ChenSammi commented on a change in pull request #1366: HDDS-1577. Add default pipeline placement policy implementation. URL: https://github.com/apache/hadoop/pull/1366#discussion_r320559908
########## File path: hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/pipeline/PipelinePlacementPolicy.java ########## @@ -0,0 +1,291 @@ +/** + * 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.hdds.scm.pipeline; + +import com.google.common.annotations.VisibleForTesting; +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.hdds.protocol.DatanodeDetails; +import org.apache.hadoop.hdds.protocol.proto.HddsProtos; +import org.apache.hadoop.hdds.scm.ScmConfigKeys; +import org.apache.hadoop.hdds.scm.container.placement.algorithms.SCMCommonPolicy; +import org.apache.hadoop.hdds.scm.container.placement.metrics.SCMNodeMetric; +import org.apache.hadoop.hdds.scm.exceptions.SCMException; +import org.apache.hadoop.hdds.scm.net.NetworkTopology; +import org.apache.hadoop.hdds.scm.net.Node; +import org.apache.hadoop.hdds.scm.node.NodeManager; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +import java.util.Collection; +import java.util.List; +import java.util.stream.Collectors; + +/** + * Pipeline placement policy that choose datanodes based on load balancing + * and network topology to supply pipeline creation. + * <p> + * 1. get a list of healthy nodes + * 2. filter out nodes that are not too heavily engaged in other pipelines + * 3. Choose an anchor node among the viable nodes which follows the algorithm + * described @SCMContainerPlacementCapacity + * 4. Choose other nodes around the anchor node based on network topology + */ +public final class PipelinePlacementPolicy extends SCMCommonPolicy { + @VisibleForTesting + static final Logger LOG = + LoggerFactory.getLogger(PipelinePlacementPolicy.class); + private final NodeManager nodeManager; + private final Configuration conf; + private final int heavyNodeCriteria; + + /** + * Constructs a Container Placement with considering only capacity. + * That is this policy tries to place containers based on node weight. + * + * @param nodeManager Node Manager + * @param conf Configuration + */ + public PipelinePlacementPolicy(final NodeManager nodeManager, + final Configuration conf) { + super(nodeManager, conf); + this.nodeManager = nodeManager; + this.conf = conf; + heavyNodeCriteria = conf.getInt( + ScmConfigKeys.OZONE_DATANODE_MAX_PIPELINE_ENGAGEMENT, + ScmConfigKeys.OZONE_DATANODE_MAX_PIPELINE_ENGAGEMENT_DEFAULT); + } + + /** + * Returns true if this node meets the criteria. + * + * @param datanodeDetails DatanodeDetails + * @return true if we have enough space. + */ + @VisibleForTesting + boolean meetCriteria(DatanodeDetails datanodeDetails, + long heavyNodeLimit) { + return (nodeManager.getPipelinesCount(datanodeDetails) <= heavyNodeLimit); + } + + /** + * Filter out viable nodes based on + * 1. nodes that are healthy + * 2. nodes that are not too heavily engaged in other pipelines + * + * @param excludedNodes - excluded nodes + * @param nodesRequired - number of datanodes required. + * @return a list of viable nodes + * @throws SCMException when viable nodes are not enough in numbers + */ + List<DatanodeDetails> filterViableNodes( + List<DatanodeDetails> excludedNodes, int nodesRequired) + throws SCMException { + // get nodes in HEALTHY state + List<DatanodeDetails> healthyNodes = + nodeManager.getNodes(HddsProtos.NodeState.HEALTHY); + if (excludedNodes != null) { + healthyNodes.removeAll(excludedNodes); + } + String msg; + if (healthyNodes.size() == 0) { + msg = "No healthy node found to allocate container."; + LOG.error(msg); + throw new SCMException(msg, SCMException.ResultCodes + .FAILED_TO_FIND_HEALTHY_NODES); + } + + if (healthyNodes.size() < nodesRequired) { + msg = String.format("Not enough healthy nodes to allocate container. %d " + + " datanodes required. Found %d", + nodesRequired, healthyNodes.size()); + LOG.error(msg); + throw new SCMException(msg, + SCMException.ResultCodes.FAILED_TO_FIND_SUITABLE_NODE); + } + + // filter nodes that meet the size and pipeline engagement criteria. + // Pipeline placement doesn't take node space left into account. + List<DatanodeDetails> healthyList = healthyNodes.stream().filter(d -> + meetCriteria(d, heavyNodeCriteria)).collect(Collectors.toList()); + + if (healthyList.size() < nodesRequired) { + msg = String.format("Unable to find enough nodes that meet " + + "the criteria that cannot engage in more than %d pipelines." + + " Nodes required: %d Found: %d", + heavyNodeCriteria, nodesRequired, healthyList.size()); + LOG.error(msg); + throw new SCMException(msg, + SCMException.ResultCodes.FAILED_TO_FIND_NODES_WITH_SPACE); + } + return healthyList; + } + + /** + * Pipeline placement choose datanodes to join the pipeline. + * + * @param excludedNodes - excluded nodes + * @param favoredNodes - list of nodes preferred. + * @param nodesRequired - number of datanodes required. + * @param sizeRequired - size required for the container or block. + * @return a list of chosen datanodeDetails + * @throws SCMException when chosen nodes are not enough in numbers + */ + @Override + public List<DatanodeDetails> chooseDatanodes( + List<DatanodeDetails> excludedNodes, List<DatanodeDetails> favoredNodes, + int nodesRequired, final long sizeRequired) throws SCMException { + // get a list of viable nodes based on criteria + List<DatanodeDetails> healthyNodes = + filterViableNodes(excludedNodes, nodesRequired); + + List<DatanodeDetails> results = new ArrayList<>(); + + // First choose an anchor nodes randomly + DatanodeDetails anchor = chooseNode(healthyNodes); + if (anchor == null) { + LOG.error("Unable to find the first healthy nodes that " + + "meet the criteria. Required nodes: {}, Found nodes: {}", + nodesRequired, results.size()); + throw new SCMException("Unable to find required number of nodes.", + SCMException.ResultCodes.FAILED_TO_FIND_SUITABLE_NODE); + } + + results.add(anchor); + nodesRequired--; + for (int x = 0; x < nodesRequired; x++) { + // invoke the choose function defined in the derived classes. + DatanodeDetails pick = + chooseNextNode(healthyNodes, excludedNodes, anchor); + if (pick != null) { + results.add(pick); + } + } + + if (results.size() < nodesRequired) { + LOG.error("Unable to find the required number of healthy nodes that " + + "meet the criteria. Required nodes: {}, Found nodes: {}", + nodesRequired, results.size()); + throw new SCMException("Unable to find required number of nodes.", + SCMException.ResultCodes.FAILED_TO_FIND_SUITABLE_NODE); + } + return results; + + } + + /** + * Find a node from the healthy list and return it after removing it from the + * list that we are operating on. + * + * @param healthyNodes - Set of healthy nodes we can choose from. + * @return chosen datanodDetails + */ + @Override + public DatanodeDetails chooseNode( + List<DatanodeDetails> healthyNodes) { + int firstNodeNdx = getRand().nextInt(healthyNodes.size()); + int secondNodeNdx = getRand().nextInt(healthyNodes.size()); + + DatanodeDetails datanodeDetails; + // There is a possibility that both numbers will be same. + // if that is so, we just return the node. + if (firstNodeNdx == secondNodeNdx) { + datanodeDetails = healthyNodes.get(firstNodeNdx); + } else { + DatanodeDetails firstNodeDetails = healthyNodes.get(firstNodeNdx); + DatanodeDetails secondNodeDetails = healthyNodes.get(secondNodeNdx); + SCMNodeMetric firstNodeMetric = + nodeManager.getNodeStat(firstNodeDetails); + SCMNodeMetric secondNodeMetric = + nodeManager.getNodeStat(secondNodeDetails); + datanodeDetails = firstNodeMetric.isGreater(secondNodeMetric.get()) + ? firstNodeDetails : secondNodeDetails; + } + healthyNodes.remove(datanodeDetails); + return datanodeDetails; + } + + /** + * Choose node based on network topology. + * @param networkTopology network topology + * @param anchor anchor datanode to start with + * @param excludedNodes excluded datanodes + * @return chosen datanode + */ + @VisibleForTesting + protected DatanodeDetails chooseNodeFromNetworkTopology( + NetworkTopology networkTopology, DatanodeDetails anchor, + List<DatanodeDetails> excludedNodes) { + if (networkTopology == null) { + return null; + } + + if (excludedNodes == null) { + return (DatanodeDetails)networkTopology.chooseRandom( + anchor.getNetworkFullPath(), new ArrayList<>()); Review comment: anchor.getNetworkFullPath -> anchor.getNetworkLocation ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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