Paper/patches/server/0856-Replace-player-chunk-loader-system.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <spottedleaf@spottedleaf.dev>
Date: Sun, 24 Jan 2021 20:27:32 -0800
Subject: [PATCH] Replace player chunk loader system

The old one has undebuggable problems. Rewriting seems
the most sensible option.

This new player chunk manager will also strictly rate limit
chunk sends so that netty threads do not get overloaded, whether
it be from the anti-xray logic or the compression itself.

Chunk loading is also rate limited in the same manner, so this
will result in a maximum responsiveness for change.

Config:
```
chunk-loading:
  min-load-radius: 2
  max-concurrent-sends: 2
  autoconfig-send-distance: true
  target-player-chunk-send-rate: 100.0
  global-max-chunk-send-rate: -1
  enable-frustum-priority: false
  global-max-chunk-load-rate: -1.0
  player-max-concurrent-loads: 25.0
  global-max-concurrent-loads: 500.0
```

min-load-radius - The radius of chunks around a player that
are not throttled for loading. The number of chunks
affected is actually the configured value plus one as this
config controls the chunks the client will be able to render.

max-concurrent-sends - The maximum number of chunks that
can be queued to send at any given time. Low values
are generally going to solve server-sided networking
bottlenecks like anti-xray and chunk compression. Client
side networking is unlikely to be helped (i.e this wont help
people running off McDonald's wifi).

autoconfig-send-distance - Whether to try to use the client's
view distance for the send view distance in the server. In the
case that no plugin has explicitly set the send distance and
the client view distance is less-than the server's send distance,
the client's view distance will be used. This will not affect
tick view distance or no-tick view distance.

target-player-chunk-send-rate - The maximum chunk send rate
an individual player will have. -1 means no limit

global-max-chunk-send-rate - The maximum chunk send rate for
the whole server. -1 means no limit

enable-frustum-priority - Whether chunks in front of a player
are prioritised to load/send first. Disabled by default
because the client can bug out due to the out of order
chunk sending.

global-max-chunk-load-rate - The maximum chunk load rate
for the whole server. -1 means no limit

player-max-concurrent-loads and global-max-concurrent-loads
The maximum number of concurrent loads for the server is
determined by the number of players on the server multiplied by the
`player-max-concurrent-loads`. It is then limited to
whatever `global-max-concurrent-loads` is configured to.

diff --git a/src/main/java/co/aikar/timings/TimingsExport.java b/src/main/java/co/aikar/timings/TimingsExport.java
index 78280fb3bcd8d792a58ece6d735e0824ea4be536..06bff37e4c1fddd3be6343049a66787c63fb420c 100644
--- a/src/main/java/co/aikar/timings/TimingsExport.java
+++ b/src/main/java/co/aikar/timings/TimingsExport.java
@@ -162,7 +162,11 @@ public class TimingsExport extends Thread {
                 pair("gamerules", toObjectMapper(world.getWorld().getGameRules(), rule -> {
                     return pair(rule, world.getWorld().getGameRuleValue(rule));
                 })),
-                pair("ticking-distance", world.getChunkSource().chunkMap.getEffectiveViewDistance())
+                // Paper start - replace chunk loader system
+                pair("ticking-distance", world.getChunkSource().chunkMap.playerChunkManager.getTargetTickViewDistance()),
+                pair("no-ticking-distance", world.getChunkSource().chunkMap.playerChunkManager.getTargetNoTickViewDistance()),
+                pair("sending-distance", world.getChunkSource().chunkMap.playerChunkManager.getTargetSendDistance())
+                // Paper end - replace chunk loader system
             ));
         }));
 
