Improve error reporting by adding file locations to exceptions #823

rolker · 2025-01-28T19:32:16Z

In order to pinpoint which launch file caused an exception, this patch intercepts exceptions and adds notes that help determine the source of the error.

This might help with #799 as well.

Signed-off-by: Roland Arsenault <[email protected]>

christophebedard

Thanks for the PR. Could you add simple before/after example outputs in the PR description (including the commands you ran to get the output, if possible) to show how this improves error reporting?

christophebedard · 2025-01-28T19:44:06Z

launch/launch/actions/include_launch_description.py

+            declared_launch_arguments = (
+                launch_description.get_launch_arguments_with_include_launch_description_actions())
+        except Exception as exc:
+            exc.add_note('while executing {}'.format(self.describe()))


Could you switch to f-strings, here and everywhere else?

Python is not my native programming language so I had to google f-strings and learned something useful. Thanks!

rolker · 2025-01-29T16:17:01Z

Example output using https://github.com/rolker/launch_error_examples

This is a simpler set of launch files than what I was dealing with when I created the patch, but still has some nested includes to better showcase the issue when dealing with complex launch files.

It should be noted that this helps with error that pop up when the launch description is executed. Errors while loading/evaluating the files tend to display the file location of the error.

Before the patch:

$ ros2 launch launch_error_example parent_launch.py 
[INFO] [launch]: All log files can be found below /home/roland/.ros/log/2025-01-29-10-47-00-892280-deadpool-41786
[INFO] [launch]: Default logging verbosity is set to INFO
[ERROR] [launch]: Caught exception in launch (see debug for traceback): 'tuple' object has no attribute 'describe_sub_entities'

$ ros2 launch -d launch_error_example parent_launch.py 
[DEBUG] [launch.launch_context]: emitting event synchronously: 'launch.events.IncludeLaunchDescription'
[INFO] [launch]: All log files can be found below /home/roland/.ros/log/2025-01-29-10-47-44-260437-deadpool-42338
[INFO] [launch]: Default logging verbosity is set to DEBUG
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x74d3999bc740>'
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x74d3999bc740>' ✓ '<launch.event_handlers.on_include_launch_description.OnIncludeLaunchDescription object at 0x74d3999bc860>'
[DEBUG] [launch]: An exception was raised in an async action/event
[DEBUG] [launch]: Traceback (most recent call last):
  File "/home/roland/ros2/rolling/build/launch/launch/launch_service.py", line 343, in run_async
    raise exception_to_raise
  File "/home/roland/ros2/rolling/build/launch/launch/launch_service.py", line 230, in _process_one_event
    await self.__process_event(next_event)
  File "/home/roland/ros2/rolling/build/launch/launch/launch_service.py", line 250, in __process_event
    visit_all_entities_and_collect_futures(entity, self.__context))
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 38, in visit_all_entities_and_collect_futures
    sub_entities = entity.visit(context)
                  ^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/action.py", line 109, in visit
    return self.execute(context)
          ^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/actions/include_launch_description.py", line 164, in execute
    launch_description.get_launch_arguments_with_include_launch_description_actions())
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/launch_description.py", line 161, in get_launch_arguments_with_include_launch_description_actions
    process_entities(self.entities, _conditional_inclusion=conditional_inclusion)
  File "/home/roland/ros2/rolling/build/launch/launch/launch_description.py", line 151, in process_entities
    process_entities(
  File "/home/roland/ros2/rolling/build/launch/launch/launch_description.py", line 151, in process_entities
    process_entities(
  File "/home/roland/ros2/rolling/build/launch/launch/launch_description.py", line 152, in process_entities
    entity.describe_sub_entities(),
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'tuple' object has no attribute 'describe_sub_entities'

[ERROR] [launch]: Caught exception in launch (see debug for traceback): 'tuple' object has no attribute 'describe_sub_entities'
[DEBUG] [launch.launch_context]: emitting event: 'launch.events.Shutdown'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x74d399ade420>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x74d399ade420>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x74d399900ce0>'

With this patch applied. Notice the added info where the exception is printed with the added notes.

