ROS2/pendulum demo freezes the system

edit

I followed https://github.com/ros2/ros2/wiki/Rea... . In the case of the talker/listener demo, ROS2 seems to work fine with both Connext DDS and Fast RTPS. Yet I have problems running pendulum_demo. As a normal user, the output is as follows:

$ RMW_IMPLEMENTATION=rmw_connext_cpp pendulum_demo 
RTI Data Distribution Service Non-commercial license is for academic, research, evaluation and personal use only. USE FOR COMMERCIAL PURPOSES IS PROHIBITED. See RTI_LICENSE.TXT for terms. Download free tools at rti.com/ncl. License issued to Non-Commercial User license@rti.com For non-production use only.
Expires on 00-jan-00 See www.rti.com for more information.
RTI Data Distribution Service Non-commercial license is for academic, research, evaluation and personal use only. USE FOR COMMERCIAL PURPOSES IS PROHIBITED. See RTI_LICENSE.TXT for terms. Download free tools at rti.com/ncl. License issued to Non-Commercial User license@rti.com For non-production use only.
Expires on 00-jan-00 See www.rti.com for more information.
Couldn't set scheduling priority and policy: Operation not permitted
mlockall failed: Cannot allocate memory
Couldn't lock all cached virtual memory.
Pagefaults from reading pages not yet mapped into RAM will be recorded.
Initial major pagefaults: 1327
Initial minor pagefaults: 9444
No results filename given, not writing results
rttest statistics:
  - Minor pagefaults: 1
  - Major pagefaults: 24
  Latency (time after deadline was missed):
    - Min: 53332 ns
    - Max: 3292539 ns
    - Mean: 123978 ns
    - Standard deviation: 354.91


PendulumMotor received 99 messages
PendulumController received 103 messages

As seen, there is no permission to set the real-time scheduling. Thus, I tried as root. In that case, only the licensing information is shown. Then the system (it seems) frezees hard or (one time) I have been logged out of the x session as if the x server crashed.

Do you have any idea why it happens? Thanks.