anuengineer commented on a change in pull request #86: HDDS-2329 Destroy pipelines on any decommission or maintenance nodes URL: https://github.com/apache/hadoop-ozone/pull/86#discussion_r341826121
########## File path: hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/DatanodeAdminMonitor.java ########## @@ -0,0 +1,269 @@ +/** + * 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 + * <p> + * http://www.apache.org/licenses/LICENSE-2.0 + * <p> + * 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.node; + +import com.google.common.annotations.VisibleForTesting; +import org.apache.hadoop.hdds.conf.OzoneConfiguration; +import org.apache.hadoop.hdds.protocol.DatanodeDetails; +import org.apache.hadoop.hdds.scm.events.SCMEvents; +import org.apache.hadoop.hdds.scm.pipeline.PipelineID; +import org.apache.hadoop.hdds.scm.pipeline.PipelineManager; +import org.apache.hadoop.hdds.server.events.EventPublisher; +import org.apache.hadoop.ozone.common.statemachine.InvalidStateTransitionException; +import org.apache.hadoop.ozone.common.statemachine.StateMachine; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.Queue; +import java.util.ArrayDeque; +import java.util.HashSet; +import java.util.Set; + +/** + * Monitor thread which watches for nodes to be decommissioned, recommissioned + * or placed into maintenance. Newly added nodes are queued in pendingNodes + * and recommissoned nodes are queued in cancelled nodes. On each monitor + * 'tick', the cancelled nodes are processed and removed from the monitor. + * Then any pending nodes are added to the trackedNodes set, where they stay + * until decommission or maintenance has ended. + * + * Once an node is placed into tracked nodes, it goes through a workflow where + * the following happens: + * + * 1. First an event is fired to close any pipelines on the node, which will + * also close any contaners. + * 2. Next the containers on the node are obtained and checked to see if new + * replicas are needed. If so, the new replicas are scheduled. + * 3. After scheduling replication, the node remains pending until replication + * has completed. + * 4. At this stage the node will complete decommission or enter maintenance. + * 5. Maintenance nodes will remain tracked by this monitor until maintenance + * is manually ended, or the maintenance window expires. + */ +public class DatanodeAdminMonitor implements DatanodeAdminMonitorInterface { + + private OzoneConfiguration conf; + private EventPublisher eventQueue; + private NodeManager nodeManager; + private PipelineManager pipelineManager; + private Queue<DatanodeAdminNodeDetails> pendingNodes = new ArrayDeque(); + private Queue<DatanodeAdminNodeDetails> cancelledNodes = new ArrayDeque(); + private Set<DatanodeAdminNodeDetails> trackedNodes = new HashSet<>(); + private StateMachine<States, Transitions> workflowSM; + + /** + * States that a node must pass through when being decommissioned or placed + * into maintenance. + */ + public enum States { + CLOSE_PIPELINES, GET_CONTAINERS, REPLICATE_CONTAINERS, + AWAIT_MAINTENANCE_END, COMPLETE + } + + /** + * Transition events that occur to move a node from one state to the next. + */ + public enum Transitions { + COMPLETE_DECOM_STAGE, COMPLETE_MAINT_STAGE, UNEXPECTED_NODE_STATE + } + + private static final Logger LOG = + LoggerFactory.getLogger(DatanodeAdminMonitor.class); + + public DatanodeAdminMonitor(OzoneConfiguration config) { + conf = config; + initializeStateMachine(); + } + + @Override + public void setConf(OzoneConfiguration config) { + conf = config; + } + + @Override + public void setEventQueue(EventPublisher eventQueue) { + this.eventQueue = eventQueue; + } + + @Override + public void setNodeManager(NodeManager nm) { + nodeManager = nm; + } + + @Override + public void setPipelineManager(PipelineManager pm) { + pipelineManager = pm; + } + + /** + * Add a node to the decommission or maintenance workflow. The node will be + * queued and added to the workflow after a defined interval. + * + * @param dn The datanode to move into an admin state + * @param endInHours For nodes going into maintenance, the number of hours + * from now for maintenance to automatically end. Ignored + * for decommissioning nodes. + */ + @Override + public synchronized void startMonitoring(DatanodeDetails dn, int endInHours) { + DatanodeAdminNodeDetails nodeDetails = + new DatanodeAdminNodeDetails(dn, workflowSM.getInitialState(), + endInHours); + cancelledNodes.remove(nodeDetails); + pendingNodes.add(nodeDetails); + } + + /** + * Remove a node from the decommission or maintenance workflow, and return it + * to service. The node will be queued and removed from decommission or + * maintenance after a defined interval. + * @param dn The datanode for which to stop decommission or maintenance. + */ + @Override + public synchronized void stopMonitoring(DatanodeDetails dn) { + DatanodeAdminNodeDetails nodeDetails = new DatanodeAdminNodeDetails(dn, + workflowSM.getInitialState(), 0); + pendingNodes.remove(nodeDetails); + cancelledNodes.add(nodeDetails); + } + + /** + * Run an iteration of the monitor. This is the main run loop, and performs + * the following checks: + * + * 1. Check for any cancelled nodes and process them + * 2. Check for any newly added nodes and add them to the workflow + * 3. Wait for any nodes which have completed closing pipelines + */ + @Override + public void run() { + try { + synchronized (this) { + processCancelledNodes(); + processPendingNodes(); + } + checkPipelinesClosed(); + if (trackedNodes.size() > 0 || pendingNodes.size() > 0) { + LOG.info("There are {} nodes tracked for decommission and "+ + "maintenance. {} pending nodes.", + trackedNodes.size(), pendingNodes.size()); + } + } catch (Exception e) { + LOG.error("Caught an error in the DatanodeAdminMonitor", e); + } + } + + @Override + public int getPendingCount() { + return pendingNodes.size(); + } + + @Override + public int getCancelledCount() { + return cancelledNodes.size(); + } + + @Override + public int getTrackedNodeCount() { + return trackedNodes.size(); + } + + @VisibleForTesting + public Set<DatanodeAdminNodeDetails> getTrackedNodes() { + return trackedNodes; + } + + /** + * Return the state machine used to transition a node through the admin + * workflow. + * @return The StateMachine used by the admin workflow + */ + @VisibleForTesting + public StateMachine<States, Transitions> getWorkflowStateMachine() { + return workflowSM; + } + + private void processCancelledNodes() { + while(!cancelledNodes.isEmpty()) { + DatanodeAdminNodeDetails dn = cancelledNodes.poll(); + trackedNodes.remove(dn); + // TODO - fire event to bring node back into service? Review comment: I don't think is needed since if the DN starts HB-ing we should be ok is what I think. @nandakumar131 , any comments? ---------------------------------------------------------------- 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: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-dev-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-dev-h...@hadoop.apache.org
