ChunkLoader can now indicate that they support parallel loading or saving

src/main/java/net/minestom/server/instance/IChunkLoader.java

@@ -5,4 +5,20 @@ import java.util.function.Consumer;
 public interface IChunkLoader {
     boolean loadChunk(Instance instance, int chunkX, int chunkZ, Consumer<Chunk> callback);
     void saveChunk(Chunk chunk, Runnable callback);
+
+    /**
+     * Does this ChunkLoader allow for multithreaded saving of chunks?
+     * @return
+     */
+    default boolean supportsParallelSaving() {
+        return false;
+    }
+
+    /**
+     * Does this ChunkLoader allow for multithreaded loading of chunks?
+     * @return
+     */
+    default boolean supportsParallelLoading() {
+        return false;
+    }
 }

src/main/java/net/minestom/server/instance/InstanceContainer.java

@@ -374,6 +374,12 @@ public class InstanceContainer extends Instance {
     @Override
     public void saveChunksToStorageFolder(Runnable callback) {
         Check.notNull(getStorageFolder(), "You cannot save the instance if no StorageFolder has been defined");
+        if(chunkLoader.supportsParallelSaving()) {
+            getChunks().parallelStream().forEach(c -> {
+                saveChunkToStorageFolder(c, null);
+            });
+            callback.run();
+        } else {
             Iterator<Chunk> chunks = getChunks().iterator();
             while (chunks.hasNext()) {
                 Chunk chunk = chunks.next();
@@ -381,6 +387,7 @@ public class InstanceContainer extends Instance {
                 saveChunkToStorageFolder(chunk, isLast ? callback : null);
             }
         }
+    }
 
     @Override
     public BlockBatch createBlockBatch() {