title: gunicorn cannot start flask
body: <p>I cannot start flask by gunicorn. When I input "gunicorn run:app", the server gives me errors. But I check that there is no service using 127.0.0.1:8000. And I can use "python run.py" to run this application.</p>
  
  <pre><code>root@ip-172-31-18-230:/var/www/vamk.help/vamk# gunicorn run:app
  [2016-05-11 02:13:09 +0000] [20288] [INFO] Starting gunicorn 19.4.5
  [2016-05-11 02:13:09 +0000] [20288] [INFO] Listening at: http://127.0.0.1:8000 (                                                                                                 20288)
  [2016-05-11 02:13:09 +0000] [20288] [INFO] Using worker: sync
  [2016-05-11 02:13:09 +0000] [20293] [INFO] Booting worker with pid: 20293
  [2016-05-11 02:13:10 +0000] [20293] [ERROR] Exception in worker process:
  Traceback (most recent call last):
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/arbiter.py", line 515, i                                                                                                 n spawn_worker
      worker.init_process()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/workers/base.py", line 1                                                                                                 22, in init_process
      self.load_wsgi()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/workers/base.py", line 1                                                                                                 30, in load_wsgi
      self.wsgi = self.app.wsgi()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/app/base.py", line 67, i                                                                                                 n wsgi
      self.callable = self.load()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/app/wsgiapp.py", line 65                                                                                                 , in load
      return self.load_wsgiapp()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/app/wsgiapp.py", line 52                                                                                                 , in load_wsgiapp
      return util.import_app(self.app_uri)
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/util.py", line 357, in i                                                                                                 mport_app
      __import__(module)
    File "/var/www/vamk.help/vamk/run.py", line 3, in &lt;module&gt;
      app.run(threaded=True, debug=app.config['DEBUG'], port=app.config['PORT'])
    File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 772, in run
      run_simple(host, port, self, **options)
    File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 677, i                                                                                                 n run_simple
      s.bind((hostname, port))
    File "/usr/lib/python2.7/socket.py", line 224, in meth
      return getattr(self._sock,name)(*args)
  error: [Errno 98] Address already in use
  Traceback (most recent call last):
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/arbiter.py", line 515, i                                                                                                 n spawn_worker
      worker.init_process()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/workers/base.py", line 1                                                                                                 22, in init_process
      self.load_wsgi()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/workers/base.py", line 1                                                                                                 30, in load_wsgi
      self.wsgi = self.app.wsgi()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/app/base.py", line 67, i                                                                                                 n wsgi
      self.callable = self.load()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/app/wsgiapp.py", line 65                                                                                                 , in load
      return self.load_wsgiapp()
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/app/wsgiapp.py", line 52                                                                                                 , in load_wsgiapp
      return util.import_app(self.app_uri)
    File "/usr/local/lib/python2.7/dist-packages/gunicorn/util.py", line 357, in i                                                                                                 mport_app
      __import__(module)
    File "/var/www/vamk.help/vamk/run.py", line 3, in &lt;module&gt;
      app.run(threaded=True, debug=app.config['DEBUG'], port=app.config['PORT'])
    File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 772, in run
      run_simple(host, port, self, **options)
    File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 677, i                                                                                                 n run_simple
      s.bind((hostname, port))
    File "/usr/lib/python2.7/socket.py", line 224, in meth
      return getattr(self._sock,name)(*args)
  error: [Errno 98] Address already in use
  </code></pre>
  
  <p>run.py</p>
  
  <pre><code>from app import app
  
  app.run(debug=app.config['DEBUG'], port=app.config['PORT'])
  </code></pre>