Paper/patches/server/1014-Optimise-chunk-tick-iteration.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sat, 23 Sep 2023 21:36:36 -0700
Subject: [PATCH] Optimise chunk tick iteration

When per-player mob spawning is enabled we do not need to randomly
shuffle the chunk list. Additionally, we can use the NearbyPlayers
class to quickly retrieve nearby players instead of possible
searching all players on the server.

diff --git a/src/main/java/io/papermc/paper/util/player/NearbyPlayers.java b/src/main/java/io/papermc/paper/util/player/NearbyPlayers.java
index c3ce8a42dddd76b7189ad5685b23f9d9f8ccadb3..17ba07cbd4792f63d88ce29d00da280f30c4abff 100644
--- a/src/main/java/io/papermc/paper/util/player/NearbyPlayers.java
+++ b/src/main/java/io/papermc/paper/util/player/NearbyPlayers.java
@@ -17,7 +17,8 @@ public final class NearbyPlayers {
         GENERAL_SMALL,
         GENERAL_REALLY_SMALL,
         TICK_VIEW_DISTANCE,
-        VIEW_DISTANCE;
+        VIEW_DISTANCE, // Paper - optimise chunk iteration
+        SPAWN_RANGE, // Paper - optimise chunk iteration
     }
 
     private static final NearbyMapType[] MOB_TYPES = NearbyMapType.values();
@@ -26,10 +27,12 @@ public final class NearbyPlayers {
     private static final int GENERAL_AREA_VIEW_DISTANCE = 33;
     private static final int GENERAL_SMALL_VIEW_DISTANCE = 10;
     private static final int GENERAL_REALLY_SMALL_VIEW_DISTANCE = 3;
+    private static final int SPAWN_RANGE_VIEW_DISTANCE = net.minecraft.server.level.DistanceManager.MOB_SPAWN_RANGE; // Paper - optimise chunk iteration
 
     public static final int GENERAL_AREA_VIEW_DISTANCE_BLOCKS = (GENERAL_AREA_VIEW_DISTANCE << 4);
     public static final int GENERAL_SMALL_AREA_VIEW_DISTANCE_BLOCKS = (GENERAL_SMALL_VIEW_DISTANCE << 4);
     public static final int GENERAL_REALLY_SMALL_AREA_VIEW_DISTANCE_BLOCKS = (GENERAL_REALLY_SMALL_VIEW_DISTANCE << 4);
+    public static final int SPAWN_RANGE_VIEW_DISTANCE_BLOCKS = (SPAWN_RANGE_VIEW_DISTANCE << 4); // Paper - optimise chunk iteration
 
     private final ServerLevel world;
     private final Reference2ReferenceOpenHashMap<ServerPlayer, TrackedPlayer[]> players = new Reference2ReferenceOpenHashMap<>();
@@ -80,6 +83,7 @@ public final class NearbyPlayers {
         players[NearbyMapType.GENERAL_REALLY_SMALL.ordinal()].update(chunk.x, chunk.z, GENERAL_REALLY_SMALL_VIEW_DISTANCE);
         players[NearbyMapType.TICK_VIEW_DISTANCE.ordinal()].update(chunk.x, chunk.z, ChunkSystem.getTickViewDistance(player));
         players[NearbyMapType.VIEW_DISTANCE.ordinal()].update(chunk.x, chunk.z, ChunkSystem.getLoadViewDistance(player));
+        players[NearbyMapType.SPAWN_RANGE.ordinal()].update(chunk.x, chunk.z, SPAWN_RANGE_VIEW_DISTANCE);
     }
 
     public TrackedChunk getChunk(final ChunkPos pos) {
diff --git a/src/main/java/net/minecraft/server/level/ChunkHolder.java b/src/main/java/net/minecraft/server/level/ChunkHolder.java
index 2b998bdbe49bf8211b755e0eb7c1bf13ac280eab..5afeb59ff25fed2d565407acacffec8383398006 100644
--- a/src/main/java/net/minecraft/server/level/ChunkHolder.java
+++ b/src/main/java/net/minecraft/server/level/ChunkHolder.java
@@ -79,11 +79,19 @@ public class ChunkHolder {
 
