sigram commented on a change in pull request #1100: SOLR-13579: Create resource management API URL: https://github.com/apache/lucene-solr/pull/1100#discussion_r363875456
########## File path: solr/core/src/java/org/apache/solr/managed/types/CacheManagerPool.java ########## @@ -0,0 +1,329 @@ +/* + * 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.solr.managed.types; + +import java.lang.invoke.MethodHandles; +import java.util.ArrayList; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.concurrent.atomic.AtomicReference; +import java.util.function.Function; + +import org.apache.solr.managed.ChangeListener; +import org.apache.solr.managed.ResourceManager; +import org.apache.solr.managed.ResourceManagerPool; +import org.apache.solr.metrics.SolrMetricsContext; +import org.apache.solr.search.SolrCache; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * An implementation of {@link org.apache.solr.managed.ResourceManagerPool} specific to + * the management of {@link org.apache.solr.search.SolrCache} instances. + * <p>This plugin calculates the total size and maxRamMB of all registered cache instances + * and adjusts each cache's limits so that the aggregated values again fit within the pool limits.</p> + * <p>In order to avoid thrashing the plugin uses a dead band (by default {@link #DEFAULT_DEAD_BAND}), + * which can be adjusted using configuration parameter {@link #DEAD_BAND_PARAM}. If monitored values don't + * exceed the limits +/- the dead band then no forcible adjustment takes place.</p> + * <p>The management strategy consists of two distinct phases: soft optimization phase and then hard limit phase.</p> + * <p><b>Soft optimization</b> tries to adjust the resource consumption based on the cache hit ratio. + * This phase is executed only if there's no total limit exceeded. Also, hit ratio is considered a valid monitored + * variable only when at least N lookups occurred since the last adjustment (default value is {@link #DEFAULT_LOOKUP_DELTA}). + * If the hit ratio is higher than a threshold (default value is {@link #DEFAULT_TARGET_HITRATIO}) then the size + * of the cache can be reduced so that the resource consumption is minimized while still keeping acceptable hit + * ratio - and vice versa.</p> + * <p>This optimization phase can only adjust the limits within a {@link #DEFAULT_MAX_ADJUST_RATIO}, i.e. increased + * or decreased values may not be larger / smaller than this multiple / fraction of the initially configured limit.</p> + * <p><b>Hard limit</b> phase follows the soft optimization phase and it forcibly reduces resource consumption of all components + * if the total usage is still above the pool limit after the first phase has completed. Each component's limit is reduced + * by the same factor, regardless of the actual population or hit ratio.</p> + */ +public class CacheManagerPool extends ResourceManagerPool<SolrCache> { + private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass()); + + public static String TYPE = "cache"; + + /** Controller dead-band - changes smaller than this ratio will be ignored. */ + public static final String DEAD_BAND_PARAM = "deadBand"; + /** Target hit ratio - high enough to be useful, low enough to avoid excessive cache size. */ + public static final String TARGET_HIT_RATIO_PARAM = "targetHitRatio"; + /** + * Maximum allowed adjustment ratio from the initial configuration value. Adjusted value may not be + * higher than multiple of this factor, and not lower than divided by this factor. + */ + public static final String MAX_ADJUST_RATIO_PARAM = "maxAdjustRatio"; + /** + * Minimum number of lookups since last adjustment to consider the reported hitRatio + * to be statistically valid. + */ + public static final String MIN_LOOKUP_DELTA_PARAM = "minLookupDelta"; + /** Default value of dead band (10%). */ + public static final double DEFAULT_DEAD_BAND = 0.1; + /** Default target hit ratio - a compromise between usefulness and limited resource usage. */ + public static final double DEFAULT_TARGET_HITRATIO = 0.8; + /** + * Default minimum