Merge pull request #3725 from mastermc05/v3.0

Async chunk loading on paper

DynmapCore/src/main/java/org/dynmap/common/chunk/GenericMapChunkCache.java

@@ -1,8 +1,10 @@
 package org.dynmap.common.chunk;
 
-import java.util.ArrayList;
+import java.util.*;
-import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
-import java.util.ListIterator;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
 
 import org.dynmap.DynmapChunk;
 import org.dynmap.DynmapCore;
@@ -37,6 +39,7 @@ public abstract class GenericMapChunkCache extends MapChunkCache {
 	private int snapcnt;
 	private GenericChunk[] snaparray; /* Index = (x-x_min) + ((z-z_min)*x_dim) */
 	private boolean[][] isSectionNotEmpty; /* Indexed by snapshot index, then by section index */
+	private AtomicInteger loadingChunks = new AtomicInteger(0); //the amount of threads loading chunks at this moment, used by async loading
 
 	private static final BlockStep unstep[] = { BlockStep.X_MINUS, BlockStep.Y_MINUS, BlockStep.Z_MINUS,
 			BlockStep.X_PLUS, BlockStep.Y_PLUS, BlockStep.Z_PLUS };
@@ -697,6 +700,14 @@ public abstract class GenericMapChunkCache extends MapChunkCache {
 	protected abstract GenericChunk getLoadedChunk(DynmapChunk ch);
 	// Load generic chunk from unloaded chunk
 	protected abstract GenericChunk loadChunk(DynmapChunk ch);
+	// Load generic chunk from existing and already loaded chunk async
+	protected Supplier<GenericChunk> getLoadedChunkAsync(DynmapChunk ch) {
+		throw new IllegalStateException("Not implemeted");
+	}
+	// Load generic chunks from unloaded chunk async
+	protected Supplier<GenericChunk> loadChunkAsync(DynmapChunk ch){
+		throw new IllegalStateException("Not implemeted");
+	}
 	
 	/**
 	 * Read NBT data from loaded chunks - needs to be called from server/world
@@ -754,10 +765,82 @@ public abstract class GenericMapChunkCache extends MapChunkCache {
 		return cnt;
 	}
 
+	/**
+	 * Read NBT data from loaded chunks - do not needs to be called from server/world
+	 * Will throw {@link IllegalStateException} if not supporting
+	 */
+	public void getLoadedChunksAsync() {
+		class SimplePair { //simple pair of the supplier that finishes read async, and a consumer that also finish his work async
+			final Supplier<GenericChunk> supplier;
+			final BiConsumer<GenericChunk, Long> consumer;
+
+			SimplePair(Supplier<GenericChunk> supplier, BiConsumer<GenericChunk, Long> consumer) {
+				this.supplier = supplier;
+				this.consumer = consumer;
+			}
+		}
+		if (!dw.isLoaded()) {
+			isempty = true;
+			unloadChunks();
+			return;
+		}
+		List<SimplePair> lastApply = new ArrayList<>();
+		for (DynmapChunk dynmapChunk : chunks) {
+			long startTime = System.nanoTime();
+			int chunkIndex = (dynmapChunk.x - x_min) + (dynmapChunk.z - z_min) * x_dim;
+			if (snaparray[chunkIndex] != null)
+				continue; // Skip if already processed
+
+			boolean vis = isChunkVisible(dynmapChunk);
+
+			/* Check if cached chunk snapshot found */
+			if (tryChunkCache(dynmapChunk, vis)) {
+				endChunkLoad(startTime, ChunkStats.CACHED_SNAPSHOT_HIT);
+			}
+			// If chunk is loaded and not being unloaded, we're grabbing its NBT data
+			else {
+				// Get generic chunk from already loaded chunk, if we can
+				Supplier<GenericChunk> supplier = getLoadedChunkAsync(dynmapChunk);
+				long startPause = System.nanoTime();
+				BiConsumer<GenericChunk, Long> consumer = (ss, reloadTime) -> {
+					if (ss == null) return;
+					long pause = reloadTime - startPause;
+					if (vis) { // If visible
+						prepChunkSnapshot(dynmapChunk, ss);
+					} else {
+						if (hidestyle == HiddenChunkStyle.FILL_STONE_PLAIN) {
+							ss = getStone();
+						} else if (hidestyle == HiddenChunkStyle.FILL_OCEAN) {
+							ss = getOcean();
+						} else {
+							ss = getEmpty();
+						}
+					}
+					snaparray[chunkIndex] = ss;
+					endChunkLoad(startTime - pause, ChunkStats.LOADED_CHUNKS);
+
+				};
+				lastApply.add(new SimplePair(supplier, consumer));
+			}
+		}
+		//impact on the main thread should be minimal, so we plan and finish the work after main thread finished it's part
+		lastApply.forEach(simplePair -> {
+			long reloadWork = System.nanoTime();
+			simplePair.consumer.accept(simplePair.supplier.get(), reloadWork);
+		});
+	}
+
 	@Override
 	public int loadChunks(int max_to_load) {
 		return getLoadedChunks() + readChunks(max_to_load);
+	}
 
