Fix ConcurrentModificationException

common/src/main/java/ctbrec/recorder/NextGenLocalRecorder.java

@@ -17,6 +17,7 @@ import java.time.ZoneId;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
@@ -68,6 +69,7 @@ public class NextGenLocalRecorder implements Recorder {
     private Config config;
     private volatile boolean recording = true;
     private ReentrantLock recorderLock = new ReentrantLock();
+    private ReentrantLock modelGroupLock = new ReentrantLock();
     private RecorderHttpClient client = new RecorderHttpClient();
     private Map<Model, Recording> recordingProcesses = Collections.synchronizedMap(new HashMap<>());
     private RecordingManager recordingManager;
@@ -808,20 +810,35 @@ public class NextGenLocalRecorder implements Recorder {
 
     @Override
     public Set<ModelGroup> getModelGroups() {
-        return config.getSettings().modelGroups;
+        modelGroupLock.lock();
+        try {
+            return new HashSet<>(config.getSettings().modelGroups);
+        } finally {
+            modelGroupLock.unlock();
+        }
     }
 
     @Override
     public void saveModelGroup(ModelGroup group) throws IOException {
         Set<ModelGroup> modelGroups = config.getSettings().modelGroups;
-        modelGroups.remove(group);
-        modelGroups.add(group);
-        config.save();
+        modelGroupLock.lock();
+        try {
+            modelGroups.remove(group);
+            modelGroups.add(group);
+            config.save();
+        } finally {
+            modelGroupLock.unlock();
+        }
     }
 
     @Override
     public void deleteModelGroup(ModelGroup group) throws IOException {
-        config.getSettings().modelGroups.remove(group);
-        config.save();
+        modelGroupLock.lock();
+        try {
+            config.getSettings().modelGroups.remove(group);
+            config.save();
+        } finally {
+            modelGroupLock.unlock();
+        }
     }
 }

common/src/main/java/ctbrec/recorder/RemoteRecorder.java

@@ -691,7 +691,7 @@ public class RemoteRecorder implements Recorder {
 
     @Override
     public Set<ModelGroup> getModelGroups() {
-        return modelGroups;
+        return new HashSet<>(modelGroups);
     }
 
     @Override