How diagnostics work
From raw files to findings: parsers, rules, scoring and rule categories.
The pipeline
A scan has four stages:
- Collect — uploaded files, Pterodactyl data and safe network probes.
- Parse — files become structured facts (properties, JVM flags, plugin list, log events, proxy settings).
- Evaluate — each rule inspects the facts and returns findings. Rules whose input is missing are skipped, never counted as passed.
- Score — findings become category scores and an overall health score (see health scores).
Anatomy of a rule
Every rule has an ID, category, severity, title, description, detection logic, detected value, expected value, recommendation and a documentation reference. New rules are added by creating one object — no other code changes.
View distance
View distance is how many chunks around each player are sent and kept loaded. Cost grows with the square of the distance. Most servers do well with 8–10.
Simulation distance
Simulation distance decides how far from a player entities and redstone tick. It is usually the biggest lever for MSPT. 5–8 is a good range.
Network compression behind a proxy
The proxy already compresses traffic to players. Between proxy and backend (usually on the same machine or network) compression only costs CPU, so set network-compression-threshold=-1 on proxied backends.
Synchronous chunk writes
With sync-chunk-writes=true the main thread waits for the disk when saving. On slow disks that creates lag spikes during autosave.
Proxy compression threshold
The proxy compresses packets above a size threshold. Around 256 bytes is a sensible default; extreme values waste CPU or bandwidth.
Java version
- Minecraft 1.20.5 and newer: Java 21 or newer
- Minecraft 1.18 – 1.20.4: Java 17 or newer
- Minecraft 1.17: Java 16 or newer
Supported Minecraft versions
Server software projects maintain recent releases only. Tickhound's reference data is dated and lives in one file, so it is easy to update.
Folia
Folia runs regions on different threads. Plugins must declare folia-supported: true in plugin.yml, otherwise they will usually fail or corrupt data.
Proxy software lifecycle
Waterfall is no longer actively maintained by PaperMC. Velocity is the maintained proxy in that ecosystem and has secure modern forwarding built in.
Server software
Paper (and forks such as Purpur and Folia) include many performance patches that plain Spigot lacks. Spigot plugins also run on Paper.