wchevreuil commented on a change in pull request #677: HBASE-23073 Add an optional costFunction to balance regions according to a capacity rule URL: https://github.com/apache/hbase/pull/677#discussion_r337923846
########## File path: hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/HeterogeneousRegionCountCostFunction.java ########## @@ -0,0 +1,306 @@ +/** + * 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.hbase.master.balancer; + +import java.io.BufferedReader; +import java.io.FileReader; +import java.io.IOException; +import java.io.InputStreamReader; +import java.util.ArrayList; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.regex.Pattern; +import java.util.regex.PatternSyntaxException; + +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.fs.FileSystem; +import org.apache.hadoop.fs.Path; +import org.apache.hadoop.hbase.ServerName; +import org.apache.yetus.audience.InterfaceAudience; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * This is an optional Cost function designed to allow region count skew across RegionServers. A + * rule file is loaded from the local FS or HDFS before balancing. It contains lines of rules. A + * rule is composed of a regexp for hostname, and a limit. For example, we could have: + * <p> + * * rs[0-9] 200 * rs1[0-9] 50 + * </p> + * RegionServers with hostname matching the first rules will have a limit of 200, and the others 50. + * If there's no match, a default is set. The costFunction is trying to fill all RegionServers + * linearly, meaning that if the global usage is at 50%, then all RegionServers should hold half of + * their capacity in terms of regions. In order to use this CostFunction, you need to set the + * following options: + * <ul> + * <li>hbase.master.balancer.stochastic.additionalCostFunctions</li> + * <li>hbase.master.balancer.stochastic.heterogeneousRegionCountRulesFile</li> + * <li>hbase.master.balancer.stochastic.heterogeneousRegionCountDefault</li> + * </ul> + */ +@InterfaceAudience.Private +public class HeterogeneousRegionCountCostFunction extends StochasticLoadBalancer.CostFunction { + + /** + * configuration used for the path where the rule file is stored. + */ + static final String HBASE_MASTER_BALANCER_HETEROGENEOUS_RULES_FILE = + "hbase.master.balancer.heterogeneousRegionCountRulesFile"; + private static final Logger LOG = + LoggerFactory.getLogger(HeterogeneousRegionCountCostFunction.class); + /** + * Default rule to apply when the rule file is not found. Default to 200. + */ + private static final String HBASE_MASTER_BALANCER_HETEROGENEOUS_RULES_DEFAULT = + "hbase.master.balancer.heterogeneousRegionCountDefault"; + /** + * Cost for the function. Default to 500, can be changed. + */ + private static final String REGION_COUNT_SKEW_COST_KEY = + "hbase.master.balancer.stochastic.heterogeneousRegionCountCost"; + private static final float DEFAULT_REGION_COUNT_SKEW_COST = 5000; + private final String rulesPath; + + /** + * Contains the rules, key is the regexp for ServerName, value is the limit + */ + private final Map<Pattern, Integer> limitPerRule; + + /** + * This is a cache, used to not go through all the limitPerRule map when searching for limit + */ + private final Map<ServerName, Integer> limitPerRS; + private final Configuration conf; + private int defaultNumberOfRegions; + + /** + * Total capacity of regions for the cluster, based on the online RS and their associated rules + */ + private int totalCapacity = 0; + double overallUsage; + + HeterogeneousRegionCountCostFunction(final Configuration conf) { + super(conf); + this.conf = conf; + this.limitPerRS = new HashMap<>(); + this.limitPerRule = new HashMap<>(); + this.setMultiplier(conf.getFloat(REGION_COUNT_SKEW_COST_KEY, DEFAULT_REGION_COUNT_SKEW_COST)); + + this.rulesPath = conf.get(HBASE_MASTER_BALANCER_HETEROGENEOUS_RULES_FILE); + + this.defaultNumberOfRegions = + conf.getInt(HBASE_MASTER_BALANCER_HETEROGENEOUS_RULES_DEFAULT, 200); + if (this.defaultNumberOfRegions < 0) { + LOG.warn("invalid configuration '" + HBASE_MASTER_BALANCER_HETEROGENEOUS_RULES_DEFAULT + + "'. Setting default to 200"); + this.defaultNumberOfRegions = 200; + } + + if (conf.getFloat(StochasticLoadBalancer.RegionCountSkewCostFunction.REGION_COUNT_SKEW_COST_KEY, + StochasticLoadBalancer.RegionCountSkewCostFunction.DEFAULT_REGION_COUNT_SKEW_COST) > 0) { + LOG.warn("regionCountCost is not set to 0, " + + " this will interfere with the HeterogeneousRegionCountCostFunction!"); + } + } + + /** + * Called once per LB invocation to give the cost function to initialize it's state, and perform + * any costly calculation. + */ + @Override + void init(final BaseLoadBalancer.Cluster cluster) { + this.cluster = cluster; + this.loadRules(); + } + + @Override + protected double cost() { + + double cost = 0; + + final double targetUsage = ((double) this.cluster.numRegions / (double) this.totalCapacity); + + for (int i = 0; i < this.cluster.numServers; i++) { + + // retrieve capacity for each RS + final ServerName sn = this.cluster.servers[i]; + final double limit = this.limitPerRS.getOrDefault(sn, defaultNumberOfRegions); + final double nbrRegions = this.cluster.regionsPerServer[i].length; + + final double usage = nbrRegions / limit; + if (usage > targetUsage) { + // cost is the number of regions above the local limit + final double localCost = (nbrRegions - Math.round(limit * targetUsage)) / limit; + cost += localCost; + } + } + return cost / (double) this.cluster.numServers; + + } + + /** + * used to load the rule files. + */ + void loadRules() { + final List<String> lines = readFile(this.rulesPath); + if (null == lines) { + LOG.warn("cannot load rules file, keeping latest rules file which has " + + this.limitPerRule.size() + " rules"); + return; + } + + LOG.info("loading rules file '" + this.rulesPath + "'"); + this.limitPerRule.clear(); + for (final String line : lines) { + try { + if (line.length() == 0) { + continue; + } + + if (line.startsWith("#")) { + continue; + } + + final String[] splits = line.split(" "); + if (splits.length != 2) { + throw new IOException( + "line '" + line + "' is malformated, " + "expected [regexp] [limit]. Skipping line"); + } + + final Pattern pattern = Pattern.compile(splits[0]); + final Integer limit = Integer.parseInt(splits[1]); + this.limitPerRule.put(pattern, limit); + } catch (final IOException | NumberFormatException | PatternSyntaxException e) { + LOG.error("error on line: " + e); + } + } + + this.rebuildCache(); + } + + /** + * used to read the rule files from either HDFS or local FS + */ + private List<String> readFile(final String filename) { + + if (null == filename) { + return null; + } + + try { + if (filename.startsWith("file:")) { Review comment: Nice adding. Mind mention it on the class javadoc comment? ---------------------------------------------------------------- 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
