TaskTracker hung after failed reconnect to the JobTracker

    this.distributedCacheManager = new TrackerDistributedCacheManager(
        this.fConf, taskController);
    this.distributedCacheManager.startCleanupThread();
    
    this.jobClient = (InterTrackerProtocol) 
    UserGroupInformation.getLoginUser().doAs(
        new PrivilegedExceptionAction<Object>() {
      public Object run() throws IOException {
        return RPC.waitForProxy(InterTrackerProtocol.class,
            InterTrackerProtocol.versionID,
            jobTrackAddr, fConf);
      }
    });