Description

mhsmith

opened on Apr 20, 2026

Issue body actions

Bug report

Bug description:

This is failing on about 10% of attempts. Usually it passes on a rerun:

• https://buildbot.python.org/#/builders/1380/builds/6364
• https://buildbot.python.org/#/builders/1380/builds/6374

But sometimes it fails on the rerun:

• https://buildbot.python.org/#/builders/1380/builds/6331
• https://buildbot.python.org/#/builders/1380/builds/6403

 ERROR: test_sock_client_racing (test.test_asyncio.test_sock_lowlevel.KqueueEventLoopTests.test_sock_client_racing)
 ----------------------------------------------------------------------
 Traceback (most recent call last):
   File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/test/test_asyncio/test_sock_lowlevel.py", line 273, in test_sock_client_racing
     self.loop.run_until_complete(asyncio.wait_for(
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
         self._basetest_sock_send_racing(listener, sock), 10))
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/asyncio/base_events.py", line 724, in run_until_complete
     return future.result()
            ~~~~~~~~~~~~~^^
   File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/asyncio/tasks.py", line 488, in wait_for
     return await fut
            ^^^^^^^^^
   File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/test/test_asyncio/test_sock_lowlevel.py", line 196, in _basetest_sock_send_racing
     sock.send(b' ' * size)
     ~~~~~~~~~^^^^^^^^^^^^^
 ConnectionResetError: [Errno 54] Connection reset by peer

@freakboy3742: FYI

CPython versions tested on:

CPython main branch

Operating systems tested on:

Other

Activity

1. mhsmith

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   testsTests in the Lib/test dirTests in the Lib/test dir

   OS-ios

   on Apr 20, 2026
2. StanFromIreland

   added

   topic-asyncio

   on Apr 20, 2026
3. freakboy3742 commented on Apr 20, 2026

   

   freakboy3742

   on Apr 20, 2026

   Contributor

   More actions

   Thanks - I had seen that; I wasn't overly concerned because (a) the failure-on-repeat rate is very low, and (b) from what I can make out, the test that is failing is a explicitly testing performance under extreme network load. Obviously it would be preferable to pass the test consistently, but it's also going to be difficult to reproduce (and I haven't had any luck to date reproducing it locally)

   FWIW - there are at least two failure modes that I've seen. They both occur on the sock_send_racing portion of the test. The sock_recv and sock_recv_into portions of the test seem to be stable. It does make me wonder if the problem is some sort of time-based reset after the first sequence of the test.

   1. Timeout on the second socket test:

    Traceback (most recent call last):
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/5F33C29B-26A9-433F-8EF2-24292B3B9DD8/iOSTestbed.app/python/lib/python3.15/asyncio/tasks.py", line 488, in wait_for
        return await fut
               ^^^^^^^^^
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/5F33C29B-26A9-433F-8EF2-24292B3B9DD8/iOSTestbed.app/python/lib/python3.15/test/test_asyncio/test_sock_lowlevel.py", line 216, in _basetest_sock_send_racing
        await self.loop.sock_sendall(sock, b'world')
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/5F33C29B-26A9-433F-8EF2-24292B3B9DD8/iOSTestbed.app/python/lib/python3.15/asyncio/selector_events.py", line 562, in sock_sendall
        return await fut
               ^^^^^^^^^
    asyncio.exceptions.CancelledError
    
    The above exception was the direct cause of the following exception:
    
    Traceback (most recent call last):
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/5F33C29B-26A9-433F-8EF2-24292B3B9DD8/iOSTestbed.app/python/lib/python3.15/test/test_asyncio/test_sock_lowlevel.py", line 273, in test_sock_client_racing
        self.loop.run_until_complete(asyncio.wait_for(
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
            self._basetest_sock_send_racing(listener, sock), 10))
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/5F33C29B-26A9-433F-8EF2-24292B3B9DD8/iOSTestbed.app/python/lib/python3.15/asyncio/base_events.py", line 724, in run_until_complete
        return future.result()
               ~~~~~~~~~~~~~^^
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/5F33C29B-26A9-433F-8EF2-24292B3B9DD8/iOSTestbed.app/python/lib/python3.15/asyncio/tasks.py", line 487, in wait_for
        async with timeouts.timeout(timeout):
                   ~~~~~~~~~~~~~~~~^^^^^^^^^
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/5F33C29B-26A9-433F-8EF2-24292B3B9DD8/iOSTestbed.app/python/lib/python3.15/asyncio/timeouts.py", line 114, in __aexit__
        raise TimeoutError from exc_val
    TimeoutError
   

   2. A connection reset error

    Traceback (most recent call last):
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/test/test_asyncio/test_sock_lowlevel.py", line 273, in test_sock_client_racing
        self.loop.run_until_complete(asyncio.wait_for(
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
            self._basetest_sock_send_racing(listener, sock), 10))
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/asyncio/base_events.py", line 724, in run_until_complete
        return future.result()
               ~~~~~~~~~~~~~^^
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/asyncio/tasks.py", line 488, in wait_for
        return await fut
               ^^^^^^^^^
      File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/test/test_asyncio/test_sock_lowlevel.py", line 196, in _basetest_sock_send_racing
        sock.send(b' ' * size)
        ~~~~~~~~~^^^^^^^^^^^^^
    ConnectionResetError: [Errno 54] Connection reset by peer
   
4. mhsmith commented on Apr 21, 2026

   

   mhsmith

   on Apr 21, 2026

   MemberAuthor

   More actions

   Also, the GitHub buildbot comments aren't including anything useful. This might be because every line in the test log has an extra space at the start.
5. serhiy-storchaka

   added this to asyncioon Jul 3, 2026
6. github-project-automation

   moved this to Todo in asyncioon Jul 3, 2026
7. kumaraditya303 commented on Jul 19, 2026

   

   kumaraditya303

   on Jul 19, 2026

   Contributor

   More actions

   What's the status of this?
8. freakboy3742 commented on Jul 19, 2026

   

   freakboy3742

   on Jul 19, 2026

   Contributor

   More actions

   It's still happening - but it's a lot less frequent than it was. Looking at the last 200 builds on Buildbot, there are:

   • 7 failures that passed on the re-run (all test_sock_client_racing failures).
   • 1 failure that failed a second time on re-run (this build, on Jun 28).

Issue actions