Java tutorial
package org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair; /** * 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. */ import java.io.File; import java.io.IOException; import java.net.URL; import java.net.URLConnection; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Map; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.metrics.MetricsContext; import org.apache.hadoop.yarn.api.records.Resource; import org.apache.hadoop.yarn.server.resourcemanager.resource.Resources; import org.apache.hadoop.yarn.server.resourcemanager.scheduler.SchedulerApp; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.w3c.dom.Text; import org.xml.sax.SAXException; /** * Maintains a list of pools as well as scheduling parameters for each pool, * such as guaranteed share allocations, from the fair scheduler config file. */ public class PoolManager { public static final Log LOG = LogFactory.getLog("org.apache.hadoop.mapred.PoolManager"); /** Time to wait between checks of the allocation file */ public static final long ALLOC_RELOAD_INTERVAL = 10 * 1000; /** * Time to wait after the allocation has been modified before reloading it * (this is done to prevent loading a file that hasn't been fully written). */ public static final long ALLOC_RELOAD_WAIT = 5 * 1000; public static final String EXPLICIT_POOL_PROPERTY = "mapred.fairscheduler.pool"; private final FairScheduler scheduler; // Minimum resource allocation for each pool private Map<String, Resource> minPoolResources = new HashMap<String, Resource>(); // Maximum amount of resources per pool private Map<String, Resource> maxPoolResources = new HashMap<String, Resource>(); // Sharing weights for each pool private Map<String, Double> poolWeights = new HashMap<String, Double>(); // Max concurrent running applications for each pool and for each user; in addition, // for users that have no max specified, we use the userMaxJobsDefault. private Map<String, Integer> poolMaxApps = new HashMap<String, Integer>(); private Map<String, Integer> userMaxApps = new HashMap<String, Integer>(); private int userMaxAppsDefault = Integer.MAX_VALUE; private int poolMaxAppsDefault = Integer.MAX_VALUE; // Min share preemption timeout for each pool in seconds. If a job in the pool // waits this long without receiving its guaranteed share, it is allowed to // preempt other jobs' tasks. private Map<String, Long> minSharePreemptionTimeouts = new HashMap<String, Long>(); // Default min share preemption timeout for pools where it is not set // explicitly. private long defaultMinSharePreemptionTimeout = Long.MAX_VALUE; // Preemption timeout for jobs below fair share in seconds. If a job remains // below half its fair share for this long, it is allowed to preempt tasks. private long fairSharePreemptionTimeout = Long.MAX_VALUE; SchedulingMode defaultSchedulingMode = SchedulingMode.FAIR; private Object allocFile; // Path to XML file containing allocations. This // is either a URL to specify a classpath resource // (if the fair-scheduler.xml on the classpath is // used) or a String to specify an absolute path (if // mapred.fairscheduler.allocation.file is used). private Map<String, Pool> pools = new HashMap<String, Pool>(); private long lastReloadAttempt; // Last time we tried to reload the pools file private long lastSuccessfulReload; // Last time we successfully reloaded pools private boolean lastReloadAttemptFailed = false; public PoolManager(FairScheduler scheduler) { this.scheduler = scheduler; } public void initialize() throws IOException, SAXException, AllocationConfigurationException, ParserConfigurationException { Configuration conf = scheduler.getConf(); this.allocFile = conf.get(FairScheduler.CONFIG_PREFIX + ".allocation.file"); if (allocFile == null) { // No allocation file specified in jobconf. Use the default allocation // file, fair-scheduler.xml, looking for it on the classpath. allocFile = new Configuration().getResource("fair-scheduler.xml"); if (allocFile == null) { LOG.error("The fair scheduler allocation file fair-scheduler.xml was " + "not found on the classpath, and no other config file is given " + "through mapred.fairscheduler.allocation.file."); } } reloadAllocs(); lastSuccessfulReload = System.currentTimeMillis(); lastReloadAttempt = System.currentTimeMillis(); // Create the default pool so that it shows up in the web UI getPool(Pool.DEFAULT_POOL_NAME); } /** * Get a pool by name, creating it if necessary */ public synchronized Pool getPool(String name) { Pool pool = pools.get(name); if (pool == null) { pool = new Pool(scheduler, name); pool.setSchedulingMode(defaultSchedulingMode); pools.put(name, pool); } return pool; } /** * Reload allocations file if it hasn't been loaded in a while */ public void reloadAllocsIfNecessary() { long time = System.currentTimeMillis(); if (time > lastReloadAttempt + ALLOC_RELOAD_INTERVAL) { lastReloadAttempt = time; if (null == allocFile) { return; } try { // Get last modified time of alloc file depending whether it's a String // (for a path name) or an URL (for a classloader resource) long lastModified; if (allocFile instanceof String) { File file = new File((String) allocFile); lastModified = file.lastModified(); } else { // allocFile is an URL URLConnection conn = ((URL) allocFile).openConnection(); lastModified = conn.getLastModified(); } if (lastModified > lastSuccessfulReload && time > lastModified + ALLOC_RELOAD_WAIT) { reloadAllocs(); lastSuccessfulReload = time; lastReloadAttemptFailed = false; } } catch (Exception e) { // Throwing the error further out here won't help - the RPC thread // will catch it and report it in a loop. Instead, just log it and // hope somebody will notice from the log. // We log the error only on the first failure so we don't fill up the // JobTracker's log with these messages. if (!lastReloadAttemptFailed) { LOG.error("Failed to reload fair scheduler config file - " + "will use existing allocations.", e); } lastReloadAttemptFailed = true; } } } /** * Updates the allocation list from the allocation config file. This file is * expected to be in the XML format specified in the design doc. * * @throws IOException if the config file cannot be read. * @throws AllocationConfigurationException if allocations are invalid. * @throws ParserConfigurationException if XML parser is misconfigured. * @throws SAXException if config file is malformed. */ public void reloadAllocs() throws IOException, ParserConfigurationException, SAXException, AllocationConfigurationException { if (allocFile == null) return; // Create some temporary hashmaps to hold the new allocs, and we only save // them in our fields if we have parsed the entire allocs file successfully. Map<String, Resource> minPoolResources = new HashMap<String, Resource>(); Map<String, Resource> maxPoolResources = new HashMap<String, Resource>(); Map<String, Integer> poolMaxApps = new HashMap<String, Integer>(); Map<String, Integer> userMaxApps = new HashMap<String, Integer>(); Map<String, Double> poolWeights = new HashMap<String, Double>(); Map<String, SchedulingMode> poolModes = new HashMap<String, SchedulingMode>(); Map<String, Long> minSharePreemptionTimeouts = new HashMap<String, Long>(); int userMaxAppsDefault = Integer.MAX_VALUE; int poolMaxAppsDefault = Integer.MAX_VALUE; long fairSharePreemptionTimeout = Long.MAX_VALUE; long defaultMinSharePreemptionTimeout = Long.MAX_VALUE; SchedulingMode defaultSchedulingMode = SchedulingMode.FAIR; // Remember all pool names so we can display them on web UI, etc. List<String> poolNamesInAllocFile = new ArrayList<String>(); // Read and parse the allocations file. DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance(); docBuilderFactory.setIgnoringComments(true); DocumentBuilder builder = docBuilderFactory.newDocumentBuilder(); Document doc; if (allocFile instanceof String) { doc = builder.parse(new File((String) allocFile)); } else { doc = builder.parse(allocFile.toString()); } Element root = doc.getDocumentElement(); if (!"allocations".equals(root.getTagName())) throw new AllocationConfigurationException( "Bad fair scheduler config " + "file: top-level element not <allocations>"); NodeList elements = root.getChildNodes(); for (int i = 0; i < elements.getLength(); i++) { Node node = elements.item(i); if (!