This is the easiest way to go: stackoverflow.com/questions/27863832/…

    – Juhani Miettunen
    Jan 22 at 10:36
















1















I have a very simple queue which is used between Python3 modules in Raspberry Pi. I want to send messages to the same queue from one Python2 module. Does not work.



Server is running in Python3 as in this example:



from multiprocessing.managers import BaseManager
import Queue
queue = Queue.Queue()
class QueueManager(BaseManager): pass
QueueManager.register('get_queue', callable=lambda:queue)
m = QueueManager(address=('', 50000), authkey='abracadabra')
s = m.get_server()
s.serve_forever()


Sender is like this:



from multiprocessing.managers import BaseManager
class QueueManager(BaseManager): pass
QueueManager.register('get_queue')
m = QueueManager(address=('foo.bar.org', 50000), authkey='abracadabra')
m.connect()
queue = m.get_queue()
queue.put('hello')


With both only in Python3 or in Python2 everything runs perfectly. If server is in Python3 and sender is in Python2, result is the following error:




Blockquote



Traceback (most recent call last):
File "sender_V2.py", line 22, in m.connect()
File "/usr/lib/python2.7/multiprocessing/managers.py", line 501, in connect >dispatch(conn, None, 'dummy')
File "/usr/lib/python2.7/multiprocessing/managers.py", line 102, in dispatch >kind, result = c.recv()
ValueError: unsupported pickle protocol: 3











share|improve this question


















  • 2





    Python 2 can't deserialise data pickled by Python 3 using the latest protocol, see e.g. docs.python.org/3/library/pickle.html#data-stream-format. There's a workaround here, but you might be better using a proper external queue where you can control the serialisation format. See also stackoverflow.com/q/54135972/3001761

    – jonrsharpe
    Jan 20 at 15:30













  • It might be easier to just use language agnostic MQ like ZeroMQ, Protobufs, or even just simple JSON over UDP.

    – Gillespie
    Jan 20 at 18:54











  • Unfortunately changing the existing solution to something new is too much work. It is surprising that compatibility mode between between Python 2 and Python 3 is not available. Should not be too difficult, because the same code using queue works exactly the same way in both pythons. Naturally with the known syntax changes.

    – Juhani Miettunen
    Jan 21 at 6:55











  • This is the easiest way to go: stackoverflow.com/questions/27863832/…

    – Juhani Miettunen
    Jan 22 at 10:36














1












1








1








I have a very simple queue which is used between Python3 modules in Raspberry Pi. I want to send messages to the same queue from one Python2 module. Does not work.



Server is running in Python3 as in this example:



from multiprocessing.managers import BaseManager
import Queue
queue = Queue.Queue()
class QueueManager(BaseManager): pass
QueueManager.register('get_queue', callable=lambda:queue)
m = QueueManager(address=('', 50000), authkey='abracadabra')
s = m.get_server()
s.serve_forever()


Sender is like this:



from multiprocessing.managers import BaseManager
class QueueManager(BaseManager): pass
QueueManager.register('get_queue')
m = QueueManager(address=('foo.bar.org', 50000), authkey='abracadabra')
m.connect()
queue = m.get_queue()
queue.put('hello')


With both only in Python3 or in Python2 everything runs perfectly. If server is in Python3 and sender is in Python2, result is the following error:




Blockquote



Traceback (most recent call last):
File "sender_V2.py", line 22, in m.connect()
File "/usr/lib/python2.7/multiprocessing/managers.py", line 501, in connect >dispatch(conn, None, 'dummy')
File "/usr/lib/python2.7/multiprocessing/managers.py", line 102, in dispatch >kind, result = c.recv()
ValueError: unsupported pickle protocol: 3











share|improve this question














I have a very simple queue which is used between Python3 modules in Raspberry Pi. I want to send messages to the same queue from one Python2 module. Does not work.



