CatServer/patches/net/minecraft/network/NetworkSystem.java.patch

--- ../src-base/minecraft/net/minecraft/network/NetworkSystem.java
+++ ../src-work/minecraft/net/minecraft/network/NetworkSystem.java
@@ -165,6 +165,13 @@
     {
         synchronized (this.networkManagers)
         {
+            // Spigot Start
+            // This prevents players from 'gaming' the server, and strategically relogging to increase their position in the tick order
+            if (org.spigotmc.SpigotConfig.playerShuffle > 0 && MinecraftServer.currentTick % org.spigotmc.SpigotConfig.playerShuffle == 0)
+            {
+                Collections.shuffle(this.networkManagers);
+            }
+            // Spigot End
             Iterator<NetworkManager> iterator = this.networkManagers.iterator();
 
             while (iterator.hasNext())
@@ -209,6 +216,9 @@
                     }
                     else
                     {
+                        // Spigot Start - Fix a race condition where a NetworkManager could be unregistered just before connection.
+                        if (networkmanager.preparing) continue;
+                        // Spigot End
                         iterator.remove();
                         networkmanager.checkDisconnected();
                     }