PawasChhokra commented on a change in pull request #1446: URL: https://github.com/apache/samza/pull/1446#discussion_r547140581
########## File path: samza-yarn/src/main/java/org/apache/samza/job/yarn/RackManager.java ########## @@ -0,0 +1,116 @@ +/* + * 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.samza.job.yarn; + +import java.io.IOException; +import java.util.HashMap; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Set; +import org.apache.hadoop.yarn.api.records.NodeReport; +import org.apache.hadoop.yarn.api.records.NodeState; +import org.apache.hadoop.yarn.client.api.impl.YarnClientImpl; +import org.apache.hadoop.yarn.exceptions.YarnException; +import org.apache.samza.clustermanager.FaultDomain; +import org.apache.samza.clustermanager.FaultDomainManager; +import org.apache.samza.clustermanager.FaultDomainType; + +public class RackManager implements FaultDomainManager { + + private final Map<String, FaultDomain> nodeToRackMap; + + public RackManager() { + this.nodeToRackMap = computeNodeToFaultDomainMap(); + } + + /** + * This method returns all the rack values in a cluster for RUNNING nodes. + * @return a set of {@link FaultDomain}s + */ + @Override + public Set<FaultDomain> getAllFaultDomains() { + return new HashSet<>(nodeToRackMap.values()); + } + + /** + * This method returns the rack a particular node resides on. + * @param host the host + * @return the {@link FaultDomain} + */ + @Override + public FaultDomain getFaultDomainOfNode(String host) { + return nodeToRackMap.get(host); + } + + /** + * This method checks if the two hostnames provided reside on the same rack. + * @param host1 hostname + * @param host2 hostname + * @return true if the hosts exist on the same rack + */ + @Override + public boolean checkHostsOnSameFaultDomain(String host1, String host2) { + return nodeToRackMap.get(host1).equals(nodeToRackMap.get(host2)); + } + + /** + * This method gets the set of racks that the given active container's corresponding standby can be placed on. + * @param host The hostname of the active container + * @return the set of racks on which this active container's standby can be scheduled + */ + @Override + public Set<FaultDomain> getAllowedFaultDomainsForSchedulingContainer(String host) { + FaultDomain activeContainerRack = nodeToRackMap.get(host); + Set<FaultDomain> standbyRacks = new HashSet<>(nodeToRackMap.values()); + standbyRacks.remove(activeContainerRack); + return standbyRacks; + } + + /** + * This method returns the cached map of nodes to racks. + * @return stored map of node to the rack it resides on + */ + @Override + public Map<String, FaultDomain> getNodeToFaultDomainMap() { + return nodeToRackMap; + } + + /** + * This method gets the node to rack (fault domain for Yarn) mapping from Yarn for all running nodes. + * @return A map of hostname to rack name. + */ + @Override + public Map<String, FaultDomain> computeNodeToFaultDomainMap() { + YarnClientImpl yarnClient = new YarnClientImpl(); + Map<String, FaultDomain> nodeToRackMap = new HashMap<>(); + try { + List<NodeReport> nodeReport = yarnClient.getNodeReports(NodeState.RUNNING); + nodeReport.forEach(report -> { + FaultDomain rack = new FaultDomain(FaultDomainType.RACK, report.getRackName()); + nodeToRackMap.put(report.getNodeId().getHost(), rack); + }); + } catch (YarnException e) { + e.printStackTrace(); Review comment: Thanks for pointing this out. I've instead thrown a SamzaException if we are unable to get node reports from Yarn, since we need that for rack awareness to work. This will take care of the other concerns that you raised. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
