libvirt断开后导致compute服务挂掉

libvirt断掉后导致compute服务挂掉，是因为在重连libvirt的时候使用

wrapped_conn = tpool.proxy_call(

                    (libvirt.virDomain, libvirt.virConnect),

                    self._connect, self.uri(), self.read_only)

该函数执行多次后卡死，使得整个compute服务卡主

这是报错的信息：

Traceback (most recent call last):

  File "/usr/lib/python2.6/site-packages/eventlet/hubs/hub.py", line 346, in fire_timers

    timer()

  File "/usr/lib/python2.6/site-packages/eventlet/hubs/timer.py", line 56, in __call__

    cb(*args, **kw)

  File "/usr/lib/python2.6/site-packages/eventlet/semaphore.py", line 121, in _do_acquire

    waiter.switch()

error: cannot switch to a different thread

暂时修改CONF.libvirt_nonblocking=false可避免

或者改为：

wrapped_conn = tpool.proxy_call(

                    (libvirt.virDomain, libvirt.virConnect),

                    self._connect, self.uri(), self.read_only,nonblocking=True)