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[pulsar-broker] add uniform load shedder strategy to distribute traff…
…ic uniformly across brokers (apache#12902) * [pulsar-broker] add uniform load shedder strategy to distribute traffic uniformly across brokers * add documentation * fixed typo in documentation
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...ar-broker/src/main/java/org/apache/pulsar/broker/loadbalance/impl/UniformLoadShedder.java
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| /** | ||
| * 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.pulsar.broker.loadbalance.impl; | ||
|
|
||
| import static org.apache.pulsar.broker.namespace.NamespaceService.HEARTBEAT_NAMESPACE_PATTERN; | ||
| import static org.apache.pulsar.broker.namespace.NamespaceService.HEARTBEAT_NAMESPACE_PATTERN_V2; | ||
| import com.google.common.collect.ArrayListMultimap; | ||
| import com.google.common.collect.Multimap; | ||
| import java.util.Map; | ||
| import org.apache.commons.lang3.mutable.MutableDouble; | ||
| import org.apache.commons.lang3.mutable.MutableInt; | ||
| import org.apache.commons.lang3.mutable.MutableObject; | ||
| import org.apache.commons.lang3.tuple.Triple; | ||
| import org.apache.pulsar.broker.BrokerData; | ||
| import org.apache.pulsar.broker.BundleData; | ||
| import org.apache.pulsar.broker.ServiceConfiguration; | ||
| import org.apache.pulsar.broker.TimeAverageMessageData; | ||
| import org.apache.pulsar.broker.loadbalance.LoadData; | ||
| import org.apache.pulsar.broker.loadbalance.LoadSheddingStrategy; | ||
| import org.apache.pulsar.policies.data.loadbalancer.LocalBrokerData; | ||
| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
|
|
||
| /** | ||
| * This strategy tends to distribute load uniformly across all brokers. This strategy checks laod difference between | ||
| * broker with highest load and broker with lowest load. If the difference is higher than configured thresholds | ||
| * {@link ServiceConfiguration#getLoadBalancerMsgRateDifferenceShedderThreshold()} and | ||
| * {@link ServiceConfiguration#getLoadBalancerMsgRateDifferenceShedderThreshold()} then it finds out bundles which can | ||
| * be unloaded to distribute traffic evenly across all brokers. | ||
| * | ||
| */ | ||
| public class UniformLoadShedder implements LoadSheddingStrategy { | ||
|
|
||
| private static final Logger log = LoggerFactory.getLogger(UniformLoadShedder.class); | ||
|
|
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| private final Multimap<String, String> selectedBundlesCache = ArrayListMultimap.create(); | ||
|
|
||
| /** | ||
| * Attempt to shed some bundles off every broker which is overloaded. | ||
| * | ||
| * @param loadData | ||
| * The load data to used to make the unloading decision. | ||
| * @param conf | ||
| * The service configuration. | ||
| * @return A map from bundles to unload to the brokers on which they are loaded. | ||
| */ | ||
| @Override | ||
| public Multimap<String, String> findBundlesForUnloading(final LoadData loadData, final ServiceConfiguration conf) { | ||
| selectedBundlesCache.clear(); | ||
| Map<String, BrokerData> brokersData = loadData.getBrokerData(); | ||
| Map<String, BundleData> loadBundleData = loadData.getBundleData(); | ||
| Map<String, Long> recentlyUnloadedBundles = loadData.getRecentlyUnloadedBundles(); | ||
|
|
||
| MutableObject<String> overloadedBroker = new MutableObject<>(); | ||
| MutableObject<String> underloadedBroker = new MutableObject<>(); | ||
| MutableDouble maxMsgRate = new MutableDouble(-1); | ||
| MutableDouble maxThroughputRate = new MutableDouble(-1); | ||
| MutableDouble minMsgRate = new MutableDouble(Integer.MAX_VALUE); | ||
| MutableDouble minThroughputgRate = new MutableDouble(Integer.MAX_VALUE); | ||
| brokersData.forEach((broker, data) -> { | ||
| double msgRate = data.getLocalData().getMsgRateIn() + data.getLocalData().getMsgRateOut(); | ||
| double throughputRate = data.getLocalData().getMsgThroughputIn() | ||
| + data.getLocalData().getMsgThroughputOut(); | ||
| if (data.getLocalData().getBundles().size() > 1 // broker with one bundle can't be considered for | ||
| // bundle unloading | ||
| && (msgRate > maxMsgRate.getValue() || throughputRate > maxThroughputRate.getValue())) { | ||
| overloadedBroker.setValue(broker); | ||
| maxMsgRate.setValue(msgRate); | ||
| maxThroughputRate.setValue(throughputRate); | ||
| } | ||
| if (msgRate < minMsgRate.getValue() || throughputRate < minThroughputgRate.getValue()) { | ||
| underloadedBroker.setValue(broker); | ||
