code: @RequirePOST
      public void doUpdateNow( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
          Jenkins.getInstance().checkPermission(Jenkins.ADMINISTER);
          
          for (NodeMonitor nodeMonitor : NodeMonitor.getAll()) {
              Thread t = nodeMonitor.triggerUpdate();
              String columnCaption = nodeMonitor.getColumnCaption();
              if (columnCaption != null) {
                  t.setName(columnCaption);
              }
          }
          rsp.forwardToPreviousPage(req);
      }
docs: Triggers the schedule update now.
  
  TODO: ajax on the client side to wait until the update completion might be nice.