topic statistics results include measurement values out of window #1531
Description
Bug report
topic statistics results don't reset by window updating so that the results include values out of a window.
For instance, this behavior can cause steady-state results hidden if the maximum value is recorded at the start-up phase.
I think statistics results should be calculated within a window.
Required Info:
- Operating System:
- Ubuntu 20.04
- Installation type:
- from source
- Version or commit hash:
- DDS implementation:
- Fast-DDS
- Client library (if applicable):
- rclcpp
Steps to reproduce issue
$ cd ~/ros2_ws/
$ git clone -b check_statistics_transition_state https://github.com/hsgwa/intra_process_ping_latency_test.git src/intra_process_ping_latency_test
$ colcon build --packages-select intra_process_ping_latency_test
$ . ~/ros2_ws/install/local_setup.bash
$ ros2 run intra_process_ping_latency_test ping_test
$ # in other terminal
$ PYTHONUNBUFFERED=1 ros2 topic echo /topic_statistics | grep message_age -A 18 --line-buffered | grep "data_type: 3" -A 1 --line-buffered | grep "data:"
# print out message_age minimum valuesHere, ping_test adjusts message_age=1s for first 10s to imitate transition state.
After that, message_age fall down to about 1 ms order value.
Expected behavior
$ PYTHONUNBUFFERED=1 ros2 topic echo /topic_statistics | grep message_age -A 18 --line-buffered | grep "data_type: 3" -A 1 --line-buffered | grep "data:"
data: 1000.388805 # Transition state. message_age are adjusted to 1000 ms
data: 1000.388805
data: 0.791165 # 10 s later
data: 0.361127 # max value doesn't include transition state.
data: 0.361127Actual behavior
$ PYTHONUNBUFFERED=1 ros2 topic echo /topic_statistics | grep message_age -A 18 --line-buffered | grep "data_type: 3" -A 1 --line-buffered | grep "data:"
data: 1001.457474 # Transition state. message_age are adjusted to 1000 ms
data: 1001.457474
data: 1001.457474
data: 1001.457474 # 10 s later
data: 1001.457474 # max value includes transition state.
data: 1001.457474
data: 1001.457474
data: 1001.457474Additional information
The above outputs omit window_start and window_stop though, every window is updated to prevent overlap.
$ PYTHONUNBUFFERED=1 ros2 topic echo /topic_statistics | grep message_age -A 18 --line-buffered | grep window -A 2
window_start:
sec: 1611812308
nanosec: 560635188
window_stop:
sec: 1611812309
nanosec: 560659761
--
window_start:
sec: 1611812309
nanosec: 560659761
window_stop:
sec: 1611812310
nanosec: 560712642
From the source code, it seems that resetting the statistics here will solve this issue.
https://github.com/ros2/rclcpp/blob/master/rclcpp/include/rclcpp/topic_statistics/subscription_topic_statistics.hpp#L154