Re: [PATCH 5/7] python/machine: handle "fast" QEMU terminations

[Willian Rampazzo]

On Thu, Nov 18, 2021 at 5:49 PM John Snow <jsnow@redhat.com> wrote:
>
> In the case that the QEMU process actually launches -- but then dies so
> quickly that we can't establish a QMP connection to it -- QEMUMachine
> currently calls _post_shutdown() assuming that it never launched the VM
> process.
>
> This isn't true, though: it "merely" may have failed to establish a QMP
> connection and the process is in the middle of its own exit path.
>
> If we don't wait for the subprocess, the caller may get a bogus `None`
> return for .exitcode(). This behavior was observed from
> device-crash-test; after the switch to Async QMP, the timings were
> changed such that it was now seemingly possible to witness the failure
> of "vm.launch()" *prior* to the exitcode becoming available.
>
> The semantic of the `_launched` property is changed in this
> patch. Instead of representing the condition "launch() executed
> successfully", it will now represent "has forked a child process
> successfully". This way, wait() when called in the exit path won't
> become a no-op.
> Signed-off-by: John Snow <jsnow@redhat.com>

Nitpick: double signed-off-by

>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  python/qemu/machine/machine.py | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
>

Reviewed-by: Willian Rampazzo <willianr@redhat.com>