number of lookups since the last adjustment. This can be treated as Bernoulli trials + * that give a 5% confidence about the statistical validity of hit ratio (<code>0.5 / sqrt(lookups)</code>). + */ + public static final long DEFAULT_LOOKUP_DELTA = 100; + /** + * Default maximum adjustment ratio from the initially configured values. + */ + public static final double DEFAULT_MAX_ADJUST_RATIO = 2.0; + + protected static final Map<String, Function<Map<String, Object>, Double>> controlledToMonitored = new HashMap<>(); + + static { + controlledToMonitored.put(SolrCache.MAX_RAM_MB_PARAM, values -> { + Number ramBytes = (Number) values.get(SolrCache.RAM_BYTES_USED_PARAM); + return ramBytes != null ? ramBytes.doubleValue() / SolrCache.MB : 0.0; + }); + controlledToMonitored.put(SolrCache.MAX_SIZE_PARAM, values -> + ((Number)values.getOrDefault(SolrCache.SIZE_PARAM, -1.0)).doubleValue()); + } + + protected double deadBand = DEFAULT_DEAD_BAND; + protected double targetHitRatio = DEFAULT_TARGET_HITRATIO; + protected long lookupDelta = DEFAULT_LOOKUP_DELTA; + protected double maxAdjustRatio = DEFAULT_MAX_ADJUST_RATIO; + protected Map<String, Long> lookups = new HashMap<>(); + protected Map<String, Map<String, Object>> initialComponentLimits = new HashMap<>(); + + public CacheManagerPool(String name, String type, ResourceManager resourceManager, Map<String, Object> poolLimits, Map<String, Object> poolParams) { + super(name, type, resourceManager, poolLimits, poolParams); + String str = String.valueOf(poolParams.getOrDefault(DEAD_BAND_PARAM, DEFAULT_DEAD_BAND)); + try { + deadBand = Double.parseDouble(str); + } catch (Exception e) { + log.warn("Invalid deadBand parameter value '" + str + "', using default " + DEFAULT_DEAD_BAND); + } + } + + @Override + public void registerComponent(SolrCache component) { + super.registerComponent(component); + initialComponentLimits.put(component.getManagedComponentId().toString(), getResourceLimits(component)); + } + + @Override + public boolean unregisterComponent(String componentId) { + lookups.remove(componentId); + initialComponentLimits.remove(componentId); + return super.unregisterComponent(componentId); + } + + @Override + public Object doSetResourceLimit(SolrCache component, String limitName, Object val) { + if (!(val instanceof Number)) { + try { + val = Long.parseLong(String.valueOf(val)); + } catch (Exception e) { + throw new IllegalArgumentException("Unsupported value type (not a number) for limit '" + limitName + "': " + val + " (" + val.getClass().getName() + ")"); + } + } + Number value = (Number)val; + if (value.longValue() > Integer.MAX_VALUE) { + throw new IllegalArgumentException("Invalid new value for limit '" + limitName +"': " + value); + } + switch (limitName) { + case SolrCache.MAX_SIZE_PARAM: + component.setMaxSize(value.intValue()); + break; + case SolrCache.MAX_RAM_MB_PARAM: + component.setMaxRamMB(value.intValue()); + break; + default: + throw new IllegalArgumentException("Unsupported limit name '" + limitName + "'"); + } + return value.intValue(); + } + + @Override + public Map<String, Object> getResourceLimits(SolrCache component) { + Map<String, Object> limits = new HashMap<>(); + limits.put(SolrCache.MAX_SIZE_PARAM, component.getMaxSize()); + limits.put(SolrCache.MAX_RAM_MB_PARAM, component.getMaxRamMB()); + return limits; + } + + @Override + public Map<String, Object> getMonitoredValues(SolrCache component) throws Exception { + Map<String, Object> values = new HashMap<>(); + values.put(SolrCache.SIZE_PARAM, component.size()); + values.put(SolrCache.RAM_BYTES_USED_PARAM, component.ramBytesUsed()); + SolrMetricsContext metricsContext = component.getSolrMetricsContext(); + if (metricsContext != null) { + Map<String, Object> metrics = metricsContext.getMetricsSnapshot(); + String key = component.getCategory().toString() + "." + metricsContext.getScope() + "." + SolrCache.HIT_RATIO_PARAM; + values.put(SolrCache.HIT_RATIO_PARAM, metrics.get(key)); + key = component.getCategory().toString() + "." + metricsContext.getScope() + "." + SolrCache.LOOKUPS_PARAM; + values.put(SolrCache.LOOKUPS_PARAM, metrics.get(key)); + } + return values; + } + + @Override + protected void doManage() throws Exception { + Map<String, Map<String, Object>> currentValues = getCurrentValues(); + Map<String, Object> totalValues = aggregateTotalValues(currentValues); + // pool limits are defined using controlled tags + poolLimits.forEach((poolLimitName, value) -> { + // only numeric limits are supported + if (value == null || !