Re: [PATCH v2] iotests.py: Let wait_migration wait even more

[John Snow <jsnow@redhat.com>]

On 12/19/19 1:36 PM, Max Reitz wrote:
> The "migration completed" event may be sent (on the source, to be
> specific) before the migration is actually completed, so the VM runstate
> will still be "finish-migrate" instead of "postmigrate".  So ask the
> users of VM.wait_migration() to specify the final runstate they desire
> and then poll the VM until it has reached that state.  (This should be
> over very quickly, so busy polling is fine.)
> 
> Without this patch, I see intermittent failures in the new iotest 280
> under high system load.  I have not yet seen such failures with other
> iotests that use VM.wait_migration() and query-status afterwards, but
> maybe they just occur even more rarely, or it is because they also wait
> on the destination VM to be running.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>

Reviewed-by: John Snow <jsnow@redhat.com>

With Kevin's suggestion on the comment touchup or without.

> ---
> v2:
> - Stop breaking 234 and 262 [Kevin]
> ---
>  tests/qemu-iotests/234        | 8 ++++----
>  tests/qemu-iotests/262        | 4 ++--
>  tests/qemu-iotests/280        | 2 +-
>  tests/qemu-iotests/iotests.py | 6 +++++-
>  4 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/tests/qemu-iotests/234 b/tests/qemu-iotests/234
> index 34c818c485..59a7f949ec 100755
> --- a/tests/qemu-iotests/234
> +++ b/tests/qemu-iotests/234
> @@ -69,9 +69,9 @@ with iotests.FilePath('img') as img_path, \
>      iotests.log(vm_a.qmp('migrate', uri='exec:cat >%s' % (fifo_a)))
>      with iotests.Timeout(3, 'Migration does not complete'):
>          # Wait for the source first (which includes setup=setup)
> -        vm_a.wait_migration()
> +        vm_a.wait_migration('postmigrate')
>          # Wait for the destination second (which does not)
> -        vm_b.wait_migration()
> +        vm_b.wait_migration('running')
>  
>      iotests.log(vm_a.qmp('query-migrate')['return']['status'])
>      iotests.log(vm_b.qmp('query-migrate')['return']['status'])
> @@ -98,9 +98,9 @@ with iotests.FilePath('img') as img_path, \
>      iotests.log(vm_b.qmp('migrate', uri='exec:cat >%s' % (fifo_b)))
>      with iotests.Timeout(3, 'Migration does not complete'):
>          # Wait for the source first (which includes setup=setup)
> -        vm_b.wait_migration()
> +        vm_b.wait_migration('postmigrate')
>          # Wait for the destination second (which does not)
> -        vm_a.wait_migration()
> +        vm_a.wait_migration('running')
>  
>      iotests.log(vm_a.qmp('query-migrate')['return']['status'])
>      iotests.log(vm_b.qmp('query-migrate')['return']['status'])
> diff --git a/tests/qemu-iotests/262 b/tests/qemu-iotests/262
> index 0963daa806..bbcb5260a6 100755
> --- a/tests/qemu-iotests/262
> +++ b/tests/qemu-iotests/262
> @@ -71,9 +71,9 @@ with iotests.FilePath('img') as img_path, \
>      iotests.log(vm_a.qmp('migrate', uri='exec:cat >%s' % (fifo)))
>      with iotests.Timeout(3, 'Migration does not complete'):
>          # Wait for the source first (which includes setup=setup)
> -        vm_a.wait_migration()
> +        vm_a.wait_migration('postmigrate')
>          # Wait for the destination second (which does not)
> -        vm_b.wait_migration()
> +        vm_b.wait_migration('running')
>  
>      iotests.log(vm_a.qmp('query-migrate')['return']['status'])
>      iotests.log(vm_b.qmp('query-migrate')['return']['status'])
> diff --git a/tests/qemu-iotests/280 b/tests/qemu-iotests/280
> index 0b1fa8e1d8..85e9114c5e 100755
> --- a/tests/qemu-iotests/280
> +++ b/tests/qemu-iotests/280
> @@ -45,7 +45,7 @@ with iotests.FilePath('base') as base_path , \
>      vm.qmp_log('migrate', uri='exec:cat > /dev/null')
>  
>      with iotests.Timeout(3, 'Migration does not complete'):
> -        vm.wait_migration()
> +        vm.wait_migration('postmigrate')
>  
>      iotests.log('\nVM is now stopped:')
>      iotests.log(vm.qmp('query-migrate')['return']['status'])
> diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
> index 13fd8b5cd2..0b62c42851 100644
> --- a/tests/qemu-iotests/iotests.py
> +++ b/tests/qemu-iotests/iotests.py
> @@ -668,12 +668,16 @@ class VM(qtest.QEMUQtestMachine):
>              }
>          ]))
>  
> -    def wait_migration(self):
> +    def wait_migration(self, expect_runstate):
>          while True:
>              event = self.event_wait('MIGRATION')
>              log(event, filters=[filter_qmp_event])
>              if event['data']['status'] == 'completed':
>                  break
> +        # The event may occur in finish-migrate, so wait for the expected
> +        # post-migration runstate
> +        while self.qmp('query-status')['return']['status'] != expect_runstate:
> +            pass
>  
>      def node_info(self, node_name):
>          nodes = self.qmp('query-named-block-nodes')
> 

-- 
—js