diff --git a/src/main/java/io/papermc/paper/chunk/PlayerChunkLoader.java b/src/main/java/io/papermc/paper/chunk/PlayerChunkLoader.java
new file mode 100644
index 0000000000000000000000000000000000000000..b53402903eb6845df361daf6b05a668608ad7b63
--- /dev/null
+++ b/src/main/java/io/papermc/paper/chunk/PlayerChunkLoader.java
@@ -0,0 +1,1128 @@
+package io.papermc.paper.chunk;
+
+import com.destroystokyo.paper.util.misc.PlayerAreaMap;
+import com.destroystokyo.paper.util.misc.PooledLinkedHashSets;
+import io.papermc.paper.configuration.GlobalConfiguration;
+import io.papermc.paper.util.CoordinateUtils;
+import io.papermc.paper.util.IntervalledCounter;
+import io.papermc.paper.util.TickThread;
+import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
+import it.unimi.dsi.fastutil.objects.Reference2IntOpenHashMap;
+import it.unimi.dsi.fastutil.objects.Reference2ObjectLinkedOpenHashMap;
+import it.unimi.dsi.fastutil.objects.ReferenceLinkedOpenHashSet;
+import net.minecraft.network.protocol.game.ClientboundSetChunkCacheCenterPacket;
+import net.minecraft.network.protocol.game.ClientboundSetChunkCacheRadiusPacket;
+import net.minecraft.network.protocol.game.ClientboundSetSimulationDistancePacket;
+import net.minecraft.server.MCUtil;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.*;
+import net.minecraft.util.Mth;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.chunk.LevelChunk;
+import org.apache.commons.lang3.mutable.MutableObject;
+import org.bukkit.craftbukkit.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.TreeSet;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public final class PlayerChunkLoader {
+
+    public static final int MIN_VIEW_DISTANCE = 2;
+    public static final int MAX_VIEW_DISTANCE = 32;
+
+    public static final int TICK_TICKET_LEVEL = 31;
+    public static final int LOADED_TICKET_LEVEL = 33;
+
+    public static int getTickViewDistance(final Player player) {
+        return getTickViewDistance(((CraftPlayer)player).getHandle());
+    }
+
+    public static int getTickViewDistance(final ServerPlayer player) {
+        final ServerLevel level = (ServerLevel)player.level;
+        final PlayerLoaderData data = level.chunkSource.chunkMap.playerChunkManager.getData(player);
+        if (data == null) {
+            return level.chunkSource.chunkMap.playerChunkManager.getTargetTickViewDistance();
+        }
+        return data.getTargetTickViewDistance();
+    }
+
+    public static int getLoadViewDistance(final Player player) {
+        return getLoadViewDistance(((CraftPlayer)player).getHandle());
+    }
+
+    public static int getLoadViewDistance(final ServerPlayer player) {
+        final ServerLevel level = (ServerLevel)player.level;
+        final PlayerLoaderData data = level.chunkSource.chunkMap.playerChunkManager.getData(player);
+        if (data == null) {
+            return level.chunkSource.chunkMap.playerChunkManager.getLoadDistance();
+        }
+        return data.getLoadDistance();
+    }
+
+    public static int getSendViewDistance(final Player player) {
+        return getSendViewDistance(((CraftPlayer)player).getHandle());
+    }
+
+    public static int getSendViewDistance(final ServerPlayer player) {
+        final ServerLevel level = (ServerLevel)player.level;
+        final PlayerLoaderData data = level.chunkSource.chunkMap.playerChunkManager.getData(player);
+        if (data == null) {
+            return level.chunkSource.chunkMap.playerChunkManager.getTargetSendDistance();
+        }
+        return data.getTargetSendViewDistance();
+    }
+
+    protected final ChunkMap chunkMap;
+    protected final Reference2ObjectLinkedOpenHashMap<ServerPlayer, PlayerLoaderData> playerMap = new Reference2ObjectLinkedOpenHashMap<>(512, 0.7f);
+    protected final ReferenceLinkedOpenHashSet<PlayerLoaderData> chunkSendQueue = new ReferenceLinkedOpenHashSet<>(512, 0.7f);
+
+    protected final TreeSet<PlayerLoaderData> chunkLoadQueue = new TreeSet<>((final PlayerLoaderData p1, final PlayerLoaderData p2) -> {
+        if (p1 == p2) {
+            return 0;
+        }
+
+        final ChunkPriorityHolder holder1 = p1.loadQueue.peekFirst();
+        final ChunkPriorityHolder holder2 = p2.loadQueue.peekFirst();
+
+        final int priorityCompare = Double.compare(holder1 == null ? Double.MAX_VALUE : holder1.priority, holder2 == null ? Double.MAX_VALUE : holder2.priority);
+
+        final int lastLoadTimeCompare = Long.compare(p1.lastChunkLoad, p2.lastChunkLoad);
+
+        if ((holder1 == null || holder2 == null || lastLoadTimeCompare == 0 || holder1.priority < 0.0 || holder2.priority < 0.0) && priorityCompare != 0) {
+            return priorityCompare;
+        }
+
+        if (lastLoadTimeCompare != 0) {
+            return lastLoadTimeCompare;
+        }
+
+        final int idCompare = Integer.compare(p1.player.getId(), p2.player.getId());
+
+        if (idCompare != 0) {
+            return idCompare;
+        }
+
+        // last resort
+        return Integer.compare(System.identityHashCode(p1), System.identityHashCode(p2));
+    });
+
+    protected final TreeSet<PlayerLoaderData> chunkSendWaitQueue = new TreeSet<>((final PlayerLoaderData p1, final PlayerLoaderData p2) -> {
+        if (p1 == p2) {
+            return 0;
+        }
+
+        final int timeCompare = Long.compare(p1.nextChunkSendTarget, p2.nextChunkSendTarget);
+        if (timeCompare != 0) {
+            return timeCompare;
+        }
+
+        final int idCompare = Integer.compare(p1.player.getId(), p2.player.getId());
+
+        if (idCompare != 0) {
+            return idCompare;
+        }
+
+        // last resort
+        return Integer.compare(System.identityHashCode(p1), System.identityHashCode(p2));
+    });
+
+
+    // no throttling is applied below this VD for loading
+
+    /**
+     * The chunks to be sent to players, provided they're send-ready. Send-ready means the chunk and its 1 radius neighbours are loaded.
+     */
+    public final PlayerAreaMap broadcastMap;
+
+    /**
+     * The chunks to be brought up to send-ready status. Send-ready means the chunk and its 1 radius neighbours are loaded.
+     */
+    public final PlayerAreaMap loadMap;
+
+    /**
+     * Areamap used only to remove tickets for send-ready chunks. View distance is always + 1 of load view distance. Thus,
+     * this map is always representing the chunks we are actually going to load.
+     */
+    public final PlayerAreaMap loadTicketCleanup;
+
+    /**
+     * The chunks to brought to ticking level. Each chunk must have 2 radius neighbours loaded before this can happen.
+     */
+    public final PlayerAreaMap tickMap;
+
+    /**
+     * -1 if defaulting to [load distance], else always in [2, load distance]
+     */
+    protected int rawSendDistance = -1;
+
+    /**
+     * -1 if defaulting to [tick view distance + 1], else always in [tick view distance + 1, 32 + 1]
+     */
+    protected int rawLoadDistance = -1;
+
+    /**
+     * Never -1, always in [2, 32]
+     */
+    protected int rawTickDistance = -1;
+
+    // methods to bridge for API
+
+    public int getTargetTickViewDistance() {
+        return this.getTickDistance();
+    }
+
+    public void setTargetTickViewDistance(final int distance) {
+        this.setTickDistance(distance);
+    }
+
+    public int getTargetNoTickViewDistance() {
+        return this.getLoadDistance() - 1;
+    }
+
+    public void setTargetNoTickViewDistance(final int distance) {
+        this.setLoadDistance(distance == -1 ? -1 : distance + 1);
+    }
+
+    public int getTargetSendDistance() {
+        return this.rawSendDistance == -1 ? this.getLoadDistance() : this.rawSendDistance;
+    }
+
+    public void setTargetSendDistance(final int distance) {
+        this.setSendDistance(distance);
+    }
+
+    // internal methods
+
+    public int getSendDistance() {
+        final int loadDistance = this.getLoadDistance();
+        return this.rawSendDistance == -1 ? loadDistance : Math.min(this.rawSendDistance, loadDistance);
+    }
+
+    public void setSendDistance(final int distance) {
+        if (distance != -1 && (distance < MIN_VIEW_DISTANCE || distance > MAX_VIEW_DISTANCE + 1)) {
+            throw new IllegalArgumentException("Send distance must be a number between " + MIN_VIEW_DISTANCE + " and " + (MAX_VIEW_DISTANCE + 1) + ", or -1, got: " + distance);
+        }
+        this.rawSendDistance = distance;
+    }
+
+    public int getLoadDistance() {
+        final int tickDistance = this.getTickDistance();
+        return this.rawLoadDistance == -1 ? tickDistance + 1 : Math.max(tickDistance + 1, this.rawLoadDistance);
+    }
+
+    public void setLoadDistance(final int distance) {
+        if (distance != -1 && (distance < MIN_VIEW_DISTANCE || distance > MAX_VIEW_DISTANCE + 1)) {
+            throw new IllegalArgumentException("Load distance must be a number between " + MIN_VIEW_DISTANCE + " and " + (MAX_VIEW_DISTANCE + 1) + ", or -1, got: " + distance);
+        }
+        this.rawLoadDistance = distance;
+    }
+
+    public int getTickDistance() {
+        return this.rawTickDistance;
+    }
+
+    public void setTickDistance(final int distance) {
+        if (distance < MIN_VIEW_DISTANCE || distance > MAX_VIEW_DISTANCE) {
+            throw new IllegalArgumentException("View distance must be a number between " + MIN_VIEW_DISTANCE + " and " + MAX_VIEW_DISTANCE + ", got: " + distance);
+        }
+        this.rawTickDistance = distance;
+    }
+
+    /*
+      Players have 3 different types of view distance:
+      1. Sending view distance
+      2. Loading view distance
+      3. Ticking view distance
+
+      But for configuration purposes (and API) there are:
+      1. No-tick view distance
+      2. Tick view distance
+      3. Broadcast view distance
+
+      These aren't always the same as the types we represent internally.
+
+      Loading view distance is always max(no-tick + 1, tick + 1)
+      - no-tick has 1 added because clients need an extra radius to render chunks
+      - tick has 1 added because it needs an extra radius of chunks to load before they can be marked ticking
+
+      Loading view distance is defined as the radius of chunks that will be brought to send-ready status, which means
+      it loads chunks in radius load-view-distance + 1.
+
+      The maximum value for send view distance is the load view distance. API can set it lower.
+     */
+
+    public PlayerChunkLoader(final ChunkMap chunkMap, final PooledLinkedHashSets<ServerPlayer> pooledHashSets) {
+        this.chunkMap = chunkMap;
+        this.broadcastMap = new PlayerAreaMap(pooledHashSets,
+                null,
+                (ServerPlayer player, int rangeX, int rangeZ, int currPosX, int currPosZ, int prevPosX, int prevPosZ,
+                 com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> newState) -> {
+                    PlayerChunkLoader.this.onChunkLeave(player, rangeX, rangeZ);
+                });
+        this.loadMap = new PlayerAreaMap(pooledHashSets,
+                null,
+                (ServerPlayer player, int rangeX, int rangeZ, int currPosX, int currPosZ, int prevPosX, int prevPosZ,
+                 com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> newState) -> {
+                    if (newState != null) {
+                        return;
+                    }
+                    PlayerChunkLoader.this.isTargetedForPlayerLoad.remove(CoordinateUtils.getChunkKey(rangeX, rangeZ));
+                });
+        this.loadTicketCleanup = new PlayerAreaMap(pooledHashSets,
+                null,
+                (ServerPlayer player, int rangeX, int rangeZ, int currPosX, int currPosZ, int prevPosX, int prevPosZ,
+                 com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> newState) -> {
+                    if (newState != null) {
+                        return;
+                    }
+                    ChunkPos chunkPos = new ChunkPos(rangeX, rangeZ);
+                    PlayerChunkLoader.this.chunkMap.level.getChunkSource().removeTicketAtLevel(TicketType.PLAYER, chunkPos, LOADED_TICKET_LEVEL, chunkPos);
+                    if (PlayerChunkLoader.this.chunkTicketTracker.remove(chunkPos.toLong())) {
+                        --PlayerChunkLoader.this.concurrentChunkLoads;
+                    }
+                });
+        this.tickMap = new PlayerAreaMap(pooledHashSets,
+                (ServerPlayer player, int rangeX, int rangeZ, int currPosX, int currPosZ, int prevPosX, int prevPosZ,
+                 com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> newState) -> {
+                    if (newState.size() != 1) {
+                        return;
+                    }
+                    LevelChunk chunk = PlayerChunkLoader.this.chunkMap.level.getChunkSource().getChunkAtIfLoadedMainThreadNoCache(rangeX, rangeZ);
+                    if (chunk == null || !chunk.areNeighboursLoaded(2)) {
+                        return;
+                    }
+
+                    ChunkPos chunkPos = new ChunkPos(rangeX, rangeZ);
+                    PlayerChunkLoader.this.chunkMap.level.getChunkSource().addTicketAtLevel(TicketType.PLAYER, chunkPos, TICK_TICKET_LEVEL, chunkPos);
+                },
+                (ServerPlayer player, int rangeX, int rangeZ, int currPosX, int currPosZ, int prevPosX, int prevPosZ,
+                 com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> newState) -> {
+                    if (newState != null) {
+                        return;
+                    }
+                    ChunkPos chunkPos = new ChunkPos(rangeX, rangeZ);
+                    PlayerChunkLoader.this.chunkMap.level.getChunkSource().removeTicketAtLevel(TicketType.PLAYER, chunkPos, TICK_TICKET_LEVEL, chunkPos);
+                });
+    }
+
+    protected final LongOpenHashSet isTargetedForPlayerLoad = new LongOpenHashSet();
+    protected final LongOpenHashSet chunkTicketTracker = new LongOpenHashSet();
+
+    public boolean isChunkNearPlayers(final int chunkX, final int chunkZ) {
+        final PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> playersInSendRange = this.broadcastMap.getObjectsInRange(chunkX, chunkZ);
+
+        return playersInSendRange != null;
+    }
+
+    public void onChunkPostProcessing(final int chunkX, final int chunkZ) {
+        this.onChunkSendReady(chunkX, chunkZ);
+    }
+
+    private boolean chunkNeedsPostProcessing(final int chunkX, final int chunkZ) {
+        final long key = CoordinateUtils.getChunkKey(chunkX, chunkZ);
+        final ChunkHolder chunk = this.chunkMap.getVisibleChunkIfPresent(key);
+
+        if (chunk == null) {
+            return false;
+        }
+
+        final LevelChunk levelChunk = chunk.getSendingChunk();
+
+        return levelChunk != null && !levelChunk.isPostProcessingDone;
+    }
+
+    // rets whether the chunk is at a loaded stage that is ready to be sent to players
+    public boolean isChunkPlayerLoaded(final int chunkX, final int chunkZ) {
+        final long key = CoordinateUtils.getChunkKey(chunkX, chunkZ);
+        final ChunkHolder chunk = this.chunkMap.getVisibleChunkIfPresent(key);
+
+        if (chunk == null) {
+            return false;
+        }
+
+        final LevelChunk levelChunk = chunk.getSendingChunk();
+
+        return levelChunk != null && levelChunk.isPostProcessingDone && this.isTargetedForPlayerLoad.contains(key);
+    }
+
+    public boolean isChunkSent(final ServerPlayer player, final int chunkX, final int chunkZ, final boolean borderOnly) {
+        return borderOnly ? this.isChunkSentBorderOnly(player, chunkX, chunkZ) : this.isChunkSent(player, chunkX, chunkZ);
+    }
+
+    public boolean isChunkSent(final ServerPlayer player, final int chunkX, final int chunkZ) {
+        final PlayerLoaderData data = this.playerMap.get(player);
+        if (data == null) {
+            return false;
+        }
+
+        return data.hasSentChunk(chunkX, chunkZ);
+    }
+
+    public boolean isChunkSentBorderOnly(final ServerPlayer player, final int chunkX, final int chunkZ) {
+        final PlayerLoaderData data = this.playerMap.get(player);
+        if (data == null) {
+            return false;
+        }
+
+        final boolean center = data.hasSentChunk(chunkX, chunkZ);
+        if (!center) {
+            return false;
+        }
+
+        return !(data.hasSentChunk(chunkX - 1, chunkZ) && data.hasSentChunk(chunkX + 1, chunkZ) &&
+            data.hasSentChunk(chunkX, chunkZ - 1) && data.hasSentChunk(chunkX, chunkZ + 1));
+    }
+
+    protected int getMaxConcurrentChunkSends() {
+        return GlobalConfiguration.get().chunkLoading.maxConcurrentSends;
+    }
+
+    protected int getMaxChunkLoads() {
+        double config = GlobalConfiguration.get().chunkLoading.playerMaxConcurrentLoads;
+        double max = GlobalConfiguration.get().chunkLoading.globalMaxConcurrentLoads;
+        return (int)Math.ceil(Math.min(config * MinecraftServer.getServer().getPlayerCount(), max <= 1.0 ? Double.MAX_VALUE : max));
+    }
+
+    protected long getTargetSendPerPlayerAddend() {
+        return GlobalConfiguration.get().chunkLoading.targetPlayerChunkSendRate <= 1.0 ? 0L : (long)Math.round(1.0e9 / GlobalConfiguration.get().chunkLoading.targetPlayerChunkSendRate);
+    }
+
+    protected long getMaxSendAddend() {
+        return GlobalConfiguration.get().chunkLoading.globalMaxChunkSendRate <= 1.0 ? 0L : (long)Math.round(1.0e9 / GlobalConfiguration.get().chunkLoading.globalMaxChunkSendRate);
+    }
+
+    public void onChunkPlayerTickReady(final int chunkX, final int chunkZ) {
+        final ChunkPos chunkPos = new ChunkPos(chunkX, chunkZ);
+        this.chunkMap.level.getChunkSource().addTicketAtLevel(TicketType.PLAYER, chunkPos, TICK_TICKET_LEVEL, chunkPos);
+    }
+
+    public void onChunkSendReady(final int chunkX, final int chunkZ) {
