The client doesn't reconnect automatically, or explicitly.  I just get BrokenPipeError over and over.


Manager:
    import multiprocessing.managers, os, sys, time
    class TestClass(object):
        def test_method(self):
            print("In test_method")
            return "TEST"

    class TestManager(multiprocessing.managers.BaseManager):
        pass

    address = ("127.0.0.1", 54321)
    TestManager.register("Test", TestClass)
    manager = TestManager(address = address, authkey = "1234".encode("utf-8"))
    manager.get_server().serve_forever()


Client:
    import multiprocessing.managers, os, sys, time

    class TestManager(multiprocessing.managers.BaseManager):
        pass

    address = ("127.0.0.1", 54321)
    TestManager.register("Test")
    manager = TestManager(address = address, authkey = "1234".encode("utf-8"))
    manager.connect()
    test_class = manager.Test()

    def call_it():
        time.sleep(1)
        result = test_class.test_method()
        print("result: '" + str(type(result)) + ", " + str(result) + "'")

    call_it()

    print("Kill and restart the server and press return")
    sys.stdin.readline()

    error = False
    while (True):
        try:
            if (error):
                print("Reconnecting")
                manager.connect()
                test_class = manager.Test()
            call_it()
            error = False
        except Exception as e:
            print("Got exception " + str(type(e)) + ", " + repr(e))
            error = True
        time.sleep(1)

Michael Boon wrote:
-------------------
> The [above] issue is pretty serious and it is preventing me from using a
> system I wrote on a larger scale.

That statement suggests you were able to get this working on a small scale -- is that correct?  What does the working small-scale code look like?

I don't think I even got this working on the small scale.  The unit test in the bug report is about as small as it gets and it doesn't work.  The issue still exists in Python 3.9.5.

Here is the test, reduced and in a single script:

--- 8< --------------------------------------------------------------------
import multiprocessing.managers, os, sys, time

if __name__ == '__main__':
    address = ("127.0.0.1", 54321)

    class TestManager(multiprocessing.managers.BaseManager):
        pass

    if sys.argv[1] == 'server':

        class TestClass(object):
            def test_method(self):
                print("In test_method")
                return "TEST"

        TestManager.register("Test", TestClass)
        manager = TestManager(address = address, authkey = "1234".encode("utf-8"))
        print('waiting...')
        manager.get_server().serve_forever()

    else:

        TestManager.register("Test")

        manager = TestManager(address = address, authkey = "1234".encode("utf-8"))
        manager.connect()
        test_class = manager.Test()

        print(test_class.test_method())

        print("Kill and restart the server and press return")
        sys.stdin.readline()

        try:
            print(test_class.test_method())
        except EOFError:
            print('EOF received\n')

        # reestablish connection
        manager.connect()
        test_class = manager.Test()

        # trigger error
        print(test_class.test_method())
--- 8< --------------------------------------------------------------------

Running it in two terminals gives (only showing client side):

---------------------------------------------------------------------------
$ ./python ~/test_mp client
TEST
Kill and restart the server and press return
# hit <return>
EOF received

Traceback (most recent call last):
  File "/home/ethan/test_mp", line 45, in <module>
    print(test_class.test_method())
  File "<string>", line 2, in test_method
  File "/source/virtualenv/lib/python3.9/multiprocessing/managers.py", line 808, in _callmethod
    conn.send((self._id, methodname, args, kwds))
  File "/source/virtualenv/lib/python3.9/multiprocessing/connection.py", line 211, in send
    self._send_bytes(_ForkingPickler.dumps(obj))
  File "/source/virtualenv/lib/python3.9/multiprocessing/connection.py", line 416, in _send_bytes
    self._send(header + buf)
  File "/source/virtualenv/lib/python3.9/multiprocessing/connection.py", line 373, in _send
    n = write(self._handle, buf)
BrokenPipeError: [Errno 32] Broken pipe
---------------------------------------------------------------------------

The problem appears to be that the call to `manager.connect()` after the EOF is not getting a new connection, but is reusing the old one (?).  This is as far as I can take this; hopefully somebody with more multiprocessing/socket skills can take it from here.

Is there anything that I can do, or the company I work for can do, to get a developer assigned to fix this bug?  It is hard to use multiprocessing remote method calls without this bug being fixed.  The software wouldn't be robust enough for production.