title: Why docker is launching so many daemon processes?
body: <p>Why docker is launching so many daemon processes ?</p>
  
  <p>It seems that Docker <a href="https://stackoverflow.com/questions/33420700/docker-daemon-processes?rq=1">forks</a> the main process into several others. For example, after a reboot, here is the output of my console when I type <code>$ htop</code> followed by F5 :</p>
  
  <p><a href="https://i.stack.imgur.com/XTc45.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/XTc45.png" alt="many docker processes"></a><br>
  <sub>(source: <a href="http://img15.hostingpics.net/pics/331078manydockerprocesses.png" rel="nofollow noreferrer">hostingpics.net</a>)</sub>  </p>
  
  <p>There is already 6 children ! However, I don't have ANY running containers, just 2 stopped ones :</p>
  
  <pre><code>$ docker ps -a
  
  CONTAINER ID        IMAGE                          COMMAND                  CREATED             STATUS                   PORTS               NAMES
  a24f25e42c50        jupyter/datascience-notebook   "tini -- start-notebo"   44 hours ago        Exited (0) 3 hours ago                       prickly_spence
  728166c38396        nginx                          "nginx -g 'daemon off"   4 days ago          Exited (0) 3 hours ago                       some-nginx
  </code></pre>
  
  <p>This is problematic since a <strong>lot</strong> of child-processes start to appear after some time... and each one of them is using about 40 MB of memory, so it becomes problematic when you got dozens of processes ! So my 2 questions are :</p>
  
  <ul>
  <li>Am I guessing right ? <code>docker run -d ...</code> will fork the parent daemon and will never kill the child ?</li>
  <li>Why do I still got 6 children processes after a reboot ? <strong>How can I clean this ?</strong></li>
  </ul>
  
  <p>In advance, thanks you very much for your help guys ! :)</p>
  
  <hr>
  
  <h3>Extra informations :</h3>
  
  <p>The <code>$ docker info</code>where you see that I run on <strong>Ubuntu 14.04.4 LTS</strong> :</p>
  
  <pre><code>Containers: 1
   Running: 0
   Paused: 0
   Stopped: 1
  Images: 1
  Server Version: 1.10.3
  Storage Driver: aufs
   Root Dir: /var/lib/docker/aufs
   Backing Filesystem: extfs
   Dirs: 10
   Dirperm1 Supported: false
  Execution Driver: native-0.2
  Logging Driver: json-file
  Plugins:
   Volume: local
   Network: null host bridge
  Kernel Version: 3.13.0-55-generic
  Operating System: Ubuntu 14.04.4 LTS
  OSType: linux
  Architecture: x86_64
  CPUs: 1
  Total Memory: 3.767 GiB
  Name: *I censored this*
  ID: *I censored this*
  WARNING: No swap limit support
  </code></pre>
  
  <p>And the <code>$ docker version</code> :</p>
  
  <pre><code>Client:
   Version:      1.10.3
   API version:  1.22
   Go version:   go1.5.3
   Git commit:   20f81dd
   Built:        Thu Mar 10 15:54:52 2016
   OS/Arch:      linux/amd64
  
  Server:
   Version:      1.10.3
   API version:  1.22
   Go version:   go1.5.3
   Git commit:   20f81dd
   Built:        Thu Mar 10 15:54:52 2016
   OS/Arch:      linux/amd64
  </code></pre>