Paper/patches/server/0338-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 c1a09c0f9ce8f9c89df2291dd3cde56b435d89f3..7fc681cd64f508d1a833255654d526c133f98269 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -358,7 +358,7 @@ 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;
 
@@ -630,7 +630,7 @@ 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 54668cfc4666b07681d03c1c2cbad0f387b89b2b..511333fc0f00c5de544f5e10ddf4c5262fdf5ee3 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);