// Send out TimeSync request
for (int site_id = 0; site_id < this.num_sites; site_id++) {
if (site_id == this.local_site_id) continue;
ProtoRpcController controller = new ProtoRpcController();
TimeSyncRequest request = TimeSyncRequest.newBuilder()
.setSenderSite(this.local_site_id)
.setT0S(System.currentTimeMillis())
.build();
this.channels[site_id].timeSync(controller, request, callback);
if (trace.val) LOG.trace("Sent TIMESYNC to " + HStoreThreadManager.formatSiteName(site_id));