     // Paper start
     public void onChunkAdd() {
-
+        // Paper start - optimise chunk tick iteration
+        if (this.needsBroadcastChanges()) {
+            this.chunkMap.needsChangeBroadcasting.add(this);
+        }
+        // Paper end - optimise chunk tick iteration
     }
 
     public void onChunkRemove() {
-
+        // Paper start - optimise chunk tick iteration
+        if (this.needsBroadcastChanges()) {
+            this.chunkMap.needsChangeBroadcasting.remove(this);
+        }
+        // Paper end - optimise chunk tick iteration
     }
     // Paper end
 
@@ -230,7 +238,7 @@ public class ChunkHolder {
 
             if (i < 0 || i >= this.changedBlocksPerSection.length) return; // CraftBukkit - SPIGOT-6086, SPIGOT-6296
             if (this.changedBlocksPerSection[i] == null) {
-                this.hasChangedSections = true;
+                this.hasChangedSections = true; this.addToBroadcastMap(); // Paper - optimise chunk tick iteration
                 this.changedBlocksPerSection[i] = new ShortOpenHashSet();
             }
 
@@ -254,6 +262,7 @@ public class ChunkHolder {
                     int k = this.lightEngine.getMaxLightSection();
 
                     if (y >= j && y <= k) {
+                        this.addToBroadcastMap(); // Paper - optimise chunk tick iteration
                         int l = y - j;
 
                         if (lightType == LightLayer.SKY) {
@@ -268,8 +277,19 @@ public class ChunkHolder {
         }
     }
 
+    // Paper start - optimise chunk tick iteration
+    public final boolean needsBroadcastChanges() {
+        return this.hasChangedSections || !this.skyChangedLightSectionFilter.isEmpty() || !this.blockChangedLightSectionFilter.isEmpty();
+    }
+
+    private void addToBroadcastMap() {
+        io.papermc.paper.util.TickThread.ensureTickThread(this.chunkMap.level, this.pos, "Asynchronous ChunkHolder update is not allowed");
+        this.chunkMap.needsChangeBroadcasting.add(this);
+    }
+    // Paper end - optimise chunk tick iteration
+
     public void broadcastChanges(LevelChunk chunk) {
-        if (this.hasChangedSections || !this.skyChangedLightSectionFilter.isEmpty() || !this.blockChangedLightSectionFilter.isEmpty()) {
+        if (this.needsBroadcastChanges()) { // Paper - moved into above, other logic needs to call
             Level world = chunk.getLevel();
             List list;
 
diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index e3c1015a5538ad74b9f109837df5916e6ce7e711..baa8497a18474ed142535749edfca200ef31f93e 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -192,6 +192,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             this.playerEntityTrackerTrackMaps[i].remove(player);
         }
         // Paper end - use distance map to optimise tracker
+        this.playerMobSpawnMap.remove(player); // Paper - optimise chunk tick iteration
     }
 
     void updateMaps(ServerPlayer player) {
@@ -241,6 +242,10 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
     }
     public final io.papermc.paper.util.player.NearbyPlayers nearbyPlayers;
     // Paper end
+    // Paper start - optimise chunk tick iteration
+    public final it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet<ChunkHolder> needsChangeBroadcasting = new it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet<>();
+    public final com.destroystokyo.paper.util.misc.PlayerAreaMap playerMobSpawnMap = new com.destroystokyo.paper.util.misc.PlayerAreaMap(this.pooledLinkedPlayerHashSets);
+    // Paper end - optimise chunk tick iteration
 
     public ChunkMap(ServerLevel world, LevelStorageSource.LevelStorageAccess session, DataFixer dataFixer, StructureTemplateManager structureTemplateManager, Executor executor, BlockableEventLoop<Runnable> mainThreadExecutor, LightChunkGetter chunkProvider, ChunkGenerator chunkGenerator, ChunkProgressListener worldGenerationProgressListener, ChunkStatusUpdateListener chunkStatusChangeListener, Supplier<DimensionDataStorage> persistentStateManagerFactory, int viewDistance, boolean dsync) {
         super(session.getDimensionPath(world.dimension()).resolve("region"), dataFixer, dsync);
@@ -410,7 +415,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
     }
     // Paper end
 
