Error on shinken restart

[camlafit]

After a service shinken restart, some error occurs :

[1464010414] ERROR: [Shinken] [ws-arbiter] Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/shinken/basemodule.py", line 164, in start_module
    self._main()
  File "/usr/local/lib/python2.7/dist-packages/shinken/basemodule.py", line 296, in _main
    self.main()
  File "/var/lib/shinken/modules/ws-arbiter/module.py", line 407, in main
    inputready, _, _ = select.select(input, [], [], 1)
error: (4, 'Interrupted system call')