what a correct use for virConnectDomainEventRegisterAny API, how to Obtain a stable expected result

HI, everyone: My target deal with network hotplug use virDomainDetachDeviceFlags. Because when the API return ,the network maybe doesn’t remove from my vm guest os. So I use virConnectDomainEventRegisterAny to register an event ID: VIR_DOMAIN_EVENT_ID_DEVICE_REMOVED , my process as follow: cb_para->call_id=virConnectDomainEventRegisterAny(cb_para->conn,cb_para->dom,VIR_DOMAIN_EVENT_ID_DEVICE_REMOVED, VIR_DOMAIN_EVENT_CALLBACK(vnf_control_del_network_cb), cb_para, vnf_control_del_network_cb_free); flags |= VIR_DOMAIN_AFFECT_CONFIG; if (virDomainIsActive(dom) == 1) { flags |= VIR_DOMAIN_AFFECT_LIVE; } ret = virDomainDetachDeviceFlags(dom, xml, flags); above code write in thread loop ,then in the same loop : while (1) { mission = vnf_mission_queue_get(task); if (mission == NULL) { sleep(1); continue; } vnf_op_process(&mission->info); // this will deal with network hotplug,will call virConnectDomainEventRegisterAny then call virDomainDetachDeviceFlags if (mission) { vnf_mission_free(mission); } if(virEventRunDefaultImpl() < 0) { // at here process the registered callback for event-registered printf();.... } } My problem is: some time , the virEventRunDefaultImpl can trigger the vnf_control_del_network_cb callback ,but some time there is nothing ,as if the VIR_DOMAIN_EVENT_ID_DEVICE_REMOVED has lost. what cause the Unpredictable behavior ? what is a correct use for virConnectDomainEventRegisterAny ? if can't trigger the vnf_control_del_network_cb callback , the memory :cb_para will mem-leak, so in order to deal the execpt ,i register a timer to process the VIR_DOMAIN_EVENT_ID_DEVICE_REMOVED timeout cb_para->timer_id = virEventAddTimeout(cb_para->time_out, vnf_control_del_network_timeout_cb, cb_para, vnf_control_del_network_cb_free); thought use the timer ,can i avoid the cb_para mem-leak, but fail to achive hotplug network .