Verify that lock is held when accessing state (#9515)

1 files changed, 3 insertions, 0 deletions

diff --git a/server/src/com/vaadin/ui/ConnectorTracker.java b/server/src/com/vaadin/ui/ConnectorTracker.java
index d454df98ee..dbada63a47 100644
--- a/server/src/com/vaadin/ui/ConnectorTracker.java
+++ b/server/src/com/vaadin/ui/ConnectorTracker.java
@@ -29,6 +29,7 @@ import com.vaadin.server.AbstractClientConnector;
 import com.vaadin.server.AbstractCommunicationManager;
 import com.vaadin.server.ClientConnector;
 import com.vaadin.server.GlobalResourceHandler;
+import com.vaadin.server.VaadinSession;
 
 /**
  * A class which takes care of book keeping of {@link ClientConnector}s for a
@@ -286,6 +287,8 @@ public class ConnectorTracker implements Serializable {
      *            The connector that should be marked clean.
      */
     public void markDirty(ClientConnector connector) {
+        assert uI.getSession() == null
+                || uI.getSession().getLock().isHeldByCurrentThread() : VaadinSession.SESSION_LOCK_MESSAGE;
         if (isWritingResponse()) {
             throw new IllegalStateException(
                     "A connector should not be marked as dirty while a response is being written.");