diff --git a/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorImpl.java b/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorImpl.java
index 17988135c80aa..e73699564a218 100644
--- a/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorImpl.java
+++ b/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorImpl.java
@@ -642,6 +642,7 @@ public void recoverIndividualDeletedMessages(PositionInfo positionInfo) {
             recoverIndividualDeletedMessages(positionInfo.getIndividualDeletedMessagesList());
         } else if (positionInfo.getIndividualDeletedMessageRangesCount() > 0) {
             List<LongListMap> rangeList = positionInfo.getIndividualDeletedMessageRangesList();
+            lock.writeLock().lock();
             try {
                 Map<Long, long[]> rangeMap = rangeList.stream().collect(Collectors.toMap(LongListMap::getKey,
                         list -> list.getValuesList().stream().mapToLong(i -> i).toArray()));
@@ -664,6 +665,8 @@ public void recoverIndividualDeletedMessages(PositionInfo positionInfo) {
             } catch (Exception e) {
                 log.warn("[{}]-{} Failed to recover individualDeletedMessages from serialized data", ledger.getName(),
                         name, e);
+            } finally {
+                lock.writeLock().unlock();
             }
         }
     }
@@ -3259,10 +3262,13 @@ void persistPositionToLedger(final LedgerHandle lh, MarkDeleteEntry mdEntry, fin
          * and deserialization error.
          */
         if (getConfig().isUnackedRangesOpenCacheSetEnabled() && getConfig().isPersistIndividualAckAsLongArray()) {
+            lock.readLock().lock();
             try {
                 internalRanges = individualDeletedMessages.toRanges(getConfig().getMaxUnackedRangesToPersist());
             } catch (Exception e) {
                 log.warn("[{}]-{} Failed to serialize individualDeletedMessages", ledger.getName(), name, e);
+            } finally {
+                lock.readLock().unlock();
             }
         }
         if (internalRanges != null && !internalRanges.isEmpty()) {