test_imaplib failed with ConnectionRefusedError on AMD64 FreeBSD Refleaks 3.15 buildbot

Build: https://buildbot.python.org/#/builders/2056/builds/483

Would it be possible to skip the test on a network error? Or would it defeat the purpose of the test?

test_imaplib_timeout_functionality_test (test.test_imaplib.NewIMAPSSLTests.test_imaplib_timeout_functionality_test) ... SENT: b'* OK IMAP4rev1'
GOT: b'JKNP0 CAPABILITY'
SENT: b'* CAPABILITY IMAP4rev1'
SENT: b'JKNP0 OK CAPABILITY completed'
ERROR

======================================================================
ERROR: test_imaplib_timeout_functionality_test (test.test_imaplib.NewIMAPSSLTests.test_imaplib_timeout_functionality_test)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/test/test_imaplib.py", line 745, in test_imaplib_timeout_functionality_test
    client = self.imap_class("localhost", addr, timeout=0.001)
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 1772, in __init__
    IMAP4.__init__(self, host, port, timeout)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 217, in __init__
    self.open(host, port, timeout)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 1785, in open
    IMAP4.open(self, host, port, timeout)
    ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 331, in open
    self.sock = self._create_socket(timeout)
                ~~~~~~~~~~~~~~~~~~~^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 1775, in _create_socket
    sock = IMAP4._create_socket(self, timeout)
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 320, in _create_socket
    return socket.create_connection(address, timeout)
           ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/socket.py", line 887, in create_connection
    raise exceptions[0]
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/socket.py", line 872, in create_connection
    sock.connect(sa)
    ~~~~~~~~~~~~^^^^
ConnectionRefusedError: [Errno 61] Connection refused

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Well, the test connects to the wrong host. On FreeBSD:

$ grep localhost /etc/hosts
::1			localhost localhost.my.domain
127.0.0.1		localhost localhost.my.domain

We could fix instead of skip.

Well, the test connects to the wrong host.

Can you elaborate? Which host is used? I would expect "localhost" to be resolved to 127.0.0.1 (IPv4) or ::1 (IPv6), the local loopback. So it should just work, no?

I failed to reproduce the issue on FreeBSD:

vstinner@freebsd$ ./python -m test test_imaplib -u all -m test_imaplib_timeout_functionality_test -v
(...)
== Tests result: SUCCESS ==
(...)

or ::1 (IPv6)

That's the problem. The server only listens on 127.0.0.1. If that connect takes over 1 ms, the TimeoutError is dropped (L890) and ::1 is tried next, which is refused.

cpython/Lib/socket.py

Lines 874 to 891 in f8e65ee

    
           for res in getaddrinfo(host, port, 0, SOCK_STREAM): 
        
               af, socktype, proto, canonname, sa = res 
        
               sock = None 
        
               try: 
        
                   sock = socket(af, socktype, proto) 
        
                   if timeout is not _GLOBAL_DEFAULT_TIMEOUT: 
        
                       sock.settimeout(timeout) 
        
                   if source_address: 
        
                       sock.bind(source_address) 
        
                   sock.connect(sa) 
        
                   # Break explicitly a reference cycle 
        
                   exceptions.clear() 
        
                   return sock 
        
               except error as exc: 
        
                   if not all_errors: 
        
                       exceptions.clear()  # raise only the last error 
        
                   exceptions.append(exc)

To reproduce, you need to add some latency on ipv4 loopback with tc netem.

Wait. What is this 1 ms timeout? Why not using support.LOOPBACK_TIMEOUT (10 sec by default).

What is this 1 ms timeout?

Because the test wants a TimeoutError(by set a very short timeout); the problem is that it gets dropped.

cpython/Lib/test/test_imaplib.py

Lines 897 to 906 in f8e65ee

    
           def test_imaplib_timeout_functionality_test(self): 
        
               class TimeoutHandler(SimpleIMAPHandler): 
        
                   def handle(self): 
        
                       time.sleep(1) 
        
                       SimpleIMAPHandler.handle(self) 
        
               _, server = self._setup(TimeoutHandler) 
        
               addr = server.server_address[1] 
        
               with self.assertRaises(TimeoutError): 
        
                   client = self.imap_class("localhost", addr, timeout=0.001)

Let me spell out the logic. The test expects a TimeoutError. The handler sleeps 1s before the greeting and the client waits 1 ms, so normally the connect to 127.0.0.1 succeeds and the timeout hits while reading the greeting.

On a busy machine the connect itself can take over 1 ms. With localhost, create_connection() drops that TimeoutError, moves on to ::1 where nothing listens, and reports only the last error, which is ConnectionRefusedError. With server.server_address there is a single address, so a slow connect raises TimeoutError as well.

gh-161336: fix host mismatch in the `test_imaplib` (#161349)

create_connection() drops that TimeoutError, moves on to ::1

Oh. That's subtle: create_connection() catches OSError and moves to the next IP address, and TimeoutError is a OSError sub-class. I see. I merged your fix.

[3.14] gh-161336: fix host mismatch in the `test_imaplib` (GH-161349) (…

[3.15] gh-161336: fix host mismatch in the `test_imaplib` (GH-161349) (…

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test_imaplib failed with ConnectionRefusedError on AMD64 FreeBSD Refleaks 3.15 buildbot #161336

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	for res in getaddrinfo(host, port, 0, SOCK_STREAM):
	af, socktype, proto, canonname, sa = res
	sock = None
	try:
	sock = socket(af, socktype, proto)
	if timeout is not _GLOBAL_DEFAULT_TIMEOUT:
	sock.settimeout(timeout)
	if source_address:
	sock.bind(source_address)
	sock.connect(sa)
	# Break explicitly a reference cycle
	exceptions.clear()
	return sock

	except error as exc:
	if not all_errors:
	exceptions.clear() # raise only the last error
	exceptions.append(exc)

	def test_imaplib_timeout_functionality_test(self):
	class TimeoutHandler(SimpleIMAPHandler):
	def handle(self):
	time.sleep(1)
	SimpleIMAPHandler.handle(self)

	_, server = self._setup(TimeoutHandler)
	addr = server.server_address[1]
	with self.assertRaises(TimeoutError):
	client = self.imap_class("localhost", addr, timeout=0.001)

test_imaplib failed with ConnectionRefusedError on AMD64 FreeBSD Refleaks 3.15 buildbot #161336

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NekoAsakura commented on Nov 4, 2026

vstinner commented on Nov 5, 2026

vstinner commented on Nov 5, 2026

NekoAsakura commented on Nov 5, 2026

vstinner commented on Nov 5, 2026

NekoAsakura commented on Nov 5, 2026

NekoAsakura commented on Nov 5, 2026

vstinner commented on Nov 5, 2026

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