In this guide, we will explore what ticks mean and what the mainthread of a server is.
How Minecraft Works
First, let's understand how Minecraft works in broad terms. Like many games, Minecraft operates with a large loop. The execution of the game (and the server) is divided into "ticks." Each "tick," the server performs a number of tasks, such as:
A Minecraft server aims to perform 20 of these "ticks" per second, which means one tick every 50 milliseconds.
When the Server Works Properly
When the server is functioning properly, the time to process a tick should be less than 50 milliseconds. If the time to process the tick is under 50 milliseconds, the server will "sleep" for the remaining time, ready to perform the next tick. Example: If the server takes 15 milliseconds to process a tick, it will then sleep for 35 milliseconds before the next tick.
When the Server Lags
If the tick takes more than 50 milliseconds, the processing of the next tick is delayed, as ticks cannot be performed in parallel. When this happens, gameplay deteriorates, and the server starts to "lag." You will receive the message "Can't keep up!" if the server has more than 2000 ms of delay in processing ticks. If a server takes more than 60 seconds, it is usually considered to be in a crash state by the watchdog.
How to Identify Why My Server is Lagging?
It's quite simple; you can generally analyze it using Spark to find the cause. We have a tutorial on this right here : Analyze your Minecraft server lags
Why Does the Server Lag?
The server "lags" because ticks are not processed on time. In Minecraft, actions are what’s called "single-threaded," meaning they are processed by a single core of the CPU (mainthread). For a zombie to attack a player, the server first needs to process several things: where the player is, where the zombie is, which path to take, is it within range, is it invisible? Once all of this is processed, the server can confirm that the zombie is attacking the player. Now, imagine the server has to do this for 500 zombies. Every 0.05 seconds, the server needs to calculate this for each zombie. When there are too many entities on a server, it can no longer handle the calculations together. This is often the case with monster farms or restricted farms with many entities. Imagine 50 chickens trapped in 2x2 blocks. Each chicken will "push" every other chicken. This results in 2500 free interactions that the server has to handle every 0.05 seconds. You can imagine the load this can place on the server.
Ticks Per Second (TPS)
TPS stands for Ticks Per Second. A server running at 20 TPS means that the requested 20 ticks are processed every second. When the server falls behind in processing ticks, it affects the subsequent ticks, and your TPS decreases. The calculation is as follows: (1000 - delay in ms) / 50 = x TPS. For example, if your server has a delay of 250 milliseconds every second, your TPS will be 15.
How Minecraft Works
First, let's understand how Minecraft works in broad terms. Like many games, Minecraft operates with a large loop. The execution of the game (and the server) is divided into "ticks." Each "tick," the server performs a number of tasks, such as:
- Processing packets sent by players (movements, block destruction/placement, attacking entities, etc.)
- Updating the positions of players and entities
- Sending packets to players about what's happening on the server (block changes, entity movements, etc.)
- Spawning monsters, their AI, pathfinding, etc.
- Processing redstone.
A Minecraft server aims to perform 20 of these "ticks" per second, which means one tick every 50 milliseconds.
When the Server Works Properly
When the server is functioning properly, the time to process a tick should be less than 50 milliseconds. If the time to process the tick is under 50 milliseconds, the server will "sleep" for the remaining time, ready to perform the next tick. Example: If the server takes 15 milliseconds to process a tick, it will then sleep for 35 milliseconds before the next tick.
When the Server Lags
If the tick takes more than 50 milliseconds, the processing of the next tick is delayed, as ticks cannot be performed in parallel. When this happens, gameplay deteriorates, and the server starts to "lag." You will receive the message "Can't keep up!" if the server has more than 2000 ms of delay in processing ticks. If a server takes more than 60 seconds, it is usually considered to be in a crash state by the watchdog.
How to Identify Why My Server is Lagging?
It's quite simple; you can generally analyze it using Spark to find the cause. We have a tutorial on this right here : Analyze your Minecraft server lags
Why Does the Server Lag?
The server "lags" because ticks are not processed on time. In Minecraft, actions are what’s called "single-threaded," meaning they are processed by a single core of the CPU (mainthread). For a zombie to attack a player, the server first needs to process several things: where the player is, where the zombie is, which path to take, is it within range, is it invisible? Once all of this is processed, the server can confirm that the zombie is attacking the player. Now, imagine the server has to do this for 500 zombies. Every 0.05 seconds, the server needs to calculate this for each zombie. When there are too many entities on a server, it can no longer handle the calculations together. This is often the case with monster farms or restricted farms with many entities. Imagine 50 chickens trapped in 2x2 blocks. Each chicken will "push" every other chicken. This results in 2500 free interactions that the server has to handle every 0.05 seconds. You can imagine the load this can place on the server.
Ticks Per Second (TPS)
TPS stands for Ticks Per Second. A server running at 20 TPS means that the requested 20 ticks are processed every second. When the server falls behind in processing ticks, it affects the subsequent ticks, and your TPS decreases. The calculation is as follows: (1000 - delay in ms) / 50 = x TPS. For example, if your server has a delay of 250 milliseconds every second, your TPS will be 15.