From e7a5cc8f06a5fdfbffda7e5a8d060bdebb55cc01 Mon Sep 17 00:00:00 2001
From: CraftBukkit/Spigot <noreply+git-craftbukkit@papermc.io>
Date: Fri, 26 Apr 2019 12:08:59 +1000
Subject: [PATCH] Don't concurrently execute ChunkGenerators by default

By: md_5 <git@md-5.net>
---
 .../craftbukkit/generator/CustomChunkGenerator.java    | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/paper-server/src/main/java/org/bukkit/craftbukkit/generator/CustomChunkGenerator.java b/paper-server/src/main/java/org/bukkit/craftbukkit/generator/CustomChunkGenerator.java
index c9d3f5f41..0dce0f73e 100644
--- a/paper-server/src/main/java/org/bukkit/craftbukkit/generator/CustomChunkGenerator.java
+++ b/paper-server/src/main/java/org/bukkit/craftbukkit/generator/CustomChunkGenerator.java
@@ -67,7 +67,15 @@ public class CustomChunkGenerator extends InternalChunkGenerator<GeneratorSettin
         CustomBiomeGrid biomegrid = new CustomBiomeGrid();
         biomegrid.biome = this.getWorldChunkManager().getBiomeBlock(x << 4, z << 4, 16, 16);
 
-        ChunkData data = generator.generateChunkData(this.world.getWorld(), random, x, z, biomegrid);
+        ChunkData data;
+        if (generator.isParallelCapable()) {
+            data = generator.generateChunkData(this.world.getWorld(), random, x, z, biomegrid);
+        } else {
+            synchronized (this) {
+                data = generator.generateChunkData(this.world.getWorld(), random, x, z, biomegrid);
+            }
+        }
+
         Preconditions.checkArgument(data instanceof CraftChunkData, "Plugins must use createChunkData(World) rather than implementing ChunkData: %s", data);
         CraftChunkData craftData = (CraftChunkData) data;
         ChunkSection[] sections = craftData.getRawChunkData();