Fixes exhaustion when loading large profiles

src/main/java/io/github/thebusybiscuit/slimefun4/Threads.java

@@ -0,0 +1,23 @@
+package io.github.thebusybiscuit.slimefun4;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+
+import org.bukkit.plugin.java.JavaPlugin;
+
+public class Threads {
+
+    @ParametersAreNonnullByDefault
+    public static void newThread(JavaPlugin plugin, String name, Runnable runnable) {
+        // TODO: Change to thread pool
+        new Thread(runnable, plugin.getName() + " - " + name).start();
+    }
+
+    public static String getCaller() {
+        // First item will be getting the call stack
+        // Second item will be this call
+        // Third item will be the func we care about being called
+        // And finally will be the caller
+        StackTraceElement element = Thread.currentThread().getStackTrace()[3];
+        return element.getClassName() + "." + element.getMethodName() + ":" + element.getLineNumber();
+    }
+}

src/main/java/io/github/thebusybiscuit/slimefun4/api/player/PlayerProfile.java

@@ -3,10 +3,12 @@
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
 import java.util.OptionalInt;
 import java.util.Set;
 import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Consumer;
 
 import javax.annotation.Nonnull;
@@ -28,6 +30,7 @@
 import io.github.bakedlibs.dough.common.ChatColors;
 import io.github.bakedlibs.dough.common.CommonPatterns;
 import io.github.bakedlibs.dough.config.Config;
+import io.github.thebusybiscuit.slimefun4.Threads;
 import io.github.thebusybiscuit.slimefun4.api.events.AsyncProfileLoadEvent;
 import io.github.thebusybiscuit.slimefun4.api.gps.Waypoint;
 import io.github.thebusybiscuit.slimefun4.api.items.HashedArmorpiece;
@@ -55,6 +58,8 @@
  */
 public class PlayerProfile {
 
+    private static final Map<UUID, Boolean> loading = new ConcurrentHashMap<>();
+
     private final UUID ownerId;
     private final String name;
 
@@ -361,17 +366,37 @@ public static boolean fromUUID(@Nonnull UUID uuid, @Nonnull Consumer<PlayerProfi
      */
     public static boolean get(@Nonnull OfflinePlayer p, @Nonnull Consumer<PlayerProfile> callback) {
         Validate.notNull(p, "Cannot get a PlayerProfile for: null!");
-
         UUID uuid = p.getUniqueId();
+
+        Debug.log(TestCase.PLAYER_PROFILE_DATA, "Getting PlayerProfile for {}", uuid);
+
         PlayerProfile profile = Slimefun.getRegistry().getPlayerProfiles().get(uuid);
 
         if (profile != null) {
+            Debug.log(TestCase.PLAYER_PROFILE_DATA, "PlayerProfile for {} was already loaded", uuid);
             callback.accept(profile);
             return true;
         }
 
-        Bukkit.getScheduler().runTaskAsynchronously(Slimefun.instance(), () -> {
+        // If we're already loading, we don't want to spin up a whole new thread and load the profile again/more
+        // This can very easily cause CPU, memory and thread exhaustion if the profile is large
+        // See #4011, #4116
+        if (loading.containsKey(uuid)) {
+            Debug.log(TestCase.PLAYER_PROFILE_DATA, "Attempted to get PlayerProfile ({}) while loading", uuid);
+            Debug.log(TestCase.PLAYER_PROFILE_DATA, "Caller: {}", Threads.getCaller());
+
+            // We can't easily consume the callback so we will throw it away in this case
+            // This will mean that if a user has attempted to do an action like open a block while
+            // their profile is still loading. Instead of it opening after a second or whatever when the
+            // profile is loaded, they will have to explicitly re-click the block/item/etc.
+            // This isn't the best but I think it's totally reasonable.
+            return false;
+        }
+
+        loading.put(uuid, true);
+        Threads.newThread(Slimefun.instance(), "PlayerProfile#get(" + uuid + ")", () -> {
             PlayerData data = Slimefun.getPlayerStorage().loadPlayerData(p.getUniqueId());
+            loading.remove(uuid);
 
             AsyncProfileLoadEvent event = new AsyncProfileLoadEvent(new PlayerProfile(p, data));
             Bukkit.getPluginManager().callEvent(event);
@@ -394,14 +419,28 @@ public static boolean get(@Nonnull OfflinePlayer p, @Nonnull Consumer<PlayerProf
      */
     public static boolean request(@Nonnull OfflinePlayer p) {
         Validate.notNull(p, "Cannot request a Profile for null");
+        Debug.log(TestCase.PLAYER_PROFILE_DATA, "Requesting PlayerProfile for {}", p.getName());
+
+        UUID uuid = p.getUniqueId();
+
+        // If we're already loading, we don't want to spin up a whole new thread and load the profile again/more
+        // This can very easily cause CPU, memory and thread exhaustion if the profile is large
+        // See #4011, #4116
+        if (loading.containsKey(uuid)) {
+            Debug.log(TestCase.PLAYER_PROFILE_DATA, "Attempted to request PlayerProfile ({}) while loading", uuid);
+            Debug.log(TestCase.PLAYER_PROFILE_DATA, "Caller: {}", Threads.getCaller());
+            return false;
+        }
 
-        if (!Slimefun.getRegistry().getPlayerProfiles().containsKey(p.getUniqueId())) {
+        if (!Slimefun.getRegistry().getPlayerProfiles().containsKey(uuid)) {
+            loading.put(uuid, true);
             // Should probably prevent multiple requests for the same profile in the future
-            Bukkit.getScheduler().runTaskAsynchronously(Slimefun.instance(), () -> {
-                PlayerData data = Slimefun.getPlayerStorage().loadPlayerData(p.getUniqueId());
+            Threads.newThread(Slimefun.instance(), "PlayerProfile#request(" + uuid + ")", () -> {
+                PlayerData data = Slimefun.getPlayerStorage().loadPlayerData(uuid);
+                loading.remove(uuid);
 
                 PlayerProfile pp = new PlayerProfile(p, data);
-                Slimefun.getRegistry().getPlayerProfiles().put(p.getUniqueId(), pp);
+                Slimefun.getRegistry().getPlayerProfiles().put(uuid, pp);
             });
 
             return false;