Tick

Nearly all video games (including Minecraft) are driven by one big program loop. Just as every gear in a clock is synchronized with the pendulum, every task involved in advancing a game simulation is synchronized with the game loop. Appropriately, one cycle of the game loop is called a tick.

Game tick[edit | edit source]

A game tick is where Minecraft's game loop runs once. The game normally runs at a fixed rate of 20 ticks per second, so one tick happens every 0.05 seconds (50 milliseconds or 1/20 seconds), making an in-game day last exactly 24 000 ticks (20 minutes). However, if the computer is unable to keep up with this speed, there are fewer game ticks per second (TPS). As the vast majority of actions are timed based on tick count rather than on wall clock time, this means that many things take longer on a slower computer.

A statistic related to ticks per second (TPS) is milliseconds per tick (MSPT), the time a server actually uses to compute a tick. The TPS can be maintained at 20 only if the MSPT is no higher than 50. The following often contribute to server-side lag:

• Hoppers constantly try to search for items above them. Cover with any solid block (except bee nests and beehives), as this stops the checks for items. Alternatively, use water flow-based transport which is faster in bulk.
• Redstone machinery. Redstone components, especially redstone dust cause excessive amounts of block updates and lag. Disabling redstone contraptions and clocks when not in use can help mitigate this.
• Mob AI. Use torches to guide hostile mob spawning. Use more efficient farms for animals.
• Random Tick Speed. When using the command /gamerule randomTickSpeed if the chosen random tick speed is too high, it can cause the MSPT to rise unusually.

The MSPT value is displayed in the F3 debug screen as "ms ticks" in Java Edition. The frame time graph (F3 + 2) shows the TPS value. Both displays are available only as a multiplayer host or singleplayer since the stats come from the integrated server of your Minecraft game.

In Java Edition, tick rates can be controlled by the command /tick.

Game process[edit | edit source]

In Java Edition, in each game loop the following actions are processed in order:

• Reset next tick time if lagging 2s behind expected tick time
• Compute next tick time
• Increment tick count
• Functions with tick or load tags are executed
• Each dimension is ticked in order of overworld, the nether, the end and custom dimensions. For each dimension:
  • Send time every 20 game ticks to players
  • Update world border bounds
  • Advance weather cycle
  • Update daylight cycle time
  • Player sleeping logic
  • Run scheduled commands
  • Scheduled block ticks
  • Scheduled fluid ticks
  • Raid logic
  • Update chunks load level
  • For all chunks in random order:
    • Spawn mobs
    • Tick ice and snow
    • Random ticks
  • Send block changes to players
  • Update points of interest
  • Unloads chunks
  • Execute block events
  • Tick dragon fight
  • For all non-passenger entities:
    • Check if it can despawn
    • Tick entity
    • Tick passengers
  • Tick block entities
  • Handle game events
• Send queued packets and handle incoming packets for each player
• Send player info to players
• Autosave every 6000 ticks
• Run pending tasks and wait for next tick

Chunk tick[edit | edit source]

As a part of a game tick, specific chunks are ticked on every game tick.

In Java Edition, chunks with loading type of entity ticking (see Chunk#Level and load type) and with horizontal distance between its center and a player (not in spectator mode) less than 128 blocks are ticked on every game tick. A few things should be noted here: first, the chunk should be loaded as an entity-ticking chunk. Second, if the chunk receives chunk tick, even if some blocks in the chunk are out of the 128-block radius, they can receive random tick as normal. Third, because 128 blocks is the horizontal distance, the player's position along the y-axis does not matter.

In Bedrock Edition, all chunks inside simulation distance (or specified in the /tickingarea command) are ticked on every game tick. Random ticking randomly occurs in blocks in ticking chunks, regardless of player position inside the chunk. The 128-block distance used in Java does not apply.

In both editions, the following things happen when a chunk gets ticked:

• Mobs naturally spawn.
• During a thunderstorm, lightning may strike somewhere in the chunk (¹⁄₁₀₀₀₀₀ chance).
• ¹⁄₁₆ chance that one column is chosen for weather checks on the topmost block:
  • If in a cold biome, water freezes into ice if possible.
  • If snowing, a snow layer is placed if possible.
    • Additionally, cauldrons can be filled with powder snow.
  • If raining, a cauldron is filled with water.
• A certain number of blocks within the chunk receive random block ticks, as described below.

Random tick[edit | edit source]

Chunks consist of one subchunk per 16 blocks of height, each one being a 16×16×16=4096 block cube. Subchunks are distributed vertically starting at the lowest y level. Every chunk tick, some blocks are chosen at random from each subchunk in the chunk. The blocks at those positions are given a "random tick".

