Having none destructive (such that preserves selection) action that can be applied to multiple items will block UI for given user and send CPU on server to 100% usage.

To reproduce:

• select number of items in the workbench
• execute some non destructive multiaction on them (Create one if you don't have anything ready, it doesn't have to do absolutely anything)
• after exectution of the action, TreePresenter will collect all selected items and fire SelectionChangedEvent on them in

  TreePresenter:144
          eventBus.fireEvent(new SelectionChangedEvent(Collections.unmodifiableSet(new HashSet<Object>(selectedItemIds))));
  

• this in turn will force evaluation of ALL actions configured in the app on EACH item ... if you have anywhere around 100 items selected, you can go for coffee before availability for all is checked ... you can use your App/DB server cpu to heat up that coffee too

• code triggered by the action gets stuck in

  info.magnolia.ui.framework.availability.AvailabilityCheckerImpl.isAvailable(AvailabilityDefinition, List<Object>)
          while (isAvailable && ruleIterator.hasNext()) {
              AvailabilityRule rule = ruleIterator.next();
              boolean ruleHolds = rule.isAvailable(idsToCheck);
              isAvailable &= ruleHolds;
          }