Race condition in test_socket

[nanjekyejoannah]

BPO	36123
Nosy	@vstinner, @miss-islington, @nanjekyejoannah
PRs	bpo-36123:race condition in test_socket #12053 [3.7] bpo-36123: Fix test_socket.testWithTimeoutTriggeredSend() race condition (GH-12053) #12056

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2019-02-26.17:50:28.467>
created_at = <Date 2019-02-26.12:43:13.548>
labels = ['3.8', 'type-bug', 'tests']
title = 'Race condition in test_socket'
updated_at = <Date 2019-02-26.17:50:28.466>
user = 'https://github.com/nanjekyejoannah'

bugs.python.org fields:

activity = <Date 2019-02-26.17:50:28.466>
actor = 'nanjekyejoannah'
assignee = 'none'
closed = True
closed_date = <Date 2019-02-26.17:50:28.467>
closer = 'nanjekyejoannah'
components = ['Tests']
creation = <Date 2019-02-26.12:43:13.548>
creator = 'nanjekyejoannah'
dependencies = []
files = []
hgrepos = []
issue_num = 36123
keywords = ['patch']
message_count = 4.0
messages = ['336658', '336690', '336694', '336704']
nosy_count = 3.0
nosy_names = ['vstinner', 'miss-islington', 'nanjekyejoannah']
pr_nums = ['12053', '12056']
priority = 'normal'
resolution = None
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue36123'
versions = ['Python 3.8']

[nanjekyejoannah]

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.

[vstinner]

New changeset 53b9e1a by Victor Stinner (Joannah Nanjekye) in branch 'master':
bpo-36123: Fix test_socket.testWithTimeoutTriggeredSend() race condition (GH-12053)
53b9e1a

[miss-islington]

New changeset 2632474 by Miss Islington (bot) in branch '3.7':
bpo-36123: Fix test_socket.testWithTimeoutTriggeredSend() race condition (GH-12053)
2632474

[nanjekyejoannah]

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