TestZkChildListener listener = new TestZkChildListener();
_zkclient.subscribeChildChanges(keyBuilder.messages("localhost_12918").getPath(), listener);
MockController controller =
new MockController(_zkaddr, clusterName, "controller_0");
controller.syncStart();
// start participants
MockParticipant[] participants = new MockParticipant[n];
for (int i = 0; i < n; i++) {
String instanceName = "localhost_" + (12918 + i);