+        final PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> playersInSendRange = this.broadcastMap.getObjectsInRange(chunkX, chunkZ);
+
+        if (playersInSendRange == null) {
+            return;
+        }
+
+        final Object[] rawData = playersInSendRange.getBackingSet();
+        for (int i = 0, len = rawData.length; i < len; ++i) {
+            final Object raw = rawData[i];
+
+            if (!(raw instanceof ServerPlayer)) {
+                continue;
+            }
+            this.onChunkSendReady((ServerPlayer)raw, chunkX, chunkZ);
+        }
+    }
+
+    public void onChunkSendReady(final ServerPlayer player, final int chunkX, final int chunkZ) {
+        final PlayerLoaderData data = this.playerMap.get(player);
+
+        if (data == null) {
+            return;
+        }
+
+        if (data.hasSentChunk(chunkX, chunkZ) || !this.isChunkPlayerLoaded(chunkX, chunkZ)) {
+            // if we don't have player tickets, then the load logic will pick this up and queue to send
+            return;
+        }
+
+        if (!data.chunksToBeSent.remove(CoordinateUtils.getChunkKey(chunkX, chunkZ))) {
+            // don't queue to send, we don't want the chunk
+            return;
+        }
+
+        final long playerPos = this.broadcastMap.getLastCoordinate(player);
+        final int playerChunkX = CoordinateUtils.getChunkX(playerPos);
+        final int playerChunkZ = CoordinateUtils.getChunkZ(playerPos);
+        final int manhattanDistance = Math.abs(playerChunkX - chunkX) + Math.abs(playerChunkZ - chunkZ);
+
+        final ChunkPriorityHolder holder = new ChunkPriorityHolder(chunkX, chunkZ, manhattanDistance, 0.0);
+        data.sendQueue.add(holder);
+    }
+
+    public void onChunkLoad(final int chunkX, final int chunkZ) {
+        if (this.chunkTicketTracker.remove(CoordinateUtils.getChunkKey(chunkX, chunkZ))) {
+            --this.concurrentChunkLoads;
+        }
+    }
+
+    public void onChunkLeave(final ServerPlayer player, final int chunkX, final int chunkZ) {
+        final PlayerLoaderData data = this.playerMap.get(player);
+
+        if (data == null) {
+            return;
+        }
+
+        data.unloadChunk(chunkX, chunkZ);
+    }
+
+    public void addPlayer(final ServerPlayer player) {
+        TickThread.ensureTickThread("Cannot add player async");
+        if (!player.isRealPlayer) {
+            return;
+        }
+        final PlayerLoaderData data = new PlayerLoaderData(player, this);
+        if (this.playerMap.putIfAbsent(player, data) == null) {
+            data.update();
+        }
+    }
+
+    public void removePlayer(final ServerPlayer player) {
+        TickThread.ensureTickThread("Cannot remove player async");
+        if (!player.isRealPlayer) {
+            return;
+        }
+
+        final PlayerLoaderData loaderData = this.playerMap.remove(player);
+        if (loaderData == null) {
+            return;
+        }
+        loaderData.remove();
+        this.chunkLoadQueue.remove(loaderData);
+        this.chunkSendQueue.remove(loaderData);
+        this.chunkSendWaitQueue.remove(loaderData);
+        synchronized (this.sendingChunkCounts) {
+            final int count = this.sendingChunkCounts.removeInt(loaderData);
+            if (count != 0) {
+                concurrentChunkSends.getAndAdd(-count);
+            }
+        }
+    }
+
+    public void updatePlayer(final ServerPlayer player) {
+        TickThread.ensureTickThread("Cannot update player async");
+        if (!player.isRealPlayer) {
+            return;
+        }
+        final PlayerLoaderData loaderData = this.playerMap.get(player);
+        if (loaderData != null) {
+            loaderData.update();
+        }
+    }
+
+    public PlayerLoaderData getData(final ServerPlayer player) {
+        return this.playerMap.get(player);
+    }
+
+    public void tick() {
+        TickThread.ensureTickThread("Cannot tick async");
+        for (final PlayerLoaderData data : this.playerMap.values()) {
+            data.update();
+        }
+        this.tickMidTick();
+    }
+
+    protected static final AtomicInteger concurrentChunkSends = new AtomicInteger();
+    protected final Reference2IntOpenHashMap<PlayerLoaderData> sendingChunkCounts = new Reference2IntOpenHashMap<>();
+    private static long nextChunkSend;
+    private void trySendChunks() {
+        final long time = System.nanoTime();
+        if (time < nextChunkSend) {
+            return;
+        }
+        // drain entries from wait queue
+        while (!this.chunkSendWaitQueue.isEmpty()) {
+            final PlayerLoaderData data = this.chunkSendWaitQueue.first();
+
+            if (data.nextChunkSendTarget > time) {
+                break;
+            }
+
+            this.chunkSendWaitQueue.pollFirst();
+
+            this.chunkSendQueue.add(data);
+        }
+
+        if (this.chunkSendQueue.isEmpty()) {
+            return;
+        }
+
+        final int maxSends = this.getMaxConcurrentChunkSends();
+        final long nextPlayerDeadline = this.getTargetSendPerPlayerAddend() + time;
+        for (;;) {
+            if (this.chunkSendQueue.isEmpty()) {
+                break;
+            }
+            final int currSends = concurrentChunkSends.get();
+            if (currSends >= maxSends) {
+                break;
+            }
+
+            if (!concurrentChunkSends.compareAndSet(currSends, currSends + 1)) {
+                continue;
+            }
+
+            // send chunk
+
+            final PlayerLoaderData data = this.chunkSendQueue.removeFirst();
+
+            final ChunkPriorityHolder queuedSend = data.sendQueue.pollFirst();
+            if (queuedSend == null) {
+                concurrentChunkSends.getAndDecrement(); // we never sent, so decrease
+                // stop iterating over players who have nothing to send
+                if (this.chunkSendQueue.isEmpty()) {
+                    // nothing left
+                    break;
+                }
+                continue;
+            }
+
+            if (!this.isChunkPlayerLoaded(queuedSend.chunkX, queuedSend.chunkZ)) {
+                throw new IllegalStateException();
+            }
+
+            data.nextChunkSendTarget = nextPlayerDeadline;
+            this.chunkSendWaitQueue.add(data);
+
+            synchronized (this.sendingChunkCounts) {
+                this.sendingChunkCounts.addTo(data, 1);
+            }
+
+            data.sendChunk(queuedSend.chunkX, queuedSend.chunkZ, () -> {
+                synchronized (this.sendingChunkCounts) {
+                    final int count = this.sendingChunkCounts.getInt(data);
+                    if (count == 0) {
+                        // disconnected, so we don't need to decrement: it will be decremented for us
+                        return;
+                    }
+                    if (count == 1) {
+                        this.sendingChunkCounts.removeInt(data);
+                    } else {
+                        this.sendingChunkCounts.put(data, count - 1);
+                    }
+                }
+
+                concurrentChunkSends.getAndDecrement();
+            });
+
+            nextChunkSend = this.getMaxSendAddend() + time;
+            if (time < nextChunkSend) {
+                break;
+            }
+        }
+    }
+
+    protected int concurrentChunkLoads;
+    // this interval prevents bursting a lot of chunk loads
+    protected static final IntervalledCounter TICKET_ADDITION_COUNTER_SHORT = new IntervalledCounter((long)(1.0e6 * 50.0)); // 50ms
+    // this interval ensures the rate is kept between ticks correctly
+    protected static final IntervalledCounter TICKET_ADDITION_COUNTER_LONG = new IntervalledCounter((long)(1.0e6 * 1000.0)); // 1000ms
+    private void tryLoadChunks() {
+        if (this.chunkLoadQueue.isEmpty()) {
+            return;
+        }
+
+        final int maxLoads = this.getMaxChunkLoads();
+        final long time = System.nanoTime();
+        boolean updatedCounters = false;
+        for (;;) {
+            final PlayerLoaderData data = this.chunkLoadQueue.pollFirst();
+
+            data.lastChunkLoad = time;
+
+            final ChunkPriorityHolder queuedLoad = data.loadQueue.peekFirst();
+            if (queuedLoad == null) {
+                if (this.chunkLoadQueue.isEmpty()) {
+                    break;
+                }
+                continue;
+            }
+
+            if (!updatedCounters) {
+                updatedCounters = true;
+                TICKET_ADDITION_COUNTER_SHORT.updateCurrentTime(time);
+                TICKET_ADDITION_COUNTER_LONG.updateCurrentTime(time);
+                data.ticketAdditionCounterShort.updateCurrentTime(time);
+                data.ticketAdditionCounterLong.updateCurrentTime(time);
+            }
+
+            if (this.isChunkPlayerLoaded(queuedLoad.chunkX, queuedLoad.chunkZ)) {
+                // already loaded!
+                data.loadQueue.pollFirst(); // already loaded so we just skip
+                this.chunkLoadQueue.add(data);
+
+                // ensure the chunk is queued to send
+                this.onChunkSendReady(queuedLoad.chunkX, queuedLoad.chunkZ);
+                continue;
+            }
+
+            final long chunkKey = CoordinateUtils.getChunkKey(queuedLoad.chunkX, queuedLoad.chunkZ);
+
+            final double priority = queuedLoad.priority;
+            // while we do need to rate limit chunk loads, the logic for sending chunks requires that tickets are present.
+            // when chunks are loaded (i.e spawn) but do not have this player's tickets, they have to wait behind the
+            // load queue. To avoid this problem, we check early here if tickets are required to load the chunk - if they
+            // aren't required, it bypasses the limiter system.
+            boolean unloadedTargetChunk = false;
+            unloaded_check:
+            for (int dz = -1; dz <= 1; ++dz) {
+                for (int dx = -1; dx <= 1; ++dx) {
+                    final int offX = queuedLoad.chunkX + dx;
+                    final int offZ = queuedLoad.chunkZ + dz;
+                    if (this.chunkMap.level.getChunkSource().getChunkAtIfLoadedMainThreadNoCache(offX, offZ) == null) {
+                        unloadedTargetChunk = true;
+                        break unloaded_check;
+                    }
+                }
+            }
+            if (unloadedTargetChunk && priority >= 0.0) {
+                // priority >= 0.0 implies rate limited chunks
+
+                final int currentChunkLoads = this.concurrentChunkLoads;
+                if (currentChunkLoads >= maxLoads || (GlobalConfiguration.get().chunkLoading.globalMaxChunkLoadRate > 0 && (TICKET_ADDITION_COUNTER_SHORT.getRate() >= GlobalConfiguration.get().chunkLoading.globalMaxChunkLoadRate || TICKET_ADDITION_COUNTER_LONG.getRate() >= GlobalConfiguration.get().chunkLoading.globalMaxChunkLoadRate))
+                    || (GlobalConfiguration.get().chunkLoading.playerMaxChunkLoadRate > 0.0 && (data.ticketAdditionCounterShort.getRate() >= GlobalConfiguration.get().chunkLoading.playerMaxChunkLoadRate || data.ticketAdditionCounterLong.getRate() >= GlobalConfiguration.get().chunkLoading.playerMaxChunkLoadRate))) {
+                    // don't poll, we didn't load it
+                    this.chunkLoadQueue.add(data);
+                    break;
+                }
+            }
+
+            // can only poll after we decide to load
+            data.loadQueue.pollFirst();
+
+            // now that we've polled we can re-add to load queue
+            this.chunkLoadQueue.add(data);
+
+            // add necessary tickets to load chunk up to send-ready
+            for (int dz = -1; dz <= 1; ++dz) {
+                for (int dx = -1; dx <= 1; ++dx) {
+                    final int offX = queuedLoad.chunkX + dx;
+                    final int offZ = queuedLoad.chunkZ + dz;
+                    final ChunkPos chunkPos = new ChunkPos(offX, offZ);
+
+                    this.chunkMap.level.getChunkSource().addTicketAtLevel(TicketType.PLAYER, chunkPos, LOADED_TICKET_LEVEL, chunkPos);
+                    if (this.chunkMap.level.getChunkSource().getChunkAtIfLoadedMainThreadNoCache(offX, offZ) != null) {
+                        continue;
+                    }
+
+                    if (priority > 0.0 && this.chunkTicketTracker.add(CoordinateUtils.getChunkKey(offX, offZ))) {
+                        // won't reach here if unloadedTargetChunk is false
+                        ++this.concurrentChunkLoads;
+                        TICKET_ADDITION_COUNTER_SHORT.addTime(time);
+                        TICKET_ADDITION_COUNTER_LONG.addTime(time);
+                        data.ticketAdditionCounterShort.addTime(time);
+                        data.ticketAdditionCounterLong.addTime(time);
+                    }
+                }
+            }
+
+            // mark that we've added tickets here
+            this.isTargetedForPlayerLoad.add(chunkKey);
+
+            // it's possible all we needed was the player tickets to queue up the send.
+            if (this.isChunkPlayerLoaded(queuedLoad.chunkX, queuedLoad.chunkZ)) {
+                // yup, all we needed.
+                this.onChunkSendReady(queuedLoad.chunkX, queuedLoad.chunkZ);
+            } else if (this.chunkNeedsPostProcessing(queuedLoad.chunkX, queuedLoad.chunkZ)) {
+                // requires post processing
+                this.chunkMap.mainThreadExecutor.execute(() -> {
+                    final long key = CoordinateUtils.getChunkKey(queuedLoad.chunkX, queuedLoad.chunkZ);
+                    final ChunkHolder holder = PlayerChunkLoader.this.chunkMap.getVisibleChunkIfPresent(key);
+
+                    if (holder == null) {
+                        return;
+                    }
+
+                    final LevelChunk chunk = holder.getSendingChunk();
+
+                    if (chunk != null && !chunk.isPostProcessingDone) {
+                        chunk.postProcessGeneration();
+                    }
+                });
+            }
+        }
+    }
+
+    public void tickMidTick() {
+        // try to send more chunks
+        this.trySendChunks();
+
+        // try to queue more chunks to load
+        this.tryLoadChunks();
+    }
+
+    static final class ChunkPriorityHolder {
+        public final int chunkX;
+        public final int chunkZ;
+        public final int manhattanDistanceToPlayer;
+        public final double priority;
+
+        public ChunkPriorityHolder(final int chunkX, final int chunkZ, final int manhattanDistanceToPlayer, final double priority) {
+            this.chunkX = chunkX;
+            this.chunkZ = chunkZ;
+            this.manhattanDistanceToPlayer = manhattanDistanceToPlayer;
+            this.priority = priority;
+        }
+    }
+
+    public static final class PlayerLoaderData {
+
+        protected static final float FOV = 110.0f;
+        protected static final double PRIORITISED_DISTANCE = 12.0 * 16.0;
+
+        // Player max sprint speed is approximately 8m/s
+        protected static final double LOOK_PRIORITY_SPEED_THRESHOLD = (10.0/20.0) * (10.0/20.0);
+        protected static final double LOOK_PRIORITY_YAW_DELTA_RECALC_THRESHOLD = 3.0f;
+
+        protected double lastLocX = Double.NEGATIVE_INFINITY;
+        protected double lastLocZ = Double.NEGATIVE_INFINITY;
+
+        protected int lastChunkX = Integer.MIN_VALUE;
+        protected int lastChunkZ = Integer.MIN_VALUE;
+
+        // this is corrected so that 0 is along the positive x-axis
+        protected float lastYaw = Float.NEGATIVE_INFINITY;
+
+        protected int lastSendDistance = Integer.MIN_VALUE;
+        protected int lastLoadDistance = Integer.MIN_VALUE;
+        protected int lastTickDistance = Integer.MIN_VALUE;
+        protected boolean usingLookingPriority;
+
+        protected final ServerPlayer player;
+        protected final PlayerChunkLoader loader;
+
+        // warning: modifications of this field must be aware that the loadQueue inside PlayerChunkLoader uses this field
+        // in a comparator!
+        protected final ArrayDeque<ChunkPriorityHolder> loadQueue = new ArrayDeque<>();
+        protected final LongOpenHashSet sentChunks = new LongOpenHashSet();
+        protected final LongOpenHashSet chunksToBeSent = new LongOpenHashSet();
+
+        protected final TreeSet<ChunkPriorityHolder> sendQueue = new TreeSet<>((final ChunkPriorityHolder p1, final ChunkPriorityHolder p2) -> {
+            final int distanceCompare = Integer.compare(p1.manhattanDistanceToPlayer, p2.manhattanDistanceToPlayer);
+            if (distanceCompare != 0) {
+                return distanceCompare;
+            }
+
+            final int coordinateXCompare = Integer.compare(p1.chunkX, p2.chunkX);
+            if (coordinateXCompare != 0) {
+                return coordinateXCompare;
+            }
+
+            return Integer.compare(p1.chunkZ, p2.chunkZ);
+        });
+
+        protected int sendViewDistance = -1;
+        protected int loadViewDistance = -1;
+        protected int tickViewDistance = -1;
+
+        protected long nextChunkSendTarget;
+
+        // this interval prevents bursting a lot of chunk loads
+        protected final IntervalledCounter ticketAdditionCounterShort = new IntervalledCounter((long)(1.0e6 * 50.0)); // 50ms
+        // this ensures the rate is kept between ticks correctly
+        protected final IntervalledCounter ticketAdditionCounterLong = new IntervalledCounter((long)(1.0e6 * 1000.0)); // 1000ms
+
+        public long lastChunkLoad;
+
+        public PlayerLoaderData(final ServerPlayer player, final PlayerChunkLoader loader) {
+            this.player = player;
+            this.loader = loader;
+        }
+
+        // these view distance methods are for api
+        public int getTargetSendViewDistance() {
