delayed child restart with incremental back-off

[Richard Carlsson]

What happened at the time was that I met up with the OTP team and discussed
it, and they eventually agreed that this was a good thing. However, it
needed more work to be accepted (and I realized a couple of weaknesses in
the implementation that I needed to address), but I never found time to do
more work on it.

        /Richard


Den sön 2 maj 2021 kl 21:01 skrev Nicolas Martyanoff <khaelin@REDACTED>:

>
> Hi,
>
> I originally posted this email on erlang-patches, but I just realized
> most developers are on erlang-questions instead. I believe this could be
> of interest.
>
>
> Nine years ago, an interesting patch [1] was submitted by Richard Carlsson
> allowing to delay the re-creation of failed children in supervisors.
>
> After a quick discussions, the official answer was that the OTP team
> would discuss about it [2]. There is no further message on the mailing
> list.
>
> Was there an official response ?
>
> I have various supervisors whose children handle network connections.
> When something goes wrong with the connection, children die and are
> immediately restarted. Most of the times, errors are transient (remote
> server restarting, temporary network issue, etc.), but retrying without
> any delay is pretty much guaranteed to fail again. And of course after a
> few retries, the application dies which is unacceptable.
>
> This kind of behaviour is a huge problem: it fills logs with multiple
> copies of identical errors and causes a system failure.
>
> In general, if I could, I would use restart delays with exponential
> backoff everywhere because in practice, restarting immediately is almost
> never the right approach: code errors do not disappear when restarting
> so they are going to get triggered again immediately, and external errors
> are not magically fixed by retrying without any delay.
>
> Is there still interest for this patch ?
>
> [1] https://erlang.org/pipermail/erlang-patches/2012-January/002575.html
> [2] https://erlang.org/pipermail/erlang-patches/2012-January/002597.html
>
> --
> Nicolas Martyanoff
> http://snowsyn.net
> khaelin@REDACTED
>
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