+	/**
+	 * Prepare the chunks async
+	 */
+	public void loadChunksAsync() {
+		getLoadedChunksAsync();
+		readChunksAsync();
 	}
 
 	public int readChunks(int max_to_load) {
@@ -840,6 +923,96 @@ public abstract class GenericMapChunkCache extends MapChunkCache {
 		return cnt;
 	}
 
+	public void readChunksAsync() {
+		class SimplePair { //pair of the chunk and the data which is readed async
+			private final Supplier<GenericChunk> supplier;
+			private final DynmapChunk chunk;
+
+			SimplePair(DynmapChunk chunk) {
+				this.chunk = chunk;
+				this.supplier = loadChunkAsync(chunk);
+			}
+		}
+		if (!dw.isLoaded()) {
+			isempty = true;
+			unloadChunks();
+			return;
+		}
+
+		List<DynmapChunk> chunks;
+		if (iterator == null) {
+			iterator = Collections.emptyListIterator();
+			chunks = new ArrayList<>(this.chunks);
+		} else {
+			chunks = new ArrayList<>();
+			iterator.forEachRemaining(chunks::add);
+		}
+		//if before increent was 0, means that we are the first, so we need to set this
+		if (loadingChunks.getAndIncrement() == 0) {
+			DynmapCore.setIgnoreChunkLoads(true);
+		}
+
+		try {
+			List<DynmapChunk> cached = new ArrayList<>();
+			List<SimplePair> notCached = new ArrayList<>();
+
+			iterator.forEachRemaining(chunks::add);
+			chunks.stream()
+					.filter(chunk -> snaparray[(chunk.x - x_min) + (chunk.z - z_min) * x_dim] == null)
+					.forEach(chunk -> {
+						if (cache.getSnapshot(dw.getName(), chunk.x, chunk.z) == null) {
+							notCached.add(new SimplePair(chunk));
+						} else {
+							cached.add(chunk);
+						}
+					});
+
+			cached.forEach(chunk -> {
+				long startTime = System.nanoTime();
+				tryChunkCache(chunk, isChunkVisible(chunk));
+				endChunkLoad(startTime, ChunkStats.CACHED_SNAPSHOT_HIT);
+			});
+			notCached.forEach(chunkSupplier -> {
+				long startTime = System.nanoTime();
+				GenericChunk chunk = chunkSupplier.supplier.get();
+				DynmapChunk dynmapChunk = chunkSupplier.chunk;
+				if (chunk != null) {
+					// If hidden
+					if (isChunkVisible(dynmapChunk)) {
+						// Prep snapshot
+						prepChunkSnapshot(dynmapChunk, chunk);
+					} else {
+						if (hidestyle == HiddenChunkStyle.FILL_STONE_PLAIN) {
+							chunk = getStone();
+						} else if (hidestyle == HiddenChunkStyle.FILL_OCEAN) {
+							chunk = getOcean();
+						} else {
+							chunk = getEmpty();
+						}
+					}
+					snaparray[(dynmapChunk.x - x_min) + (dynmapChunk.z - z_min) * x_dim] = chunk;
+					endChunkLoad(startTime, ChunkStats.UNLOADED_CHUNKS);
+				} else {
+					endChunkLoad(startTime, ChunkStats.UNGENERATED_CHUNKS);
+				}
+			});
+
+			isempty = true;
+			/* Fill missing chunks with empty dummy chunk */
+			for (int i = 0; i < snaparray.length; i++) {
+				if (snaparray[i] == null) {
+					snaparray[i] = getEmpty();
+				} else if (!snaparray[i].isEmpty) {
+					isempty = false;
+				}
+			}
+		} finally {
+			if (loadingChunks.decrementAndGet() == 0) {
+				DynmapCore.setIgnoreChunkLoads(false);
+			}
+		}
+	}
+
 	/**
 	 * Test if done loading
 	 */

bukkit-helper-116-2/src/main/java/org/dynmap/bukkit/helper/v116_2/BukkitVersionHelperSpigot116_2.java