| minMsgRate.setValue(msgRate); | ||
| minThroughputgRate.setValue(throughputRate); | ||
| } | ||
| }); | ||
|
|
||
| // find the difference between two brokers based on msgRate and throughout and check if the load distribution | ||
| // discrepancy is higher than threshold. if that matches then try to unload bundle from overloaded brokers to | ||
| // give chance of uniform load distribution. | ||
| double msgRateDifferencePercentage = ((maxMsgRate.getValue() - minMsgRate.getValue()) * 100) | ||
| / (minMsgRate.getValue()); | ||
| double msgThroughputDifferenceRate = maxThroughputRate.getValue() / minThroughputgRate.getValue(); | ||
|
|
||
| // if the threshold matches then find out how much load needs to be unloaded by considering number of msgRate | ||
| // and throughput. | ||
| boolean isMsgRateThresholdExceeded = conf.getLoadBalancerMsgRateDifferenceShedderThreshold() > 0 | ||
| && msgRateDifferencePercentage > conf.getLoadBalancerMsgRateDifferenceShedderThreshold(); | ||
| boolean isMsgThroughputThresholdExceeded = conf | ||
| .getLoadBalancerMsgThroughputMultiplierDifferenceShedderThreshold() > 0 | ||
| && msgThroughputDifferenceRate > conf | ||
| .getLoadBalancerMsgThroughputMultiplierDifferenceShedderThreshold(); | ||
|
|
||
| if (isMsgRateThresholdExceeded || isMsgThroughputThresholdExceeded) { | ||
| if (log.isDebugEnabled()) { | ||
| log.debug( | ||
| "Found bundles for uniform load balancing. " | ||
| + "overloaded broker {} with (msgRate,throughput)= ({},{}) " | ||
| + "and underloaded broker {} with (msgRate,throughput)= ({},{})", | ||
| overloadedBroker.getValue(), maxMsgRate.getValue(), maxThroughputRate.getValue(), | ||
| underloadedBroker.getValue(), minMsgRate.getValue(), minThroughputgRate.getValue()); | ||
| } | ||
| MutableInt msgRateRequiredFromUnloadedBundles = new MutableInt( | ||
| (int) ((maxMsgRate.getValue() - minMsgRate.getValue()) / 2)); | ||
| MutableInt msgThroughtputRequiredFromUnloadedBundles = new MutableInt( | ||
| (int) ((maxThroughputRate.getValue() - minThroughputgRate.getValue()) / 2)); | ||
| LocalBrokerData overloadedBrokerData = brokersData.get(overloadedBroker.getValue()).getLocalData(); | ||
|
|
||
| if (overloadedBrokerData.getBundles().size() > 1) { | ||
| // Sort bundles by throughput, then pick the bundle which can help to reduce load uniformly with | ||
| // under-loaded broker | ||
| loadBundleData.entrySet().stream() | ||
| .filter(e -> !HEARTBEAT_NAMESPACE_PATTERN.matcher(e.getKey()).matches() | ||
| && !HEARTBEAT_NAMESPACE_PATTERN_V2.matcher(e.getKey()).matches() | ||
| && overloadedBrokerData.getBundles().contains(e.getKey())) | ||
| .map((e) -> { | ||
| String bundle = e.getKey(); | ||
| BundleData bundleData = e.getValue(); | ||
| TimeAverageMessageData shortTermData = bundleData.getShortTermData(); | ||
| double throughput = isMsgRateThresholdExceeded | ||
| ? shortTermData.getMsgRateIn() + shortTermData.getMsgRateOut() | ||
| : shortTermData.getMsgThroughputIn() + shortTermData.getMsgThroughputOut(); | ||
| return Triple.of(bundle, bundleData, throughput); | ||
| }).filter(e -> !recentlyUnloadedBundles.containsKey(e.getLeft())) | ||
| .filter(e -> overloadedBrokerData.getBundles().contains(e.getLeft())) | ||
| .sorted((e1, e2) -> Double.compare(e2.getRight(), e1.getRight())).forEach((e) -> { | ||
| String bundle = e.getLeft(); | ||
| BundleData bundleData = e.getMiddle(); | ||
| TimeAverageMessageData shortTermData = bundleData.getShortTermData(); | ||
| double throughput = shortTermData.getMsgThroughputIn() | ||
| + shortTermData.getMsgThroughputOut(); | ||
| double bundleMsgRate = shortTermData.getMsgRateIn() + shortTermData.getMsgRateOut(); | ||
| if (isMsgRateThresholdExceeded) { | ||
| if (bundleMsgRate <= (msgRateRequiredFromUnloadedBundles.getValue() | ||
| + 1000/* delta */)) { | ||
| log.info("Found bundle to unload with msgRate {}", bundleMsgRate); | ||
| msgRateRequiredFromUnloadedBundles.add(-bundleMsgRate); | ||
| selectedBundlesCache.put(overloadedBroker.getValue(), bundle); | ||
| } | ||
| } else { | ||
| if (throughput <= (msgThroughtputRequiredFromUnloadedBundles.getValue())) { | ||
| log.info("Found bundle to unload with throughput {}", throughput); | ||
| msgThroughtputRequiredFromUnloadedBundles.add(-throughput); | ||
| selectedBundlesCache.put(overloadedBroker.getValue(), bundle); | ||
| } | ||
| } | ||
| }); | ||
| } | ||
| } | ||
|
|
||
| return selectedBundlesCache; | ||
| } | ||
| } |
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