// Wait for region servers to report in.
this.serverManager.waitForRegionServers(status);
// Check zk for regionservers that are up but didn't register
for (ServerName sn: this.regionServerTracker.getOnlineServers()) {
    if (!this.serverManager.isServerOnline(sn)) {
    // Not registered; add it.LOG.info("Registering server found up in zk but who has not yet " +"reported in: " + sn);this.serverManager.recordNewServer(sn, HServerLoad.EMPTY_HSERVERLOAD);}
}

      // Try and register with the Master; tell it we are here.  Break if// server is stopped or the clusterup flag is down or hdfs went wacky.while (keepLooping()) {MapWritable w = reportForDuty();if (w == null) {LOG.warn("reportForDuty failed; sleeping and then retrying.");this.sleeper.sleep();} else {handleReportForDutyResponse(w);break;}}

 // The main run loop.while (!this.stopped && isHealthy()) {　　long now = System.currentTimeMillis();

　　　if ((now - lastMsg) >= msgInterval) {
　　　　　　doMetrics();
　　　　　　tryRegionServerReport();
　　　　　　lastMsg = System.currentTimeMillis();
　　　　}

}

 void regionServerReport(ServerName sn, HServerLoad hsl)throws YouAreDeadException, PleaseHoldException {checkIsDead(sn, "REPORT");if (!this.onlineServers.containsKey(sn)) {// Already have this host+port combo and its just different start code?
      checkAlreadySameHostPort(sn);// Just let the server in. Presume master joining a running cluster.// recordNewServer is what happens at the end of reportServerStartup.// The only thing we are skipping is passing back to the regionserver// the ServerName to use. Here we presume a master has already done// that so we'll press on with whatever it gave us for ServerName.
      recordNewServer(sn, hsl);} else {this.onlineServers.put(sn, hsl);}}

this.startcode = System.currentTimeMillis();...result = this.hbaseMaster.regionServerStartup(port, this.startcode, now);...this.serverNameFromMasterPOV = new ServerName(hostnameFromMasterPOV,
this.isa.getPort(), this.startcode);...this.hbaseMaster.regionServerReport(this.serverNameFromMasterPOV.getVersionedBytes(), hsl);