Re: [PATCH] tests/acceptance: Fix race conditions in s390x tests & skip fedora on gitlab-CI

[Cornelia Huck <cohuck@redhat.com>]

On Fri,  8 Jan 2021 19:56:45 +0100
Thomas Huth <thuth@redhat.com> wrote:

> There was a race condition in the first test where there was already the
> "crw" output in the dmesg, but the "0.0.4711" entry has not been created
> in the /sys fs yet. Fix it by waiting until it is there.
> 
> The second test has even more problems on gitlab-CI. Even after adding some
> more synchronization points (that wait for some messages in the "dmesg"
> output to make sure that the modules got loaded correctly), there are still
> occasionally some hangs in this test when it is running in the gitlab-CI.
> So far I was unable to reproduce these hangs locally on my computer, so
> this issue might take a while to debug. Thus disable the 2nd test in the
> gitlab-CI until the problems are better understood and fixed.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/acceptance/machine_s390_ccw_virtio.py | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/acceptance/machine_s390_ccw_virtio.py b/tests/acceptance/machine_s390_ccw_virtio.py
> index eccf26b262..4028c99afc 100644
> --- a/tests/acceptance/machine_s390_ccw_virtio.py
> +++ b/tests/acceptance/machine_s390_ccw_virtio.py
> @@ -12,6 +12,7 @@
>  import os
>  import tempfile
>  
> +from avocado import skipIf
>  from avocado_qemu import Test
>  from avocado_qemu import exec_command_and_wait_for_pattern
>  from avocado_qemu import wait_for_console_pattern
> @@ -133,8 +134,10 @@ class S390CCWVirtioMachine(Test):
>          self.vm.command('device_add', driver='virtio-net-ccw',
>                          devno='fe.0.4711', id='net_4711')
>          self.wait_for_crw_reports()
> -        exec_command_and_wait_for_pattern(self, 'ls /sys/bus/ccw/devices/',
> -                                          '0.0.4711')
> +        exec_command_and_wait_for_pattern(self, 'for i in 1 2 3 4 5 6 7 ; do '
> +                    'if [ -e /sys/bus/ccw/devices/*4711 ]; then break; fi ;'
> +                    'sleep 1 ; done ; ls /sys/bus/ccw/devices/',
> +                    '0.0.4711')

I'm wondering whether we should introduce a generic helper function for
"execute command repeatedly, if the expected result did not yet show
up", or "wait for a file/directory to exist". It's probably not
uncommon for a desired outcome to arrive asynchronously, and having a
function for waiting/retrying could be handy.

>          # and detach it again
>          self.clear_guest_dmesg()
>          self.vm.command('device_del', id='net_4711')