Re: [PATCH] iotests/testrunner: Flush after run_test()

[Eric Blake]

On Fri, May 06, 2022 at 03:42:15PM +0200, Hanna Reitz wrote:
> When stdout is not a terminal, the buffer may not be flushed at each end
> of line, so we should flush after each test is done.  This is especially
> apparent when run by check-block, in two ways:
> 
> First, when running make check-block -jX with X > 1, progress indication
> was missing, even though testrunner.py does theoretically print each
> test's status once it has been run, even in multi-processing mode.
> Flushing after each test restores this progress indication.
> 
> Second, sometimes make check-block failed altogether, with an error
> message that "too few tests [were] run".  I presume that's because one
> worker process in the job pool did not get to flush its stdout before
> the main process exited, and so meson did not get to see that worker's
> test results.  In any case, by flushing at the end of run_test(), the
> problem has disappeared for me.
> 
> Signed-off-by: Hanna Reitz <hreitz@redhat.com>
> ---
>  tests/qemu-iotests/testrunner.py | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Eric Blake <eblake@redhat.com>

> 
> diff --git a/tests/qemu-iotests/testrunner.py 
> b/tests/qemu-iotests/testrunner.py
> index aae70a8341..10d9e8ef27 100644
> --- a/tests/qemu-iotests/testrunner.py
> +++ b/tests/qemu-iotests/testrunner.py
> @@ -378,6 +378,7 @@ def run_test(self, test: str,
>              else:
>                  print(res.casenotrun)
>  
> +        sys.stdout.flush()
>          return res
>  
>      def run_tests(self, tests: List[str], jobs: int = 1) -> bool:
> -- 
> 2.35.1
> 
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org