From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sat, 7 Jan 2017 15:41:58 -0500
Subject: [PATCH] Enforce Sync Player Saves

Saving players async is extremely dangerous. This will force it to main
the same way we handle async chunk loads.

diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index 005e63978a306c695e21b26498937a3b81fb2b38..6341127b5b0230da7417ab2f8c36bf963742d788 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -997,10 +997,12 @@ public abstract class PlayerList {
     }
 
     public void saveAll() {
+        io.papermc.paper.util.MCUtil.ensureMain("Save Players" , () -> { // Paper - Ensure main
         for (int i = 0; i < this.players.size(); ++i) {
             this.save((ServerPlayer) this.players.get(i));
         }
 
+        return null; }); // Paper - ensure main
     }
 
     public UserWhiteList getWhiteList() {