-    private static double euclideanDistanceSquared(ChunkPos pos, Entity entity) {
+    public static double euclideanDistanceSquared(ChunkPos pos, Entity entity) { // Paper - optimise chunk iteration - public
         double d0 = (double) SectionPos.sectionToBlockCoord(pos.x, 8);
         double d1 = (double) SectionPos.sectionToBlockCoord(pos.z, 8);
         double d2 = d0 - entity.getX();
diff --git a/src/main/java/net/minecraft/server/level/DistanceManager.java b/src/main/java/net/minecraft/server/level/DistanceManager.java
index 68550d4497a5f10bf653482f79be77373df53f27..55f96545d6db95e3e657502a7910d96fded1113e 100644
--- a/src/main/java/net/minecraft/server/level/DistanceManager.java
+++ b/src/main/java/net/minecraft/server/level/DistanceManager.java
@@ -50,7 +50,7 @@ public abstract class DistanceManager {
     private static final int INITIAL_TICKET_LIST_CAPACITY = 4;
     final Long2ObjectMap<ObjectSet<ServerPlayer>> playersPerChunk = new Long2ObjectOpenHashMap();
     // Paper - rewrite chunk system
-    private final DistanceManager.FixedPlayerDistanceChunkTracker naturalSpawnChunkCounter = new DistanceManager.FixedPlayerDistanceChunkTracker(8);
+    public static final int MOB_SPAWN_RANGE = 8; //private final DistanceManager.FixedPlayerDistanceChunkTracker naturalSpawnChunkCounter = new DistanceManager.FixedPlayerDistanceChunkTracker(8); // Paper - optimise chunk tick iteration
     // Paper - rewrite chunk system
     private final ChunkMap chunkMap; // Paper
 
@@ -136,7 +136,7 @@ public abstract class DistanceManager {
         long i = chunkcoordintpair.toLong();
 
         // Paper - no longer used
-        this.naturalSpawnChunkCounter.update(i, 0, true);
+        //this.naturalSpawnChunkCounter.update(i, 0, true); // Paper - optimise chunk tick iteration
         //this.playerTicketManager.update(i, 0, true); // Paper - no longer used
         //this.tickingTicketsTracker.addTicket(TicketType.PLAYER, chunkcoordintpair, this.getPlayerTicketLevel(), chunkcoordintpair); // Paper - no longer used
     }
@@ -150,7 +150,7 @@ public abstract class DistanceManager {
         if (objectset != null) objectset.remove(player); // Paper - some state corruption happens here, don't crash, clean up gracefully.
         if (objectset == null || objectset.isEmpty()) { // Paper
             this.playersPerChunk.remove(i);
-            this.naturalSpawnChunkCounter.update(i, Integer.MAX_VALUE, false);
+            //this.naturalSpawnChunkCounter.update(i, Integer.MAX_VALUE, false); // Paper - optimise chunk tick iteration
             //this.playerTicketManager.update(i, Integer.MAX_VALUE, false); // Paper - no longer used
             //this.tickingTicketsTracker.removeTicket(TicketType.PLAYER, chunkcoordintpair, this.getPlayerTicketLevel(), chunkcoordintpair); // Paper - no longer used
         }
@@ -192,13 +192,11 @@ public abstract class DistanceManager {
     }
 
     public int getNaturalSpawnChunkCount() {
-        this.naturalSpawnChunkCounter.runAllUpdates();
-        return this.naturalSpawnChunkCounter.chunks.size();
+        return this.chunkMap.playerMobSpawnMap.size(); // Paper - optimise chunk tick iteration
     }
 
     public boolean hasPlayersNearby(long chunkPos) {
-        this.naturalSpawnChunkCounter.runAllUpdates();
-        return this.naturalSpawnChunkCounter.chunks.containsKey(chunkPos);
+        return this.chunkMap.playerMobSpawnMap.getObjectsInRange(chunkPos) != null; // Paper - optimise chunk tick iteration
     }
 
     public String getDebugStatus() {
diff --git a/src/main/java/net/minecraft/server/level/ServerChunkCache.java b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
index 5152979bf81345fc365e7b16028c7d970d2f5856..6e212f672579a3e08dc362c287be59ca5170d717 100644
--- a/src/main/java/net/minecraft/server/level/ServerChunkCache.java
+++ b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
@@ -516,18 +516,43 @@ public class ServerChunkCache extends ChunkSource {
 
             gameprofilerfiller.push("pollingChunks");
             gameprofilerfiller.push("filteringLoadedChunks");
-            List<ServerChunkCache.ChunkAndHolder> list = Lists.newArrayListWithCapacity(this.chunkMap.size());
-            Iterator iterator = this.chunkMap.getChunks().iterator();
             if (this.level.getServer().tickRateManager().runsNormally()) this.level.timings.chunkTicks.startTiming(); // Paper
 
