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  1. Minecraft: Java Edition
  2. MC-275437

Fast moving entities freeze the server which causes watchdog crash

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    • Icon: Bug Bug
    • Resolution: Fixed
    • 24w36a
    • 24w33a, 24w34a, 24w35a
    • None
    • Community Consensus
    • Collision, Crash, Entities
    • Very Important
    • Platform

      When using any tnt cannon entities move too fast thus load too many chunks which freezes the server which then crashes due to watchdog.

      Previously entities werent loading chunks on their path thus didnt freeze the server, but 24w33a completely reworked entities colliding with interactable blocks (pressure plates, nether portals, lava cauldrons, powdered snow, etc) which makes entities load chunks.
      Previously entities checked collisions with said blocks only at the end of their tick, but since 24w33a they search the entire path that entity covered in a tick for said blocks, this search loads and generates chunks which freezes the game.

      Example:
      1.21 no lag:
      https://youtu.be/HRet2xJvzhU
      24w33a minute of lag and the server crashes due to watchdog:
      https://youtu.be/x_pddUNtNBQ
      crash report from second video

      Please note this is a very tmc (tech mc community) sensitive issue, it breaks the entire field of cannon tech, to fix it we can suggest limiting said search to only first ~10 blocks of path that entity took.
      the mentioned "raycast" is performed in the
      addCollisionsAlongTravel()
      in the
      BlockGetter.java

      This issue is related to MC-275298

            HugoHagglund [Mojang] SHugoh
            Savvvage_ Savva
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              Created:
              Updated:
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