@Override
    protected void process(DistributionMessage message, boolean warn) {
      if (message instanceof CompactResponse) {
        final Set<PersistentID> persistentIds = ((CompactResponse) message).getPersistentIds();
        if (persistentIds != null && !persistentIds.isEmpty()) {
          results.put(message.getSender(), persistentIds);
        }
      }
      super.process(message, warn);
    }
An instruction to all members with cache that they should compact their disk stores.
geode-core/src/main/java/org/apache/geode/internal/admin/remote/CompactRequest.java