CatServer/patches/net/minecraft/world/storage/MapStorage.java.patch

--- ../src-base/minecraft/net/minecraft/world/storage/MapStorage.java
+++ ../src-work/minecraft/net/minecraft/world/storage/MapStorage.java
@@ -56,9 +56,14 @@
                             throw new RuntimeException("Failed to instantiate " + clazz, exception);
                         }
 
-                        FileInputStream fileinputstream = new FileInputStream(file1);
-                        NBTTagCompound nbttagcompound = CompressedStreamTools.readCompressed(fileinputstream);
-                        fileinputstream.close();
+                        // CatServer start
+                        NBTTagCompound nbttagcompound = null;
+                        synchronized (MapStorage.this) {
+                            FileInputStream fileinputstream = new FileInputStream(file1);
+                            nbttagcompound = CompressedStreamTools.readCompressed(fileinputstream);
+                            fileinputstream.close();
+                        }
+                        // CatServer end
                         worldsaveddata.readFromNBT(nbttagcompound.getCompoundTag("data"));
                     }
                 }
@@ -114,10 +119,21 @@
                 if (file1 != null)
                 {
                     NBTTagCompound nbttagcompound = new NBTTagCompound();
-                    nbttagcompound.setTag("data", data.writeToNBT(new NBTTagCompound()));
-                    FileOutputStream fileoutputstream = new FileOutputStream(file1);
-                    CompressedStreamTools.writeCompressed(nbttagcompound, fileoutputstream);
-                    fileoutputstream.close();
+                    // CatServer start
+                    nbttagcompound.setTag("data", data.writeToNBT(new NBTTagCompound()).copy());
+                    Runnable runnable = () -> {
+                        try {
+                            synchronized (MapStorage.this) {
+                                FileOutputStream fileoutputstream = new FileOutputStream(file1);
+                                CompressedStreamTools.writeCompressed(nbttagcompound, fileoutputstream);
+                                fileoutputstream.close();
+                            }
+                        } catch (Exception e) {
+                            e.printStackTrace();
+                        }
+                    };
+                    catserver.server.CatServer.scheduleAsyncTask(runnable);
+                    // CatServer end
                 }
             }
             catch (Exception exception)