Fixes to many multithreading crashes and freezes

kryonet/src/io/anuke/kryonet/DefaultThreadImpl.java

@@ -1,8 +1,14 @@
 package io.anuke.kryonet;
 
 import io.anuke.mindustry.core.ThreadHandler.ThreadProvider;
+import io.anuke.ucore.entities.Entity;
+import io.anuke.ucore.entities.EntityGroup;
+import io.anuke.ucore.entities.EntityGroup.EntityContainer;
 import io.anuke.ucore.util.Log;
 
+import java.util.Iterator;
+import java.util.concurrent.CopyOnWriteArrayList;
+
 public class DefaultThreadImpl implements ThreadProvider {
     private Thread thread;
 
@@ -47,4 +53,43 @@ public class DefaultThreadImpl implements ThreadProvider {
     public void notify(Object object) {
         object.notify();
     }
+
+    @Override
+    public <T extends Entity> void switchContainer(EntityGroup<T> group) {
+        group.setContainer(new ConcurrentContainer<>());
+    }
+
+    static class ConcurrentContainer<T> implements EntityContainer<T>{
+        private CopyOnWriteArrayList<T> list = new CopyOnWriteArrayList<>();
+
+        @Override
+        public int size() {
+            return list.size();
+        }
+
+        @Override
+        public void add(T item) {
+            list.add(item);
+        }
+
+        @Override
+        public void clear() {
+            list.clear();
+        }
+
+        @Override
+        public void remove(T item) {
+            list.remove(item);
+        }
+
+        @Override
+        public T get(int index) {
+            return list.get(index);
+        }
+
+        @Override
+        public Iterator<T> iterator() {
+            return list.iterator();
+        }
+    }
 }

kryonet/src/io/anuke/kryonet/KryoServer.java

@@ -23,6 +23,7 @@ import io.anuke.mindustry.net.Streamable;
 import io.anuke.mindustry.net.Streamable.StreamBegin;
 import io.anuke.mindustry.net.Streamable.StreamChunk;
 import io.anuke.ucore.UCore;
+import io.anuke.ucore.core.Timers;
 import io.anuke.ucore.util.Log;
 import org.java_websocket.WebSocket;
 import org.java_websocket.exceptions.WebsocketNotConnectedException;
@@ -296,7 +297,7 @@ public class KryoServer implements ServerProvider {
     }
 
     private void handleException(Throwable e){
-        Gdx.app.postRunnable(() -> { throw new RuntimeException(e);});
+        Timers.run(0f, () -> { throw new RuntimeException(e);});
     }
 
     KryoConnection getByKryoID(int id){