(node instanceof Element)) continue; Element element = (Element) node; if ("pool".equals(element.getTagName())) { String poolName = element.getAttribute("name"); poolNamesInAllocFile.add(poolName); NodeList fields = element.getChildNodes(); for (int j = 0; j < fields.getLength(); j++) { Node fieldNode = fields.item(j); if (!(fieldNode instanceof Element)) continue; Element field = (Element) fieldNode; if ("minResources".equals(field.getTagName())) { String text = ((Text) field.getFirstChild()).getData().trim(); int val = Integer.parseInt(text); minPoolResources.put(poolName, Resources.createResource(val)); } else if ("maxResources".equals(field.getTagName())) { String text = ((Text) field.getFirstChild()).getData().trim(); int val = Integer.parseInt(text); maxPoolResources.put(poolName, Resources.createResource(val)); } else if ("maxRunningApps".equals(field.getTagName())) { String text = ((Text) field.getFirstChild()).getData().trim(); int val = Integer.parseInt(text); poolMaxApps.put(poolName, val); } else if ("weight".equals(field.getTagName())) { String text = ((Text) field.getFirstChild()).getData().trim(); double val = Double.parseDouble(text); poolWeights.put(poolName, val); } else if ("minSharePreemptionTimeout".equals(field.getTagName())) { String text = ((Text) field.getFirstChild()).getData().trim(); long val = Long.parseLong(text) * 1000L; minSharePreemptionTimeouts.put(poolName, val); } else if ("schedulingMode".equals(field.getTagName())) { String text = ((Text) field.getFirstChild()).getData().trim(); poolModes.put(poolName, parseSchedulingMode(text)); } } if (maxPoolResources.containsKey(poolName) && minPoolResources.containsKey(poolName) && Resources.lessThan(maxPoolResources.get(poolName), minPoolResources.get(poolName))) { LOG.warn(String.format("Pool %s has max resources %d less than min resources %d", poolName, maxPoolResources.get(poolName), minPoolResources.get(poolName))); } } else if ("user".equals(element.getTagName())) { String userName = element.getAttribute("name"); NodeList fields = element.getChildNodes(); for (int j = 0; j < fields.getLength(); j++) { Node fieldNode = fields.item(j); if (!(fieldNode instanceof Element)) continue; Element field = (Element) fieldNode; if ("maxRunningApps".equals(field.getTagName())) { String text = ((Text) field.getFirstChild()).getData().trim(); int val = Integer.parseInt(text); userMaxApps.put(userName, val); } } } else if ("userMaxAppsDefault".equals(element.getTagName())) { String text = ((Text) element.getFirstChild()).getData().trim(); int val = Integer.parseInt(text); userMaxAppsDefault = val; } else if ("poolMaxAppsDefault".equals(element.getTagName())) { String text = ((Text) element.getFirstChild()).getData().trim(); int val = Integer.parseInt(text); poolMaxAppsDefault = val; } else if ("fairSharePreemptionTimeout".equals(element.getTagName())) { String text = ((Text) element.getFirstChild()).getData().trim(); long val = Long.parseLong(text) * 1000L; fairSharePreemptionTimeout = val; } else if ("defaultMinSharePreemptionTimeout".equals(element.getTagName())) { String text = ((Text) element.getFirstChild()).getData().trim(); long val = Long.parseLong(text) * 1000L; defaultMinSharePreemptionTimeout = val; } else if ("defaultPoolSchedulingMode".equals(element.getTagName())) { String text = ((Text) element.getFirstChild()).getData().trim(); defaultSchedulingMode = parseSchedulingMode(text); } else { LOG.warn("Bad element in allocations file: " + element.getTagName()); } } // Commit the reload; also create