Running multiple instances of Rails Server

Question

I am new to Rails, so please forgive me if this is obvious.

I am doing a lot of experimenting, creating to applications, testing features, etc. It got my first scaff

Answer 1

In the current version Rails 5.2.0 and Ruby 2.4.1p111, starting two instances of server for the same app is possible with multiple PIDs.

$ rails s 
=> Booting Puma
=> Rails 5.2.0 application starting in development 
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.11.4 (ruby 2.4.1-p111), codename: Love Song
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://0.0.0.0:3000
Use Ctrl-C to stop

Now starting one more server on different port fails with pid issues.

$ rails s -p 3001
=> Booting Puma
=> Rails 5.2.0 application starting in development 
=> Run `rails server -h` for more startup options
A server is already running. Check /Users/biju/app1/tmp/pids/server.pid.
Exiting

Below approach of starting server works to use multiple instances of application.

$ rails s -p 3001 -P 321412
=> Booting Puma
=> Rails 5.2.0 application starting in development 
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.11.4 (ruby 2.4.1-p111), codename: Love Song
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://localhost:3001
Use Ctrl-C to stop