@@ -37,11 +37,13 @@ import net.minecraft.server.v1_16_R2.MinecraftServer;
  * Helper for isolation of bukkit version specific issues
  */
 public class BukkitVersionHelperSpigot116_2 extends BukkitVersionHelperGeneric {
+    private final boolean unsafeAsync;
     private Field watercolorfield;
     
     public BukkitVersionHelperSpigot116_2() {
 		Class biomefog =  getNMSClass("net.minecraft.server.BiomeFog");
 		watercolorfield = getPrivateField(biomefog, new String[] { "c" }, int.class);
+         this.unsafeAsync = true;
     }
     
     /**
@@ -69,6 +71,12 @@ public class BukkitVersionHelperSpigot116_2 extends BukkitVersionHelperGeneric {
     }
     
     private Object[] biomelist;
+
+    @Override
+    public boolean isUnsafeAsync() {
+        return unsafeAsync;
+    }
+
     /**
      * Get list of defined biomebase objects
      */

bukkit-helper-116-3/src/main/java/org/dynmap/bukkit/helper/v116_3/BukkitVersionHelperSpigot116_3.java

@@ -37,11 +37,13 @@ import net.minecraft.server.v1_16_R2.BlockPosition;
  * Helper for isolation of bukkit version specific issues
  */
 public class BukkitVersionHelperSpigot116_3 extends BukkitVersionHelperGeneric {
+    private final boolean unsafeAsync;
     private Field watercolorfield;
     
     public BukkitVersionHelperSpigot116_3() {
-		Class biomefog =  getNMSClass("net.minecraft.server.BiomeFog");
+        Class biomefog =  getNMSClass("net.minecraft.server.BiomeFog");
-		watercolorfield = getPrivateField(biomefog, new String[] { "c" }, int.class);
+        watercolorfield = getPrivateField(biomefog, new String[] { "c" }, int.class);
+        this.unsafeAsync = true;
     }
     
     /**
@@ -69,6 +71,12 @@ public class BukkitVersionHelperSpigot116_3 extends BukkitVersionHelperGeneric {
     }
     
     private Object[] biomelist;
+
+    @Override
+    public boolean isUnsafeAsync() {
+        return unsafeAsync;
+    }
+
     /**
      * Get list of defined biomebase objects
      */

bukkit-helper-116-4/src/main/java/org/dynmap/bukkit/helper/v116_4/BukkitVersionHelperSpigot116_4.java

@@ -26,11 +26,13 @@ import java.util.List;
  * Helper for isolation of bukkit version specific issues
  */
 public class BukkitVersionHelperSpigot116_4 extends BukkitVersionHelperGeneric {
+    private final boolean unsafeAsync;
     private Field watercolorfield;
     
     public BukkitVersionHelperSpigot116_4() {
 		Class biomefog =  getNMSClass("net.minecraft.server.BiomeFog");
 		watercolorfield = getPrivateField(biomefog, new String[] { "c" }, int.class);
+         this.unsafeAsync = true;
     }
     
     /**
@@ -58,7 +60,13 @@ public class BukkitVersionHelperSpigot116_4 extends BukkitVersionHelperGeneric {
     }
     
     private Object[] biomelist;
-    /**
+
+    @Override
+    public boolean isUnsafeAsync() {
+	    return unsafeAsync;
+    }
+
+     /**
      * Get list of defined biomebase objects
      */
     @Override

bukkit-helper-116/src/main/java/org/dynmap/bukkit/helper/v116/BukkitVersionHelperSpigot116.java

@@ -36,11 +36,13 @@ import net.minecraft.server.v1_16_R1.BlockPosition;
  * Helper for isolation of bukkit version specific issues
  */
 public class BukkitVersionHelperSpigot116 extends BukkitVersionHelperGeneric {
+    private final boolean unsafeAsync;
     private Field watercolorfield;
     
     public BukkitVersionHelperSpigot116() {
 		Class biomefog =  getNMSClass("net.minecraft.server.BiomeFog");
 		watercolorfield = getPrivateField(biomefog, new String[] { "c" }, int.class);
+	        this.unsafeAsync = true;
     }
     
