Erlang based chat (load balancing and notifications distribution) -

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we going develop backend our messenger, have 1 idea want describe here, maybe can give me advice.

1) idea:

nginx - redirects request random node (round robin) -> erlang cluster - redirects actual node (we choose node minimum number of processes) -> handshake -> upgrade websocket.

every node in cluster has ets table contains number of processes every node (fields - node, num_processes). every node, every 5 secs sends number of processes nodes in cluster.

so don't need have master node, because every node can load balancing.

2) additional question:

is idea register user's active websocket connections (pids) globally gproc? need list every user send notifications through ws enduser.

1) yep - scheme. improvement can make increment load of remote node every time balance load node. keeping estimate remote node load , stops sending load 1 node 5 seconds @ time. every time receive broadcast node, overwrite local estimate - fix missing updates , ensure estimates stay within small amount of actual remote value.

2) use gproc named property {username, true} each websocket process - let find websocket sessions user throughout cluster.

i forget underlying protocol gproc uses global registrations , cost you'll have registering/deregistering properties time throughout cluster. worked on similar system (user presence , messaging sessions , multi-node load balancing) while , ended writing ngproc in order support cheap name lookup conflict resolution after partitions. it's available open source , might provide ideas can use.


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