title: gunicorn worker crash at winch signal when using eventlet as worker class
body: <p>So I have a flask app that needs to run with <code>gunicorn --worker-class eventlet</code>.</p>
  
  <p>But when I start the app like this in an iterm2 pane, the worker crashes when I resize the pane (send winch signal):</p>
  
  <pre><code>[2016-11-07 11:03:38 +0800] [57382] [INFO] Handling signal: winch
  [2016-11-07 11:03:38 +0800] [57385] [ERROR] Exception in worker process
  Traceback (most recent call last):
    File "/usr/local/lib/python2.7/site-packages/gunicorn/arbiter.py", line 557, in spawn_worker
      worker.init_process()
    File "/usr/local/lib/python2.7/site-packages/gunicorn/workers/geventlet.py", line 96, in init_process
      super(EventletWorker, self).init_process()
    File "/usr/local/lib/python2.7/site-packages/gunicorn/workers/base.py", line 132, in init_process
      self.run()
    File "/usr/local/lib/python2.7/site-packages/gunicorn/workers/geventlet.py", line 125, in run
      eventlet.sleep(1.0)
    File "/usr/local/lib/python2.7/site-packages/eventlet/greenthread.py", line 34, in sleep
      hub.switch()
    File "/usr/local/lib/python2.7/site-packages/eventlet/hubs/hub.py", line 294, in switch
      return self.greenlet.switch()
    File "/usr/local/lib/python2.7/site-packages/eventlet/hubs/hub.py", line 346, in run
      self.wait(sleep_time)
    File "/usr/local/lib/python2.7/site-packages/eventlet/hubs/kqueue.py", line 100, in wait
      result = self._control([], self.MAX_EVENTS, seconds)
    File "/usr/local/lib/python2.7/site-packages/eventlet/hubs/kqueue.py", line 43, in _control
      return self.kqueue.control(events, max_events, timeout)
  OSError: [Errno 4] Interrupted system call
  [2016-11-07 11:03:38 +0800] [57385] [INFO] Worker exiting (pid: 57385)
  Exception TypeError: TypeError("'NoneType' object is not callable",) in &lt;bound method Client.__del__ of &lt;etcd.client.Client object at 0x10290a5d0&gt;&gt; ignored
  [2016-11-07 11:03:38 +0800] [57394] [INFO] Booting worker with pid: 57394
  </code></pre>
  
  <p>FYI:
  * I also use grpc in my code.
  * This doesn't occur on my remote centos 7 server, only my mac</p>