It's been a while since I've touched Phoenix, but from memory it uses separate process pools (meaning lightweight BEAM VM processes) for the http connection, ap

It's been a while since I've touched Phoenix, but from memory it uses separate process pools (meaning lightweight BEAM VM processes) for the http connection, application code, database connections, and probably any other external dependency. A crash in an application process is handled by the http process that sent the work to it. That being said, you return errors in a similar way to other languages if they're expected during the system's operation rather than crashes. Again it's been a while since I had to work with it.