PaperMC/patches/server/0329-Don-t-move-existing-players-to-world-spawn.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Thu, 9 Apr 2020 21:20:33 -0400
Subject: [PATCH] Don't move existing players to world spawn

This can cause a nasty server lag the spawn chunks are not kept loaded
or they aren't finished loading yet, or if the world spawn radius is
larger than the keep loaded range.

By skipping this, we avoid potential for a large spike on server start.

== AT ==
public net.minecraft.server.level.ServerPlayer fudgeSpawnLocation(Lnet/minecraft/server/level/ServerLevel;)V

diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index 4d73ccb30fde83497405b6a6a788f69e0349aec1..be5ca29b0c8e1a78fc84885bb4b1c112fefdb63b 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -417,7 +417,7 @@ public class ServerPlayer extends net.minecraft.world.entity.player.Player {
         this.server = server;
         this.stats = server.getPlayerList().getPlayerStats(this);
         this.advancements = server.getPlayerList().getPlayerAdvancements(this);
-        this.moveTo(this.adjustSpawnLocation(world, world.getSharedSpawnPos()).getBottomCenter(), 0.0F, 0.0F);
+        // this.moveTo(this.adjustSpawnLocation(world, world.getSharedSpawnPos()).getBottomCenter(), 0.0F, 0.0F); // Paper - Don't move existing players to world spawn
         this.updateOptions(clientOptions);
         this.object = null;
 
@@ -854,7 +854,7 @@ public class ServerPlayer extends net.minecraft.world.entity.player.Player {
                 position = Vec3.atCenterOf(world.getSharedSpawnPos());
             }
             this.setLevel(world);
-            this.setPos(position);
+            this.setPosRaw(position.x(), position.y(), position.z()); // Paper - don't register to chunks yet
         }
         this.gameMode.setLevel((ServerLevel) world);
     }
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index 768754f11d72921e1206e7bd029c94fae650ae82..d238dbd78fd18da46c703351cccc70c0b07622db 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -226,6 +226,7 @@ public abstract class PlayerList {
         // Paper start - Entity#getEntitySpawnReason
         if (optional.isEmpty()) {
             player.spawnReason = org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.DEFAULT; // set Player SpawnReason to DEFAULT on first login
+            player.moveTo(player.adjustSpawnLocation(worldserver1, worldserver1.getSharedSpawnPos()).getBottomCenter(), 0.0F, 0.0F);
         }
         // Paper end - Entity#getEntitySpawnReason
         player.setServerLevel(worldserver1);