title: Phusion Passenger process stuck on (forking...) Rails
body: <p>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 <code>sudo /usr/sbin/passenger-memory-stats</code> reports the following.</p>
  
  <pre><code>--------- 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
  </code></pre>
  
  <p>I have the <code>passenger_max_pool_size 2</code>. <code>sudo /usr/sbin/passenger-status</code> reports that two are currently open. The server is receiving no hits at the moment besides me using the site.</p>
  
  <pre><code>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
  </code></pre>
  
  <p>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 <code>2008  344.2 MB  89.4 MB  Passenger AppPreloader: /home/ubuntu/my-app (forking...)</code> always shows now and sometimes even has two of those when before the update I always had the process show without the <code>(forking...)</code>.</p>