-            while (iterator.hasNext()) {
-                ChunkHolder playerchunk = (ChunkHolder) iterator.next();
-                LevelChunk chunk = playerchunk.getTickingChunk();
+            // Paper start - optimise chunk tick iteration
+            ChunkMap playerChunkMap = this.chunkMap;
+            for (ServerPlayer player : this.level.players) {
+                if (!player.affectsSpawning || player.isSpectator()) {
+                    playerChunkMap.playerMobSpawnMap.remove(player);
+                    player.playerNaturallySpawnedEvent = null;
+                    player.lastEntitySpawnRadiusSquared = -1.0;
+                    continue;
+                }
+
+                int viewDistance = io.papermc.paper.chunk.system.ChunkSystem.getTickViewDistance(player);
 
-                if (chunk != null) {
-                    list.add(new ServerChunkCache.ChunkAndHolder(chunk, playerchunk));
+                // copied and modified from isOutisdeRange
+                int chunkRange = (int)level.spigotConfig.mobSpawnRange;
+                chunkRange = (chunkRange > viewDistance) ? viewDistance : chunkRange;
+                chunkRange = (chunkRange > DistanceManager.MOB_SPAWN_RANGE) ? DistanceManager.MOB_SPAWN_RANGE : chunkRange;
+
+                com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent event = new com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent(player.getBukkitEntity(), (byte)chunkRange);
+                event.callEvent();
+                if (event.isCancelled() || event.getSpawnRadius() < 0) {
+                    playerChunkMap.playerMobSpawnMap.remove(player);
+                    player.playerNaturallySpawnedEvent = null;
+                    player.lastEntitySpawnRadiusSquared = -1.0;
+                    continue;
                 }
+
+                int range = Math.min(event.getSpawnRadius(), DistanceManager.MOB_SPAWN_RANGE); // limit to max spawn range
+                int chunkX = io.papermc.paper.util.CoordinateUtils.getChunkCoordinate(player.getX());
+                int chunkZ = io.papermc.paper.util.CoordinateUtils.getChunkCoordinate(player.getZ());
+
+                playerChunkMap.playerMobSpawnMap.addOrUpdate(player, chunkX, chunkZ, range);
+                player.lastEntitySpawnRadiusSquared = (double)((range << 4) * (range << 4)); // used in anyPlayerCloseEnoughForSpawning
+                player.playerNaturallySpawnedEvent = event;
             }
+            // Paper end - optimise chunk tick iteration
 
             if (this.level.getServer().tickRateManager().runsNormally()) {
                 gameprofilerfiller.popPush("naturalSpawnCount");
@@ -562,38 +587,107 @@ public class ServerChunkCache extends ChunkSource {
                 gameprofilerfiller.popPush("spawnAndTick");
                 boolean flag = this.level.getGameRules().getBoolean(GameRules.RULE_DOMOBSPAWNING) && !this.level.players().isEmpty(); // CraftBukkit
 
