Paper/patches/server/0373-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 206a66b6e403c8b7e60ff5b31eb478303d34b272..8754a37b405e96d2f5d02ef6b9864afac136212a 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -333,7 +333,7 @@ public class ServerPlayer extends Player {
         this.stats = server.getPlayerList().getPlayerStats(this);
         this.advancements = server.getPlayerList().getPlayerAdvancements(this);
         this.setMaxUpStep(1.0F);
-        this.fudgeSpawnLocation(world);
+        //this.fudgeSpawnLocation(world); // Paper - don't move to spawn on login, only first join
 
         this.cachedSingleHashSet = new com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<>(this); // Paper
 
@@ -567,7 +567,7 @@ public class ServerPlayer extends Player {
                 position = Vec3.atCenterOf(((ServerLevel) world).getSharedSpawnPos());
             }
             this.level = world;
-            this.setPos(position.x(), position.y(), position.z());
+            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 2e61c92787625fc9c116cd6d8dc9097c2f7d709f..187b3dc881f226963af5b61a2c4b957ecf537cf5 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -223,6 +223,8 @@ public abstract class PlayerList {
             worldserver1 = worldserver;
         }
 
+        if (nbttagcompound == null) player.fudgeSpawnLocation(worldserver1); // Paper - only move to spawn on first login, otherwise, stay where you are....
+
         player.setLevel(worldserver1);
         String s1 = "local";