Phusion Passenger process stuck on (forking...) Rails - ruby-on-rails

Question

Today I updated to the newest updated package for Nginx and Passenger. After the update, my app now has a (forking...) process that wasn't there before and doesn't seem to go away. Yet it is taking up memory and sudo /usr/sbin/passenger-memory-stats reports the following.
--------- Nginx processes ----------
PID PPID VMSize Private Name
------------------------------------
1338 1 186.0 MB 0.8 MB nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
1345 1338 186.3 MB 1.1 MB nginx: worker process
### Processes: 2
### Total private dirty RSS: 1.91 MB
---- Passenger processes -----
PID VMSize Private Name
------------------------------
1312 378.8 MB 2.1 MB Passenger watchdog
1320 663.8 MB 4.2 MB Passenger core
1768 211.5 MB 29.0 MB Passenger AppPreloader: /home/ubuntu/my-app
1987 344.1 MB 52.2 MB Passenger AppPreloader: /home/ubuntu/my-app (forking...)
2008 344.2 MB 41.1 MB Passenger AppPreloader: /home/ubuntu/my-app (forking...)
### Processes: 5
### Total private dirty RSS: 128.62 MB
I have the passenger_max_pool_size 2. sudo /usr/sbin/passenger-status reports that two are currently open. The server is receiving no hits at the moment besides me using the site.
Version : 5.3.0
Date : 2018-05-14 00:41:05 +0000
Instance: ql2TTnkw (nginx/1.14.0 Phusion_Passenger/5.3.0)
----------- General information -----------
Max pool size : 2
App groups : 1
Processes : 2
Requests in top-level queue : 0
----------- Application groups -----------
/home/ubuntu/my-app (production):
App root: /home/ubuntu/my-app
Requests in queue: 0
* PID: 1987 Sessions: 0 Processed: 1 Uptime: 3m 36s
CPU: 0% Memory : 52M Last used: 3m 36s ago
* PID: 2008 Sessions: 0 Processed: 1 Uptime: 3m 35s
CPU: 0% Memory : 41M Last used: 3m 35s ago
Passenger never did this before the update and keeps the (forking...) always there now and it seems to have two apps running when it only needs one. I have searched their documents and know when it uses forking and when it doesn't and when it kills app automatically after a certain amount of time. Did they update something with the newest update that I missed in the docs? It seems that 2008 344.2 MB 89.4 MB Passenger AppPreloader: /home/ubuntu/my-app (forking...) always shows now and sometimes even has two of those when before the update I always had the process show without the (forking...).

Answer 1

This is normal for Passenger >= 5.3.
Source: I'm a dev at Phusion who works on Passenger.