instance create:
nova/api/servers.create -- self.compute_api.create -- self.compute_task_api.build_instances
-- self.conductor_compute_rpcapi.build_instances(conductorp/api.py) -- cctxt.cast(context, ‘build_instances‘, **kw)
从nova api到conductor的调用为异步
conductor manager 里面:
1. hosts = self._schedule_instances:
-- self.scheduler_client.select_destinations -- self.scheduler_rpcapi.select_destinations -- cctxt.call(ctxt, ‘select_destinations‘
从conductor调用select_destinations到scheduler采用同步
2. self.compute_rpcapi.build_and_run_instance:
cctxt.cast(ctxt, ‘build_and_run_instance -- utils.spawn_n -- eventlet.spawn_n
从conductor调用到compute为异步调用
原文：http://www.cnblogs.com/allcloud/p/5108718.html