Server is running in Python3 as in this example:



from multiprocessing.managers import BaseManager
import Queue
queue = Queue.Queue()
class QueueManager(BaseManager): pass
QueueManager.register('get_queue', callable=lambda:queue)
m = QueueManager(address=('', 50000), authkey='abracadabra')
s = m.get_server()
s.serve_forever()


Sender is like this:



from multiprocessing.managers import BaseManager
class QueueManager(BaseManager): pass
QueueManager.register('get_queue')
m = QueueManager(address=('foo.bar.org', 50000), authkey='abracadabra')
m.connect()
queue = m.get_queue()
queue.put('hello')


With both only in Python3 or in Python2 everything runs perfectly. If server is in Python3 and sender is in Python2, result is the following error:




Blockquote



Traceback (most recent call last):
File "sender_V2.py", line 22, in m.connect()
File "/usr/lib/python2.7/multiprocessing/managers.py", line 501, in connect >dispatch(conn, None, 'dummy')
File "/usr/lib/python2.7/multiprocessing/managers.py", line 102, in dispatch >kind, result = c.recv()
ValueError: unsupported pickle protocol: 3








python python-3.x






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Jan 20 at 15:24









Juhani MiettunenJuhani Miettunen

61




61








  • 2





    Python 2 can't deserialise data pickled by Python 3 using the latest protocol, see e.g. docs.python.org/3/library/pickle.html#data-stream-format. There's a workaround here, but you might be better using a proper external queue where you can control the serialisation format. See also stackoverflow.com/q/54135972/3001761

    – jonrsharpe
    Jan 20 at 15:30













  • It might be easier to just use language agnostic MQ like ZeroMQ, Protobufs, or even just simple JSON over UDP.

    – Gillespie
    Jan 20 at 18:54











  • Unfortunately changing the existing solution to something new is too much work. It is surprising that compatibility mode between between Python 2 and Python 3 is not available. Should not be too difficult, because the same code using queue works exactly the same way in both pythons. Naturally with the known syntax changes.

    – Juhani Miettunen
    Jan 21 at 6:55











  • This is the easiest way to go: stackoverflow.com/questions/27863832/…

    – Juhani Miettunen
    Jan 22 at 10:36














  • 2





    Python 2 can't deserialise data pickled by Python 3 using the latest protocol, see e.g. docs.python.org/3/library/pickle.html#data-stream-format. There's a workaround here, but you might be better using a proper external queue where you can control the serialisation format. See also stackoverflow.com/q/54135972/3001761

    – jonrsharpe
    Jan 20 at 15:30













  • It might be easier to just use language agnostic MQ like ZeroMQ, Protobufs, or even just simple JSON over UDP.

    – Gillespie
    Jan 20 at 18:54











  • Unfortunately changing the existing solution to something new is too much work. It is surprising that compatibility mode between between Python 2 and Python 3 is not available. Should not be too difficult, because the same code using queue works exactly the same way in both pythons. Naturally with the known syntax changes.

    – Juhani Miettunen
    Jan 21 at 6:55











  • This is the easiest way to go: stackoverflow.com/questions/27863832/…

    – Juhani Miettunen
    Jan 22 at 10:36








2




2





Python 2 can't deserialise data pickled by Python 3 using the latest protocol, see e.g. docs.python.org/3/library/pickle.html#data-stream-format. There's a workaround here, but you might be better using a proper external queue where you can control the serialisation format. See also stackoverflow.com/q/54135972/3001761

– jonrsharpe
Jan 20 at 15:30







Python 2 can't deserialise data pickled by Python 3 using the latest protocol, see e.g. docs.python.org/3/library/pickle.html#data-stream-format. There's a workaround here, but you might be better using a proper external queue where you can control the serialisation format. See also stackoverflow.com/q/54135972/3001761

– jonrsharpe
Jan 20 at 15:30















It might be easier to just use language agnostic MQ like ZeroMQ, Protobufs, or even just simple JSON over UDP.

– Gillespie
Jan 20 at 18:54





It might be easier to just use language agnostic MQ like ZeroMQ, Protobufs, or even just simple JSON over UDP.

– Gillespie
Jan 20 at 18:54













Unfortunately changing the existing solution to something new is too much work. It is surprising that compatibility mode between between Python 2 and Python 3 is not available. Should not be too difficult, because the same code using queue works exactly the same way in both pythons. Naturally with the known syntax changes.

– Juhani Miettunen
Jan 21 at 6:55





Unfortunately changing the existing solution to something new is too much work. It is surprising that compatibility mode between between Python 2 and Python 3 is not available. Should not be too difficult, because the same code using queue works exactly the same way in both pythons. Naturally with the known syntax changes.

– Juhani Miettunen
Jan 21 at 6:55













This is the easiest way to go: stackoverflow.com/questions/27863832/…

– Juhani Miettunen
Jan 22 at 10:36





This is the easiest way to go: stackoverflow.com/questions/27863832/…

– Juhani Miettunen
Jan 22 at 10:36












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