In order to enable this recovery mode, you can set SPARK_DAEMON_JAVA_OPTS in spark-env using this configuration:

-Dspark.deploy.recoveryMode=ZOOKEEPER

override def isLeader() {
    synchronized {
      // could have lost leadership by now.
      if (!leaderLatch.hasLeadership) {
        return
      }

      logInfo("We have gained leadership")
      updateLeadershipStatus(true)
    }
  }

  override def notLeader() {
    synchronized {
      // could have gained leadership by now.
      if (leaderLatch.hasLeadership) {
        return
      }

      logInfo("We have lost leadership")
      updateLeadershipStatus(false)
    }
  }

  private def updateLeadershipStatus(isLeader: Boolean) {
    if (isLeader && status == LeadershipStatus.NOT_LEADER) {
      status = LeadershipStatus.LEADER
      masterInstance.electedLeader()
    } else if (!isLeader && status == LeadershipStatus.LEADER) {
      status = LeadershipStatus.NOT_LEADER
      masterInstance.revokedLeadership()
    }
  }

  override def electedLeader() {
    self.send(ElectedLeader)
  }

  override def revokedLeadership() {
    self.send(RevokedLeadership)
  }

ls /spark/leader_election
[_c_6b494d00-cf91-4d69-8828-942377bafdf1-latch-0000000217, _c_c1f4c10f-9479-4a55-b660-0497c0b54f89-latch-0000000218]

2.3 StandBy Master 节点的恢复

    case ElectedLeader =>
      val (storedApps, storedDrivers, storedWorkers) = persistenceEngine.readPersistedData(rpcEnv)
      state = if (storedApps.isEmpty && storedDrivers.isEmpty && storedWorkers.isEmpty) {
        RecoveryState.ALIVE
      } else {
        RecoveryState.RECOVERING
      }
      logInfo("I have been elected leader! New state: " + state)
      if (state == RecoveryState.RECOVERING) {
        beginRecovery(storedApps, storedDrivers, storedWorkers)
        recoveryCompletionTask = forwardMessageThread.schedule(new Runnable {
          override def run(): Unit = Utils.tryLogNonFatalError {
            self.send(CompleteRecovery)
          }
        }, WORKER_TIMEOUT_MS, TimeUnit.MILLISECONDS)
      }

2.3.1 获取具体的信息

 ls /spark/master_status  
[worker_worker-20170329184022-192.168.121.101-55109, worker_worker-20170330035822-192.168.121.102-41307]

private def beginRecovery(storedApps: Seq[ApplicationInfo], storedDrivers: Seq[DriverInfo],
      storedWorkers: Seq[WorkerInfo]) {
    for (app <- storedApps) {
      logInfo("Trying to recover app: " + app.id)
      try {
        registerApplication(app)
        app.state = ApplicationState.UNKNOWN
        app.driver.send(MasterChanged(self, masterWebUiUrl))
      } catch {
        case e: Exception => logInfo("App " + app.id + " had exception on reconnect")
      }
    }

    for (driver <- storedDrivers) {
      // Here we just read in the list of drivers. Any drivers associated with now-lost workers
      // will be re-launched when we detect that the worker is missing.
      drivers += driver
    }

    for (worker <- storedWorkers) {
      logInfo("Trying to recover worker: " + worker.id)
      try {
        registerWorker(worker)
        worker.state = WorkerState.UNKNOWN
        worker.endpoint.send(MasterChanged(self, masterWebUiUrl))
      } catch {
        case e: Exception => logInfo("Worker " + worker.id + " had exception on reconnect")
      }
    }
  }

2.3.2.1 恢复Application

  private def completeRecovery() {
    // Ensure "only-once" recovery semantics using a short synchronization period.
    if (state != RecoveryState.RECOVERING) { return }
    state = RecoveryState.COMPLETING_RECOVERY

    // Kill off any workers and apps that didn‘t respond to us.
    workers.filter(_.state == WorkerState.UNKNOWN).foreach(removeWorker)
    apps.filter(_.state == ApplicationState.UNKNOWN).foreach(finishApplication)

    // Reschedule drivers which were not claimed by any workers
    drivers.filter(_.worker.isEmpty).foreach { d =>
      logWarning(s"Driver ${d.id} was not found after master recovery")
      if (d.desc.supervise) {
        logWarning(s"Re-launching ${d.id}")
        relaunchDriver(d)
      } else {
        removeDriver(d.id, DriverState.ERROR, None)
        logWarning(s"Did not re-launch ${d.id} because it was not supervised")
      }
    }

    state = RecoveryState.ALIVE
    schedule()
    logInfo("Recovery complete - resuming operations!")
  }

2.3.2.2 恢复Worker

recoveryCompletionTask = forwardMessageThread.schedule(new Runnable {
          override def run(): Unit = Utils.tryLogNonFatalError {
            self.send(CompleteRecovery)
          }
        }, WORKER_TIMEOUT_MS, TimeUnit.MILLISECONDS)

RecoveryState.ALIVE
RecoveryState.RECOVERING
RecoveryState.COMPLETING_RECOVERY
RecoveryState.STANDBY

--master spark://raintungmaster:7077,raintungslave1:7077