nipunbatra8 commented on code in PR #14964: URL: https://github.com/apache/lucene/pull/14964#discussion_r2252161206
########## lucene/core/src/java/org/apache/lucene/index/BandwidthCappedMergeScheduler.java: ########## @@ -0,0 +1,159 @@ +/* + * 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.lucene.index; + +import java.io.IOException; +import org.apache.lucene.index.MergePolicy.OneMerge; + +/** + * A {@link MergeScheduler} that extends {@link ConcurrentMergeScheduler} with bandwidth tracking + * and limiting capabilities. This scheduler maintains a bandwidth rate bucket that is divided among + * active merges. When bandwidth is limited, merges are throttled to preserve system resources. + * + * <p>Key features: Global bandwidth rate bucket with configurable capacity, dynamic per-merge + * throttling. + * + * @lucene.experimental + */ +// nocommit +public class BandwidthCappedMergeScheduler extends ConcurrentMergeScheduler { + + /** Floor for IO write rate limit (we will never go any lower than this) */ + private static final double MIN_MERGE_MB_PER_SEC = 5.0; + + /** Ceiling for IO write rate limit (we will never go any higher than this) */ + private static final double MAX_MERGE_MB_PER_SEC = 10240.0; + + /** Initial value for IO write rate limit */ + private static final double START_MB_PER_SEC = 1000.0; + + /** Global bandwidth rate bucket in MB/s */ + private double bandwidthRateBucket = START_MB_PER_SEC; + + /** Default constructor with 1000 MB/s bandwidth rate bucket */ + public BandwidthCappedMergeScheduler() { + super(); + } + + /** Set the global bandwidth rate bucket in MB/s (default 1000 MB/s) */ + public void setBandwidthRateBucket(double mbPerSec) { + if (mbPerSec < MIN_MERGE_MB_PER_SEC || mbPerSec > MAX_MERGE_MB_PER_SEC) { + throw new IllegalArgumentException( + "Bandwidth rate must be between " + + MIN_MERGE_MB_PER_SEC + + " and " + + MAX_MERGE_MB_PER_SEC + + " MB/s"); + } + this.bandwidthRateBucket = mbPerSec; + updateMergeThreads(); + } + + /** Get the global bandwidth rate bucket in MB/s */ + public double getBandwidthRateBucket() { + return bandwidthRateBucket; + } + + /** Distributes the global bandwidth rate bucket evenly among all active merge threads. */ + @Override + protected synchronized void updateMergeThreads() { + super.updateMergeThreads(); + int activeMerges = 0; + for (MergeThread mergeThread : mergeThreads) { + if (mergeThread.isAlive()) { + activeMerges++; + } + } + double perMergeRate = + activeMerges > 0 + ? Math.max( + MIN_MERGE_MB_PER_SEC, + Math.min(MAX_MERGE_MB_PER_SEC, bandwidthRateBucket / activeMerges)) + : Double.POSITIVE_INFINITY; + + // Apply the calculated rate limit to each active merge thread + for (MergeThread mergeThread : mergeThreads) { + if (mergeThread.isAlive()) { + mergeThread.rateLimiter.setMBPerSec(perMergeRate); + } + } + } + + /** Creates a custom merge thread with bandwidth tracking capabilities. */ + @Override + protected synchronized MergeThread getMergeThread(MergeSource mergeSource, OneMerge merge) + throws IOException { + return new BandwidthTrackingMergeThread(mergeSource, merge); + } + + /** Returns a string representation including the current bandwidth rate bucket setting. */ + @Override + public String toString() { + return getClass().getSimpleName() + + ": " + + super.toString() + + ", bandwidthRateBucket=" + + bandwidthRateBucket + + " MB/s"; + } + + /** Merge thread that logs the rate limiter value after merge completes. */ + protected class BandwidthTrackingMergeThread extends MergeThread { + private final double mergeBandwidthMB; + + /** Creates a new BandwidthTrackingMergeThread for the given merge. */ + public BandwidthTrackingMergeThread(MergeSource mergeSource, OneMerge merge) { + super(mergeSource, merge); + this.mergeBandwidthMB = merge.estimatedMergeBytes / (1024.0 * 1024.0); + } + + @Override + public void run() { + long startTime = System.currentTimeMillis(); + try { + if (verbose()) { + message( + "Starting bandwidth-capped merge: " + + getSegmentName(merge) + + " (estimated=" + + mergeBandwidthMB + + " MB)"); + } + super.run(); // IO throttling is handled by the RateLimiter + } finally { + long duration = System.currentTimeMillis() - startTime; + if (verbose()) { + double mbPerSec = mergeBandwidthMB / Math.max(duration / 1000.0, 0.001); Review Comment: The duration or mbPerSec? I have the 0.001 to avoid division by zero problems in case the duration was computed as 0. -- 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. To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org 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
