| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.hadoop.yarn.server.resourcemanager; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.curator.framework.CuratorFramework; |
| import org.apache.curator.framework.recipes.leader.LeaderLatch; |
| import org.apache.curator.framework.recipes.leader.LeaderLatchListener; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.ha.HAServiceProtocol; |
| import org.apache.hadoop.service.AbstractService; |
| import org.apache.hadoop.yarn.conf.HAUtil; |
| import org.apache.hadoop.yarn.conf.YarnConfiguration; |
| |
| import java.io.IOException; |
| |
| /** |
| * Leader election implementation that uses Curator. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public class CuratorBasedElectorService extends AbstractService |
| implements EmbeddedElector, LeaderLatchListener { |
| public static final Log LOG = |
| LogFactory.getLog(CuratorBasedElectorService.class); |
| private LeaderLatch leaderLatch; |
| private CuratorFramework curator; |
| private RMContext rmContext; |
| private String latchPath; |
| private String rmId; |
| private ResourceManager rm; |
| |
| public CuratorBasedElectorService(RMContext rmContext, ResourceManager rm) { |
| super(CuratorBasedElectorService.class.getName()); |
| this.rmContext = rmContext; |
| this.rm = rm; |
| } |
| |
| @Override |
| protected void serviceInit(Configuration conf) throws Exception { |
| rmId = HAUtil.getRMHAId(conf); |
| String clusterId = YarnConfiguration.getClusterId(conf); |
| String zkBasePath = conf.get( |
| YarnConfiguration.AUTO_FAILOVER_ZK_BASE_PATH, |
| YarnConfiguration.DEFAULT_AUTO_FAILOVER_ZK_BASE_PATH); |
| latchPath = zkBasePath + "/" + clusterId; |
| curator = rm.getCurator(); |
| initAndStartLeaderLatch(); |
| super.serviceInit(conf); |
| } |
| |
| private void initAndStartLeaderLatch() throws Exception { |
| leaderLatch = new LeaderLatch(curator, latchPath, rmId); |
| leaderLatch.addListener(this); |
| leaderLatch.start(); |
| } |
| |
| @Override |
| protected void serviceStop() throws Exception { |
| closeLeaderLatch(); |
| super.serviceStop(); |
| } |
| |
| @Override |
| public void rejoinElection() { |
| try { |
| closeLeaderLatch(); |
| Thread.sleep(1000); |
| initAndStartLeaderLatch(); |
| } catch (Exception e) { |
| LOG.info("Fail to re-join election.", e); |
| } |
| } |
| |
| @Override |
| public String getZookeeperConnectionState() { |
| return "Connected to zookeeper : " + |
| curator.getZookeeperClient().isConnected(); |
| } |
| |
| @Override |
| public void isLeader() { |
| LOG.info(rmId + "is elected leader, transitioning to active"); |
| try { |
| rmContext.getRMAdminService().transitionToActive( |
| new HAServiceProtocol.StateChangeRequestInfo( |
| HAServiceProtocol.RequestSource.REQUEST_BY_ZKFC)); |
| } catch (Exception e) { |
| LOG.info(rmId + " failed to transition to active, giving up leadership", |
| e); |
| notLeader(); |
| rejoinElection(); |
| } |
| } |
| |
| private void closeLeaderLatch() throws IOException { |
| if (leaderLatch != null) { |
| leaderLatch.close(); |
| } |
| } |
| |
| @Override |
| public void notLeader() { |
| LOG.info(rmId + " relinquish leadership"); |
| try { |
| rmContext.getRMAdminService().transitionToStandby( |
| new HAServiceProtocol.StateChangeRequestInfo( |
| HAServiceProtocol.RequestSource.REQUEST_BY_ZKFC)); |
| } catch (Exception e) { |
| LOG.info(rmId + " did not transition to standby successfully."); |
| } |
| } |
| |
| // only for testing |
| @VisibleForTesting |
| public CuratorFramework getCuratorClient() { |
| return this.curator; |
| } |
| } |