any pool defined in the alloc file // if it does not already exist, so it can be displayed on the web UI. synchronized (this) { this.minPoolResources = minPoolResources; this.maxPoolResources = maxPoolResources; this.poolMaxApps = poolMaxApps; this.userMaxApps = userMaxApps; this.poolWeights = poolWeights; this.minSharePreemptionTimeouts = minSharePreemptionTimeouts; this.userMaxAppsDefault = userMaxAppsDefault; this.poolMaxAppsDefault = poolMaxAppsDefault; this.fairSharePreemptionTimeout = fairSharePreemptionTimeout; this.defaultMinSharePreemptionTimeout = defaultMinSharePreemptionTimeout; this.defaultSchedulingMode = defaultSchedulingMode; for (String name : poolNamesInAllocFile) { Pool pool = getPool(name); if (poolModes.containsKey(name)) { pool.setSchedulingMode(poolModes.get(name)); } else { pool.setSchedulingMode(defaultSchedulingMode); } } } } private SchedulingMode parseSchedulingMode(String text) throws AllocationConfigurationException { text = text.toLowerCase(); if (text.equals("fair")) { return SchedulingMode.FAIR; } else if (text.equals("fifo")) { return SchedulingMode.FIFO; } else { throw new AllocationConfigurationException( "Unknown scheduling mode : " + text + "; expected 'fifo' or 'fair'"); } } /** * Get the minimum resource allocation for the given pool. * @return the cap set on this pool, or 0 if not set. */ public Resource getMinResources(String pool) { if (minPoolResources.containsKey(pool)) { return minPoolResources.get(pool); } else { return Resources.createResource(0); } } /** * Get the maximum resource allocation for the given pool. * @return the cap set on this pool, or Integer.MAX_VALUE if not set. */ Resource getMaxResources(String poolName) { if (maxPoolResources.containsKey(poolName)) { return maxPoolResources.get(poolName); } else { return Resources.createResource(Integer.MAX_VALUE); } } /** * Add an app in the appropriate pool */ public synchronized void addApp(SchedulerApp app) { getPool(app.getQueueName()).addApp(app); } /** * Remove an app */ public synchronized void removeJob(SchedulerApp app) { getPool(app.getQueueName()).removeJob(app); } /** * Change the pool of a particular job. TODO I don't think we can support this public synchronized void setPool(JobInProgress job, String pool) { removeJob(job); job.getJobConf().set(EXPLICIT_POOL_PROPERTY, pool); addJob(job); } */ /** * Get a collection of all pools */ public synchronized Collection<Pool> getPools() { return pools.values(); } /** * Get all pool names that have been seen either in the allocation file or in * a MapReduce job. */ public synchronized Collection<String> getPoolNames() { List<String> list = new ArrayList<String>(); for (Pool pool : getPools()) { list.add(pool.getName()); } Collections.sort(list); return list; } public int getUserMaxApps(String user) { if (userMaxApps.containsKey(user)) { return userMaxApps.get(user); } else { return userMaxAppsDefault; } } public int getPoolMaxApps(String pool) { if (poolMaxApps.containsKey(pool)) { return poolMaxApps.get(pool); } else { return poolMaxAppsDefault; } } public double getPoolWeight(String pool) { if (poolWeights.containsKey(pool)) { return poolWeights.get(pool); } else { return 1.0; } } /** * Get a pool's min share preemption timeout, in milliseconds. This is the * time after which jobs in the pool may kill other pools' tasks if they * are below their min share. */ public long getMinSharePreemptionTimeout(String pool) { if (minSharePreemptionTimeouts.containsKey(pool)) { return minSharePreemptionTimeouts.get(pool); } else { return defaultMinSharePreemptionTimeout; } } /** * Get the fair share preemption, in milliseconds. This is the time * after which any job may kill other jobs' tasks if it is below half * its fair share. */ public long getFairSharePreemptionTimeout() { return fairSharePreemptionTimeout; } /* synchronized void updateMetrics() { for (Pool pool : pools.values()) { pool.updateMetrics(); } } */ }