Looking at the buildbot failures, there is a race condition in a test_socket test: def _testWithTimeoutTriggeredSend(self): address = self.serv.getsockname() with open(support.TESTFN, 'rb') as file: with socket.create_connection(address, timeout=0.01) as sock: meth = self.meth_from_sock(sock) self.assertRaises(socket.timeout, meth, file) def testWithTimeoutTriggeredSend(self): conn = self.accept_conn() conn.recv(88192) on slow buildbot, create_connection() fails with a timeout exception sometimes because the server fails to start listing in less than 10 ms. https://buildbot.python.org/all/#/builders/167/builds/597 ====================================================================== ERROR: testWithTimeoutTriggeredSend (test.test_socket.SendfileUsingSendTest) ---------------------------------------------------------------------- Traceback (most recent call last): File "/usr/home/buildbot/python/3.x.koobs-freebsd10.nondebug/build/Lib/test/test_socket.py", line 5796, in testWithTimeoutTriggeredSend conn = self.accept_conn() File "/usr/home/buildbot/python/3.x.koobs-freebsd10.nondebug/build/Lib/test/test_socket.py", line 5607, in accept_conn conn, addr = self.serv.accept() File "/usr/home/buildbot/python/3.x.koobs-freebsd10.nondebug/build/Lib/socket.py", line 212, in accept fd, addr = self._accept() socket.timeout: timed out ====================================================================== ERROR: testWithTimeoutTriggeredSend (test.test_socket.SendfileUsingSendTest) ---------------------------------------------------------------------- Traceback (most recent call last): File "/usr/home/buildbot/python/3.x.koobs-freebsd10.nondebug/build/Lib/test/test_socket.py", line 335, in _tearDown raise exc File "/usr/home/buildbot/python/3.x.koobs-freebsd10.nondebug/build/Lib/test/test_socket.py", line 353, in clientRun test_func() File "/usr/home/buildbot/python/3.x.koobs-freebsd10.nondebug/build/Lib/test/test_socket.py", line 5791, in _testWithTimeoutTriggeredSend with socket.create_connection(address, timeout=0.01) as sock: File "/usr/home/buildbot/python/3.x.koobs-freebsd10.nondebug/build/Lib/socket.py", line 727, in create_connection raise err File "/usr/home/buildbot/python/3.x.koobs-freebsd10.nondebug/build/Lib/socket.py", line 716, in create_connection sock.connect(sa) socket.timeout: timed out Note: Reported my Victor. I created the bug to track.

 New changeset 53b9e1a1c1d86187ad6fbee492b697ef8be74205 by Victor Stinner (Joannah Nanjekye) in branch 'master': bpo-36123: Fix test_socket.testWithTimeoutTriggeredSend() race condition (GH-12053) https://github.com/python/cpython/commit/53b9e1a1c1d86187ad6fbee492b697ef8be74205 

 New changeset 2632474957fa9c6311af21be6906d1234853f288 by Miss Islington (bot) in branch '3.7': bpo-36123: Fix test_socket.testWithTimeoutTriggeredSend() race condition (GH-12053) https://github.com/python/cpython/commit/2632474957fa9c6311af21be6906d1234853f288 

I am closing this as it has been fixed by this PR <https://github.com/python/cpython/pull/12053>