(value instanceof Number)) { + return; + } + double poolLimitValue = ((Number)value).doubleValue(); + if (poolLimitValue <= 0) { + return; + } + Function<Map<String, Object>, Double> func = controlledToMonitored.get(poolLimitName); + if (func == null) { + return; + } + Double totalValue = func.apply(totalValues); + if (totalValue.doubleValue() <= 0.0) { + return; + } + double totalDelta = poolLimitValue - totalValue.doubleValue(); + + // dead band to avoid thrashing + if (Math.abs(totalDelta / poolLimitValue) < deadBand) { + return; + } + + List<SolrCache> adjustableComponents = new ArrayList<>(); + components.forEach((name, component) -> { + Map<String, Object> resourceLimits = getResourceLimits((SolrCache) component); + Object limit = resourceLimits.get(poolLimitName); + // XXX we could attempt here to control eg. ramBytesUsed by adjusting maxSize limit + // XXX and vice versa if the current limit is undefined or unsupported + if (limit == null || !(limit instanceof Number)) { + return; + } + double currentResourceLimit = ((Number)limit).doubleValue(); + if (currentResourceLimit <= 0) { // undefined or unsupported + return; + } + adjustableComponents.add(component); + }); + optimize(adjustableComponents, currentValues, poolLimitName, poolLimitValue, totalValue.doubleValue()); + }); + } + + /** + * Manage all eligible components that support this pool limit. + */ + private void optimize(List<SolrCache> components, Map<String, Map<String, Object>> currentValues, String limitName, + double poolLimitValue, double totalValue) { + // changeRatio > 1.0 means there are available free resources + // changeRatio < 1.0 means there's shortage of resources + final AtomicReference<Double> changeRatio = new AtomicReference<>(poolLimitValue / totalValue); + + // ========================== OPTIMIZATION ============================== + // if the situation is not critical (ie. total consumption is less than max) + // try to proactively optimize by reducing the size of caches with too high hitRatio + // (because a lower hit ratio is still acceptable if it means saving resources) and + // expand the size of caches with too low hitRatio + final AtomicReference<Double> newTotalValue = new AtomicReference<>(totalValue); + components.forEach(component -> { + long currentLookups = ((Number)currentValues.get(component.getManagedComponentId().toString()).get(SolrCache.LOOKUPS_PARAM)).longValue(); + long lastLookups = lookups.computeIfAbsent(component.getManagedComponentId().toString(), k -> 0L); + if (currentLookups < lastLookups + lookupDelta) { + // too little data, skip the optimization + return; + } + Map<String, Object> resourceLimits = getResourceLimits(component); + double currentLimit = ((Number)resourceLimits.get(limitName)).doubleValue(); + double currentHitRatio = ((Number)currentValues.get(component.getManagedComponentId().toString()).get(SolrCache.HIT_RATIO_PARAM)).doubleValue(); + Number initialLimit = (Number)initialComponentLimits.get(component.getManagedComponentId().toString()).get(limitName); + if (initialLimit == null) { + // can't optimize because we don't know how far off we are from the initial setting + return; + } + if (currentHitRatio < targetHitRatio) { + if (changeRatio.get() < 1.0) { + // don't expand if we're already short on resources + return; + } + // expand to increase the hitRatio, but not more than maxAdjustRatio from the initialLimit + double newLimit = currentLimit * changeRatio.get(); Review comment: Good point, fixed. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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