From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Andrew Steinborn <git@steinborn.me>
Date: Sat, 3 Oct 2020 04:15:09 -0400
Subject: [PATCH] Lazily track plugin scoreboards by default

On servers with plugins that constantly churn through scoreboards, there is a risk of
degraded GC performance due to the number of scoreboards held on by weak references.
Most plugins don't even need the (vanilla) functionality that requires all plugin
scoreboards to be tracked by the server. Instead, only track scoreboards when an
objective is added with a non-dummy criteria.

This is a breaking change, however the change is a much more sensible default. In case
this breaks your workflow you can always force all scoreboards to be tracked with
settings.track-plugin-scoreboards in paper.yml.

diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
index 545948f20efd6c8dd42140b565af94cd6b52b661..7d50aded88f5b7dfebaea1aebc86231f7b5c4e25 100644
--- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
@@ -462,4 +462,9 @@ public class PaperConfig {
     private static void maxJoinsPerTick() {
         maxJoinsPerTick = getInt("settings.max-joins-per-tick", 3);
     }
+
+    public static boolean trackPluginScoreboards;
+    private static void trackPluginScoreboards() {
+        trackPluginScoreboards = getBoolean("settings.track-plugin-scoreboards", false);
+    }
 }
diff --git a/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboard.java b/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboard.java
index 6ea491f6308317059c4bc6735abbdce370df0f34..88bc3fbfa3bfb27cc4f9003a99cbce6e58def98f 100644
--- a/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboard.java
+++ b/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboard.java
@@ -19,6 +19,7 @@ import org.bukkit.scoreboard.Team;
 
 public final class CraftScoreboard implements org.bukkit.scoreboard.Scoreboard {
     final Scoreboard board;
+    boolean registeredGlobally = false; // Paper
 
     CraftScoreboard(Scoreboard board) {
         this.board = board;
@@ -66,6 +67,12 @@ public final class CraftScoreboard implements org.bukkit.scoreboard.Scoreboard {
         Validate.isTrue(board.getObjective(name) == null, "An objective of name '" + name + "' already exists");
 
         CraftCriteria craftCriteria = CraftCriteria.getFromBukkit(criteria);
+        // Paper start
+        if (craftCriteria.criteria != net.minecraft.server.IScoreboardCriteria.DUMMY && !registeredGlobally) {
+            net.minecraft.server.MinecraftServer.getServer().server.getScoreboardManager().registerScoreboardForVanilla(this);
+            registeredGlobally = true;
+        }
+        // Paper end
         ScoreboardObjective objective = board.registerObjective(name, craftCriteria.criteria, CraftChatMessage.fromStringOrNull(displayName), CraftScoreboardTranslations.fromBukkitRender(renderType));
         return new CraftObjective(this, objective);*/ // Paper
         return registerNewObjective(name, criteria, io.papermc.paper.adventure.PaperAdventure.LEGACY_SECTION_UXRC.deserialize(displayName), renderType); // Paper
diff --git a/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboardManager.java b/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboardManager.java
index 73663bcea163cda26f531902141a9ad3ad7eba57..9c30a79cc55c6455aa18e3798728deaacc3434ca 100644
--- a/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboardManager.java
+++ b/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboardManager.java
@@ -30,6 +30,7 @@ public final class CraftScoreboardManager implements ScoreboardManager {
 
     public CraftScoreboardManager(MinecraftServer minecraftserver, net.minecraft.world.scores.Scoreboard scoreboardServer) {
         mainScoreboard = new CraftScoreboard(scoreboardServer);
+        mainScoreboard.registeredGlobally = true; // Paper
         server = minecraftserver;
         scoreboards.add(mainScoreboard);
     }
@@ -43,10 +44,22 @@ public final class CraftScoreboardManager implements ScoreboardManager {
     public CraftScoreboard getNewScoreboard() {
         org.spigotmc.AsyncCatcher.catchOp("scoreboard creation"); // Spigot
         CraftScoreboard scoreboard = new CraftScoreboard(new ScoreboardServer(server));
+        // Paper start
+        if (com.destroystokyo.paper.PaperConfig.trackPluginScoreboards) {
+            scoreboard.registeredGlobally = true;
         scoreboards.add(scoreboard);
+        }
+        // Paper end
         return scoreboard;
     }
 
+    // Paper start
+    public void registerScoreboardForVanilla(CraftScoreboard scoreboard) {
+        org.spigotmc.AsyncCatcher.catchOp("scoreboard registration");
+        scoreboards.add(scoreboard);
+    }
+    // Paper end
+
     // CraftBukkit method
     public CraftScoreboard getPlayerBoard(CraftPlayer player) {
         CraftScoreboard board = playerBoards.get(player);