Interesting interaction between set_up_ament=True and nodes exiting gracefully

[cullenwren-volair]

Was recently trying to figure out why I could not get my nodes to exit gracefully on shutdown and I traced it back to the set_up_ament flag being true in my nodes ros_py_binary rule. I was able to fail the test found in examples/lifecycle by setting set_up_ament=True for lifecycle_talker rule

Does this interaction make sense / is it intentional?

To me, it seems to stem from that when set_up_ament=True, the PID of what ros_launch thinks the node is different from the nodes actual PID, but not sure why that would be.

Sure, steps to re-create:
in examples/lifecycle/BUILD.bazel make the change

ros2_cpp_binary(
    name = "lifecycle_talker",
    srcs = ["lifecycle_talker.cc"],
+   set_up_ament = True,
    deps = [
        "@ros2_common_interfaces//:cpp_std_msgs",
        "@ros2_rcl_interfaces//:cpp_lifecycle_msgs",
        "@ros2_rclcpp//:rclcpp",
        "@ros2_rclcpp//:rclcpp_lifecycle",
    ],
)

run the test in the examples/lifecycle folder
witrhin the log:

======================================================================
FAIL: test_talker_graceful_shutdown (tests.TestLifecyclePubSubAfterShutdown)
Test lifecycle talker graceful shutdown.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/ubuntu/.cache/bazel/_bazel_ubuntu/9871e3f5514bc8b2cd22ccc79c1fe02d/sandbox/linux-sandbox/2/execroot/com_github_mvukov_rules_ros2_examples/bazel-out/k8-fastbuild/bin/lifecycle/tests.runfiles/com_github_mvukov_rules_ros2_examples/lifecycle/tests.py", line 149, in test_talker_graceful_shutdown
    launch_testing.asserts.assertExitCodes(proc_info, process=talker_node)
  File "/home/ubuntu/.cache/bazel/_bazel_ubuntu/9871e3f5514bc8b2cd22ccc79c1fe02d/sandbox/linux-sandbox/2/execroot/com_github_mvukov_rules_ros2_examples/bazel-out/k8-fastbuild/bin/lifecycle/tests.runfiles/ros2_launch/launch_testing/launch_testing/asserts/assert_exit_codes.py", line 62, in assertExitCodes
    assert info.returncode in allowable_exit_codes, 'Proc {} exited with code {}'.format(
AssertionError: Proc lifecycle_talker-1 exited with code -15

full log: test.log

[mvukov]

Hi, can you paste the error log here for the reference, please?

[cullenwren-volair]

Added to the description

[ahans]

Great observation that it's due to the PID changing. When I read this, it was immediately clear that this is introduced by the wrapper that we use to set AMENT_PREFIX_PATH. I created #169 with a fix and that seems to make it work.

Since we use the same wrapper for ros_py_binary, this should fix that issue as well. @cullenwren-volair Could you give it a try please? Thanks!

[cullenwren-volair]

Those changes resolved it for me! Thanks for the quick response to this 😄