ros2: rqt_bag shows only one data of multiple topics

[nonanonno]

I have a rosbag file which has two topics: /chatter (std_msgs/msg/String) and /number (std_msgs/msg/Int32). But when I show it in rqt_bag, there is a case that displays only /chatter data for both /chatter and /number like the following figure.

I think this happens when the timestamp of two topics are exactly same. In this case, /chatter is 1FPS and /number is 2FPS. So if I seek timeline to time only /number is publishing, I can see both /chatter and /number correctly.

Enviornment

• Ubuntu 22.04
• ROS2 Humble
• rqt_bag version: 1.1.4

[nonanonno]

when the timestamp of two topics are exactly same

This is because I have used python script which uses rosbag2_py.SequentialWriter to create rosbag file.

[guihomework]

I confirm this bug, but I recorded using ros2 bag record /imu /clock on Ubuntu 22.04 ros rolling (19 April download) using rqt_bag-1.3.1/rqt_bag_plugins-1.3.1

and rqt_bag -v rosbag2_2023_04_21-09_39_18 to visualize
both raw show imu data and not the clock although I requested a display of clock first (was already showing imu data)

verbose output

PluginManager._discover() using cached plugin discovery information
QtBindingHelper using pyqt
PerspectiveManager.switch_perspective() switching to perspective "@rqt_bag__Bag"
MainWindow.restore_settings()
PluginManager.restore_settings_without_plugins()
MainWindow.restore_state()
PluginManager.load_plugin(rqt_bag/Bag, 0)
MainWindow.save_setup()
RosPyPluginProvider._init_node() initialize ROS node "rqt_gui_py_node_1911"
Start called on RclpySpinner, spinning ros2 node
RospkgPluginProvider._find_plugins() crawling for plugins of type 'rqt_bag'
rqt_bag.TimelineFrame.load_plugins() loaded plugin "rqt_bag_plugins/BagImagePlugin"
rqt_bag.TimelineFrame.load_plugins() loaded plugin "rqt_bag_plugins/BagPlotPlugin"
PluginManager._load_plugin_restore()
PluginManager._load_plugin(rqt_bag/Bag#0) successful
Loading 'b'rosbag2_2023_04_21-09_39_18'' ...
Loading bag from metadata file "rosbag2_2023_04_21-09_39_18" Succeeded
Topics from this bag: ['/clock', '/imu']
PluginHandler.restore_settings()
PluginHandler.emit_restore_settings_completed()
PluginManager._emit_load_plugin_completed()
Setting timeline left: 1682062761.1051958 right: 1682062767.0358496
Setting playhead Time(nanoseconds=1682062761105195776, clock_type=SYSTEM_TIME)
MainWindow.restore_state()
Done loading 'b'rosbag2_2023_04_21-09_39_18''
Setting timeline left: 1682062761.1051958 right: 1682062767.0358496
press, rel=PyQt5.QtCore.QPoint(268, 87), global=PyQt5.QtCore.QPoint(535, 1360), diff=PyQt5.QtCore.QPoint(535, 1360)
press, rel=PyQt5.QtCore.QPoint(265, 88), global=PyQt5.QtCore.QPoint(532, 1361), diff=PyQt5.QtCore.QPoint(532, 1361)
TimelinePopupMenu process action <PyQt5.QtWidgets.QAction object at 0x7fd55c6ead40>
Adding listener to topic /clock of type <class 'rqt_bag.plugins.raw_view.RawView'>
TimelinePopupMenu process action <PyQt5.QtWidgets.QAction object at 0x7fd596864670>
Adding listener to topic /imu of type <class 'rqt_bag.plugins.raw_view.RawView'>

[berndpfrommer]

I'm seeing the same bug with two image topics that have identical time stamps. It's very confusing.

[Yadunund]

Also happening on Iron as reported #147

[arneboe]

This happens to me for all messages, not just with the same timestamp.
I attached a debugger an can see that the ListenerEvent is posted correctly in message_listener_thread.py:82.
But the event is received by all views. I.e. a view for topic "a" will also receive the messages for topic "b".
I have no idea why that happens

Could something be broken in the qt integration? The events are handled by qt?