spark is a tool that shows what your Minecraft server spends its time on. On Paper and Purpur it's already built in – you don't need to install anything.
Quick check: is the server running smoothly?
Enter in the console:
spark tps
| Value | Meaning |
|---|---|
| TPS | ticks per second. 20 is perfect, below 18 players notice lag |
| Tick durations (ms) | how long one tick takes. Below 50 ms all is well |
| CPU usage | how heavily the processor is used |
Finding the cause: the profiler
spark profiler start --timeout 60
spark now records for 60 seconds – ideally exactly while it's lagging. Afterwards a link appears in the console (https://spark.lucko.me/…). Open it in your browser: at the top you see how much time each part of the server needs. Expand the largest entries – often there's the name of a plugin or something like entity (too many animals/creatures) or hopper.
Overall state: the health report
spark health
After a few seconds it shows a link with TPS, memory, CPU and storage at a glance.
Typical causes and what helps
- A plugin at the top: update the plugin, check its settings or remove it as a test.
- Many animals or creatures: reduce large animal farms, e.g. with breeding limits via a plugin.
- Hoppers and redstone: large sorting systems and clock circuits slow things down.
- World generation while exploring: generate the world in advance – with Chunky.
Good to know
- In the game the commands work with
/in front, e.g./spark tps– you need admin rights (OP) for that. - The report link is public, but only for whoever knows it. Feel free to share it with us if you need help.
- If spark shows no clear cause and memory is at its limit, more RAM helps – see My server is lagging.