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00
Guided beta caseProintermediateQoS durability

Late subscribers miss the map

Allow a late-starting visualizer to receive the current static map without republishing continuously.

Pairs with QoS policies in ROS 2 Systems Debugging. Read the concept first, then diagnose it here.

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Operator report

Subscribers started with the system receive `/map`; subscribers started later wait forever.

Ubuntu 24.04, ROS 2 Jazzy, Python and C++ nodes, browser telemetry workspace

01

System boundary

Trace only the relevant path.

3 nodes
  1. 01map server→
  2. 02/map→
  3. 03late visualizerOUT
02

How this lab works

You diagnose it. No command list.

Open the repair workspace and gather your own evidence in a real terminal. No diagnostic commands are handed to you - finding the fault is the exercise. Stuck? Progressive hints unlock inside the workspace.

03

Verification

Pass more than the visible symptom.

4 checks
  • Late subscriber receives map
  • Only one map sample is required
  • Hidden regression behavior
  • Root cause explanation