I have a Registry to create dynamic GenServers (each holding users’ parameters). I want to be able to take advantage of GenServer’s distributed multi_call / abcast, but since I’m using Registry, I must use a via tuple. Seems that mutli_call doesn’t like via tuples… Am I doing something wrong, is thi…

Yes, both syn and swarm can register arbitrary erlang terms as groups / names. I heartily recommend syn, by the way. It’s very pleasant to work with. I’ve never used it for anything big, though, but it seems to do a fairly decent job of auto-synchronizing names/groups on/after netsplits.

Digging through Erlang code for gen_server I see that start_monitor only accepts an atom as the name.. Erlang-OTP/lib/stdlib/src/gen_server.erl at master · blackberry/Erlang-OTP · GitHub Any ideas how I can do something similar with as much ease as multi_call / abcast, or will I have to implement s…

multi_call and abcast are about sending calls/casts across nodes rather than on the same machine.

Right, so my question is - how do I create dynamically-named GenServers and cast to them across multiple nodes? What I mean is - I could have multiple GenServers with the same dynamically-generated name on different nodes. I want to be able to retrieve all params I’ve saved on those GenServers rega…

I think you’re looking for a process registry that works in a distributed manner. Registry is only a local process registry, so maybe it’s not the right choice for you? Maybe swarm or syn are a better match for your case.

Thanks! I was thinking about Swarm actually, but was wondering if there was anything native that I could use instead. Also - do names in Swarm have to be unique? If I start two GenServers with the same name, will sending to that name send to both?

Hmm.. I’m not sure that it would. My scenario is this: a user connects with certain params, and I need to save those params. The same user can connect multiple times, with either similar or different params, but what is constant is his user_id (which in this case would be the “group”). I need to be …

One approach might be to have an aggregate store of user-related information, either on a centralised node or distributed using something like Riak Core or Mnesia, and have all nodes write to and read from there. A simpler option, though potentially a bottleneck, would be the following: on each nod…

I think that it’s possible to use any term as the group name, as is usually the case with systems like these.

Thanks a lot for the replies, guys! I will give syn/swarm a try, if you say that it can accept arbitrary terms as group names then I’m happy :slight_smile:

Elixir Programming Language Forum

Registry and multi_call / abcast

Questions & Help Questions

arjan April 1, 2017, 9:40am 7

Swarm supports process grouping, that might do the trick?