Warn

A Folia ONLY region-aware performance warning plugin. Monitors MSPT, CPU, and RAM per region and warns players when thresholds are exceeded.

Features

• Per-region MSPT monitoring — warns only players in the affected region
• Per-region CPU monitoring — measures actual thread CPU time per Folia region
• Server-wide RAM monitoring — warns all players
• OP notifications — operators receive all warnings plus region coordinates
• Configurable thresholds and durations — all via config.yml
• Alarm sound — plays a configurable sound to warned players
• Reloadable — /warn reload to apply config changes without restart

Requirements

• Folia 1.21.4+ (Paper 26.1+)
• Java 21+

Installation

1. Download Warn-1.0-SNAPSHOT.jar from Releases
2. Place it in your server's plugins/ folder
3. Restart the server (or load with a plugin manager)
4. Edit plugins/Warn/config.yml to adjust thresholds

Configuration

# MSPT monitoring (milliseconds per tick)
mspt:
  enabled: true
  threshold: 45.0       # warn when MSPT exceeds this
  duration: 10          # must exceed threshold for this many seconds

# CPU monitoring (percentage 0-100+)
cpu:
  enabled: true
  threshold: 90.0
  duration: 10

# RAM monitoring (percentage 0-100)
ram:
  enabled: true
  threshold: 90.0
  duration: 10

# General
check-interval: 1        # seconds between checks
warning-cooldown: 15     # seconds between warnings (anti-spam)

# Alarm sound
alarm:
  enabled: true
  sound: "BLOCK_NOTE_BLOCK_PLING"
  volume: 1.0
  pitch: 1.0
  duration: 3            # seconds to repeat
  interval: 2            # ticks between plays (2 = 10/sec)

# Messages (MiniMessage format)
messages:
  mspt-warning: "<red>⚠ MSPT is high (<mspt>ms) in your region!</red>"
  mspt-warning-op: "<red>⚠ MSPT is high (<mspt>ms) in region <region> (~<x> ~<z>)!</red>"
  cpu-warning: "<red>⚠ CPU usage is high (<cpu>%) in your region!</red>"
  cpu-warning-op: "<red>⚠ CPU usage is high (<cpu>%) in region <region> (~<x> ~<z>)!</red>"
  ram-warning: "<red>⚠ Server RAM usage is high (<ram>%)!</red>"

Commands

Command	Permission	Description
/warn reload	warn.admin	Reload config.yml

Permissions

Permission	Default	Description
warn.admin	op	Allows /warn reload
warn.notify	op	Receive all warnings + region coordinates (OP-level notifications)

How it works

MSPT

Every check interval, a task is scheduled on each player's Folia region via RegionScheduler.execute(). The scheduling delay approximates the region's MSPT. Players are grouped by region, and if a region exceeds the MSPT threshold for the configured duration, only players in that region receive a warning.

Operators receive all MSPT warnings regardless of region, with the lagging region's approximate block coordinates.

CPU

CPU utilization is measured independently from MSPT using ThreadMXBean.getCurrentThreadCpuTime(). Each region's tick thread records its cumulative CPU time. The delta between consecutive measurements divided by wall-clock time gives actual per-thread CPU usage — not derived from MSPT.

RAM

Standard JVM heap monitoring: (totalMemory - freeMemory) / maxMemory × 100. Warnings go to all players since RAM is shared.

Warning flow

1. Metric exceeds threshold → timer starts
2. Metric stays above threshold for duration seconds → warning triggers
3. Warning cooldown prevents spam for warning-cooldown seconds
4. Alarm sound plays to each warned player for the configured duration

Building

./gradlew clean jar

Output: build/libs/Warn-1.0-SNAPSHOT.jar

License

MIT