+            final int tickViewDistance = this.tickViewDistance == -1 ? this.loader.getTickDistance() : this.tickViewDistance;
+            final int loadViewDistance = Math.max(tickViewDistance + 1, this.loadViewDistance == -1 ? this.loader.getLoadDistance() : this.loadViewDistance);
+            final int clientViewDistance = this.getClientViewDistance();
+            final int sendViewDistance = Math.min(loadViewDistance, this.sendViewDistance == -1 ? (!GlobalConfiguration.get().chunkLoading.autoconfigSendDistance || clientViewDistance == -1 ? this.loader.getSendDistance() : clientViewDistance + 1) : this.sendViewDistance);
+            return sendViewDistance;
+        }
+
+        public void setTargetSendViewDistance(final int distance) {
+            if (distance != -1 && (distance < MIN_VIEW_DISTANCE || distance > MAX_VIEW_DISTANCE + 1)) {
+                throw new IllegalArgumentException("Send view distance must be a number between " + MIN_VIEW_DISTANCE + " and " + (MAX_VIEW_DISTANCE + 1) + " or -1, got: " + distance);
+            }
+            this.sendViewDistance = distance;
+        }
+
+        public int getTargetNoTickViewDistance() {
+            return (this.loadViewDistance == -1 ? this.getLoadDistance() : this.loadViewDistance) - 1;
+        }
+
+        public void setTargetNoTickViewDistance(final int distance) {
+            if (distance != -1 && (distance < MIN_VIEW_DISTANCE || distance > MAX_VIEW_DISTANCE)) {
+                throw new IllegalArgumentException("Simulation distance must be a number between " + MIN_VIEW_DISTANCE + " and " + MAX_VIEW_DISTANCE + " or -1, got: " + distance);
+            }
+            this.loadViewDistance = distance == -1 ? -1 : distance + 1;
+        }
+
+        public int getTargetTickViewDistance() {
+            return this.tickViewDistance == -1 ? this.loader.getTickDistance() : this.tickViewDistance;
+        }
+
+        public void setTargetTickViewDistance(final int distance) {
+            if (distance != -1 && (distance < MIN_VIEW_DISTANCE || distance > MAX_VIEW_DISTANCE)) {
+                throw new IllegalArgumentException("View distance must be a number between " + MIN_VIEW_DISTANCE + " and " + MAX_VIEW_DISTANCE + " or -1, got: " + distance);
+            }
+            this.tickViewDistance = distance;
+        }
+
+        protected int getLoadDistance() {
+            final int tickViewDistance = this.tickViewDistance == -1 ? this.loader.getTickDistance() : this.tickViewDistance;
+
+            return Math.max(tickViewDistance + 1, this.loadViewDistance == -1 ? this.loader.getLoadDistance() : this.loadViewDistance);
+        }
+
+        public boolean hasSentChunk(final int chunkX, final int chunkZ) {
+            return this.sentChunks.contains(CoordinateUtils.getChunkKey(chunkX, chunkZ));
+        }
+
+        public void sendChunk(final int chunkX, final int chunkZ, final Runnable onChunkSend) {
+            if (this.sentChunks.add(CoordinateUtils.getChunkKey(chunkX, chunkZ))) {
+                this.player.getLevel().getChunkSource().chunkMap.updateChunkTracking(this.player,
+                        new ChunkPos(chunkX, chunkZ), new MutableObject<>(), false, true); // unloaded, loaded
+                this.player.connection.connection.execute(onChunkSend);
+            } else {
+                throw new IllegalStateException();
+            }
+        }
+
+        public void unloadChunk(final int chunkX, final int chunkZ) {
+            if (this.sentChunks.remove(CoordinateUtils.getChunkKey(chunkX, chunkZ))) {
+                this.player.getLevel().getChunkSource().chunkMap.updateChunkTracking(this.player,
+                        new ChunkPos(chunkX, chunkZ), null, true, false); // unloaded, loaded
+            }
+        }
+
+        protected static boolean wantChunkLoaded(final int centerX, final int centerZ, final int chunkX, final int chunkZ,
+                                                 final int sendRadius) {
+            // expect sendRadius to be = 1 + target viewable radius
+            return ChunkMap.isChunkInRange(chunkX, chunkZ, centerX, centerZ, sendRadius);
+        }
+
+        protected static boolean triangleIntersects(final double p1x, final double p1z, // triangle point
+                                                    final double p2x, final double p2z, // triangle point
+                                                    final double p3x, final double p3z, // triangle point
+
+                                                    final double targetX, final double targetZ) { // point
+            // from barycentric coordinates:
+            // targetX = a*p1x + b*p2x + c*p3x
+            // targetZ = a*p1z + b*p2z + c*p3z
+            // 1.0     = a*1.0 + b*1.0 + c*1.0
+            // where a, b, c >= 0.0
+            // so, if any of a, b, c are less-than zero then there is no intersection.
+
+            // d = ((p2z - p3z)(p1x - p3x) + (p3x - p2x)(p1z - p3z))
+            // a = ((p2z - p3z)(targetX - p3x) + (p3x - p2x)(targetZ - p3z)) / d
+            // b = ((p3z - p1z)(targetX - p3x) + (p1x - p3x)(targetZ - p3z)) / d
+            // c = 1.0 - a - b
+
+            final double d = (p2z - p3z)*(p1x - p3x) + (p3x - p2x)*(p1z - p3z);
+            final double a = ((p2z - p3z)*(targetX - p3x) + (p3x - p2x)*(targetZ - p3z)) / d;
+
+            if (a < 0.0 || a > 1.0) {
+                return false;
+            }
+
+            final double b = ((p3z - p1z)*(targetX - p3x) + (p1x - p3x)*(targetZ - p3z)) / d;
+            if (b < 0.0 || b > 1.0) {
+                return false;
+            }
+
+            final double c = 1.0 - a - b;
+
+            return c >= 0.0 && c <= 1.0;
+        }
+
+        public void remove() {
+            this.loader.broadcastMap.remove(this.player);
+            this.loader.loadMap.remove(this.player);
+            this.loader.loadTicketCleanup.remove(this.player);
+            this.loader.tickMap.remove(this.player);
+        }
+
+        protected int getClientViewDistance() {
+            return this.player.clientViewDistance == null ? -1 : Math.max(0, this.player.clientViewDistance.intValue());
+        }
+
+        public void update() {
+            final int tickViewDistance = this.tickViewDistance == -1 ? this.loader.getTickDistance() : this.tickViewDistance;
+            // load view cannot be less-than tick view + 1
+            final int loadViewDistance = Math.max(tickViewDistance + 1, this.loadViewDistance == -1 ? this.loader.getLoadDistance() : this.loadViewDistance);
+            // send view cannot be greater-than load view
+            final int clientViewDistance = this.getClientViewDistance();
+            final int sendViewDistance = Math.min(loadViewDistance, this.sendViewDistance == -1 ? (!GlobalConfiguration.get().chunkLoading.autoconfigSendDistance || clientViewDistance == -1 ? this.loader.getSendDistance() : clientViewDistance + 1) : this.sendViewDistance);
+
+            final double posX = this.player.getX();
+            final double posZ = this.player.getZ();
+            final float yaw = MCUtil.normalizeYaw(this.player.yRot + 90.0f); // mc yaw 0 is along the positive z axis, but obviously this is really dumb - offset so we are at positive x-axis
+
+            // in general, we really only want to prioritise chunks in front if we know we're moving pretty fast into them.
+            final boolean useLookPriority = GlobalConfiguration.get().chunkLoading.enableFrustumPriority && (this.player.getDeltaMovement().horizontalDistanceSqr() > LOOK_PRIORITY_SPEED_THRESHOLD ||
+                    this.player.getAbilities().flying);
+
+            // make sure we're in the send queue
+            this.loader.chunkSendWaitQueue.add(this);
+
+            if (
+                // has view distance stayed the same?
+                    sendViewDistance == this.lastSendDistance
+                            && loadViewDistance == this.lastLoadDistance
+                            && tickViewDistance == this.lastTickDistance
+
+                            && (this.usingLookingPriority ? (
+                                    // has our block stayed the same (this also accounts for chunk change)?
+                                    Mth.floor(this.lastLocX) == Mth.floor(posX)
+                                    && Mth.floor(this.lastLocZ) == Mth.floor(posZ)
+                            ) : (
+                                    // has our chunk stayed the same
+                                    (Mth.floor(this.lastLocX) >> 4) == (Mth.floor(posX) >> 4)
+                                    && (Mth.floor(this.lastLocZ) >> 4) == (Mth.floor(posZ) >> 4)
+                            ))
+
+                            // has our decision about look priority changed?
+                            && this.usingLookingPriority == useLookPriority
+
+                            // if we are currently using look priority, has our yaw stayed within recalc threshold?
+                            && (!this.usingLookingPriority || Math.abs(yaw - this.lastYaw) <= LOOK_PRIORITY_YAW_DELTA_RECALC_THRESHOLD)
+            ) {
+                // nothing we care about changed, so we're not re-calculating
+                return;
+            }
+
+            final int centerChunkX = Mth.floor(posX) >> 4;
+            final int centerChunkZ = Mth.floor(posZ) >> 4;
+
+            final boolean needsChunkCenterUpdate = (centerChunkX != this.lastChunkX) || (centerChunkZ != this.lastChunkZ);
+            this.loader.broadcastMap.addOrUpdate(this.player, centerChunkX, centerChunkZ, sendViewDistance);
+            this.loader.loadMap.addOrUpdate(this.player, centerChunkX, centerChunkZ, loadViewDistance);
+            this.loader.loadTicketCleanup.addOrUpdate(this.player, centerChunkX, centerChunkZ, loadViewDistance + 1);
+            this.loader.tickMap.addOrUpdate(this.player, centerChunkX, centerChunkZ, tickViewDistance);
+
+            if (sendViewDistance != this.lastSendDistance) {
+                // update the view radius for client
+                // note that this should be after the map calls because the client wont expect unload calls not in its VD
+                // and it's possible we decreased VD here
+                this.player.connection.send(new ClientboundSetChunkCacheRadiusPacket(sendViewDistance));
+            }
+            if (tickViewDistance != this.lastTickDistance) {
+                this.player.connection.send(new ClientboundSetSimulationDistancePacket(tickViewDistance));
+            }
+
+            this.lastLocX = posX;
+            this.lastLocZ = posZ;
+            this.lastYaw = yaw;
+            this.lastSendDistance = sendViewDistance;
+            this.lastLoadDistance = loadViewDistance;
+            this.lastTickDistance = tickViewDistance;
+            this.usingLookingPriority = useLookPriority;
+
+            this.lastChunkX = centerChunkX;
+            this.lastChunkZ = centerChunkZ;
+
+            // points for player "view" triangle:
+
+            // obviously, the player pos is a vertex
+            final double p1x = posX;
+            final double p1z = posZ;
+
+            // to the left of the looking direction
+            final double p2x = PRIORITISED_DISTANCE * Math.cos(Math.toRadians(yaw + (double)(FOV / 2.0))) // calculate rotated vector
+                    + p1x; // offset vector
+            final double p2z = PRIORITISED_DISTANCE * Math.sin(Math.toRadians(yaw + (double)(FOV / 2.0))) // calculate rotated vector
+                    + p1z; // offset vector
+
+            // to the right of the looking direction
+            final double p3x = PRIORITISED_DISTANCE * Math.cos(Math.toRadians(yaw - (double)(FOV / 2.0))) // calculate rotated vector
+                    + p1x; // offset vector
+            final double p3z = PRIORITISED_DISTANCE * Math.sin(Math.toRadians(yaw - (double)(FOV / 2.0))) // calculate rotated vector
+                    + p1z; // offset vector
+
+            // now that we have all of our points, we can recalculate the load queue
+
+            final List<ChunkPriorityHolder> loadQueue = new ArrayList<>();
+
+            // clear send queue, we are re-sorting
+            this.sendQueue.clear();
+            // clear chunk want set, vd/position might have changed
+            this.chunksToBeSent.clear();
+
+            final int searchViewDistance = Math.max(loadViewDistance, sendViewDistance);
+
+            for (int dx = -searchViewDistance; dx <= searchViewDistance; ++dx) {
+                for (int dz = -searchViewDistance; dz <= searchViewDistance; ++dz) {
+                    final int chunkX = dx + centerChunkX;
+                    final int chunkZ = dz + centerChunkZ;
+                    final int squareDistance = Math.max(Math.abs(dx), Math.abs(dz));
+                    final boolean sendChunk = squareDistance <= sendViewDistance && wantChunkLoaded(centerChunkX, centerChunkZ, chunkX, chunkZ, sendViewDistance);
+
+                    if (this.hasSentChunk(chunkX, chunkZ)) {
+                        // already sent (which means it is also loaded)
+                        if (!sendChunk) {
+                            // have sent the chunk, but don't want it anymore
+                            // unload it now
+                            this.unloadChunk(chunkX, chunkZ);
+                        }
+                        continue;
+                    }
+
+                    final boolean loadChunk = squareDistance <= loadViewDistance;
+
+                    final boolean prioritised = useLookPriority && triangleIntersects(
+                            // prioritisation triangle
+                            p1x, p1z, p2x, p2z, p3x, p3z,
+
+                            // center of chunk
+                            (double)((chunkX << 4) | 8), (double)((chunkZ << 4) | 8)
+                    );
+
+                    final int manhattanDistance = Math.abs(dx) + Math.abs(dz);
+
+                    final double priority;
+
+                    if (squareDistance <= GlobalConfiguration.get().chunkLoading.minLoadRadius) {
+                        // priority should be negative, and we also want to order it from center outwards
+                        // so we want (0,0) to be the smallest, and (minLoadedRadius,minLoadedRadius) to be the greatest
+                        priority = -((2 * GlobalConfiguration.get().chunkLoading.minLoadRadius + 1) - manhattanDistance);
+                    } else {
+                        if (prioritised) {
+                            // we don't prioritise these chunks above others because we also want to make sure some chunks
+                            // will be loaded if the player changes direction
+                            priority = (double)manhattanDistance / 6.0;
+                        } else {
+                            priority = (double)manhattanDistance;
+                        }
+                    }
+
+                    final ChunkPriorityHolder holder = new ChunkPriorityHolder(chunkX, chunkZ, manhattanDistance, priority);
+
+                    if (!this.loader.isChunkPlayerLoaded(chunkX, chunkZ)) {
+                        if (loadChunk) {
+                            loadQueue.add(holder);
+                            if (sendChunk) {
+                                this.chunksToBeSent.add(CoordinateUtils.getChunkKey(chunkX, chunkZ));
+                            }
+                        }
+                    } else {
+                        // loaded but not sent: so queue it!
+                        if (sendChunk) {
+                            this.sendQueue.add(holder);
+                        }
+                    }
+                }
+            }
+
+            loadQueue.sort((final ChunkPriorityHolder p1, final ChunkPriorityHolder p2) -> {
+                return Double.compare(p1.priority, p2.priority);
+            });
+
+            // we're modifying loadQueue, must remove
+            this.loader.chunkLoadQueue.remove(this);
+
+            this.loadQueue.clear();
+            this.loadQueue.addAll(loadQueue);
+
+            // must re-add
+            this.loader.chunkLoadQueue.add(this);
+
+            // update the chunk center
+            // this must be done last so that the client does not ignore any of our unload chunk packets
+            if (needsChunkCenterUpdate) {
+                this.player.connection.send(new ClientboundSetChunkCacheCenterPacket(centerChunkX, centerChunkZ));
+            }
+        }
+    }
+}
diff --git a/src/main/java/net/minecraft/network/Connection.java b/src/main/java/net/minecraft/network/Connection.java
index c561a2f28fa1e9a327982c4587c4552cd85a7336..868d4913f63b3f4752f7f1cdcd81e118e482c474 100644
--- a/src/main/java/net/minecraft/network/Connection.java
+++ b/src/main/java/net/minecraft/network/Connection.java
@@ -100,6 +100,28 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
     public boolean queueImmunity = false;
     public ConnectionProtocol protocol;
     // Paper end
+    // Paper start - add pending task queue
+    private final Queue<Runnable> pendingTasks = new java.util.concurrent.ConcurrentLinkedQueue<>();
+    public void execute(final Runnable run) {
+        if (this.channel == null || !this.channel.isRegistered()) {
+            run.run();
+            return;
+        }
+        final boolean queue = !this.queue.isEmpty();
+        if (!queue) {
+            this.channel.eventLoop().execute(run);
+        } else {
+            this.pendingTasks.add(run);
+            if (this.queue.isEmpty()) {
+                // something flushed async, dump tasks now
+                Runnable r;
+                while ((r = this.pendingTasks.poll()) != null) {
+                    this.channel.eventLoop().execute(r);
+                }
+            }
+        }
+    }
+    // Paper end - add pending task queue
 