In Java Edition, the number of blocks chosen from each subchunk is specified by /gamerule randomTickSpeed (defaults to 3), and one block can be chosen multiple times in one chunk tick. In Bedrock Edition, it also depends on randomTickSpeed (defaults to 1), but it specifies only relative speed instead of the exact number.

Most blocks ignore this tick, but some use it to do something:

• Crops may grow or uproot.
• Mushrooms may spread or uproot.
• Vines may spread.
• Fire may burn out or spread.
• Ice and snow layers may melt.
• Leaves may decay.
• Farmland hydration is updated.
• Cacti, sugar cane, kelp, bamboo, chorus flowers, mangrove propagules and sweet berry bushes may grow.
• Grass blocks and mycelium may spread.
• Grass blocks, mycelium, and nylium may decay (only if the condition is met).
• Saplings may grow into a tree.
• Lava may set fires nearby.
• Mud may turn into clay if placed on top of a block with pointed dripstone underneath.
• Lit redstone ore turns off.
• Nether portal blocks may spawn a zombified piglin.
• Turtle eggs crack or hatch.
• Campfire smoke appears.
• Budding amethyst may grow an amethyst bud on any of its sides as longs as there is no solid block.
• Copper blocks (or any of its non-oxidized variants) may advance one stage in oxidation.
• Pointed dripstone may fill a cauldron below.
• Pointed dripstone may grow a stalagmite/stalactite if the conditions are met.

Because random block ticks are granted randomly, there is no way to predict when a block can receive its next tick. In Java Edition, the median time between ticks is 47.30 seconds (${\displaystyle {\log }_{\frac{4096-3}{4096}}(0.5)\approx }$ 946.03 game ticks). That is, there is a 50% chance for the interval to be equal or shorter than 47.30 seconds and a 50% chance for it to be equal or longer than 47.30. However, sometimes it is much longer or shorter: for example, there is a 1.38% chance for the interval to be less than one second and a 1.23% chance for the interval to be over five minutes. On average, blocks are updated every 68.27 seconds (${\displaystyle \frac{4096}{3}\approx }$ 1365.33 game ticks). For the math behind these numbers, see the Wikipedia entries for the geometric distribution.

Scheduled tick[edit | edit source]

Some blocks can request a tick sometime in the future. These "scheduled ticks" are used for things that have to happen in a predictable pattern—for instance, redstone repeaters schedule a tick to change state in Java Edition, water schedules a tick when it needs to move.

As a part of a game tick, each block position that has requested a scheduled block tick gets ticked on the specific game tick.

In Java Edition, there are two types of scheduled ticks: block ticks and fluid ticks. Block ticks are executed first based on priority, and then based on scheduling order. A lower value for priority results in earlier execution during the scheduled tick phase. If a redstone repeater is facing the back or side of another diode, its block tick has a priority of -3. If a redstone repeater is depowering, it has a priority of -2. Otherwise, the repeater has a priority of -1. If a redstone comparator is facing the back or side of another diode, it has a priority of -1. All other block ticks have a priority of 0. Then, each block with a scheduled fluid tick get a tick. Fluid ticks do not use priorities and are ordered based on scheduling order.

In Java Edition, the maximum number of scheduled ticks per game tick is 65,536. In Bedrock Edition, the maximum number of scheduled ticks in a chunk per game tick is 100.

Redstone tick[edit | edit source]

The term redstone tick is a unit of time that describes a delay of two game ticks, creating a ¹⁄₁₀ of a second delay.

In Java Edition, redstone ticks are actually not a "real" thing that's handled by distinct game logic, but a term coined by the community to make communication about redstone easier, since most redstone components have delays of multiples of 2 game ticks. For example, a redstone repeater can have a delay of 2, 4, 6, or 8 game ticks, which could instead be described as having a delay of 1 to 4 redstone ticks.

• The downsides of using "redstone ticks" to describe timing behavior are: it suggests a (non-existent) mandatory alignment to multiples of 2 game ticks, and that certain features (like scaffolding or leaves propagating updates, or a piston with 1gt start delay) randomly introduce "half–redstone ticks," potentially introducing to the learner the (incorrect) idea that other fractional values might exist. As a result, more specialized technical Minecraft players typically stick with game ticks as the preferred unit of measurement for delays in redstone contraptions.

In Bedrock Edition, redstone ticks are actually a real thing in the game as the redstone system is calculated by concurrent threads. The transmission of the redstone signal is influenced by redstone ticks.

Piston tick[edit | edit source]

This feature is exclusive to Java Edition. 

The Immediate Update Theory holds that pistons' start delay is 0, the entity stage to the block event stage is a game tick, or in other words, the game tick is divided by the end of block event. This type of "game tick" is called Piston tick(pt). The start delay of note blocks is the same as pistons, it's 0pt. The delay of scheduled-tick components based on piston-tick timing are unfixed.

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