@Override
    public String toString() {
        return "search node in cluster = " + clusterName + " key = " + key + " hostname = "+ hostname +
               " path = " + pathIndex + " in group " + group + " statusIsKnown = " + statusIsKnown + " working = " + working +
               " activeDocs = " + getActiveDocuments() + " targetActiveDocs = " + getTargetActiveDocuments();
    }
Returns the active documents on this node. If unknown, 0 is returned.
container-search/src/main/java/com/yahoo/search/dispatch/searchcluster/Node.java