     // Paper start - allow controlled flushing
     volatile boolean canFlush = true;
@@ -488,6 +510,7 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
         return false;
     }
     private boolean processQueue() {
+        try { // Paper - add pending task queue
         if (this.queue.isEmpty()) return true;
         // Paper start - make only one flush call per sendPacketQueue() call
         final boolean needsFlush = this.canFlush;
@@ -519,6 +542,12 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
             }
         }
         return true;
+        } finally { // Paper start - add pending task queue
+            Runnable r;
+            while ((r = this.pendingTasks.poll()) != null) {
+                this.channel.eventLoop().execute(r);
+            }
+        } // Paper end - add pending task queue
     }
     // Paper end
 
diff --git a/src/main/java/net/minecraft/server/MCUtil.java b/src/main/java/net/minecraft/server/MCUtil.java
index 1eb71004a19866590a3d27fa6e72842934989177..7034af8ad42940c5af6b9032b9873ce36c55a2a7 100644
--- a/src/main/java/net/minecraft/server/MCUtil.java
+++ b/src/main/java/net/minecraft/server/MCUtil.java
@@ -647,7 +647,8 @@ public final class MCUtil {
             });
 
             worldData.addProperty("name", world.getWorld().getName());
-            worldData.addProperty("view-distance", world.spigotConfig.viewDistance);
+            worldData.addProperty("view-distance", world.getChunkSource().chunkMap.playerChunkManager.getTargetNoTickViewDistance()); // Paper - replace chunk loader system
+            worldData.addProperty("tick-view-distance", world.getChunkSource().chunkMap.playerChunkManager.getTargetTickViewDistance()); // Paper - replace chunk loader system
             worldData.addProperty("keep-spawn-loaded", world.keepSpawnInMemory);
             worldData.addProperty("keep-spawn-loaded-range", world.paperConfig().spawn.keepSpawnLoadedRange * 16);
             worldData.addProperty("visible-chunk-count", visibleChunks.size());
diff --git a/src/main/java/net/minecraft/server/level/ChunkHolder.java b/src/main/java/net/minecraft/server/level/ChunkHolder.java
index 5482be03a667939ff009b6810d5cc90c8601e983..11cd31691307749e925930c4b6e10e3f3b4fad25 100644
--- a/src/main/java/net/minecraft/server/level/ChunkHolder.java
+++ b/src/main/java/net/minecraft/server/level/ChunkHolder.java
@@ -76,6 +76,17 @@ public class ChunkHolder {
     public ServerLevel getWorld() { return chunkMap.level; } // Paper
     boolean isUpdateQueued = false; // Paper
     private final ChunkMap chunkMap; // Paper
+    // Paper start - no-tick view distance
+    public final LevelChunk getSendingChunk() {
+        // it's important that we use getChunkAtIfLoadedImmediately to mirror the chunk sending logic used
+        // in Chunk's neighbour callback
+        LevelChunk ret = this.chunkMap.level.getChunkSource().getChunkAtIfLoadedImmediately(this.pos.x, this.pos.z);
+        if (ret != null && ret.areNeighboursLoaded(1)) {
+            return ret;
+        }
+        return null;
+    }
+    // Paper end - no-tick view distance
 
     // Paper start - optimise anyPlayerCloseEnoughForSpawning
     // cached here to avoid a map lookup
@@ -268,7 +279,7 @@ public class ChunkHolder {
 
     public void blockChanged(BlockPos pos) {
         if (!pos.isInsideBuildHeightAndWorldBoundsHorizontal(levelHeightAccessor)) return; // Paper - SPIGOT-6086 for all invalid locations; avoid acquiring locks
-        LevelChunk chunk = this.getTickingChunk();
+        LevelChunk chunk = this.getSendingChunk(); // Paper - no-tick view distance
 
         if (chunk != null) {
             int i = this.levelHeightAccessor.getSectionIndex(pos.getY());
@@ -284,14 +295,15 @@ public class ChunkHolder {
     }
 
     public void sectionLightChanged(LightLayer lightType, int y) {
-        Either<ChunkAccess, ChunkHolder.ChunkLoadingFailure> either = (Either) this.getFutureIfPresent(ChunkStatus.FEATURES).getNow(null); // CraftBukkit - decompile error
+        // Paper start - no-tick view distance
 
-        if (either != null) {
-            ChunkAccess ichunkaccess = (ChunkAccess) either.left().orElse(null); // CraftBukkit - decompile error
+        if (true) {
+            ChunkAccess ichunkaccess = this.getAvailableChunkNow();
 
             if (ichunkaccess != null) {
                 ichunkaccess.setUnsaved(true);
-                LevelChunk chunk = this.getTickingChunk();
+                LevelChunk chunk = this.getSendingChunk();
+                // Paper end - no-tick view distance
 
                 if (chunk != null) {
                     int j = this.lightEngine.getMinLightSection();
@@ -394,9 +406,28 @@ public class ChunkHolder {
     }
 
     public void broadcast(Packet<?> packet, boolean onlyOnWatchDistanceEdge) {
-        this.playerProvider.getPlayers(this.pos, onlyOnWatchDistanceEdge).forEach((entityplayer) -> {
-            entityplayer.connection.send(packet);
-        });
+        // Paper start - per player view distance
+        // there can be potential desync with player's last mapped section and the view distance map, so use the
+        // view distance map here.
+        com.destroystokyo.paper.util.misc.PlayerAreaMap viewDistanceMap = this.chunkMap.playerChunkManager.broadcastMap; // Paper - replace old player chunk manager
+        com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> players = viewDistanceMap.getObjectsInRange(this.pos);
+        if (players == null) {
+            return;
+        }
+
+        Object[] backingSet = players.getBackingSet();
+        for (int i = 0, len = backingSet.length; i < len; ++i) {
+            Object temp = backingSet[i];
+            if (!(temp instanceof ServerPlayer)) {
+                continue;
+            }
+            ServerPlayer player = (ServerPlayer)temp;
+            if (!this.chunkMap.playerChunkManager.isChunkSent(player, this.pos.x, this.pos.z, onlyOnWatchDistanceEdge)) {
+                continue;
+            }
+            player.connection.send(packet);
+        }
+        // Paper end - per player view distance
     }
 
     public CompletableFuture<Either<ChunkAccess, ChunkHolder.ChunkLoadingFailure>> getOrScheduleFuture(ChunkStatus targetStatus, ChunkMap chunkStorage) {
diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index 39915f1c71fae142725ae2977a4eb0c483b4967a..77c89376495d90d0e7cbf6cd02c9a1c8d9a4340b 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -218,6 +218,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
     public final com.destroystokyo.paper.util.misc.PlayerAreaMap playerMobSpawnMap; // this map is absent from updateMaps since it's controlled at the start of the chunkproviderserver tick
     public final com.destroystokyo.paper.util.misc.PlayerAreaMap playerChunkTickRangeMap;
     // Paper end - optimise ChunkMap#anyPlayerCloseEnoughForSpawning
+    public final io.papermc.paper.chunk.PlayerChunkLoader playerChunkManager = new io.papermc.paper.chunk.PlayerChunkLoader(this, this.pooledLinkedPlayerHashSets); // Paper - replace chunk loader
     // Paper start - use distance map to optimise tracker
     public static boolean isLegacyTrackingEntity(Entity entity) {
         return entity.isLegacyTrackingEntity;
@@ -237,6 +238,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
     // Paper end - use distance map to optimise tracker
 
     void addPlayerToDistanceMaps(ServerPlayer player) {
+        this.playerChunkManager.addPlayer(player); // Paper - replace chunk loader
         int chunkX = MCUtil.getChunkCoordinate(player.getX());
         int chunkZ = MCUtil.getChunkCoordinate(player.getZ());
         // Paper start - use distance map to optimise entity tracker
@@ -244,7 +246,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             com.destroystokyo.paper.util.misc.PlayerAreaMap trackMap = this.playerEntityTrackerTrackMaps[i];
             int trackRange = this.entityTrackerTrackRanges[i];
 
-            trackMap.add(player, chunkX, chunkZ, Math.min(trackRange, this.getEffectiveViewDistance()));
+            trackMap.add(player, chunkX, chunkZ, Math.min(trackRange, io.papermc.paper.chunk.PlayerChunkLoader.getSendViewDistance(player))); // Paper - per player view distances
         }
         // Paper end - use distance map to optimise entity tracker
         // Note: players need to be explicitly added to distance maps before they can be updated
@@ -274,6 +276,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             this.playerMobDistanceMap.remove(player);
         }
         // Paper end - per player mob spawning
+        this.playerChunkManager.removePlayer(player); // Paper - replace chunk loader
     }
 
     void updateMaps(ServerPlayer player) {
@@ -285,7 +288,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             com.destroystokyo.paper.util.misc.PlayerAreaMap trackMap = this.playerEntityTrackerTrackMaps[i];
             int trackRange = this.entityTrackerTrackRanges[i];
 
-            trackMap.update(player, chunkX, chunkZ, Math.min(trackRange, this.getEffectiveViewDistance()));
+            trackMap.update(player, chunkX, chunkZ, Math.min(trackRange, io.papermc.paper.chunk.PlayerChunkLoader.getSendViewDistance(player))); // Paper - per player view distances
         }
         // Paper end - use distance map to optimise entity tracker
         this.playerChunkTickRangeMap.update(player, chunkX, chunkZ, DistanceManager.MOB_SPAWN_RANGE); // Paper - optimise ChunkMap#anyPlayerCloseEnoughForSpawning
@@ -295,6 +298,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             this.playerMobDistanceMap.update(player, chunkX, chunkZ, this.distanceManager.getSimulationDistance());
         }
         // Paper end - per player mob spawning
+        this.playerChunkManager.updatePlayer(player); // Paper - replace chunk loader
     }
     // Paper end
     // Paper start
@@ -1449,11 +1453,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
         completablefuture1.thenAcceptAsync((either) -> {
             either.ifLeft((chunk) -> {
                 this.tickingGenerated.getAndIncrement();
-                MutableObject<java.util.Map<Object, ClientboundLevelChunkWithLightPacket>> mutableobject = new MutableObject<>(); // Paper - Anti-Xray - Bypass
-
-                this.getPlayers(chunkcoordintpair, false).forEach((entityplayer) -> {
-                    this.playerLoadedChunk(entityplayer, mutableobject, chunk);
-                });
+                // Paper - no-tick view distance - moved to Chunk neighbour update
             });
         }, (runnable) -> {
             this.mainThreadMailbox.tell(ChunkTaskPriorityQueueSorter.message(holder, runnable));
@@ -1622,33 +1622,24 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             int k = this.viewDistance;
 
             this.viewDistance = j;
-            this.distanceManager.updatePlayerTickets(this.viewDistance + 1);
-            Iterator objectiterator = this.updatingChunks.getVisibleValuesCopy().iterator(); // Paper
-
-            while (objectiterator.hasNext()) {
-                ChunkHolder playerchunk = (ChunkHolder) objectiterator.next();
-                ChunkPos chunkcoordintpair = playerchunk.getPos();
-                MutableObject<java.util.Map<Object, ClientboundLevelChunkWithLightPacket>> mutableobject = new MutableObject<>(); // Paper - Anti-Xray - Bypass
-
-                this.getPlayers(chunkcoordintpair, false).forEach((entityplayer) -> {
-                    SectionPos sectionposition = entityplayer.getLastSectionPos();
-                    boolean flag = ChunkMap.isChunkInRange(chunkcoordintpair.x, chunkcoordintpair.z, sectionposition.x(), sectionposition.z(), k);
-                    boolean flag1 = ChunkMap.isChunkInRange(chunkcoordintpair.x, chunkcoordintpair.z, sectionposition.x(), sectionposition.z(), this.viewDistance);
-
-                    this.updateChunkTracking(entityplayer, chunkcoordintpair, mutableobject, flag, flag1);
-                });
-            }
+            this.playerChunkManager.setLoadDistance(this.viewDistance); // Paper - replace player loader system
         }
 
     }
 
-    protected void updateChunkTracking(ServerPlayer player, ChunkPos pos, MutableObject<java.util.Map<Object, ClientboundLevelChunkWithLightPacket>> packet, boolean oldWithinViewDistance, boolean newWithinViewDistance) { // Paper - Anti-Xray - Bypass
+    // Paper start - replace player loader system
+    public void setTickViewDistance(int distance) {
+        this.playerChunkManager.setTickDistance(distance);
+    }
+    // Paper end - replace player loader system
+
+    public void updateChunkTracking(ServerPlayer player, ChunkPos pos, MutableObject<java.util.Map<Object, ClientboundLevelChunkWithLightPacket>> packet, boolean oldWithinViewDistance, boolean newWithinViewDistance) { // Paper - Anti-Xray - Bypass // Paper - public
         if (player.level == this.level) {
             if (newWithinViewDistance && !oldWithinViewDistance) {
                 ChunkHolder playerchunk = this.getVisibleChunkIfPresent(pos.toLong());
 
                 if (playerchunk != null) {
-                    LevelChunk chunk = playerchunk.getTickingChunk();
+                    LevelChunk chunk = playerchunk.getSendingChunk(); // Paper - replace chunk loader system
 
                     if (chunk != null) {
                         this.playerLoadedChunk(player, packet, chunk);
@@ -1679,7 +1670,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
 
     void dumpChunks(Writer writer) throws IOException {
         CsvOutput csvwriter = CsvOutput.builder().addColumn("x").addColumn("z").addColumn("level").addColumn("in_memory").addColumn("status").addColumn("full_status").addColumn("accessible_ready").addColumn("ticking_ready").addColumn("entity_ticking_ready").addColumn("ticket").addColumn("spawning").addColumn("block_entity_count").addColumn("ticking_ticket").addColumn("ticking_level").addColumn("block_ticks").addColumn("fluid_ticks").build(writer);
-        TickingTracker tickingtracker = this.distanceManager.tickingTracker();
+        // Paper - replace loader system
         ObjectBidirectionalIterator objectbidirectionaliterator = this.updatingChunks.getVisibleMap().clone().long2ObjectEntrySet().fastIterator(); // Paper
 
         while (objectbidirectionaliterator.hasNext()) {
@@ -1695,7 +1686,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             // CraftBukkit - decompile error
             csvwriter.writeRow(chunkcoordintpair.x, chunkcoordintpair.z, playerchunk.getTicketLevel(), optional.isPresent(), optional.map(ChunkAccess::getStatus).orElse(null), optional1.map(LevelChunk::getFullStatus).orElse(null), ChunkMap.printFuture(playerchunk.getFullChunkFuture()), ChunkMap.printFuture(playerchunk.getTickingChunkFuture()), ChunkMap.printFuture(playerchunk.getEntityTickingChunkFuture()), this.distanceManager.getTicketDebugString(i), this.anyPlayerCloseEnoughForSpawning(chunkcoordintpair), optional1.map((chunk) -> {
                 return chunk.getBlockEntities().size();
-            }).orElse(0), tickingtracker.getTicketDebugString(i), tickingtracker.getLevel(i), optional1.map((chunk) -> {
+            }).orElse(0), "Use ticket level", -1000, optional1.map((chunk) -> { // Paper - replace loader system
                 return chunk.getBlockTicks().count();
             }).orElse(0), optional1.map((chunk) -> {
                 return chunk.getFluidTicks().count();
@@ -1929,15 +1920,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             this.removePlayerFromDistanceMaps(player); // Paper - distance maps
         }
 
