so it matters to isolate requests from each other… but not to isolate the logic inside the requests from cascading into the whole request failing? no like retries or anything like that? talking to an unreliable api? maybe a chatroom as a process?
NinekoTheCat
sodapopcan
In a recent Phoenix project that I’ve added no processes to myself yet:
ies> Process.list() |> length()
242
Ya, I’d say there’s a few under the hood 
3
LostKobrakai
That’s where the “where it makes sense”/“where you need isolation” part comes in. It requires domain knowledge to make that judgement call. No framework can make those decisions for you.
0
NinekoTheCat
the TLDR (as far as I understand):
use actors to encapsulate mutable state (or face lock issues) nothing else
0
NinekoTheCat
I’m sorry if I sound dumb but I’m just trying to grasp were this feature of the Erlang VM which keeps getting talked about but rarely used (on purpose?) Is for and where it’s right.
0
dimitarvp
- Processes (the actors) are used plenty in every Phoenix project, it was just made invisible to you and for your convenience. For example: the DB repo is basically a pool of connections but each connection is held up by a single process.
- Each request is in a new process. If you have 50 currently active requests, you have 50 extra processes. If you have 2000 currently active requests then you have 2000 extra processes.
- Libraries like
Oban(for background jobs) use processes pervasively.
Frameworks like Phoenix already make use of processes. From then on it’s on you if you want to use extra processes.
As others have said, don’t use processes to model logic. Use processes to model separate runtime entities (like a task that needs to download stuff from 3rd party API, for example).
No, they are used for other purposes as well. See above.
4
sodapopcan
It’s used all the time. Elixir code can’t run outside of a process. Even just booting up a vanilla REPL ($ iex) spawns 60 processes.
I’m no expert on the topic and I would search this forum for discussion about it as there is a bunch.
The TL;DR is model your business domain in pure functions, then run those functions in processes. Many of your examples are correct, like yes, a chatroom would run inside its own process. If you’re using LiveView in Phoenix, every user connection is a process.
4
NinekoTheCat
dimitarvp
If by “calling a webhook” you mean “my app is being called by an external entity” then yes.
When you have an Elixir app then every network request to it is being serviced by a separate process.
If you open 5 browser tabs and hit your Elixir web app / site from all 5 then that leads to your Elixir app spawning 5 separate processes and each of them is serving their requests in parallel, independently.
1