I added debug traces in PR 7260. test_ignore() failed, but it may be related to my debug traces, since the failure is different.


test_multiprocessing_fork.test_ignore() failure:

test_ignore (test.test_multiprocessing_fork.TestIgnoreEINTR) ...
parent: pid=20159
parent: start child
parent: p=<Process(Process-3, started daemon)>
parent: p.ident=20176
ERROR

======================================================================
ERROR: test_ignore (test.test_multiprocessing_fork.TestIgnoreEINTR)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/python/cpython/Lib/test/_test_multiprocessing.py", line 4389, in test_ignore
    self.assertEqual(conn.recv(), 'ready')
  File "/home/travis/build/python/cpython/Lib/multiprocessing/connection.py", line 250, in recv
    buf = self._recv_bytes()
  File "/home/travis/build/python/cpython/Lib/multiprocessing/connection.py", line 407, in _recv_bytes
    buf = self._recv(4)
  File "/home/travis/build/python/cpython/Lib/multiprocessing/connection.py", line 383, in _recv
    raise EOFError
EOFError


test_multiprocessing_fork.test_ignore() success:

test_ignore (test.test_multiprocessing_fork.TestIgnoreEINTR) ...
parent: pid=11713
parent: start child
parent: p=<Process(Process-3, started daemon)>
parent: p.ident=28998
[INFO/Process-3] child process calling self.run()
child: pid=28998
child: register SIGUSR1 handler, send ready
child: wait 1234
parent: ready received
parent: first SIGUSR1
child: got SIGUSR1
parent: send 1234
parent: wait 1234
child: send back 1234
child: big blocking send
parent: second SIGUSR1
parent: wait bytes
child: got SIGUSR1
child: done
[INFO/Process-3] process shutting down
[INFO/Process-3] process shutting down
[INFO/Process-3] process exiting with exitcode 0
[INFO/Process-3] process exiting with exitcode 0
parent: join child
parent: done
ok