xLimbo

Minecraft 版本： 1.18.2 1.19 1.19.1 1.19.2 1.19.3 1.19.4 1.20 1.20.1 1.20.2 1.20.3 1.20.4 1.20.5 1.20.6 1.21 1.21.1 1.21.2 1.21.3 1.21.4 1.21.5 1.21.6 1.21.7 1.21.8 1.21.9 1.21.10 1.21.11 26.1 26.1.1 26.1.2 26.2

平台： paper purpur

标签： management utility worldgen

A rock-solid fallback / limbo server plugin for Paper (Pufferfish) networks. When your
main server crashes, restarts or becomes unreachable, players routed to xLimbo land in an empty
void world — creative mode, flight enabled, on an unbreakable glass floor — so they stay connected
to the network instead of being disconnected. When the main server is back, they hop straight over
with /join (or automatically).

xLimbo is built to never go down: every code path fails safe. It never throws out of
enable/reload, never blocks the main thread, never disables itself on a bad config value, and no
single player action can lag, crash, grief or escape the sandbox.

✨ Features

• Void world owned by the plugin — created programmatically with an ultra-cheap generator
  (one shared glass-floor layer per chunk; caves, decorations, structures, mobs and noise all
  disabled). Ephemeral: autosave off, spawn chunks not kept loaded, optional safe reset on restart.
• Join flow — players are put in creative + flight and async-teleported to a bounded,
  spread-out random spawn (chunk preloaded first, so the join tick never blocks on generation).
• World border bounds all roaming and caps total chunk generation; random spawns always land
  inside it.
• /join — sends the player to the main server via the proxy (BungeeCord Connect message),
  with configurable aliases, permission and a per-player cooldown to stop proxy spam.
• Optional auto-join — send players back automatically after a delay.
• Optional action bar — repeating hint (component parsed once, reused each cycle).
• Message control — suppress join/quit/death broadcasts; optional custom join message and
  chat clear. All text is MiniMessage and fully configurable.
• /xlimbo reload / /xlimbo info — reload re-reads and re-validates config and re-applies live.
  A few settings are restart-only: join-command.aliases, world.name, world.floor-y and
  world.floor-block (the world/generator is fixed at creation).
• Exploit resistance (all individually toggleable, safe defaults on): unbreakable floor, void
  rescue, blocked portals, no liquids, no gravity blocks, no fire, no explosions, no mob spawns,
  no redstone, no item drops, entity-item blocking + periodic cleanup, and an optional build-rate
  guard against lag machines.

? Requirements

• Paper 1.18.2+ (or a fork like Pufferfish / Purpur)
• Java 21 runtime

? Install

1. Grab a jar (see Downloads below) and drop it in your xLimbo server's plugins/ folder.
2. Start the server once — xLimbo creates the xlimbo world and writes a default config.yml.
3. Edit plugins/xLimbo/config.yml to taste, then run /xlimbo reload (most settings apply live;
   aliases, world.name, floor-y and floor-block need a restart).
4. Point your proxy's fallback/xlimbo server at this instance and set main-server in the config to
   the proxy name of the server you want /join to send players to.

⌨️ Commands & permissions

⚙️ Recommended server-level tuning

Some performance and security tuning lives outside the plugin. For a fallback server that
should stay flat under load:

• server.properties
  • view-distance=4, simulation-distance=4 (xLimbo also sets these per-world, but the global
    default matters for any other world and for the initial spawn world).
  • spawn-protection=0, allow-nether=false.
  • online-mode=false only behind a proxy — and only with secure forwarding (below).
• spigot.yml — lower entity-tracking-range values and merge-radius; keep
  view-distance in step.
• pufferfish.yml / Paper's config/paper-world-defaults.yml — tighten entity activation
  ranges, disable ticking far from players, and keep max-auto-save-chunks-per-tick low
  (xLimbo runs with autosave off anyway).
• Proxy forwarding security (important): the /join "Connect" plugin message can be spoofed
  by clients if forwarding isn't secured. Configure Velocity modern forwarding (or a
  BungeeCord IP-forwarding guard / firewall so only the proxy can reach the backend) so players
  can't impersonate the proxy or move themselves around the network. The plugin cannot enforce
  this — it must be set up on the proxy + server.

⚡ How it stays fast & stable

• Immutable settings snapshot. Config is parsed once into an immutable object (with MiniMessage
  components pre-parsed) and swapped atomically on /xlimbo reload. No hot path — per-tick,
  per-chunk or per-event — ever reads getConfig() or re-parses MiniMessage.
• O(1) generation. The generator writes one floor layer and disables every vanilla phase via
  the shouldGenerate* hooks, with a single fixed biome. Chunk cost is flat no matter how far
  players roam, and the world border caps how far that can go.
• Async where it matters. Join teleports use teleportAsync after getChunkAtAsync preloads
  the destination, so the join tick never blocks on generation. World creation happens once at
  startup, never during ticks; the optional world reset uses an absolute path, never throws and
  never runs while players are on.
• Ephemeral world. Autosave off, spawn chunks not kept in memory, reduced view/simulation
  distance — the world doesn't bloat disk or RAM.
• Register only what's enabled. Listeners and tasks are only registered for enabled features,
  and torn down/rebuilt cleanly on reload — no leaked tasks, no dead handlers.
• Fail-safe everywhere. onEnable/reload are wrapped so they can never throw out; a failing
  feature is logged and skipped rather than taking the server (and everyone on the network) down.