-                Util.shuffle(list, this.level.random);
-                // Paper start - call player naturally spawn event
-                int chunkRange = level.spigotConfig.mobSpawnRange;
-                chunkRange = (chunkRange > level.spigotConfig.viewDistance) ? (byte) level.spigotConfig.viewDistance : chunkRange;
-                chunkRange = Math.min(chunkRange, 8);
-                for (ServerPlayer entityPlayer : this.level.players()) {
-                    entityPlayer.playerNaturallySpawnedEvent = new com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent(entityPlayer.getBukkitEntity(), (byte) chunkRange);
-                    entityPlayer.playerNaturallySpawnedEvent.callEvent();
+                // Paper start - optimise chunk tick iteration
+                for (ServerPlayer player : this.level.players) {
+                    if (!player.affectsSpawning || player.isSpectator()) {
+                        playerChunkMap.playerMobSpawnMap.remove(player);
+                        player.playerNaturallySpawnedEvent = null;
+                        player.lastEntitySpawnRadiusSquared = -1.0;
+                        continue;
+                    }
+
+                    int viewDistance = io.papermc.paper.chunk.system.ChunkSystem.getTickViewDistance(player);
+
+                    // copied and modified from isOutisdeRange
+                    int chunkRange = (int)level.spigotConfig.mobSpawnRange;
+                    chunkRange = (chunkRange > viewDistance) ? viewDistance : chunkRange;
+                    chunkRange = (chunkRange > DistanceManager.MOB_SPAWN_RANGE) ? DistanceManager.MOB_SPAWN_RANGE : chunkRange;
+
+                    com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent event = new com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent(player.getBukkitEntity(), (byte)chunkRange);
+                    event.callEvent();
+                    if (event.isCancelled() || event.getSpawnRadius() < 0) {
+                        playerChunkMap.playerMobSpawnMap.remove(player);
+                        player.playerNaturallySpawnedEvent = null;
+                        player.lastEntitySpawnRadiusSquared = -1.0;
+                        continue;
+                    }
+
+                    int range = Math.min(event.getSpawnRadius(), DistanceManager.MOB_SPAWN_RANGE); // limit to max spawn range
+                    int chunkX = io.papermc.paper.util.CoordinateUtils.getChunkCoordinate(player.getX());
+                    int chunkZ = io.papermc.paper.util.CoordinateUtils.getChunkCoordinate(player.getZ());
+
+                    playerChunkMap.playerMobSpawnMap.addOrUpdate(player, chunkX, chunkZ, range);
+                    player.lastEntitySpawnRadiusSquared = (double)((range << 4) * (range << 4)); // used in anyPlayerCloseEnoughForSpawning
+                    player.playerNaturallySpawnedEvent = event;
                 }
-                // Paper end
+                // Paper end - optimise chunk tick iteration
                 int l = this.level.getGameRules().getInt(GameRules.RULE_RANDOMTICKING);
                 boolean flag1 = this.level.ticksPerSpawnCategory.getLong(org.bukkit.entity.SpawnCategory.ANIMAL) != 0L && this.level.getLevelData().getGameTime() % this.level.ticksPerSpawnCategory.getLong(org.bukkit.entity.SpawnCategory.ANIMAL) == 0L; // CraftBukkit
-                Iterator iterator1 = list.iterator();
 
                 int chunksTicked = 0; // Paper
-                while (iterator1.hasNext()) {
-                    ServerChunkCache.ChunkAndHolder chunkproviderserver_a = (ServerChunkCache.ChunkAndHolder) iterator1.next();
-                    LevelChunk chunk1 = chunkproviderserver_a.chunk;
+                // Paper start - optimise chunk tick iteration
+                io.papermc.paper.util.player.NearbyPlayers nearbyPlayers = this.chunkMap.getNearbyPlayers(); // Paper - optimise chunk tick iteration
+                Iterator<LevelChunk> chunkIterator;
+                if (this.level.paperConfig().entities.spawning.perPlayerMobSpawns) {
+                    chunkIterator = this.tickingChunks.iterator();
+                } else {
+                    chunkIterator = this.tickingChunks.unsafeIterator();
+                    List<LevelChunk> shuffled = Lists.newArrayListWithCapacity(this.tickingChunks.size());
+                    while (chunkIterator.hasNext()) {
+                        shuffled.add(chunkIterator.next());
+                    }
+                    Util.shuffle(shuffled, this.level.random);
+                    chunkIterator = shuffled.iterator();
+                }
+                try {
+                // Paper end - optimise chunk tick iteration
+                while (chunkIterator.hasNext()) {
+                    LevelChunk chunk1 = chunkIterator.next(); // Paper - optimise chunk tick iteration
                     ChunkPos chunkcoordintpair = chunk1.getPos();
 
