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 2e9c3b45052ad641bee091ee28cc57b93cd19ffe..6ab0a51b421dc696aec292f2db955311c9cc31e3 100644
--- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
@@ -457,4 +457,9 @@ 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 e3036fe23fa2be100044332c432d1ad5b4872823..b298fbd66b66c83e2ede6871025eaeecb409f28b 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;
@@ -45,6 +46,12 @@ 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);
     }
diff --git a/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboardManager.java b/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftScoreboardManager.java
index ca2be30609159e6ca98b363d75cbc3ac550bca31..6fa2e271f7f01cd0bf247e2071fa33bd8c5c6cbe 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.server.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);
