Spawn chunk

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Spawn chunks are chunks found at the world spawn point which are not unloaded from the memory, unlike normal chunks.

Introduction[edit]

Normally, old chunks beyond player's chunk loading distance get unloaded from the memory and new chunks get loaded into the memory. Because of this, events such as redstone mechanisms and farms in unloaded chunks stop processing. Since spawn chunks remain loaded, events occurring in them continue to process, even if no players are nearby. If the world spawn is set to a laggy area using commands, such as an area with many redstone clocks, lag is present wherever the player is in the world.

Behavior[edit]

Illustration of chunk propagation.

The so called "spawn chunks" behavior arises from a start ticket which is created for the world spawn chunk. This ticket has a level of 22 which "propagates," or flows, to neighbouring chunks. Each time the level flows, it increases its level by 1 until the maximum of 44 is reached. This behavior is illustrated by the picture to the right.

Different levels of propagation have diffrent behaviors. These levels are divided into 4 load types.

Load Type Level Properties
Entity Ticking 31 and below In the spawn chunks, this consists of a 19×19 chunk area. All game aspects are active.
Ticking 32 The margin of the 21×21 area. All game aspects are active except that entities are not processed (do not move) and chunk ticks aren't either.
Border 33 The margin of the 23×23 area. Only some game aspects are active (redstone and command blocks do not work).
Inaccessible 34 and above No game aspects are active, but world generation still occurs.

Limitations[edit]

There are some limitations which may affect the behavior of spawn chunks.

Idle timeout

Each dimension has its own "idle timeout." Without a player or forceloaded chunks in the overworld, this timeout eventually expires. When the timeout expires, some behaviors such as entity processing stop for spawn chunks and the rest of the dimension. The timeout can be reset by frequently sending entities through a portal.

Chunk tick

Only chunks which are centered within 128 blocks of a player are ticked on every game tick. This stops events caused by random ticking, such as crop growth.

Entities
  • Hostile mobs more than 128 blocks from a player despawn.
  • Passive mobs only spawn inside a 240×240 block area around the player.
  • Passive mobs present in the spawn chunks count towards the mob cap. This often prevents friendly mobs from naturally spawning elsewhere in the world.

Changing location[edit]

A new world spawn point can be set using /setworldspawn. If no coordinates are provided, the block position that the player is currently standing on becomes the spawn point. The chunk where the world spawn is located is then given a start ticket with a level of 22 and the ticket for the old spawn chunks is cleared.