$ ros2 launch launch_error_example parent_launch.py 
[INFO] [launch]: All log files can be found below /home/roland/.ros/log/2025-01-29-10-50-46-363663-deadpool-45119
[INFO] [launch]: Default logging verbosity is set to INFO
[ERROR] [launch]: Caught exception in launch (see debug for traceback): 'tuple' object has no attribute 'describe_sub_entities'

$ ros2 launch -d launch_error_example parent_launch.py 
[DEBUG] [launch.launch_context]: emitting event synchronously: 'launch.events.IncludeLaunchDescription'
[INFO] [launch]: All log files can be found below /home/roland/.ros/log/2025-01-29-10-51-29-159327-deadpool-45707
[INFO] [launch]: Default logging verbosity is set to DEBUG
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x79c2e55cc4d0>'
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x79c2e55cc4d0>' ✓ '<launch.event_handlers.on_include_launch_description.OnIncludeLaunchDescription object at 0x79c2e55cecf0>'
[DEBUG] [launch]: An exception was raised in an async action/event
[DEBUG] [launch]: Traceback (most recent call last):
  File "/home/roland/ros2/rolling/build/launch/launch/launch_service.py", line 343, in run_async
    raise exception_to_raise
  File "/home/roland/ros2/rolling/build/launch/launch/launch_service.py", line 230, in _process_one_event
    await self.__process_event(next_event)
  File "/home/roland/ros2/rolling/build/launch/launch/launch_service.py", line 250, in __process_event
    visit_all_entities_and_collect_futures(entity, self.__context))
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 38, in visit_all_entities_and_collect_futures
    sub_entities = entity.visit(context)
                  ^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/action.py", line 109, in visit
    return self.execute(context)
          ^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/actions/include_launch_description.py", line 166, in execute
    launch_description.get_launch_arguments_with_include_launch_description_actions())
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/roland/ros2/rolling/build/launch/launch/launch_description.py", line 165, in get_launch_arguments_with_include_launch_description_actions
    process_entities(self.entities, _conditional_inclusion=conditional_inclusion)
  File "/home/roland/ros2/rolling/build/launch/launch/launch_description.py", line 152, in process_entities
    process_entities(
  File "/home/roland/ros2/rolling/build/launch/launch/launch_description.py", line 152, in process_entities
    process_entities(
  File "/home/roland/ros2/rolling/build/launch/launch/launch_description.py", line 153, in process_entities
    entity.describe_sub_entities(),
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'tuple' object has no attribute 'describe_sub_entities'
entity: (IncludeLaunchDescription(PathJoin('FindPackageShare(pkg='turtlesim') + 'launch' + 'multisim.launch.py'')),)
entity: <launch.launch_description.LaunchDescription object at 0x79c2e543be30>
entity: IncludeLaunchDescription(PathJoin('FindPackageShare(pkg='launch_error_example') + 'launch' + 'bar_launch.py''))
while executing IncludeLaunchDescription(/home/roland/ros2/rolling/install/launch_error_example/share/launch_error_example/launch/parent_launch.py)

[ERROR] [launch]: Caught exception in launch (see debug for traceback): 'tuple' object has no attribute 'describe_sub_entities'
[DEBUG] [launch.launch_context]: emitting event: 'launch.events.Shutdown'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x79c2e5ef0110>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x79c2e5ef0110>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x79c2e5555520>'

Signed-off-by: Roland Arsenault <[email protected]>

rolker added 2 commits January 28, 2025 14:15

Improve error reporting by adding file locations to exceptions

1492777

Signed-off-by: Roland Arsenault <[email protected]>

Fix formating errors caught by flake.

a1630ba

Signed-off-by: Roland Arsenault <[email protected]>

christophebedard reviewed Jan 28, 2025

View reviewed changes

Switch to f strings

68360f0

Signed-off-by: Roland Arsenault <[email protected]>

rolker mentioned this pull request Feb 5, 2025

Provide more meaningful output on error ros2/launch_ros#291

Open

Yadunund assigned christophebedard Feb 6, 2025

Yadunund requested a review from christophebedard February 6, 2025 21:06

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Improve error reporting by adding file locations to exceptions #823

Improve error reporting by adding file locations to exceptions #823

rolker commented Jan 28, 2025

christophebedard left a comment

christophebedard Jan 28, 2025

rolker Jan 29, 2025

rolker commented Jan 29, 2025

Improve error reporting by adding file locations to exceptions #823

Are you sure you want to change the base?

Improve error reporting by adding file locations to exceptions #823

Conversation

rolker commented Jan 28, 2025

christophebedard left a comment

Choose a reason for hiding this comment

christophebedard Jan 28, 2025

Choose a reason for hiding this comment

rolker Jan 29, 2025

Choose a reason for hiding this comment

rolker commented Jan 29, 2025