Issue with ROS2 publishing and subscribing frequency discrepancy

[hariteja2408]

I'm encountering a problem with my ROS2 setup involving publishing and subscribing to a topic with image data. I've configured my publisher node to publish using the following command:

ros2 run image_tools cam2image --ros-args -p width:=1280 -p height:=780

Additionally, I've enabled the LARGE_DATA option. Initially, when publishing using this configuration, I observe a frequency of 10Hz in the system. However, when subscribing to the same topic on another system with identical configurations, I only receive a frequency of 2Hz.

Moreover, I've noticed that the publisher frequency gradually decreases over time in both systems, eventually stabilizing at 2Hz. This behavior persists even when the LARGE_DATA option is disabled.

I'm seeking assistance in understanding why enabling LARGE_DATA doesn't seem to affect the performance as expected and why the publisher frequency decreases over time. Could someone please provide insights into these issues and suggest potential solutions?

[JesusPoderoso]

Hi @hariteja2408 thanks for using Vulcanexus.
The frequency decrease you describe may have been caused by several reasons.

On one hand, it may be caused by system limitations. Please check if following these troubleshooting steps improves the behavior. In addition to that, as long as TPC already takes charge of making the communication reliable, set all reliability QoS as BEST_EFFORT to reduce metatraffic.

On the other hand, if the communication between systems is through a local network with, for instance, a typical router, the receiving frequency can be affected by the router's bandwidth in those cases when the data is that large. Encoding the images would reduce the message size so the bandwidth limitation takes less weight in the network throughput. Let us know if that is your use case.