ros2 runtime_error ai_generated partial

[WARN] [topic_statistics]: Received message on topic '/scan' with sequence number 123, expected 124

ID: ros2/ros2-topic-statistics-mismatch

Also available as: JSON · Markdown · 中文
80%Fix Rate
82%Confidence
1Evidence
2024-03-05First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
ros2:humble active — — —
ros2:iron active — — —
ros2:rolling active — — —
rclcpp:18.0.0 active — — —

Root Cause

Topic statistics monitoring detected a gap in message sequence numbers, indicating dropped messages or out-of-order delivery, often due to network congestion, high CPU load, or QoS incompatibility.

generic

中文

主题统计监控检测到消息序列号有间隔，表示消息丢失或乱序传递，通常由于网络拥塞、CPU 负载高或 QoS 不兼容导致。

Official Documentation

https://docs.ros.org/en/humble/Tutorials/Intermediate/Topic-Statistics.html

Workarounds

  1. 75% success Check network bandwidth and CPU usage. If high, reduce the publishing rate or use a more efficient serialization. Example: ros2 topic hz /scan # Check current rate ros2 topic bw /scan # Check bandwidth If bandwidth is high, adjust the publisher to use a lower rate or reduce message size. 
    Check network bandwidth and CPU usage. If high, reduce the publishing rate or use a more efficient serialization. Example:
ros2 topic hz /scan  # Check current rate
ros2 topic bw /scan   # Check bandwidth

If bandwidth is high, adjust the publisher to use a lower rate or reduce message size.
  2. 85% success If using unreliable QoS (e.g., BEST_EFFORT), switch to RELIABLE QoS to reduce drops. In publisher code: from rclpy.qos import QoSProfile, ReliabilityPolicy qos = QoSProfile(depth=10, reliability=ReliabilityPolicy.RELIABLE) self.publisher = self.create_publisher(LaserScan, '/scan', qos) 
    If using unreliable QoS (e.g., BEST_EFFORT), switch to RELIABLE QoS to reduce drops. In publisher code:
from rclpy.qos import QoSProfile, ReliabilityPolicy

qos = QoSProfile(depth=10, reliability=ReliabilityPolicy.RELIABLE)
self.publisher = self.create_publisher(LaserScan, '/scan', qos)

中文步骤

  1. 检查网络带宽和 CPU 使用率。如果过高，降低发布速率或使用更高效的序列化。示例：
ros2 topic hz /scan  # 检查当前速率
ros2 topic bw /scan   # 检查带宽

如果带宽高，调整发布器使用较低速率或减小消息大小。
  2. 如果使用不可靠的 QoS（例如 BEST_EFFORT），切换到 RELIABLE QoS 以减少丢失。在发布器代码中：
from rclpy.qos import QoSProfile, ReliabilityPolicy

qos = QoSProfile(depth=10, reliability=ReliabilityPolicy.RELIABLE)
self.publisher = self.create_publisher(LaserScan, '/scan', qos)

Dead Ends

Common approaches that don't work:

  1. Disabling topic statistics without investigating the root cause 60% fail

    This hides the symptom but does not address the underlying message loss, which may affect application behavior.

  2. Increasing the publisher's publishing rate to compensate 80% fail

    Higher rate increases network and CPU load, potentially worsening the problem.