diff --git a/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorContainer.java b/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorContainer.java
index ef9a546a50781..f9591d9ee6aba 100644
--- a/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorContainer.java
+++ b/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorContainer.java
@@ -105,11 +105,21 @@ private boolean shouldTrackInHeap(ManagedCursor cursor) {
     }
 
     public PositionImpl getSlowestReadPositionForActiveCursors() {
-        return heap.isEmpty() ? null : (PositionImpl) heap.get(0).cursor.getReadPosition();
+        long stamp = rwLock.readLock();
+        try {
+            return heap.isEmpty() ? null : (PositionImpl) heap.get(0).cursor.getReadPosition();
+        } finally {
+            rwLock.unlockRead(stamp);
+        }
     }
 
     public PositionImpl getSlowestMarkDeletedPositionForActiveCursors() {
-        return heap.isEmpty() ? null : (PositionImpl) heap.get(0).cursor.getMarkDeletedPosition();
+        long stamp = rwLock.readLock();
+        try {
+            return heap.isEmpty() ? null : (PositionImpl) heap.get(0).cursor.getMarkDeletedPosition();
+        } finally {
+            rwLock.unlockRead(stamp);
+        }
     }
 
     public ManagedCursor get(String name) {