gunicorn_django syncworker socket error

app.log

Traceback (most recent call last):
  File "/home/oreore/app/env/lib/python2.6/site-packages/gunicorn/workers/sync.py", line 33, in run
    client, addr = self.socket.accept()
  File "/usr/lib64/python2.6/socket.py", line 197, in accept
    sock, addr = self._sock.accept()
error: [Errno 11] Resource temporarily unavailable

Here is my environemnt

$ pip freeze
Django==1.4.1
MySQL-python==1.2.3
distribute==0.6.10
django-uni-form==0.9.0
gunicorn==0.14.5
raven==2.0.3
requests==0.13.5
simplejson==2.4.0
slumber==0.4.2
virtualenv==1.5.1
wsgiref==0.1.2

run by supervisord like below.

exec gunicorn_django -c "${APP_PATH}/etc/gunicorn.py" 

It works almost properly but creates error log... :-(

I get this too.