Re: Supervisor and configuration update — how to do it?

Loïc Hoguin essen@REDACTED
Wed May 20 08:35:50 CEST 2020

In Ranch 2.0 the options are put in an ets table, and then fetched from 
those tables in the supervisor init functions. The same could be done 
using persistent_term.

On 20/05/2020 07:36, Max Lapshin wrote:
> Hi.
> Our flussonic has big amount of code related to smooth configuration
> update. Almost all configuration parameters can be changed on fly: it
> is very important, because we handle big amounts of video traffic.  It
> is very bad to leave 20 000 people without video if you want to
> reconfigure single channel.
> We have to fight with supervisor concepts: we do not accept
> configuration in start_link/init, because it may change later.
> Usually code is looking so:
> init([Options]) ->
>    {ok, update_options(Options, #state{})}.
> handle_info({update_options, Options}, #state{} = State) ->
>    {noreply, update_options(Options, State)};
> Such approach doesn't work well with supervisor: if process is
> restarted, it will be restarted with old Options.
> My question is: is such approach antipattern for OTP?
> Maybe someone else has already met with it and has some ideas about
> it, like modifying supervisor.erl to change MFA?

Loïc Hoguin

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