-        for (int k = i - this.viewDistance - 1; k <= i + this.viewDistance + 1; ++k) {
-            for (int l = j - this.viewDistance - 1; l <= j + this.viewDistance + 1; ++l) {
-                if (ChunkMap.isChunkInRange(k, l, i, j, this.viewDistance)) {
-                    ChunkPos chunkcoordintpair = new ChunkPos(k, l);
-
-                    this.updateChunkTracking(player, chunkcoordintpair, new MutableObject(), !added, added);
-                }
-            }
-        }
+        // Paper - handled by player chunk loader
 
     }
 
@@ -1945,7 +1928,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
         SectionPos sectionposition = SectionPos.of((EntityAccess) player);
 
         player.setLastSectionPos(sectionposition);
-        player.connection.send(new ClientboundSetChunkCacheCenterPacket(sectionposition.x(), sectionposition.z()));
+        //player.connection.send(new ClientboundSetChunkCacheCenterPacket(sectionposition.x(), sectionposition.z())); // Paper - handled by player chunk loader
         return sectionposition;
     }
 
@@ -1990,65 +1973,40 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
         int k1;
         int l1;
 
-        if (Math.abs(i1 - i) <= this.viewDistance * 2 && Math.abs(j1 - j) <= this.viewDistance * 2) {
-            k1 = Math.min(i, i1) - this.viewDistance - 1;
-            l1 = Math.min(j, j1) - this.viewDistance - 1;
-            int i2 = Math.max(i, i1) + this.viewDistance + 1;
-            int j2 = Math.max(j, j1) + this.viewDistance + 1;
-
-            for (int k2 = k1; k2 <= i2; ++k2) {
-                for (int l2 = l1; l2 <= j2; ++l2) {
-                    boolean flag3 = ChunkMap.isChunkInRange(k2, l2, i1, j1, this.viewDistance);
-                    boolean flag4 = ChunkMap.isChunkInRange(k2, l2, i, j, this.viewDistance);
-
-                    this.updateChunkTracking(player, new ChunkPos(k2, l2), new MutableObject(), flag3, flag4);
-                }
-            }
-        } else {
-            boolean flag5;
-            boolean flag6;
-
-            for (k1 = i1 - this.viewDistance - 1; k1 <= i1 + this.viewDistance + 1; ++k1) {
-                for (l1 = j1 - this.viewDistance - 1; l1 <= j1 + this.viewDistance + 1; ++l1) {
-                    if (ChunkMap.isChunkInRange(k1, l1, i1, j1, this.viewDistance)) {
-                        flag5 = true;
-                        flag6 = false;
-                        this.updateChunkTracking(player, new ChunkPos(k1, l1), new MutableObject(), true, false);
-                    }
-                }
-            }
-
-            for (k1 = i - this.viewDistance - 1; k1 <= i + this.viewDistance + 1; ++k1) {
-                for (l1 = j - this.viewDistance - 1; l1 <= j + this.viewDistance + 1; ++l1) {
-                    if (ChunkMap.isChunkInRange(k1, l1, i, j, this.viewDistance)) {
-                        flag5 = false;
-                        flag6 = true;
-                        this.updateChunkTracking(player, new ChunkPos(k1, l1), new MutableObject(), false, true);
-                    }
-                }
-            }
-        }
+        // Paper - replaced by PlayerChunkLoader
 
         this.updateMaps(player); // Paper - distance maps
+        this.playerChunkManager.updatePlayer(player); // Paper - respond to movement immediately
 
     }
 
     @Override
     public List<ServerPlayer> getPlayers(ChunkPos chunkPos, boolean onlyOnWatchDistanceEdge) {
-        Set<ServerPlayer> set = this.playerMap.getPlayers(chunkPos.toLong());
-        Builder<ServerPlayer> builder = ImmutableList.builder();
-        Iterator iterator = set.iterator();
+        // Paper start - per player view distance
+        // there can be potential desync with player's last mapped section and the view distance map, so use the
+        // view distance map here.
+        List<ServerPlayer> ret = new java.util.ArrayList<>(4);
 
-        while (iterator.hasNext()) {
-            ServerPlayer entityplayer = (ServerPlayer) iterator.next();
-            SectionPos sectionposition = entityplayer.getLastSectionPos();
+        com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> players = this.playerChunkManager.broadcastMap.getObjectsInRange(chunkPos);
+        if (players == null) {
+            return ret;
+        }
 
-            if (onlyOnWatchDistanceEdge && ChunkMap.isChunkOnRangeBorder(chunkPos.x, chunkPos.z, sectionposition.x(), sectionposition.z(), this.viewDistance) || !onlyOnWatchDistanceEdge && ChunkMap.isChunkInRange(chunkPos.x, chunkPos.z, sectionposition.x(), sectionposition.z(), this.viewDistance)) {
-                builder.add(entityplayer);
+        Object[] backingSet = players.getBackingSet();
+        for (int i = 0, len = backingSet.length; i < len; ++i) {
+            Object temp = backingSet[i];
+            if (!(temp instanceof ServerPlayer)) {
+                continue;
+            }
+            ServerPlayer player = (ServerPlayer)temp;
+            if (!this.playerChunkManager.isChunkSent(player, chunkPos.x, chunkPos.z, onlyOnWatchDistanceEdge)) {
+                continue;
             }
+            ret.add(player);
         }
 
-        return builder.build();
+        return ret;
+        // Paper end - per player view distance
     }
 
     public void addEntity(Entity entity) {
@@ -2417,7 +2375,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
                 double vec3d_dx = player.getX() - this.entity.getX();
                 double vec3d_dz = player.getZ() - this.entity.getZ();
                 // Paper end - remove allocation of Vec3D here
-                double d0 = (double) Math.min(this.getEffectiveRange(), (ChunkMap.this.viewDistance - 1) * 16);
+                double d0 = (double) Math.min(this.getEffectiveRange(), io.papermc.paper.chunk.PlayerChunkLoader.getSendViewDistance(player) * 16); // Paper - per player view distance
                 double d1 = vec3d_dx * vec3d_dx + vec3d_dz * vec3d_dz; // Paper
                 double d2 = d0 * d0;
                 boolean flag = d1 <= d2 && this.entity.broadcastToPlayer(player);
diff --git a/src/main/java/net/minecraft/server/level/DistanceManager.java b/src/main/java/net/minecraft/server/level/DistanceManager.java
index f581a9f79b2357118d912a15344ff94df3b0c50e..d1b5c25b7455174e908cd6ed66789fa700190604 100644
--- a/src/main/java/net/minecraft/server/level/DistanceManager.java
+++ b/src/main/java/net/minecraft/server/level/DistanceManager.java
@@ -51,8 +51,8 @@ public abstract class DistanceManager {
     public final Long2ObjectOpenHashMap<SortedArraySet<Ticket<?>>> tickets = new Long2ObjectOpenHashMap();
     //private final DistanceManager.ChunkTicketTracker ticketTracker = new DistanceManager.ChunkTicketTracker(); // Paper - replace ticket level propagator
     public static final int MOB_SPAWN_RANGE = 8; // private final ChunkMapDistance.b f = new ChunkMapDistance.b(8); // Paper - no longer used
-    private final TickingTracker tickingTicketsTracker = new TickingTracker();
-    private final DistanceManager.PlayerTicketTracker playerTicketManager = new DistanceManager.PlayerTicketTracker(33);
+    //private final TickingTracker tickingTicketsTracker = new TickingTracker(); // Paper - no longer used
+    //private final DistanceManager.PlayerTicketTracker playerTicketManager = new DistanceManager.PlayerTicketTracker(33); // Paper - no longer used
     // Paper start use a queue, but still keep unique requirement
     public final java.util.Queue<ChunkHolder> pendingChunkUpdates = new java.util.ArrayDeque<ChunkHolder>() {
         @Override
@@ -133,7 +133,7 @@ public abstract class DistanceManager {
         java.util.function.Predicate<Ticket<?>> removeIf = (ticket) -> {
             final boolean ret = ticket.timedOut(ticketCounter);
             if (ret) {
-                this.tickingTicketsTracker.removeTicket(currChunk[0], ticket);
+                //this.tickingTicketsTracker.removeTicket(currChunk[0], ticket); // Paper - no longer used
             }
             return ret;
         };
@@ -153,7 +153,7 @@ public abstract class DistanceManager {
                 if (ticket.timedOut(this.ticketTickCounter)) {
                     iterator.remove();
                     flag = true;
-                    this.tickingTicketsTracker.removeTicket(entry.getLongKey(), ticket);
+                    //this.tickingTicketsTracker.removeTicket(entry.getLongKey(), ticket); // Paper - no longer used
                 }
             }
 
@@ -184,9 +184,9 @@ public abstract class DistanceManager {
     protected long ticketLevelUpdateCount; // Paper - replace ticket level propagator
     public boolean runAllUpdates(ChunkMap chunkStorage) {
         //this.f.a(); // Paper - no longer used
-        this.tickingTicketsTracker.runAllUpdates();
+        //this.tickingTicketsTracker.runAllUpdates(); // Paper - no longer used
         org.spigotmc.AsyncCatcher.catchOp("DistanceManagerTick"); // Paper
-        this.playerTicketManager.runAllUpdates();
+        // this.playerTicketManager.runAllUpdates(); // Paper - no longer used
         boolean flag = this.ticketLevelPropagator.propagateUpdates(); // Paper - replace ticket level propagator
 
         if (flag) {
@@ -351,7 +351,7 @@ public abstract class DistanceManager {
         long j = chunkcoordintpair.toLong();
 
         boolean added = this.addTicket(j, ticket); // CraftBukkit
-        this.tickingTicketsTracker.addTicket(j, ticket);
+        //this.tickingTicketsTracker.addTicket(j, ticket); // Paper - no longer used
         return added; // CraftBukkit
     }
 
@@ -366,7 +366,7 @@ public abstract class DistanceManager {
         long j = chunkcoordintpair.toLong();
 
         boolean removed = this.removeTicket(j, ticket); // CraftBukkit
-        this.tickingTicketsTracker.removeTicket(j, ticket);
+        //this.tickingTicketsTracker.removeTicket(j, ticket); // Paper - no longer used
         return removed; // CraftBukkit
     }
 
@@ -488,10 +488,10 @@ public abstract class DistanceManager {
 
         if (forced) {
             this.addTicket(i, ticket);
-            this.tickingTicketsTracker.addTicket(i, ticket);
+            //this.tickingTicketsTracker.addTicket(i, ticket); // Paper - no longer used
         } else {
             this.removeTicket(i, ticket);
-            this.tickingTicketsTracker.removeTicket(i, ticket);
+            //this.tickingTicketsTracker.removeTicket(i, ticket); // Paper - no longer used
         }
 
     }
@@ -504,8 +504,8 @@ public abstract class DistanceManager {
             return new ObjectOpenHashSet();
         })).add(player);
         //this.f.update(i, 0, true); // Paper - no longer used
-        this.playerTicketManager.update(i, 0, true);
-        this.tickingTicketsTracker.addTicket(TicketType.PLAYER, chunkcoordintpair, this.getPlayerTicketLevel(), chunkcoordintpair);
+        //this.playerTicketManager.update(i, 0, true); // Paper - no longer used
+        //this.tickingTicketsTracker.addTicket(TicketType.PLAYER, chunkcoordintpair, this.getPlayerTicketLevel(), chunkcoordintpair); // Paper - no longer used
     }
 
     public void removePlayer(SectionPos pos, ServerPlayer player) {
@@ -518,8 +518,8 @@ public abstract class DistanceManager {
         if (objectset == null || objectset.isEmpty()) { // Paper
             this.playersPerChunk.remove(i);
             //this.f.update(i, Integer.MAX_VALUE, false); // Paper - no longer used
-            this.playerTicketManager.update(i, Integer.MAX_VALUE, false);
-            this.tickingTicketsTracker.removeTicket(TicketType.PLAYER, chunkcoordintpair, this.getPlayerTicketLevel(), chunkcoordintpair);
+            //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
         }
 
     }
@@ -529,11 +529,17 @@ public abstract class DistanceManager {
     }
 
     public boolean inEntityTickingRange(long chunkPos) {
-        return this.tickingTicketsTracker.getLevel(chunkPos) < 32;
+        // Paper start - replace player chunk loader system
+        ChunkHolder holder = this.chunkMap.getVisibleChunkIfPresent(chunkPos);
+        return holder != null && holder.isEntityTickingReady();
+        // Paper end - replace player chunk loader system
     }
 
     public boolean inBlockTickingRange(long chunkPos) {
-        return this.tickingTicketsTracker.getLevel(chunkPos) < 33;
+        // Paper start - replace player chunk loader system
+        ChunkHolder holder = this.chunkMap.getVisibleChunkIfPresent(chunkPos);
+        return holder != null && holder.isTickingReady();
+        // Paper end - replace player chunk loader system
     }
 
     protected String getTicketDebugString(long pos) {
@@ -543,20 +549,16 @@ public abstract class DistanceManager {
     }
 
     protected void updatePlayerTickets(int viewDistance) {
-        this.playerTicketManager.updateViewDistance(viewDistance);
+        this.chunkMap.playerChunkManager.setTargetNoTickViewDistance(viewDistance); // Paper - route to player chunk manager
     }
 
     public void updateSimulationDistance(int simulationDistance) {
-        if (simulationDistance != this.simulationDistance) {
-            this.simulationDistance = simulationDistance;
-            this.tickingTicketsTracker.replacePlayerTicketsLevel(this.getPlayerTicketLevel());
-        }
-
+        this.chunkMap.playerChunkManager.setTargetTickViewDistance(simulationDistance); // Paper - route to player chunk manager
     }
 
     // Paper start
     public int getSimulationDistance() {
-        return this.simulationDistance;
+        return this.chunkMap.playerChunkManager.getTargetTickViewDistance(); // Paper - route to player chunk manager
     }
     // Paper end
 
