Subscription count is 0 after subscriber is created in ros foxy

[sim-lab-dev]

Problem description

I have created two nodes for publishing and subscribing odometry message in ros foxy.There are about 6 different types of subscriber and 6 publisher in one node. The publishing node only publishes odometry message in 100 hz. But when the subscriber is created by rclcpp no message is received occasionally. By using "occasionally" means about 1/20 for subscriber to lost connection to publisher. And also when I use ros2 info to check the topic status, the subscription count is 0. So is there anybody knows why the subscriber can't receive message.

Required Info:

• Operating System:
  • Ubuntu20.04
• Installation type:
  • Binaries
• Version or commit hash:
  • Ros foxy
• DDS implementation:
  • Default
• Client library (if applicable):

[fujitatomoya]

this is not much an information, but hopefully helpful.

• Can you use ROS Humble instead? Foxy is already E.O.L.
• Can you restart the ros2 daemon with ros2 daemon stop and then ros2 daemon start, and ros2 topic info xxx? (if this finds the subscription, probably node graph in daemon is not updated.)

[sim-lab-dev]

this is not much an information, but hopefully helpful.

• Can you use ROS Humble instead? Foxy is already E.O.L.
• Can you restart the ros2 daemon with ros2 daemon stop and then ros2 daemon start, and ros2 topic info xxx? (if this finds the subscription, probably node graph in daemon is not updated.)

• Do you mean ROS Humble is more stable than Foxy?
• Restarting the ros2 daemon can find the subscription but the callback function is not called

This link found Ros Foxy has a bug in topic message. Not sure if the problem is caused by the bug

[fujitatomoya]

Do you mean ROS Humble is more stable than Foxy?

yes, I do. Humble is maintained distro.

This #1301 found Ros Foxy has a bug in topic message. Not sure if the problem is caused by the bug

foxy uses Fast-DDS 2.1.x, eProsima/Fast-DDS#2906 has been merged, i believe the final foxy release should include this bug fix.

[sim-lab-dev]

Do you mean ROS Humble is more stable than Foxy?

yes, I do. Humble is maintained distro.

This #1301 found Ros Foxy has a bug in topic message. Not sure if the problem is caused by the bug

foxy uses Fast-DDS 2.1.x, eProsima/Fast-DDS#2906 has been merged, i believe the final foxy release should include this bug fix.

I found that the following two cases the messages were received normally:

• Config the fast-dds to use UDP transport instead of Shared Memory
• Using the cyclone-dds instead of fast-dds
  In the first case I guessed the buffer size was not large enough and I also tried to increase the segment size of the fast-dds in Shared Memory mode, but it didn't work.