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Rosbag record with start-paused feature ingores `/tf_static` #1302

Closed michalpelka closed 9 months ago

michalpelka commented 1 year ago

Description

We are recording the rosbag with such parameters:

ros2 bag record  /odom /tf /tf_static   --use-sim-time --start-paused --max-cache-size 10737418240 --no-discovery

Our system produces a simulated clock. We need to start in a "paused" state to mitigate the issue raised by my colleague #1276. The ros2 bag record does not record the one message published in \tf_static. If you open created database and run such query, it will return 0:

 SELECT COUNT (messages.data) FROM messages INNER JOIN topics ON messages.topic_id== topics.id WHERE topics.name LIKE "/tf_static"

Expected Behavior

I would like to ros2 bag record to keep messages that are latched (like tf_static) and record it even with --start-paused. Please adjust the correct timestamp to not bring behavior from #1276.

Actual Behavior

There are no recorded messages in '/tf_static' topic.

To Reproduce

** Steps to reproduce the behavior, e.g.

  1. Open one terminal and run ros2 run tf2_ros static_transform_publisher 1 2 3 0.5 0.1 -1.0 foo bar
  2. Open the second terminal and run ros2 bag record --start-paused /tf_static
  3. Hit space to resume and then CRTL+C to stop recording
  4. Investigate created bag with ros2 bag info, it will have 0 messages recorded

Note : if you omit --start-paused in point 2, the resulting bag will contain expected one message.

System (please complete the following information)

Additional context

Add any other context about the problem here

MichaelOrlov commented 1 year ago

@michalpelka I have a suspicious that --no-discovery is the key in your scenario with --start-paused flag. Can you please try it without --no-discovery flag?

MichaelOrlov commented 1 year ago

@michalpelka Sorry for confusion from my previous message this is certainly unrelated to the --no-discovery flag. --start-paused behave as expected and probably not what you need for your scenario. In paused mode recorder receiving messages and dropping them without saving to the storage. It was made by design and we can't do better since if subscription already created callback will be called on message arrive. We can't pause on subscription level. https://github.com/ros2/rosbag2/blob/18216763ac13d942ee582c4b658962e49179ba3d/rosbag2_transport/src/rosbag2_transport/recorder.cpp#L431-L444

emersonknapp commented 1 year ago

Agreed that this seems like a bad interaction between latched topics (transient local durability) and --start-paused. Maybe there is some fix around waiting to create subscriptions until first resume, at least for topics with transient local durability? In any case, that's a little finicky and would take some care - there is no way to know if a message is received because it was latched or because it was new, the publisher just sends out messages to newly-detected subscriptions.

For this particular case, I think the real fix is https://github.com/ros2/rosbag2/pull/1354. That will backport easily into Iron and should require only a little tweaking to backport to Humble, there are no required API changes, just documentation and implementation.

MichaelOrlov commented 9 months ago