@Override
      public void run() {
        // Get the sessionIds to touch and clear the set inside synchronization
        Set<String> sessionIds;
        sessionIds = new HashSet<>(getSessionsToTouch());
        getSessionsToTouch().clear();

        // Touch the sessions we currently have
        if (!sessionIds.isEmpty()) {
          getSessionCache().touchSessions(sessionIds);
          if (getLogger().isDebugEnabled()) {
            getLogger().debug(DeltaSessionManager.this + ": Touched sessions: " + sessionIds);
          }
        }
      }
For debugging: return a list of all session ids currently active
extensions/geode-modules/src/main/java/org/apache/geode/modules/session/catalina/DeltaSessionManager.java