     /**
@@ -59,7 +61,13 @@ public class BukkitVersionHelperSpigot116 extends BukkitVersionHelperGeneric {
     }
     
     private Object[] biomelist;
-    /**
+
+    @Override
+    public boolean isUnsafeAsync() {
+        return unsafeAsync;
+    }
+
+     /**
      * Get list of defined biomebase objects
      */
     @Override

bukkit-helper-117/src/main/java/org/dynmap/bukkit/helper/v117/BukkitVersionHelperSpigot117.java

@@ -58,11 +58,19 @@ import java.util.Map;
 /**
  * Helper for isolation of bukkit version specific issues
  */
-public class BukkitVersionHelperSpigot117 extends BukkitVersionHelper {    
+public class BukkitVersionHelperSpigot117 extends BukkitVersionHelper {
+    private final boolean unsafeAsync;
+
     public BukkitVersionHelperSpigot117() {
+        this.unsafeAsync = true;
     }
-    
+
-    /**
+    @Override
+    public boolean isUnsafeAsync() {
+        return unsafeAsync;
+    }
+
+     /**
      * Get block short name list
      */
     @Override

bukkit-helper-118-2/src/main/java/org/dynmap/bukkit/helper/v118_2/AsyncChunkProvider118_2.java

@@ -0,0 +1,60 @@
+package org.dynmap.bukkit.helper.v118_2;
+
+import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.server.level.WorldServer;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Objects;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+
+/**
+ * The provider used to work with paper libs
+ * Because paper libs need java 17 we can't interact with them directly
+ */
+public class AsyncChunkProvider118_2 {
+    private final Thread ioThread;
+    private final Method getChunk;
+    private final Predicate<NBTTagCompound> ifFailed;
+    AsyncChunkProvider118_2 () {
+        try {
+            Predicate<NBTTagCompound> ifFailed1 = null;
+            Method getChunk1 = null;
+            Thread ioThread1 = null;
+            try {
+                Class<?> threadClass = Class.forName("com.destroystokyo.paper.io.PaperFileIOThread");
+                Class<?>[] classes = threadClass.getClasses();
+                Class<?> holder = Arrays.stream(classes).filter(aClass -> aClass.getSimpleName().equals("Holder")).findAny().orElseThrow(RuntimeException::new);
+                ioThread1 = (Thread) holder.getField("INSTANCE").get(null);
+                getChunk1 = threadClass.getMethod("loadChunkDataAsync", WorldServer.class, int.class, int.class, int.class, Consumer.class, boolean.class, boolean.class, boolean.class);
+                NBTTagCompound failure = (NBTTagCompound) threadClass.getField("FAILURE_VALUE").get(null);
+                ifFailed1 = nbtTagCompound -> nbtTagCompound == failure;
+            } catch (ClassNotFoundException | NoSuchFieldException | IllegalAccessException | NoSuchMethodException e) {
+                e.printStackTrace();
+            }
+            ifFailed = Objects.requireNonNull(ifFailed1);
+            getChunk = Objects.requireNonNull(getChunk1);
+            ioThread = Objects.requireNonNull(ioThread1);
+        } catch (Throwable e) {
+            e.printStackTrace();
+            throw new RuntimeException(e);
+        }
+    }
+    public CompletableFuture<NBTTagCompound> getChunk(WorldServer world, int x, int y) throws InvocationTargetException, IllegalAccessException {
+        CompletableFuture<Object> future = new CompletableFuture<>();
+        getChunk.invoke(ioThread,world,x,y,5,(Consumer<Object>) future::complete, false, true, true);
+        return future.thenApply((resultFuture) -> {
+            if (resultFuture == null) return null;
+            try {
+                NBTTagCompound compound =  (NBTTagCompound) resultFuture.getClass().getField("chunkData").get(resultFuture);
+                return ifFailed.test(compound) ? null : compound;
+            } catch (IllegalAccessException | NoSuchFieldException e) {
+                e.printStackTrace();
+            }
+            return null;
+        });
+    }
+}

bukkit-helper-118-2/src/main/java/org/dynmap/bukkit/helper/v118_2/BukkitVersionHelperSpigot118_2.java