@@ -613,10 +615,7 @@ public abstract class DistanceManager {
 
     }
 
-    @VisibleForTesting
-    TickingTracker tickingTracker() {
-        return this.tickingTicketsTracker;
-    }
+    // Paper - replace player chunk loader
 
     public void removeTicketsOnClosing() {
         ImmutableSet<TicketType<?>> immutableset = ImmutableSet.of(TicketType.UNKNOWN, TicketType.POST_TELEPORT, TicketType.LIGHT, TicketType.FUTURE_AWAIT, TicketType.ASYNC_LOAD, TicketType.REQUIRED_LOAD, TicketType.CHUNK_RELIGHT, ca.spottedleaf.starlight.common.light.StarLightInterface.CHUNK_WORK_TICKET); // Paper - add additional tickets to preserve
@@ -633,7 +632,7 @@ public abstract class DistanceManager {
                 if (!immutableset.contains(ticket.getType())) {
                     iterator.remove();
                     flag = true;
-                    this.tickingTicketsTracker.removeTicket(entry.getLongKey(), ticket);
+                    // this.tickingTicketsTracker.removeTicket(entry.getLongKey(), ticket); // Paper - no longer used
                 }
             }
 
@@ -672,6 +671,7 @@ public abstract class DistanceManager {
     }
     // CraftBukkit end
 
+    /* Paper - replace old loader system
     private class ChunkTicketTracker extends ChunkTracker {
 
         public ChunkTicketTracker() {
@@ -890,4 +890,5 @@ public abstract class DistanceManager {
             return distance <= this.viewDistance - 2;
         }
     }
+     */ // Paper - replace old loader system
 }
diff --git a/src/main/java/net/minecraft/server/level/ServerChunkCache.java b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
index 96a232f22b1c270b91635ce9c7c6cacc63b026cc..59acbf6249f8f5285504c0ddea448a3433d1d68d 100644
--- a/src/main/java/net/minecraft/server/level/ServerChunkCache.java
+++ b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
@@ -844,17 +844,10 @@ public class ServerChunkCache extends ChunkSource {
     // Paper end
 
     public boolean isPositionTicking(long pos) {
-        ChunkHolder playerchunk = this.getVisibleChunkIfPresent(pos);
-
-        if (playerchunk == null) {
-            return false;
-        } else if (!this.level.shouldTickBlocksAt(pos)) {
-            return false;
-        } else {
-            Either<LevelChunk, ChunkHolder.ChunkLoadingFailure> either = (Either) playerchunk.getTickingChunkFuture().getNow(null); // CraftBukkit - decompile error
-
-            return either != null && either.left().isPresent();
-        }
+        // Paper start - replace player chunk loader system
+        ChunkHolder holder = this.chunkMap.getVisibleChunkIfPresent(pos);
+        return holder != null && holder.isTickingReady();
+        // Paper end - replace player chunk loader system
     }
 
     public void save(boolean flush) {
@@ -911,6 +904,7 @@ public class ServerChunkCache extends ChunkSource {
         this.level.getProfiler().popPush("chunks");
         if (tickChunks) {
             this.level.timings.chunks.startTiming(); // Paper - timings
+            this.chunkMap.playerChunkManager.tick(); // Paper - this is mostly is to account for view distance changes
             this.tickChunks();
             this.level.timings.chunks.stopTiming(); // Paper - timings
         }
@@ -1024,13 +1018,13 @@ public class ServerChunkCache extends ChunkSource {
                 // Paper end - optimise chunk tick iteration
                 ChunkPos chunkcoordintpair = chunk1.getPos();
 
-                if (this.level.isNaturalSpawningAllowed(chunkcoordintpair) && this.chunkMap.anyPlayerCloseEnoughForSpawning(holder, chunkcoordintpair, false)) { // Paper - optimise anyPlayerCloseEnoughForSpawning
+                if ((true || this.level.isNaturalSpawningAllowed(chunkcoordintpair)) && this.chunkMap.anyPlayerCloseEnoughForSpawning(holder, chunkcoordintpair, false)) { // Paper - optimise anyPlayerCloseEnoughForSpawning // Paper - replace player chunk loader system
                     chunk1.incrementInhabitedTime(j);
                     if (flag2 && (this.spawnEnemies || this.spawnFriendlies) && this.level.getWorldBorder().isWithinBounds(chunkcoordintpair) && this.chunkMap.anyPlayerCloseEnoughForSpawning(holder, chunkcoordintpair, true)) { // Spigot // Paper - optimise anyPlayerCloseEnoughForSpawning & 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 - replace player chunk loader system
                         this.level.tickChunk(chunk1, k);
                         if ((chunksTicked++ & 1) == 0) net.minecraft.server.MinecraftServer.getServer().executeMidTickTasks(); // Paper
                     }
@@ -1259,6 +1253,7 @@ public class ServerChunkCache extends ChunkSource {
         public boolean pollTask() {
         try {
             boolean execChunkTask = com.destroystokyo.paper.io.chunk.ChunkTaskManager.pollChunkWaitQueue() || ServerChunkCache.this.level.asyncChunkTaskManager.pollNextChunkTask(); // Paper
+            ServerChunkCache.this.chunkMap.playerChunkManager.tickMidTick(); // Paper
             if (ServerChunkCache.this.runDistanceManagerUpdates()) {
                 return true;
             } else {
diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
index 856ef0c487af8e8c5689d58decc9acf8d52971c9..836841987ff5dd4901f75f47028a60d8d1b6e04a 100644
--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
@@ -677,7 +677,7 @@ public class ServerLevel extends Level implements WorldGenLevel {
                         gameprofilerfiller.push("checkDespawn");
                         entity.checkDespawn();
                         gameprofilerfiller.pop();
-                        if (this.chunkSource.chunkMap.getDistanceManager().inEntityTickingRange(entity.chunkPosition().toLong())) {
+                        if (true || this.chunkSource.chunkMap.getDistanceManager().inEntityTickingRange(entity.chunkPosition().toLong())) { // Paper - now always true if in the ticking list
                             Entity entity1 = entity.getVehicle();
 
                             if (entity1 != null) {
@@ -710,7 +710,10 @@ public class ServerLevel extends Level implements WorldGenLevel {
 
     @Override
     public boolean shouldTickBlocksAt(long chunkPos) {
-        return this.chunkSource.chunkMap.getDistanceManager().inBlockTickingRange(chunkPos);
+        // Paper start - replace player chunk loader system
+        ChunkHolder holder = this.chunkSource.chunkMap.getVisibleChunkIfPresent(chunkPos);
+        return holder != null && holder.isTickingReady();
+        // Paper end - replace player chunk loader system
     }
 
     protected void tickTime() {
@@ -2454,7 +2457,7 @@ public class ServerLevel extends Level implements WorldGenLevel {
     private boolean isPositionTickingWithEntitiesLoaded(long chunkPos) {
         // Paper start - optimize is ticking ready type functions
         ChunkHolder chunkHolder = this.chunkSource.chunkMap.getVisibleChunkIfPresent(chunkPos);
-        return chunkHolder != null && this.chunkSource.isPositionTicking(chunkPos) && chunkHolder.isTickingReady() && this.areEntitiesLoaded(chunkPos);
+        return chunkHolder != null && chunkHolder.isTickingReady() && this.areEntitiesLoaded(chunkPos); // Paper - no longer need to check with chunk source
         // Paper end
     }
 
diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index 94931d058118cb2a928ca53e154114690413dace..c7915e930316e30382fbf0986e185f18f67b4503 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -2475,5 +2475,5 @@ public class ServerPlayer extends Player {
     }
     // CraftBukkit end
 
-    public final int getViewDistance() { return this.getLevel().getChunkSource().chunkMap.viewDistance - 1; } // Paper - placeholder
+    public final int getViewDistance() { throw new UnsupportedOperationException("Use PlayerChunkLoader"); } // Paper - placeholder
 }
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index 54f6a064116043b9c40c55895678a779b9f2627e..eb7056c71dfe5a8a58efb7aa5856fb371edb13cd 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -274,7 +274,7 @@ public abstract class PlayerList {
         boolean flag1 = gamerules.getBoolean(GameRules.RULE_REDUCEDDEBUGINFO);
 
         // Spigot - view distance
-        playerconnection.send(new ClientboundLoginPacket(player.getId(), worlddata.isHardcore(), player.gameMode.getGameModeForPlayer(), player.gameMode.getPreviousGameModeForPlayer(), this.server.levelKeys(), this.registryHolder, worldserver1.dimensionTypeId(), worldserver1.dimension(), BiomeManager.obfuscateSeed(worldserver1.getSeed()), this.getMaxPlayers(), worldserver1.spigotConfig.viewDistance, worldserver1.spigotConfig.simulationDistance, flag1, !flag, worldserver1.isDebug(), worldserver1.isFlat(), player.getLastDeathLocation()));
+        playerconnection.send(new ClientboundLoginPacket(player.getId(), worlddata.isHardcore(), player.gameMode.getGameModeForPlayer(), player.gameMode.getPreviousGameModeForPlayer(), this.server.levelKeys(), this.registryHolder, worldserver1.dimensionTypeId(), worldserver1.dimension(), BiomeManager.obfuscateSeed(worldserver1.getSeed()), this.getMaxPlayers(), worldserver1.getChunkSource().chunkMap.playerChunkManager.getTargetSendDistance(), worldserver1.getChunkSource().chunkMap.playerChunkManager.getTargetTickViewDistance(), flag1, !flag, worldserver1.isDebug(), worldserver1.isFlat(), player.getLastDeathLocation())); // Paper - replace old player chunk management
         player.getBukkitEntity().sendSupportedChannels(); // CraftBukkit
         playerconnection.send(new ClientboundCustomPayloadPacket(ClientboundCustomPayloadPacket.BRAND, (new FriendlyByteBuf(Unpooled.buffer())).writeUtf(this.getServer().getServerModName())));
         playerconnection.send(new ClientboundChangeDifficultyPacket(worlddata.getDifficulty(), worlddata.isDifficultyLocked()));
@@ -943,8 +943,8 @@ public abstract class PlayerList {
         // CraftBukkit start
         LevelData worlddata = worldserver1.getLevelData();
         entityplayer1.connection.send(new ClientboundRespawnPacket(worldserver1.dimensionTypeId(), worldserver1.dimension(), BiomeManager.obfuscateSeed(worldserver1.getSeed()), entityplayer1.gameMode.getGameModeForPlayer(), entityplayer1.gameMode.getPreviousGameModeForPlayer(), worldserver1.isDebug(), worldserver1.isFlat(), flag, entityplayer1.getLastDeathLocation()));
-        entityplayer1.connection.send(new ClientboundSetChunkCacheRadiusPacket(worldserver1.spigotConfig.viewDistance)); // Spigot
-        entityplayer1.connection.send(new ClientboundSetSimulationDistancePacket(worldserver1.spigotConfig.simulationDistance)); // Spigot
+        entityplayer1.connection.send(new ClientboundSetChunkCacheRadiusPacket(worldserver1.getChunkSource().chunkMap.playerChunkManager.getTargetSendDistance())); // Spigot // Paper - replace old player chunk management
+        entityplayer1.connection.send(new ClientboundSetSimulationDistancePacket(worldserver1.getChunkSource().chunkMap.playerChunkManager.getTargetTickViewDistance())); // Spigot // Paper - replace old player chunk management
         entityplayer1.spawnIn(worldserver1);
         entityplayer1.unsetRemoved();
         entityplayer1.connection.teleport(new Location(worldserver1.getWorld(), entityplayer1.getX(), entityplayer1.getY(), entityplayer1.getZ(), entityplayer1.getYRot(), entityplayer1.getXRot()));
@@ -1513,7 +1513,7 @@ public abstract class PlayerList {
 
     public void setViewDistance(int viewDistance) {
         this.viewDistance = viewDistance;
-        this.broadcastAll(new ClientboundSetChunkCacheRadiusPacket(viewDistance));
+        //this.broadcastAll(new ClientboundSetChunkCacheRadiusPacket(viewDistance)); // Paper - move into setViewDistance
         Iterator iterator = this.server.getAllLevels().iterator();
 
         while (iterator.hasNext()) {
@@ -1528,7 +1528,7 @@ public abstract class PlayerList {
 
     public void setSimulationDistance(int simulationDistance) {
         this.simulationDistance = simulationDistance;
-        this.broadcastAll(new ClientboundSetSimulationDistancePacket(simulationDistance));
+        //this.broadcastAll(new ClientboundSetSimulationDistancePacket(simulationDistance)); // Paper - handled by playerchunkloader
         Iterator iterator = this.server.getAllLevels().iterator();
 
         while (iterator.hasNext()) {
diff --git a/src/main/java/net/minecraft/world/entity/boss/enderdragon/EnderDragon.java b/src/main/java/net/minecraft/world/entity/boss/enderdragon/EnderDragon.java
index 3a6e5893181ed681099f2748abca738af45ec9c9..bb51a85b33e1701c2e445305d68d3453772f73df 100644
--- a/src/main/java/net/minecraft/world/entity/boss/enderdragon/EnderDragon.java
+++ b/src/main/java/net/minecraft/world/entity/boss/enderdragon/EnderDragon.java
@@ -660,7 +660,7 @@ public class EnderDragon extends Mob implements Enemy {
                 // this.world.b(1028, this.getChunkCoordinates(), 0);
                 //int viewDistance = ((WorldServer) this.world).getServer().getViewDistance() * 16; // Paper - updated to use worlds actual view distance incase we have to uncomment this due to removal of player view distance API
                 for (net.minecraft.server.level.ServerPlayer player : (List<net.minecraft.server.level.ServerPlayer>) ((ServerLevel)level).players()) {
-                    final int viewDistance = player.getViewDistance(); // TODO apply view distance api patch
+                    final int viewDistance = io.papermc.paper.chunk.PlayerChunkLoader.getSendViewDistance(player); // Paper - route to player chunk loader
                     double deltaX = this.getX() - player.getX();
                     double deltaZ = this.getZ() - player.getZ();
                     double distanceSquared = deltaX * deltaX + deltaZ * deltaZ;
diff --git a/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java b/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java
index b3e2e834f4f151497bf842796dd8e3a8b5143f1b..4fb40aa91e0961f1974c74c88fa68359e4ad6b16 100644
--- a/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java
+++ b/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java
@@ -278,7 +278,7 @@ public class WitherBoss extends Monster implements PowerableMob, RangedAttackMob
                     // this.world.globalLevelEvent(1023, new BlockPosition(this), 0);
                     //int viewDistance = ((ServerLevel) this.level).getCraftServer().getViewDistance() * 16; // Paper - updated to use worlds actual view distance incase we have to uncomment this due to removal of player view distance API
                     for (ServerPlayer player : (List<ServerPlayer>)this.level.players()) { // Paper
-                        final int viewDistance = player.getViewDistance(); // TODO apply view distance api patch
+                        final int viewDistance = io.papermc.paper.chunk.PlayerChunkLoader.getSendViewDistance(player); // Paper - route to player chunk loader
                         double deltaX = this.getX() - player.getX();
                         double deltaZ = this.getZ() - player.getZ();
                         double distanceSquared = deltaX * deltaX + deltaZ * deltaZ;
diff --git a/src/main/java/net/minecraft/world/item/EnderEyeItem.java b/src/main/java/net/minecraft/world/item/EnderEyeItem.java
index 0b3e9e4ed162a6d9e1f3f55b9522b75c94d13254..fa1ff2e79954089552974cefedfcbff2225738ec 100644
--- a/src/main/java/net/minecraft/world/item/EnderEyeItem.java
+++ b/src/main/java/net/minecraft/world/item/EnderEyeItem.java
@@ -62,9 +62,10 @@ public class EnderEyeItem extends Item {
 
