Hello
we have a difficult to find problem with a Python script, where an CNN for license plate recognition runs using Intel OpenVino and the communication to other programs is done using ZeroMQ. We are not sure what causes the problem, but as it causes so much network traffic that other PCs cannot communicate anymore, a problem with ZeroMQ seems possible.
Problem description:
We have a Python script, which runs 3 different CNNs using the Inference Engine from OpenVino 2018R5 on images from Ethernet cameras, which are retrieved with OpenCV VideoCapture. In addition ZeroMQ is used to pass results to other programs (via tcp). The used hardware is either an Intel NUC7BNH, an NUC7DNH or an NUC8BEH (on the NUC8 no freeze was observed until now). The OS is an Ubuntu 16.04 (with patched kernel 4.7.0.intel.r5.0 or kernel 4.15.0-15-generic (freezes happen less frequent with kernel 4.15). The script is running multiple times in separated Docker containers together with programs in other docker containers.
What happens is that the Linux freezes randomly after some time (sometimes after a few minutes, sometimes after a few hours but also two are now running for many days without a problem). When it freezes no ACPI shutdown works, the screen freezes and even the Magic SysRq keys have no effect. A strange side effect is that a lot of network traffic is created (so much traffic that the network dies and no PC on the switch can communicate). The logs (kern.log, syslog) show nothing special.
If anyone observed a similar problem or has an idea, what can cause this behavior, please let me know.
Greetings,
Thomas