@@ -64,12 +64,25 @@ import java.util.Set;
  * Helper for isolation of bukkit version specific issues
  */
 public class BukkitVersionHelperSpigot118_2 extends BukkitVersionHelper { 
-		
+    private final boolean unsafeAsync;
+
     public BukkitVersionHelperSpigot118_2() {
-    	
+        boolean unsafeAsync1;
+        try {
+            Class.forName("com.destroystokyo.paper.io.PaperFileIOThread");
+            unsafeAsync1 = false;
+        } catch (ClassNotFoundException e) {
+            unsafeAsync1 = true;
+        }
+        this.unsafeAsync = unsafeAsync1;
     }
-    
+
-    /**
+    @Override
+    public boolean isUnsafeAsync() {
+        return unsafeAsync;
+    }
+
+     /**
      * Get block short name list
      */
     @Override

bukkit-helper-118-2/src/main/java/org/dynmap/bukkit/helper/v118_2/MapChunkCache118_2.java

@@ -1,8 +1,11 @@
 package org.dynmap.bukkit.helper.v118_2;
 
+import org.bukkit.Bukkit;
 import org.bukkit.World;
+import org.bukkit.craftbukkit.v1_18_R2.CraftServer;
 import org.bukkit.craftbukkit.v1_18_R2.CraftWorld;
 import org.dynmap.DynmapChunk;
+import org.dynmap.bukkit.helper.BukkitVersionHelper;
 import org.dynmap.bukkit.helper.BukkitWorld;
 import org.dynmap.common.chunk.GenericChunk;
 import org.dynmap.common.chunk.GenericChunkCache;
@@ -14,38 +17,68 @@ import net.minecraft.world.level.chunk.storage.ChunkRegionLoader;
 import net.minecraft.world.level.chunk.Chunk;
 
 import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
 import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Supplier;
 
 /**
  * Container for managing chunks - dependent upon using chunk snapshots, since rendering is off server thread
  */
 public class MapChunkCache118_2 extends GenericMapChunkCache {
-	private World w;
+    private static final AsyncChunkProvider118_2 provider = BukkitVersionHelper.helper.isUnsafeAsync() ? null : new AsyncChunkProvider118_2();
-	/**
+    private World w;
-	 * Construct empty cache
+    /**
-	 */
+     * Construct empty cache
-	public MapChunkCache118_2(GenericChunkCache cc) {
+     */
-		super(cc);
+    public MapChunkCache118_2(GenericChunkCache cc) {
-	}
+        super(cc);
+    }
 
-	// Load generic chunk from existing and already loaded chunk
+    // Load generic chunk from existing and already loaded chunk
-	protected GenericChunk getLoadedChunk(DynmapChunk chunk) {
+    protected GenericChunk getLoadedChunk(DynmapChunk chunk) {
-        CraftWorld cw = (CraftWorld) w;
+        return getLoadedChunk(chunk, false).get();
-        NBTTagCompound nbt = null;
+    }
-        GenericChunk gc = null;
+    @Override
-        if (cw.isChunkLoaded(chunk.x, chunk.z)) {
+    protected Supplier<GenericChunk> getLoadedChunkAsync(DynmapChunk ch) {
-            Chunk c = cw.getHandle().getChunkIfLoaded(chunk.x,  chunk.z);
+        return getLoadedChunk(ch, true);
-            if ((c != null) && c.o) {	// c.loaded
+    }
-				nbt = ChunkRegionLoader.a(cw.getHandle(), c);
+
-            }
+    @Override
-            if (nbt != null) {
+    protected Supplier<GenericChunk> loadChunkAsync(DynmapChunk chunk){
-            	gc = parseChunkFromNBT(new NBT.NBTCompound(nbt));
+        try {
-            }
+            CompletableFuture<NBTTagCompound> nbt = provider.getChunk(((CraftWorld) w).getHandle(), chunk.x, chunk.z);
+            return () -> {
+                NBTTagCompound compound = nbt.join();
+                return compound == null ? null : parseChunkFromNBT(new NBT.NBTCompound(compound));
+            };
+        } catch (InvocationTargetException | IllegalAccessException ignored) {
+            return () -> null;
         }
-    	return gc;
+    }
-	}
+
-	// Load generic chunk from unloaded chunk
+    private Supplier<GenericChunk> getLoadedChunk(DynmapChunk chunk, boolean async) {
-	protected GenericChunk loadChunk(DynmapChunk chunk) {
+        CraftWorld cw = (CraftWorld) w;
+        if (!cw.isChunkLoaded(chunk.x, chunk.z)) return () -> null;
+        Chunk c = cw.getHandle().getChunkIfLoaded(chunk.x, chunk.z); //already safe async on vanilla
+        if ((c == null) || c.o) return () -> null;    // c.loaded
+        if (async) { //the data of the chunk may change while we write, better to write it sync
+            CompletableFuture<NBTTagCompound> nbt = CompletableFuture.supplyAsync(() -> ChunkRegionLoader.a(cw.getHandle(), c), ((CraftServer) Bukkit.getServer()).getServer());
+            return () -> {
+                    NBTTagCompound compound = nbt.join();
+                    return compound == null ? null : parseChunkFromNBT(new NBT.NBTCompound(compound));
+            };
+        } else {
+            NBTTagCompound nbt = ChunkRegionLoader.a(cw.getHandle(), c);
+            GenericChunk genericChunk;
+            if (nbt != null) genericChunk = parseChunkFromNBT(new NBT.NBTCompound(nbt));
+            else genericChunk = null;
+            return () -> genericChunk;
+        }
+
+    }
+    // Load generic chunk from unloaded chunk
+    protected GenericChunk loadChunk(DynmapChunk chunk) {
         CraftWorld cw = (CraftWorld) w;
         NBTTagCompound nbt = null;
         ChunkCoordIntPair cc = new ChunkCoordIntPair(chunk.x, chunk.z);
@@ -55,13 +88,13 @@ public class MapChunkCache118_2 extends GenericMapChunkCache {
         } catch (IOException iox) {
         }
         if (nbt != null) {
-        	gc = parseChunkFromNBT(new NBT.NBTCompound(nbt));
+            gc = parseChunkFromNBT(new NBT.NBTCompound(nbt));
         }
-    	return gc;
+        return gc;
-	}
+    }
 