                     // CraftBukkit start - Use relative location for far away sounds
                     // world.b(1038, blockposition1.c(1, 0, 1), 0);
-                    int viewDistance = world.getCraftServer().getViewDistance() * 16;
+                    //int viewDistance = world.getCraftServer().getViewDistance() * 16; // Paper - apply view distance patch
                     BlockPos soundPos = blockposition1.offset(1, 0, 1);
                     for (ServerPlayer player : world.getServer().getPlayerList().players) {
+                        final int viewDistance = io.papermc.paper.chunk.PlayerChunkLoader.getSendViewDistance(player); // Paper - apply view distance patch
                         double deltaX = soundPos.getX() - player.getX();
                         double deltaZ = soundPos.getZ() - player.getZ();
                         double distanceSquared = deltaX * deltaX + deltaZ * deltaZ;
diff --git a/src/main/java/net/minecraft/world/level/Level.java b/src/main/java/net/minecraft/world/level/Level.java
index 17c0110fd5ccb8399af797cc892ca285b1fb7964..c118efaadd0e3e29f9adcd65c11ecabfc6d76216 100644
--- a/src/main/java/net/minecraft/world/level/Level.java
+++ b/src/main/java/net/minecraft/world/level/Level.java
@@ -627,6 +627,11 @@ public abstract class Level implements LevelAccessor, AutoCloseable {
 
             if ((i & 2) != 0 && (!this.isClientSide || (i & 4) == 0) && (this.isClientSide || chunk == null || (chunk.getFullStatus() != null && chunk.getFullStatus().isOrAfter(ChunkHolder.FullChunkStatus.TICKING)))) { // allow chunk to be null here as chunk.isReady() is false when we send our notification during block placement
                 this.sendBlockUpdated(blockposition, iblockdata1, iblockdata, i);
+                // Paper start - per player view distance - allow block updates for non-ticking chunks in player view distance
+                // if copied from above
+            } else if ((i & 2) != 0 && (!this.isClientSide || (i & 4) == 0) && (this.isClientSide || chunk == null || ((ServerLevel)this).getChunkSource().chunkMap.playerChunkManager.broadcastMap.getObjectsInRange(MCUtil.getCoordinateKey(blockposition)) != null)) { // Paper - replace old player chunk management
+                ((ServerLevel)this).getChunkSource().blockChanged(blockposition);
+                // Paper end - per player view distance
             }
 
             if ((i & 1) != 0) {
diff --git a/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java b/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
index d870cefbe5b7485f423817f4f639e3e2a304640c..2292cb0e0c1a3e0ed34b941f028136bfb0bff13e 100644
--- a/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
+++ b/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
@@ -191,6 +191,43 @@ public class LevelChunk extends ChunkAccess {
 
     protected void onNeighbourChange(final long bitsetBefore, final long bitsetAfter) {
 
+        // Paper start - no-tick view distance
+        ServerChunkCache chunkProviderServer = ((ServerLevel)this.level).getChunkSource();
+        net.minecraft.server.level.ChunkMap chunkMap = chunkProviderServer.chunkMap;
+        // this code handles the addition of ticking tickets - the distance map handles the removal
+        if (!areNeighboursLoaded(bitsetBefore, 2) && areNeighboursLoaded(bitsetAfter, 2)) {
+            if (chunkMap.playerChunkManager.tickMap.getObjectsInRange(this.coordinateKey) != null) { // Paper - replace old player chunk loading system
+                // now we're ready for entity ticking
+                chunkProviderServer.mainThreadProcessor.execute(() -> {
+                    // double check that this condition still holds.
+                    if (LevelChunk.this.areNeighboursLoaded(2) && chunkMap.playerChunkManager.tickMap.getObjectsInRange(LevelChunk.this.coordinateKey) != null) { // Paper - replace old player chunk loading system
+                        chunkMap.playerChunkManager.onChunkPlayerTickReady(this.chunkPos.x, this.chunkPos.z); // Paper - replace old player chunk
+                        chunkProviderServer.addTicketAtLevel(net.minecraft.server.level.TicketType.PLAYER, LevelChunk.this.chunkPos, 31, LevelChunk.this.chunkPos); // 31 -> entity ticking, TODO check on update
+                    }
+                });
+            }
+        }
+
+        // this code handles the chunk sending
+        if (!areNeighboursLoaded(bitsetBefore, 1) && areNeighboursLoaded(bitsetAfter, 1)) {
+            // Paper start - replace old player chunk loading system
+            if (chunkMap.playerChunkManager.isChunkNearPlayers(this.chunkPos.x, this.chunkPos.z)) {
+                // the post processing is expensive, so we don't want to run it unless we're actually near
+                // a player.
+                chunkProviderServer.mainThreadProcessor.execute(() -> {
+                    if (!LevelChunk.this.areNeighboursLoaded(1)) {
+                        return;
+                    }
+                    LevelChunk.this.postProcessGeneration();
+                    if (!LevelChunk.this.areNeighboursLoaded(1)) {
+                        return;
+                    }
+                    chunkMap.playerChunkManager.onChunkSendReady(this.chunkPos.x, this.chunkPos.z);
+                });
+            }
+            // Paper end - replace old player chunk loading system
+        }
+        // Paper end - no-tick view distance
     }
 
     public final boolean isAnyNeighborsLoaded() {
@@ -815,6 +852,7 @@ public class LevelChunk extends ChunkAccess {
         // Paper end - neighbour cache
         org.bukkit.Server server = this.level.getCraftServer();
         this.level.getChunkSource().addLoadedChunk(this); // Paper
+        ((ServerLevel)this.level).getChunkSource().chunkMap.playerChunkManager.onChunkLoad(this.chunkPos.x, this.chunkPos.z); // Paper - rewrite player chunk management
         if (server != null) {
             /*
              * If it's a new world, the first few chunks are generated inside
@@ -939,7 +977,10 @@ public class LevelChunk extends ChunkAccess {
         });
     }
 
+    public boolean isPostProcessingDone; // Paper - replace chunk loader system
+
     public void postProcessGeneration() {
+        try { // Paper - replace chunk loader system
         ChunkPos chunkcoordintpair = this.getPos();
 
         for (int i = 0; i < this.postProcessing.length; ++i) {
@@ -977,6 +1018,11 @@ public class LevelChunk extends ChunkAccess {
 
         this.pendingBlockEntities.clear();
         this.upgradeData.upgrade(this);
+        } finally { // Paper start - replace chunk loader system
+            this.isPostProcessingDone = true;
+            this.level.getChunkSource().chunkMap.playerChunkManager.onChunkPostProcessing(this.chunkPos.x, this.chunkPos.z);
+        }
+        // Paper end - replace chunk loader system
     }
 
     @Nullable
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
index 1bbc73dcdf890a9383795ffeb0d368293f7146a5..c4f7aa9ffb72d2bc555ace64bb8cedc5c2545d8b 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
@@ -2281,43 +2281,56 @@ public class CraftWorld extends CraftRegionAccessor implements World {
     // Spigot start
     @Override
     public int getViewDistance() {
-        return world.spigotConfig.viewDistance;
+        return getHandle().getChunkSource().chunkMap.playerChunkManager.getTargetNoTickViewDistance(); // Paper - replace old player chunk management
     }
 
     @Override
     public int getSimulationDistance() {
-        return world.spigotConfig.simulationDistance;
+        return getHandle().getChunkSource().chunkMap.playerChunkManager.getTargetTickViewDistance(); // Paper - replace old player chunk management
     }
     // Spigot end
     // Paper start - view distance api
     @Override
     public void setViewDistance(int viewDistance) {
-        throw new UnsupportedOperationException(); //TODO
+        // Paper start - replace old player chunk management
+        if (viewDistance < 2 || viewDistance > 32) {
+            throw new IllegalArgumentException("View distance " + viewDistance + " is out of range of [2, 32]");
+        }
+        net.minecraft.server.level.ChunkMap chunkMap = getHandle().getChunkSource().chunkMap;
+        chunkMap.setViewDistance(viewDistance);
+        // Paper end - replace old player chunk management
     }
 
+    // Paper start - replace old player chunk management
     @Override
     public void setSimulationDistance(int simulationDistance) {
-        throw new UnsupportedOperationException(); //TODO
+        // Paper start - replace old player chunk management
+        if (simulationDistance < 2 || simulationDistance > 32) {
+            throw new IllegalArgumentException("Simulation distance " + simulationDistance + " is out of range of [2, 32]");
+        }
+        net.minecraft.server.level.ChunkMap chunkMap = getHandle().getChunkSource().chunkMap;
+        chunkMap.setTickViewDistance(simulationDistance);
     }
+    // Paper end - replace old player chunk management
 
     @Override
     public int getNoTickViewDistance() {
-        throw new UnsupportedOperationException(); //TODO
+        return this.getViewDistance(); // Paper - replace old player chunk management
     }
 
     @Override
     public void setNoTickViewDistance(int viewDistance) {
-        throw new UnsupportedOperationException(); //TODO
+        this.setViewDistance(viewDistance); // Paper - replace old player chunk management
     }
 
     @Override
     public int getSendViewDistance() {
-        throw new UnsupportedOperationException(); //TODO
+        return getHandle().getChunkSource().chunkMap.playerChunkManager.getTargetSendDistance(); // Paper - replace old player chunk management
     }
 
     @Override
     public void setSendViewDistance(int viewDistance) {
-        throw new UnsupportedOperationException(); //TODO
+        getHandle().getChunkSource().chunkMap.playerChunkManager.setSendDistance(viewDistance); // Paper - replace old player chunk management
     }
     // Paper end - view distance api
 
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index 2acb9f0d675650e73ff58011250dab04f01ecfee..f74802748438f4d40fb5ab772a209dfb2ee406e6 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -541,45 +541,80 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         }
     }
 
+    // Paper start - implement view distances
     @Override
     public int getViewDistance() {
-        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
+        net.minecraft.server.level.ChunkMap chunkMap = this.getHandle().getLevel().getChunkSource().chunkMap;
+        io.papermc.paper.chunk.PlayerChunkLoader.PlayerLoaderData data = chunkMap.playerChunkManager.getData(this.getHandle());
+        if (data == null) {
+            return chunkMap.playerChunkManager.getTargetNoTickViewDistance();
+        }
+        return data.getTargetNoTickViewDistance();
     }
 
     @Override
     public void setViewDistance(int viewDistance) {
-        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
+        net.minecraft.server.level.ChunkMap chunkMap = this.getHandle().getLevel().getChunkSource().chunkMap;
+        io.papermc.paper.chunk.PlayerChunkLoader.PlayerLoaderData data = chunkMap.playerChunkManager.getData(this.getHandle());
+        if (data == null) {
+            throw new IllegalStateException("Player is not attached to world");
+        }
+
+        data.setTargetNoTickViewDistance(viewDistance);
     }
 
     @Override
     public int getSimulationDistance() {
-        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
+        net.minecraft.server.level.ChunkMap chunkMap = this.getHandle().getLevel().getChunkSource().chunkMap;
+        io.papermc.paper.chunk.PlayerChunkLoader.PlayerLoaderData data = chunkMap.playerChunkManager.getData(this.getHandle());
+        if (data == null) {
+            return chunkMap.playerChunkManager.getTargetTickViewDistance();
+        }
+        return data.getTargetTickViewDistance();
     }
 
     @Override
     public void setSimulationDistance(int simulationDistance) {
-        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
+        net.minecraft.server.level.ChunkMap chunkMap = this.getHandle().getLevel().getChunkSource().chunkMap;
+        io.papermc.paper.chunk.PlayerChunkLoader.PlayerLoaderData data = chunkMap.playerChunkManager.getData(this.getHandle());
+        if (data == null) {
+            throw new IllegalStateException("Player is not attached to world");
+        }
+
+        data.setTargetTickViewDistance(simulationDistance);
     }
 
     @Override
     public int getNoTickViewDistance() {
-        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
+        return this.getViewDistance();
     }
 
     @Override
     public void setNoTickViewDistance(int viewDistance) {
-        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
+        this.setViewDistance(viewDistance);
     }
 
     @Override
     public int getSendViewDistance() {
-        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
+        net.minecraft.server.level.ChunkMap chunkMap = this.getHandle().getLevel().getChunkSource().chunkMap;
+        io.papermc.paper.chunk.PlayerChunkLoader.PlayerLoaderData data = chunkMap.playerChunkManager.getData(this.getHandle());
+        if (data == null) {
+            return chunkMap.playerChunkManager.getTargetSendDistance();
+        }
+        return data.getTargetSendViewDistance();
     }
 
     @Override
     public void setSendViewDistance(int viewDistance) {
-        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
+        net.minecraft.server.level.ChunkMap chunkMap = this.getHandle().getLevel().getChunkSource().chunkMap;
+        io.papermc.paper.chunk.PlayerChunkLoader.PlayerLoaderData data = chunkMap.playerChunkManager.getData(this.getHandle());
+        if (data == null) {
+            throw new IllegalStateException("Player is not attached to world");
+        }
+
+        data.setTargetSendViewDistance(viewDistance);
     }
+    // Paper end - implement view distances
 
     @Override
     public <T> T getClientOption(com.destroystokyo.paper.ClientOption<T> type) {