Fix race condition in SnapshotsService (#101652)

* Fix race condition in SnapshotsService

* Update docs/changelog/101652.yaml

Author: volodk85

docs/changelog/101652.yaml

@@ -0,0 +1,5 @@
+pr: 101652
+summary: Fix race condition in `SnapshotsService`
+area: Snapshot/Restore
+type: bug
+issues: []

server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java

@@ -162,7 +162,7 @@ public class SnapshotsService extends AbstractLifecycleComponent implements Clus
     /**
      * Listeners for snapshot deletion keyed by delete uuid as returned from {@link SnapshotDeletionsInProgress.Entry#uuid()}
      */
-    private final Map<String, List<ActionListener<Void>>> snapshotDeletionListeners = new HashMap<>();
+    private final Map<String, List<ActionListener<Void>>> snapshotDeletionListeners = new ConcurrentHashMap<>();
 
     // Set of repositories currently running either a snapshot finalization or a snapshot delete.
     private final Set<String> currentlyFinalizing = Collections.synchronizedSet(new HashSet<>());