-	public void setChunks(BukkitWorld dw, List<DynmapChunk> chunks) {
+    public void setChunks(BukkitWorld dw, List<DynmapChunk> chunks) {
-		this.w = dw.getWorld();
+        this.w = dw.getWorld();
-		super.setChunks(dw, chunks);
+        super.setChunks(dw, chunks);
-	}
+    }
 }

bukkit-helper-118/src/main/java/org/dynmap/bukkit/helper/v118/BukkitVersionHelperSpigot118.java

@@ -63,12 +63,18 @@ import java.util.Set;
 /**
  * Helper for isolation of bukkit version specific issues
  */
-public class BukkitVersionHelperSpigot118 extends BukkitVersionHelper { 
+public class BukkitVersionHelperSpigot118 extends BukkitVersionHelper {
-		
+    private final boolean unsafeAsync;
+
     public BukkitVersionHelperSpigot118() {
-    	
+        this.unsafeAsync = true;
     }
-    
+
+    @Override
+    public boolean isUnsafeAsync() {
+        return unsafeAsync;
+    }
+
     /**
      * Get block short name list
      */

bukkit-helper/src/main/java/org/dynmap/bukkit/helper/BukkitVersionHelper.java

@@ -34,6 +34,10 @@ public abstract class BukkitVersionHelper {
     protected BukkitVersionHelper() {
         
     }
+    /**
+     * Get if it's unsafe to load chunks async
+     */
+    public abstract boolean isUnsafeAsync();
     /**
      * Get list of defined biomebase objects
      */

bukkit-helper/src/main/java/org/dynmap/bukkit/helper/BukkitVersionHelperCB.java

@@ -54,6 +54,12 @@ public class BukkitVersionHelperCB extends BukkitVersionHelperGeneric {
         isBadUnload = HDBlockModels.checkVersionRange(mcver, "1.9-");
         Log.verboseinfo("MCVER=" + mcver + ", isBadUnload=" + isBadUnload);
     }
+
+    @Override
+    public boolean isUnsafeAsync() {
+        return true;
+    }
+
     @Override
     protected String getNMSPackage() {
         Server srv = Bukkit.getServer();

bukkit-helper/src/main/java/org/dynmap/bukkit/helper/BukkitVersionHelperGlowstone.java

