public void resetInstance(String clusterName, List<String> instanceNames) {
// TODO: not mp-safe
ZKHelixDataAccessor accessor =
new ZKHelixDataAccessor(clusterName, new ZkBaseDataAccessor<ZNRecord>(_zkClient));
Builder keyBuilder = accessor.keyBuilder();
List<ExternalView> extViews = accessor.getChildValues(keyBuilder.externalViews());
Set<String> resetInstanceNames = new HashSet<String>(instanceNames);
for (String instanceName : resetInstanceNames) {
List<String> resetPartitionNames = new ArrayList<String>();
for (ExternalView extView : extViews) {