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I've recently started seeing this failure repeatably on Linux (Ubuntu Jaunty):
[195/364] test_multiprocessing
Process Process-133:
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
 self.run()
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 95, in run
 self._target(*self._args, **self._kwargs)
 File "/home/vinay/projects/python/default/Lib/test/test_multiprocessing.py", line 2005, in _remote
 client.connect(address)
ConnectionRefusedError: [Errno 111] Connection refused
/home/vinay/projects/python/default/Lib/multiprocessing/process.py:274: ResourceWarning: unclosed <socket.socket object, fd=15, family=2, type=1, proto=0>
 traceback.print_exc()

Some more information: after the above-described appears, the test hangs. When interrupted with a Ctrl+C, this is displayed:
^CProcess PoolWorker-104:
Process PoolWorker-102:
Process PoolWorker-105:1:
Process PoolWorker-101:
Process PoolWorker-105:4:
Process PoolWorker-105:3:
Process PoolWorker-105:2:
Process PoolWorker-103:
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
Process Process-132:
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 258, in _bootstrap
Warning -- threading._dangling was modified by test_multiprocessing
Warning -- multiprocessing.process._dangling was modified by test_multiprocessing
 self.run()
 File "/home/vinay/projects/python/default/Lib/multiprocessing/process.py", line 95, in run
 self._target(*self._args, **self._kwargs)
 File "/home/vinay/projects/python/default/Lib/test/test_multiprocessing.py", line 1989, in _listener
 new_conn, addr = l.accept()
 File "/home/vinay/projects/python/default/Lib/socket.py", line 135, in accept
 fd, addr = self._accept()
KeyboardInterrupt
/home/vinay/projects/python/default/Lib/multiprocessing/process.py:274: ResourceWarning: unclosed <socket.socket object, fd=17, family=2, type=1, proto=0>
 traceback.print_exc()
test test_multiprocessing crashed -- Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/test/test_multiprocessing.py", line 2825, in test_main
 run(suite)
 File "/home/vinay/projects/python/default/Lib/test/support.py", line 1407, in run_unittest
 _run_suite(suite)
 File "/home/vinay/projects/python/default/Lib/test/support.py", line 1373, in _run_suite
 result = runner.run(suite)
 File "/home/vinay/projects/python/default/Lib/test/support.py", line 1272, in run
 test(result)
 File "/home/vinay/projects/python/default/Lib/unittest/suite.py", line 67, in __call__
 return self.run(*args, **kwds)
 File "/home/vinay/projects/python/default/Lib/unittest/suite.py", line 105, in run
 test(result)
 File "/home/vinay/projects/python/default/Lib/unittest/suite.py", line 67, in __call__
 return self.run(*args, **kwds)
 File "/home/vinay/projects/python/default/Lib/unittest/suite.py", line 105, in run
 test(result)
 File "/home/vinay/projects/python/default/Lib/unittest/suite.py", line 67, in __call__
 return self.run(*args, **kwds)
 File "/home/vinay/projects/python/default/Lib/unittest/suite.py", line 105, in run
 test(result)
 File "/home/vinay/projects/python/default/Lib/unittest/case.py", line 492, in __call__
 return self.run(*args, **kwds)
 File "/home/vinay/projects/python/default/Lib/unittest/case.py", line 440, in run
 self._executeTestPart(testMethod, outcome, isTest=True)
 File "/home/vinay/projects/python/default/Lib/unittest/case.py", line 385, in _executeTestPart
 function()
 File "/home/vinay/projects/python/default/Lib/test/test_multiprocessing.py", line 2038, in test_pickling
 new_conn = lconn.recv()
 File "/home/vinay/projects/python/default/Lib/multiprocessing/connection.py", line 252, in recv
 buf = self._recv_bytes()
 File "/home/vinay/projects/python/default/Lib/multiprocessing/connection.py", line 398, in _recv_bytes
 buf = self._recv(4)
 File "/home/vinay/projects/python/default/Lib/multiprocessing/connection.py", line 377, in _recv
 chunk = read(handle, remaining)
KeyboardInterrupt
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
 File "/home/vinay/projects/python/default/Lib/multiprocessing/managers.py", line 729, in _callmethod
 conn = self._tls.connection
AttributeError: 'ForkAwareLocal' object has no attribute 'connection'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
 File "Lib/test/regrtest.py", line 1237, in runtest_inner
 File "/home/vinay/projects/python/default/Lib/test/test_multiprocessing.py", line 2829, in test_main
 ManagerMixin.pool.terminate()
 File "<string>", line 2, in terminate
 File "/home/vinay/projects/python/default/Lib/multiprocessing/managers.py", line 733, in _callmethod
 self._connect()
 File "/home/vinay/projects/python/default/Lib/multiprocessing/managers.py", line 720, in _connect
 conn = self._Client(self._token.address, authkey=self._authkey)
 File "/home/vinay/projects/python/default/Lib/multiprocessing/connection.py", line 469, in Client
 c = SocketClient(address)
 File "/home/vinay/projects/python/default/Lib/multiprocessing/connection.py", line 585, in SocketClient
 s.connect(address)
FileNotFoundError: [Errno 2] No such file or directory

> I've recently started seeing this failure repeatably on Linux (Ubuntu 
> Jaunty):
The test is newly enabled. Does "repeatably" mean you always get the failure?
I have not seen any failures on the Linux buildbots.

> Does "repeatably" mean you always get the failure?
Yes, every time. The first symptom is always a ConnectionRefusedError.
> I have not seen any failures on the Linux buildbots.
I'm running a fairly old version of Ubuntu, which might be relevant, or it may be that the connection is being refused because it's clashing with something else just on the test machine. In general this machine is just used for Python builds and tests, but I do run some services (e.g. Jenkins). Or it might be a race condition - the test machine is a VM and does have somewhat different timing characteristics from those of real hardware.

New changeset 3d900c9641c9 by Richard Oudkerk in branch 'default':
Issue #14727: Fix race in test_multiprocessing
http://hg.python.org/cpython/rev/3d900c9641c9 

I found a race where a connection attempt could happen before the listening socket's listen() method was called.
Vinay, could you update and try again please.

test_multiprocessing now passes. Thanks for the quick turnaround.