Fix UI freeze caused by OnlineMonitor

The lock to prevent concurrent access to the list models caused
the app to freeze, if the models list contained many models, because
the OnlineMonitor would block access until it checked the online
state of every model.

src/main/java/ctbrec/recorder/LocalRecorder.java

@@ -166,7 +166,12 @@ public class LocalRecorder implements Recorder {
 
     @Override
     public List<Model> getModelsRecording() {
+        lock.lock();
+        try {
             return Collections.unmodifiableList(new ArrayList<>(models));
+        } finally {
+            lock.unlock();
+        }
     }
 
     @Override
@@ -308,8 +313,6 @@ public class LocalRecorder implements Recorder {
         public void run() {
             running = true;
             while (running) {
-                lock.lock();
-                try {
                 for (Model model : getModelsRecording()) {
                     try {
                         if (!recordingProcesses.containsKey(model)) {
@@ -324,9 +327,6 @@ public class LocalRecorder implements Recorder {
                         LOG.error("Couldn't check if model {} is online", model.getName(), e);
                     }
                 }
-                } finally {
-                    lock.unlock();
-                }
 
                 try {
                     if (running)