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Verify It Yourself

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Aplite36 edited this page Jul 27, 2026 · 1 revision

Verify It Yourself

Do not take the claim on trust. It takes about five minutes to try to break.

The test

  1. In server.properties, set simulation-distance=2. This is the trick that makes the test visible: it shrinks what a player loads from several hundred chunks to a handful, so ChunkCarts' own loading is the only thing left moving.
  2. Build a closed loop of powered rail, 32 by 32 is plenty, and put a cart on it.
  3. Run /chunkcarts list to see exactly which chunks are held, and for which journeys.
  4. Run /tick sprint 72000, an hour of game time in a couple of minutes, and watch the held chunk count fall to zero and stay there while the cart is still going round.
  5. Check the log for SLACK_EXHAUSTED. That is the loop detector firing.

Step 1 is the one people skip, and skipping it is why the test appears to fail. At a normal simulation distance a player standing anywhere near the loop is already holding every chunk the cart passes through, so nothing ChunkCarts does or stops doing changes what is loaded.

Then try to defeat it

  • Wind the loop into a figure of eight.
  • Make it enormous.
  • Use a long there and back shuttle instead of a loop.
  • Use a furnace cart, so no redstone is involved at all.

A track shape that keeps chunks loaded indefinitely on default settings is a serious bug. Please open an issue.

Why the loop cases end

A journey is only ever allowed to continue while the cart is making progress away from where it set off. That is the whole design rather than a heuristic bolted on afterwards, which is why the shuttle and the furnace cart end the same way the plain loop does: none of them can keep beating their own furthest distance from the start.

The tolerance for winding track is progress-slack-chunks, covered in Configuration. Every reason a journey can end is listed in Journey Outcomes.

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