Paper/patches/server/0398-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.

diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index ff965e67ba260a7a8e94514f8eca745f81c200b2..1d585171862972fef62e903aeacb507d2383cb80 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -309,7 +309,7 @@ public class ServerPlayer extends Player {
         this.stats = server.getPlayerList().getStatisticManager(this);
         this.advancements = server.getPlayerList().getPlayerAdvancements(this);
         this.maxUpStep = 1.0F;
-        this.fudgeSpawnLocation(world);
+        //this.c(worldserver); // Paper - don't move to spawn on login, only first join
 
         this.cachedSingleHashSet = new com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<>(this); // Paper
 
@@ -528,7 +528,7 @@ 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 f98a1c32e0c209473cf7268cbd8245ab9c134d28..18485689bcbf7818c3ca5b82086acef51888603b 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -207,6 +207,8 @@ 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";