The Killd Board / Hopper minecarts
How many hopper minecarts does it take to crash a Minecraft server?
4,400, and it died at 10,685. Put that next to the block hopper run further down the board, which needed 528,397 to reach the same point, and the hopper minecart comes out roughly 120 times more expensive per unit.
Paper 1.21.11 · AMD Ryzen 7 9700X · 6GB allocated
Why hopper minecarts cost so much
A hopper minecart is two things wearing one skin. It is an entity, so it is ticked, moved and collided like any other entity. It is also a container that scans the block above it for items to pull in. Neither half is expensive on its own. Paying for both, on every one of them, every tick, is what makes the minecart version the classic killer of redstone servers.
How we tested it
Everything spawned into a single chunk, in one pile, with the server left running until the tick rate gave up. The server ran Paper 1.21.11 on an AMD Ryzen 7 9700X with 6GB allocated, which is the same hardware and the same RAM policy as an ordinary Hostd plan. We watched TPS and tick times rather than guessing, wrote down the count where the server first fell behind, and kept spawning until it either died or made it clear it was not going to.
If you are building a big sorting system, use block hoppers and chest minecarts on rails rather than a queue of hopper minecarts. The board puts a hard number on how much that choice is worth.
What this means for your server
If your own server is printing Can't keep up! Is the server overloaded? the cause is the same shape as this one: something in the tick loop is taking longer than its 50ms budget. Roastd reads your RAM allocation, view distance, player slots, JVM flags and logs and names which of those it is. No account, no world upload, no charge.
Questions about hopper minecarts
Are hopper minecarts worse than hoppers for server lag?
By an enormous margin. Our board puts hopper minecarts in trouble at 4,400 and plain block hoppers at 528,397, roughly 120 times more. The minecart is an entity and a container in one object, so it pays entity tick cost and container scanning cost at once.
How do I reduce hopper lag on a Minecraft server?
Cut the number of hoppers that are actively scanning. Lock unused hoppers with a redstone signal, use water streams or chest minecarts to move items over distance instead of hopper chains, and replace hopper minecart queues with block hoppers. If you are on Paper, the hopper settings in paper-world-defaults.yml let you throttle scanning further.
Elsewhere on the board
Keep reading
Rent the machine we keep breaking
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