From 18144b7a0a593e46bd170815ff7351ed84ecdcbc Mon Sep 17 00:00:00 2001
From: cpw <cpw+github@weeksfamily.ca>
Date: Mon, 26 Feb 2018 22:49:56 -0500
Subject: [PATCH] Fix the ForgeChunkManager to use the writebehind FileIO
 thread for writing (#4777)

the chunk file. Closes #4775

This is a performance tweak - doing File IO on the server thread during
world saves causes significant lag spikes. This is one of many.
---
 .../common/ForgeChunkManager.java             | 23 +++++++++++--------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/main/java/net/minecraftforge/common/ForgeChunkManager.java b/src/main/java/net/minecraftforge/common/ForgeChunkManager.java
index d87e7057d..9878e704c 100644
--- a/src/main/java/net/minecraftforge/common/ForgeChunkManager.java
+++ b/src/main/java/net/minecraftforge/common/ForgeChunkManager.java
@@ -44,6 +44,7 @@ import net.minecraft.world.World;
 import net.minecraft.world.WorldServer;
 import net.minecraft.world.chunk.Chunk;
 import net.minecraft.world.chunk.storage.AnvilChunkLoader;
+import net.minecraft.world.storage.ThreadedFileIOBase;
 import net.minecraftforge.common.config.ConfigCategory;
 import net.minecraftforge.common.config.Configuration;
 import net.minecraftforge.common.config.Property;
@@ -944,15 +945,19 @@ public class ForgeChunkManager
                 }
             }
         }
-        try
-        {
-            CompressedStreamTools.write(forcedChunkData, chunkLoaderData);
-        }
-        catch (IOException e)
-        {
-            FMLLog.log.warn("Unable to write forced chunk data to {} - chunkloading won't work", chunkLoaderData.getAbsolutePath(), e);
-            return;
-        }
+
+        // Write the actual file on the IO thread rather than blocking the server thread
+        ThreadedFileIOBase.getThreadedIOInstance().queueIO(() -> {
+            try
+            {
+                CompressedStreamTools.write(forcedChunkData, chunkLoaderData);
+            }
+            catch (IOException e)
+            {
+                FMLLog.log.warn("Unable to write forced chunk data to {} - chunkloading won't work", chunkLoaderData.getAbsolutePath(), e);
+            }
+            return false;
+        });
     }
 
     static void loadEntity(Entity entity)