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From:   Brendan Higgins <brendanhiggins@google.com>
Date:   Wed, 6 Oct 2021 10:49:30 -0700
Message-ID: <CAFd5g445HFVd0e=r7y3JELCPkD=_T7QUq2K0BgKEeyG2Hi2qgw@mail.gmail.com>
Subject: Re: [PATCH v2] kunit: tool: yield output from run_kernel in real time
To:     Daniel Latypov <dlatypov@google.com>
Cc:     davidgow@google.com, linux-kernel@vger.kernel.org,
        kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org,
        skhan@linuxfoundation.org
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On Mon, Oct 4, 2021 at 6:13 PM Daniel Latypov <dlatypov@google.com> wrote:
>
> Currently, `run_kernel()` dumps all the kernel output to a file
> (.kunit/test.log) and then opens the file and yields it to callers.
> This made it easier to respect the requested timeout, if any.
>
> But it means that we can't yield the results in real time, either to the
> parser or to stdout (if --raw_output is set).
>
> This change spins up a background thread to enforce the timeout, which
> allows us to yield the kernel output in real time, while also copying it
> to the .kunit/test.log file.
> It's also careful to ensure that the .kunit/test.log file is complete,
> even in the kunit_parser throws an exception/otherwise doesn't consume
> every line, see the new `finally` block and unit test.
>
> For example:
>
> $ ./tools/testing/kunit/kunit.py run --arch=x86_64 --raw_output
> <configure + build steps>
> ...
> <can now see output from QEMU in real time>
>
> This does not currently have a visible effect when --raw_output is not
> passed, as kunit_parser.py currently only outputs everything at the end.
> But that could change, and this patch is a necessary step towards
> showing parsed test results in real time.
>
> Signed-off-by: Daniel Latypov <dlatypov@google.com>

Awesome! Thanks for finally fixing this!

Reviewed-by: Brendan Higgins <brendanhiggins@google.com>