Test to reproduce PyTango#292

The architecture is as following. We have one DS called DeviceServer which exports in total two devices, each of a different class. These two classes are:

• Device1 with one attribute attr1
• Device2 with two attributes attr1 and attr2

What we will do:

1. Subscribe to attr1 configuration events of the Device1 device.
2. Subscribe to attr1 change events of the Device2 device.
3. Subscribe to attr2 change events of the Device2 device with a callback which will unsubscribe from the previously subscribed attr1 configuration events of the Device1 device.

In order to reproduce the problem:

1. Register in Tango Database one DeviceServer DS with instance name test with 2 devices of Device1 and Device2 classes, with the following names: test/device1/1, test/device2/1 respectively.

   tango_admin --add-server DeviceServer/test Device1 test/device1/1    
   tango_admin --add-server DeviceServer/test Device2 test/device2/1

2. Start DeviceServer: python3 DeviceServer.py test
3. Start client1: python3 client1.py

The output should look similar to:

/usr/bin/python3.5 /home/zreszela/workspace/test-tango-unsub/client1.py
MainThread:__DeviceProxy.__subscribe_event_attrib(attr1): before self.__subscribe_event
2020-02-14 23:48:04.251696 TEST/DEVICE1/1 ATTR1 ATTR_CONF label='attr1'; unit=''
MainThread:__DeviceProxy.__subscribe_event_attrib(attr1): after self.__subscribe_event; id = 1
MainThread:__DeviceProxy.__subscribe_event(1): before event_map_lock acquire
MainThread:__DeviceProxy.__subscribe_event(1): after event_map_lock acquire
MainThread:__DeviceProxy.__subscribe_event(1): after event_map_lock release
MainThread:__DeviceProxy.__subscribe_event_attrib(attr1): before self.__subscribe_event
2020-02-14 23:48:05.258605 TEST/DEVICE2/1 ATTR1 CHANGE [ATTR_VALID] 0.0
MainThread:__DeviceProxy.__subscribe_event_attrib(attr1): after self.__subscribe_event; id = 2
MainThread:__DeviceProxy.__subscribe_event(2): before event_map_lock acquire
MainThread:__DeviceProxy.__subscribe_event(2): after event_map_lock acquire
MainThread:__DeviceProxy.__subscribe_event(2): after event_map_lock release
MainThread:__DeviceProxy.__subscribe_event_attrib(attr2): before self.__subscribe_event
MainThread:__DeviceProxy__unsubscribe_event(1): before event_map_lock acquire
MainThread:__DeviceProxy__unsubscribe_event(1): after event_map_lock acquire
MainThread:__DeviceProxy__unsubscribe_event(1): after event_map_lock release
MainThread:__DeviceProxy__unsubscribe_event(1): before self.__unsubscribe_event
MainThread:__DeviceProxy__unsubscribe_event(1): after self.__unsubscribe_event
MainThread:__DeviceProxy.__subscribe_event_attrib(attr2): after self.__subscribe_event; id = 3
MainThread:__DeviceProxy.__subscribe_event(3): before event_map_lock acquire
MainThread:__DeviceProxy.__subscribe_event(3): after event_map_lock acquire
MainThread:__DeviceProxy.__subscribe_event(3): after event_map_lock release
2020-02-14 23:48:16.236785 TEST/DEVICE2/1 ATTR1 CHANGE [API_EventTimeout] Event channel is not responding anymore, maybe the server or event system is down
2020-02-14 23:48:16.237584 TEST/DEVICE2/1 ATTR1 IDL5_CHANGE [ATTR_VALID] 0.0
ERROR: API_EventTimeout
2020-02-14 23:48:26.242668 TEST/DEVICE2/1 ATTR1 CHANGE [API_EventTimeout] Event channel is not responding anymore, maybe the server or event system is down
2020-02-14 23:48:26.243339 TEST/DEVICE2/1 ATTR1 IDL5_CHANGE [ATTR_VALID] 0.0
ERROR: API_EventTimeout
2020-02-14 23:48:36.248675 TEST/DEVICE2/1 ATTR1 CHANGE [API_EventTimeout] Event channel is not responding anymore, maybe the server or event system is down
2020-02-14 23:48:36.249320 TEST/DEVICE2/1 ATTR1 IDL5_CHANGE [ATTR_VALID] 0.0
ERROR: API_EventTimeout

Alternatively build and run the C++ client:

1. g++ client1.cpp -o client1 -I/usr/include/tango -ltango -lzmq -lomniORB4 -lomnithread -lCOS4 -lomniDynamic4 -g
2. ./client1