atris commented on a change in pull request #1626: URL: https://github.com/apache/lucene-solr/pull/1626#discussion_r447185389
########## File path: solr/core/src/java/org/apache/solr/util/circuitbreaker/MemoryCircuitBreaker.java ########## @@ -0,0 +1,97 @@ +/* + * 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.util.circuitbreaker; + +import java.lang.management.ManagementFactory; +import java.lang.management.MemoryMXBean; + +import org.apache.solr.core.SolrCore; + +/** + * Tracks the current JVM heap usage and triggers if it exceeds the defined percentage of the maximum + * heap size allocated to the JVM. This circuit breaker is a part of the default CircuitBreakerManager + * so is checked for every request -- hence it is realtime. Once the memory usage goes below the threshold, + * it will start allowing queries again. + * + * The memory threshold is defined as a percentage of the maximum memory allocated -- see memoryCircuitBreakerThreshold + * in solrconfig.xml + */ + +public class MemoryCircuitBreaker extends CircuitBreaker { + private static final MemoryMXBean MEMORY_MX_BEAN = ManagementFactory.getMemoryMXBean(); + + private final long currentMaxHeap = MEMORY_MX_BEAN.getHeapMemoryUsage().getMax(); + + // Assumption -- the value of these parameters will be set correctly before invoking printDebugInfo() + private ThreadLocal<Long> seenMemory = new ThreadLocal<>(); + private ThreadLocal<Long> allowedMemory = new ThreadLocal<>(); + + public MemoryCircuitBreaker(SolrCore solrCore) { + super(solrCore); + + if (currentMaxHeap <= 0) { + throw new IllegalArgumentException("Invalid JVM state for the max heap usage"); + } + } + + // TODO: An optimization can be to trip the circuit breaker for a duration of time + // after the circuit breaker condition is matched. This will optimize for per call + // overhead of calculating the condition parameters but can result in false positives. + @Override + public boolean isCircuitBreakerGauntletTripped() { + if (!isCircuitBreakerEnabled()) { + return false; + } + + allowedMemory.set(getCurrentMemoryThreshold()); + + seenMemory.set(calculateLiveMemoryUsage()); + + return (seenMemory.get() >= allowedMemory.get()); + } + + @Override + public String printDebugInfo() { + return "seenMemory=" + seenMemory.get() + " allowedMemory=" + allowedMemory.get(); + } + + private long getCurrentMemoryThreshold() { + int thresholdValueInPercentage = solrCore.getSolrConfig().memoryCircuitBreakerThreshold; + double thresholdInFraction = thresholdValueInPercentage / (double) 100; + long actualLimit = (long) (currentMaxHeap * thresholdInFraction); + + if (actualLimit <= 0) { + throw new IllegalStateException("Memory limit cannot be less than or equal to zero"); + } + + return actualLimit; + } + + /** + * Calculate the live memory usage for the system. This method has package visibility + * to allow using for testing + * @return Memory usage in bytes + */ + protected long calculateLiveMemoryUsage() { + // NOTE: MemoryUsageGaugeSet provides memory usage statistics but we do not use them + // here since MemoryUsageGaugeSet provides combination of heap and non heap usage and Review comment: Better wording, thanks! ---------------------------------------------------------------- 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 --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