-                    if (this.level.isNaturalSpawningAllowed(chunkcoordintpair) && this.chunkMap.anyPlayerCloseEnoughForSpawning(chunkcoordintpair)) {
+                    // Paper start - optimise chunk tick iteration
+                    com.destroystokyo.paper.util.maplist.ReferenceList<ServerPlayer> playersNearby
+                        = nearbyPlayers.getPlayers(chunkcoordintpair, io.papermc.paper.util.player.NearbyPlayers.NearbyMapType.SPAWN_RANGE);
+                    if (playersNearby == null) {
+                        continue;
+                    }
+
+                    Object[] rawData = playersNearby.getRawData();
+                    boolean spawn = false;
+                    boolean tick = false;
+                    for (int itr = 0, len = playersNearby.size(); itr < len; ++itr) {
+                        ServerPlayer player = (ServerPlayer)rawData[itr];
+                        if (player.isSpectator()) {
+                            continue;
+                        }
+
+                        double distance = ChunkMap.euclideanDistanceSquared(chunkcoordintpair, player);
+                        spawn |= player.lastEntitySpawnRadiusSquared >= distance;
+                        tick |= ((double)io.papermc.paper.util.player.NearbyPlayers.SPAWN_RANGE_VIEW_DISTANCE_BLOCKS) * ((double)io.papermc.paper.util.player.NearbyPlayers.SPAWN_RANGE_VIEW_DISTANCE_BLOCKS) >= distance;
+                        if (spawn & tick) {
+                            break;
+                        }
+                    }
+                    if (tick && chunk1.chunkStatus.isOrAfter(net.minecraft.server.level.FullChunkStatus.ENTITY_TICKING)) {
+                        // Paper end - optimise chunk tick iteration
                         chunk1.incrementInhabitedTime(j);
-                        if (flag && (this.spawnEnemies || this.spawnFriendlies) && this.level.getWorldBorder().isWithinBounds(chunkcoordintpair) && this.chunkMap.anyPlayerCloseEnoughForSpawning(chunkcoordintpair, true)) { // Spigot
+                        if (spawn && flag && (this.spawnEnemies || this.spawnFriendlies) && this.level.getWorldBorder().isWithinBounds(chunkcoordintpair)) { // Spigot // Paper - optimise chunk tick iteration
                             NaturalSpawner.spawnForChunk(this.level, chunk1, spawnercreature_d, this.spawnFriendlies, this.spawnEnemies, flag1);
                         }
 
-                        if (this.level.shouldTickBlocksAt(chunkcoordintpair.toLong())) {
+                        if (true || this.level.shouldTickBlocksAt(chunkcoordintpair.toLong())) { // Paper - optimise chunk tick iteration
                             this.level.tickChunk(chunk1, l);
                             if ((chunksTicked++ & 1) == 0) net.minecraft.server.MinecraftServer.getServer().executeMidTickTasks(); // Paper
                         }
                     }
                 }
+                // Paper start - optimise chunk tick iteration
+                } finally {
+                    if (chunkIterator instanceof io.papermc.paper.util.maplist.IteratorSafeOrderedReferenceSet.Iterator safeIterator) {
+                        safeIterator.finishedIterating();
+                    }
+                }
+                // Paper end - optimise chunk tick iteration
                 this.level.timings.chunkTicks.stopTiming(); // Paper
 
                 gameprofilerfiller.popPush("customSpawners");
@@ -605,11 +699,23 @@ public class ServerChunkCache extends ChunkSource {
             }
 
             gameprofilerfiller.popPush("broadcast");
-            list.forEach((chunkproviderserver_a1) -> {
+            // Paper - optimise chunk tick iteration
                 this.level.timings.broadcastChunkUpdates.startTiming(); // Paper - timing
-                chunkproviderserver_a1.holder.broadcastChanges(chunkproviderserver_a1.chunk);
+            // Paper start - optimise chunk tick iteration
+            if (!this.chunkMap.needsChangeBroadcasting.isEmpty()) {
+                it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet<ChunkHolder> copy = this.chunkMap.needsChangeBroadcasting.clone();
+                this.chunkMap.needsChangeBroadcasting.clear();
+                for (ChunkHolder holder : copy) {
+                    holder.broadcastChanges(holder.getFullChunkNowUnchecked()); // LevelChunks are NEVER unloaded
+                    if (holder.needsBroadcastChanges()) {
+                        // I DON'T want to KNOW what DUMB plugins might be doing.
+                        this.chunkMap.needsChangeBroadcasting.add(holder);
+                    }
+                }
+            }
+            // Paper end - optimise chunk tick iteration
                 this.level.timings.broadcastChunkUpdates.stopTiming(); // Paper - timing
-            });
+            // Paper - optimise chunk tick iteration
             gameprofilerfiller.pop();
             gameprofilerfiller.pop();
         }
diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index 695a103f2517f3e888e86e76f3615bd69b00a175..5fe743567f2e9cf0f9442ddd87453c51af8060e6 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -325,6 +325,9 @@ public class ServerPlayer extends Player {
         });
     }
     // Paper end - replace player chunk loader
+    // Paper start - optimise chunk tick iteration
+    public double lastEntitySpawnRadiusSquared = -1.0;
+    // Paper end - optimise chunk tick iteration
 
     public ServerPlayer(MinecraftServer server, ServerLevel world, GameProfile profile, ClientInformation clientOptions) {
         super(world, world.getSharedSpawnPos(), world.getSharedSpawnAngle(), profile);