Restarting siblings vs. restarting nieces

[Sid Hussmann]

Thank you, Martin and Christian, for the time and care you took for your
explanation.

I now better understand how to design that part of our system in a
deterministic and reliable way.

Kind regards,
Sid

On 2/6/23 07:37, Christian Helmuth wrote:
> Hello,
> 
> On Sun, Feb 05, 2023 at 13:42:06 CET, Martin Stein wrote:
>> Let me share the outcome of our offline discussion with the mailing list:
>>
>> As far as I understand it, while Genode's init has the feature of
>> restarting direct service clients when their session disappears, this
>> doesn't apply in your scenario because of the server being wrapped in an
>> additional sub-init.
>>
>> In such case, you have to manually take care for restarting your
>> clients. A client, AFAIK deliberately doesn't consider the case that the
>> outside world is terminating its session. So, it seems natural to me
>> that you run into unpredictable behavior if you don't have some kind of
>> manager that kills the client before terminating its session.
> 
> Thanks for this wrapup, Martin, it perfectly reflects my stance on the
> matter too.
> 
> Regarding the followong question...
> 
>> Exception and try to re-establish the session. The two clients use
>> the `vfs` plugin mechanism to access the `File_system` session
>> provided by `rump`. During a restart of `rump` the clients sometimes
>> page-fault and sometimes "live on" while responding to heartbeats
>> but otherwise seem to be malfunctioning. Is the `vfs` plugin
>> mechanism designed to handle these outages?
> 
> We refrained from implementing "probing" or "automatic retry" in many
> places where the it is hard to nail down a sensible default policy. I
> expect the VFS plugin misses your desired recover feature for this
> reason.
> 
> Regards
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