Prevent killing UI if heartbeats are pending (#10371)

Fixes #9663

1 files changed, 18 insertions, 5 deletions

diff --git a/server/src/main/java/com/vaadin/server/VaadinService.java b/server/src/main/java/com/vaadin/server/VaadinService.java
index d086b68a12..9b9c7fd913 100644
--- a/server/src/main/java/com/vaadin/server/VaadinService.java
+++ b/server/src/main/java/com/vaadin/server/VaadinService.java
@@ -1363,12 +1363,25 @@ public abstract class VaadinService implements Serializable {
     public boolean isUIActive(UI ui) {
         if (ui.isClosing()) {
             return false;
-        } else {
-            long now = System.currentTimeMillis();
-            int timeout = 1000 * getHeartbeatTimeout();
-            return timeout < 0
-                    || now - ui.getLastHeartbeatTimestamp() < timeout;
         }
+
+        // Check for long running tasks
+        Lock lockInstance = ui.getSession().getLockInstance();
+        if (lockInstance instanceof ReentrantLock) {
+            if (((ReentrantLock) lockInstance).hasQueuedThreads()) {
+                /*
+                 * Someone is trying to access the session. Leaving all UIs
+                 * alive for now. A possible kill decision will be made at a
+                 * later time when the session access has ended.
+                 */
+                return true;
+            }
+        }
+
+        // Check timeout
+        long now = System.currentTimeMillis();
+        int timeout = 1000 * getHeartbeatTimeout();
+        return timeout < 0 || now - ui.getLastHeartbeatTimestamp() < timeout;
     }
 
     /**