@@ -32,7 +32,12 @@ public class BukkitVersionHelperGlowstone extends BukkitVersionHelper {
             throw new IllegalArgumentException("Error initializing dynmap - Glowstone version incompatible!");
         }
     }
-    
+
+    @Override
+    public boolean isUnsafeAsync() {
+        return true;
+    }
+
     @Override
     public Object[] getBiomeBaseList() {
         return new Object[0];

spigot/src/main/java/org/dynmap/bukkit/DynmapPlugin.java

@@ -104,6 +104,7 @@ import org.dynmap.common.DynmapPlayer;
 import org.dynmap.common.DynmapServerInterface;
 import org.dynmap.common.chunk.GenericChunkCache;
 import org.dynmap.common.DynmapListenerManager.EventType;
+import org.dynmap.common.chunk.GenericMapChunkCache;
 import org.dynmap.hdmap.HDMap;
 import org.dynmap.markers.MarkerAPI;
 import org.dynmap.modsupport.ModSupportImpl;
@@ -514,46 +515,62 @@ public class DynmapPlugin extends JavaPlugin implements DynmapAPI {
             final MapChunkCache cc = c;
 
             while(!cc.isDoneLoading()) {
-                Future<Boolean> f = core.getServer().callSyncMethod(new Callable<Boolean>() {
+                if (BukkitVersionHelper.helper.isUnsafeAsync()) {
-                    public Boolean call() throws Exception {
+                    Future<Boolean> f = core.getServer().callSyncMethod(new Callable<Boolean>() {
-                        boolean exhausted = true;
+                        public Boolean call() throws Exception {
-                        
+                            boolean exhausted = true;
-                        if (prev_tick != cur_tick) {
+
-                            prev_tick = cur_tick;
+                            if (prev_tick != cur_tick) {
-                            cur_tick_starttime = System.nanoTime();
+                                prev_tick = cur_tick;
-                        }                            
+                                cur_tick_starttime = System.nanoTime();
-                        if(chunks_in_cur_tick > 0) {
-                            boolean done = false;
-                            while (!done) {
-                                int cnt = chunks_in_cur_tick;
-                                if (cnt > 5) cnt = 5;
-                                chunks_in_cur_tick -= cc.loadChunks(cnt);
-                                exhausted = (chunks_in_cur_tick == 0) || ((System.nanoTime() - cur_tick_starttime) > perTickLimit);
-                                done = exhausted || cc.isDoneLoading();
                             }
+                            if (chunks_in_cur_tick > 0) {
+                                boolean done = false;
+                                while (!done) {
+                                    int cnt = chunks_in_cur_tick;
+                                    if (cnt > 5) cnt = 5;
+                                    chunks_in_cur_tick -= cc.loadChunks(cnt);
+                                    exhausted = (chunks_in_cur_tick == 0) || ((System.nanoTime() - cur_tick_starttime) > perTickLimit);
+                                    done = exhausted || cc.isDoneLoading();
+                                }
+                            }
+                            return exhausted;
                         }
-                        return exhausted;
+                    });
+                    if (f == null) {
+                        return null;
+                    }
+                    Boolean delay;
+                    try {
+                        delay = f.get();
+                    } catch (CancellationException cx) {
+                        return null;
+                    } catch (InterruptedException cx) {
+                        return null;
+                    } catch (ExecutionException ex) {
+                        Log.severe("Exception while fetching chunks: ", ex.getCause());
+                        return null;
+                    } catch (Exception ix) {
+                        Log.severe(ix);
+                        return null;
+                    }
+
+                    if ((delay != null) && delay.booleanValue()) {
+                        try {
+                            Thread.sleep(25);
+                        } catch (InterruptedException ix) {
+                        }
+                    }
+                } else {
+                    if (prev_tick != cur_tick) {
+                        prev_tick = cur_tick;
+                        cur_tick_starttime = System.nanoTime();
+                    }
+                    if (cc instanceof GenericMapChunkCache) {
+                        ((GenericMapChunkCache) cc).loadChunksAsync();
+                    } else {
+                        cc.loadChunks(Integer.MAX_VALUE);
                     }
-                });
-                if (f == null) {
-                    return null;
-                }
-                Boolean delay;
-                try {
-                    delay = f.get();
-                } catch (CancellationException cx) {
-                    return null;
-                } catch (InterruptedException cx) {
-                    return null;
-                } catch (ExecutionException ex) {
-                    Log.severe("Exception while fetching chunks: ", ex.getCause());
-                    return null;
-                } catch (Exception ix) {
-                    Log.severe(ix);
-                    return null;
-                }
-                if((delay != null) && delay.booleanValue()) {
-                    try { Thread.sleep(25); } catch (InterruptedException ix) {}
                 }
             }
             /* If cancelled due to world unload return nothing */