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Messages drop on slow subscriber although queue not full / empty Problem Setup: ROS noetic, Ubuntu20. I have a slow

Added an answer but was not able to accept it as correct since I have < 10 points.

Problem

Setup: ROS noetic, Ubuntu20.

I have a slow pose estimation node which subscribes to incoming images with a low frequency of only 2Hz. The images are published by a rosbag with 20Hz. The bag contains about 800 images (colored, 1280x1024px) , so they should easily fit into the 10k elements queue of the publisher (rosbag play --queue=10000) and subscriber (message_filters.TimeSynchronizer([image_sub, info_sub],10000)

I would expect that the subscriber queues the incoming images so that every single image can be processed one after another. But instead, already after 3 image messages the dropping of messages starts so that in the end ~60% of the messages are dropped.

While debugging the message_filter.TimeSynchronizer (synchronizes CameraInfo and Image subscriber) I could see that the image queue is never longer than 1, while the camera info queue grew proportional to the published messages.

Solution While searching for a solution I learned that message transport in ROS happens with TCP/UDP. Through this hint

Messages drop on slow subscriber although queue not full / empty Discalimer: The problem I am describing here is already

Messages drop on slow subscriber although queue not full / empty Discalimer: The problem I am describing here is already

It fails with g++ test.cpp -o test so it is pretty sure unrelated to ROS.

Could isolate the problem to <cstring>. This fails with the same error message. I am fairly new to ros and to c++.

Could isolate the problem to <cstring>. This fails with the same error message. I am fairly new to ros and to c++.

Yes, it still fails.

Added the code and the cmakelist. @gvdhoorn i was able compile your example without any problems. With include <ros/r

Added the code and the cmakelist. @gvdhoorn i was able compile your example without any problems. With include <ros/r

Added the code and the cmakelist. @gvdhoorn i was able compile your example without any problems. With include <ros r

Added the code and the cmakelist. @gvdhoorn i was able compile your example without any problems. With include <ros r

Added the code and the cmakelist. @gvdhoorn i was able compile your example without any problems.

cstring incompability when include <ros ros.h=""> Out of nowhere my ros kinetic project fails building with the st

cstring incompability when include <ros ros.h=""> Out of nowhere my ros kinetic project fails building with the st