Unit test test.test_socket.ThreadedVSOCKSocketStreamTest.testStream hangs on WSL2 ubuntu

[peterjpxie]

Bug report

unit test test.test_socket.ThreadedVSOCKSocketStreamTest.testStream hangs on WSL2 ubuntu.

I added some print and it seems vsock does not work on WSL though /dev/vsock exists, HAVE_SOCKET_VSOCK() == True.

$ ls /dev/vsock
/dev/vsock

Modified test_socket.py snippet:

@unittest.skipIf(fcntl is None, "need fcntl")
@unittest.skipUnless(HAVE_SOCKET_VSOCK,
 'VSOCK sockets required for this test.')
@unittest.skipUnless(get_cid() != 2,
 "This test can only be run on a virtual guest.")
class ThreadedVSOCKSocketStreamTest(unittest.TestCase, ThreadableTest):

 def __init__(self, methodName='runTest'):
 print('__init__')
 unittest.TestCase.__init__(self, methodName=methodName)
 ThreadableTest.__init__(self)

 def setUp(self):
 print('setUp')
 self.serv = socket.socket(socket.AF_VSOCK, socket.SOCK_STREAM)
 self.addCleanup(self.serv.close)
 self.serv.bind((socket.VMADDR_CID_ANY, VSOCKPORT))
 self.serv.listen()
 self.serverExplicitReady()
 print('Before serv.accept')
 self.conn, self.connaddr = self.serv.accept()
 print('After serv.accept')
 self.addCleanup(self.conn.close)
 print('end - setUp')

 def clientSetUp(self):
 print('clientSetup')
 time.sleep(0.1)
 self.cli = socket.socket(socket.AF_VSOCK, socket.SOCK_STREAM)
 self.addCleanup(self.cli.close)
 cid = get_cid()
 print('cid: ', cid)
 print('before cli.connect')
 self.cli.connect((cid, VSOCKPORT))
 print('end - clientSetup')

 def testStream(self):
 print('testStream')
 msg = self.conn.recv(1024)
 self.assertEqual(msg, MSG)

 def _testStream(self):
 self.cli.send(MSG)
 self.cli.close()

Test outputs:

./python -m unittest -v test.test_socket.ThreadedVSOCKSocketStreamTest.testStream
__init__
testStream (test.test_socket.ThreadedVSOCKSocketStreamTest.testStream) ... setUp
Before serv.accept
clientSetup
cid: 4294967295
before cli.connect
^CTraceback (most recent call last):
 File "/home/peter/repo/cpython/Lib/runpy.py", line 198, in _run_module_as_main
 return _run_code(code, main_globals, None,
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 File "/home/peter/repo/cpython/Lib/runpy.py", line 88, in _run_code
 exec(code, run_globals)
 File "/home/peter/repo/cpython/Lib/unittest/__main__.py", line 18, in <module>
 main(module=None)
 File "/home/peter/repo/cpython/Lib/unittest/main.py", line 102, in __init__
 self.runTests()
 ...
 File "/home/peter/repo/cpython/Lib/unittest/case.py", line 576, in _callSetUp
 self.setUp()
 File "/home/peter/repo/cpython/Lib/test/test_socket.py", line 376, in _setUp
 self.__setUp()
 File "/home/peter/repo/cpython/Lib/test/test_socket.py", line 520, in setUp
 self.conn, self.connaddr = self.serv.accept()
 ^^^^^^^^^^^^^^^^^^
 File "/home/peter/repo/cpython/Lib/socket.py", line 295, in accept
 fd, addr = self._accept()
 ^^^^^^^^^^^^^^
KeyboardInterrupt

Your environment

• CPython versions tested on:
  both Python 3.12.0a4+ and Python 3.10.9+
• Operating system and architecture:
  Windows 10 home 19044.2486 + WSL2 Ubuntu 22.04

uname -r
5.15.79.1-microsoft-standard-WSL2
>>> platform.release()
'5.15.79.1-microsoft-standard-WSL2'

cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=22.04
DISTRIB_CODENAME=jammy
DISTRIB_DESCRIPTION="Ubuntu 22.04 LTS"

Suggestions

• Make it work and pass on WSL2
• Skip the test on WSL2
• Add a timeout so it does not hang at least

Linked PRs

• gh-101384: add socket timeout to ThreadedVSOCKSocketStreamTest and skip it on WSL #101418
• gh-101384: add socket timeout to ThreadedVSOCKSocketStreamTest and skip it on WSL #101419
• [3.12] gh-101384: Add socket timeout to ThreadedVSOCKSocketStreamTest and skip it on WSL (GH-101419) #115585
• [3.11] gh-101384: Add socket timeout to ThreadedVSOCKSocketStreamTest and skip it on WSL (GH-101419) #115586

[peterjpxie]

I am going to make changes to these two points if no objections.

• Skip the test on WSL
• Add a timeout so it does not hang at least

[hugovk]

Closing as the PRs have been merged and backported. Please let us know if there's still more to do. Thanks!