Bring over merge metrics from stateless (#128617)

Relates to an effort to combine the merge schedulers from stateless and stateful. The stateless merge scheduler has MergeMetrics that we want in both stateless and stateful. This PR copies over the merge metrics from the stateless merge scheduler into the combined merge scheduler.

Relates ES-9687

server/src/internalClusterTest/java/org/elasticsearch/index/engine/ThreadPoolMergeSchedulerStressTestIT.java

@@ -88,12 +88,14 @@ public class ThreadPoolMergeSchedulerStressTestIT extends ESSingleNodeTestCase {
             protected ElasticsearchMergeScheduler createMergeScheduler(
                 ShardId shardId,
                 IndexSettings indexSettings,
-                @Nullable ThreadPoolMergeExecutorService threadPoolMergeExecutorService
+                @Nullable ThreadPoolMergeExecutorService threadPoolMergeExecutorService,
+                MergeMetrics mergeMetrics
             ) {
                 ElasticsearchMergeScheduler mergeScheduler = super.createMergeScheduler(
                     shardId,
                     indexSettings,
-                    threadPoolMergeExecutorService
+                    threadPoolMergeExecutorService,
+                    mergeMetrics
                 );
                 assertThat(mergeScheduler, instanceOf(ThreadPoolMergeScheduler.class));
                 // assert there is a single merge executor service for all shards

server/src/internalClusterTest/java/org/elasticsearch/index/shard/IndexShardIT.java

@@ -52,6 +52,7 @@ import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.VersionType;
 import org.elasticsearch.index.engine.CommitStats;
 import org.elasticsearch.index.engine.Engine;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.engine.NoOpEngine;
 import org.elasticsearch.index.flush.FlushStats;
 import org.elasticsearch.index.mapper.MapperMetrics;
@@ -680,7 +681,8 @@ public class IndexShardIT extends ESSingleNodeTestCase {
             null,
             MapperMetrics.NOOP,
             new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+            MergeMetrics.NOOP
         );
     }
 

server/src/internalClusterTest/java/org/elasticsearch/indices/IndexingMemoryControllerIT.java

@@ -88,7 +88,8 @@ public class IndexingMemoryControllerIT extends ESSingleNodeTestCase {
                 config.getIndexCommitListener(),
                 config.isPromotableToPrimary(),
                 config.getMapperService(),
-                config.getEngineResetLock()
+                config.getEngineResetLock(),
+                config.getMergeMetrics()
             );
         }
 

server/src/main/java/org/elasticsearch/index/IndexModule.java

@@ -43,6 +43,7 @@ import org.elasticsearch.index.cache.query.IndexQueryCache;
 import org.elasticsearch.index.cache.query.QueryCache;
 import org.elasticsearch.index.engine.Engine;
 import org.elasticsearch.index.engine.EngineFactory;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.engine.ThreadPoolMergeExecutorService;
 import org.elasticsearch.index.mapper.IdFieldMapper;
 import org.elasticsearch.index.mapper.MapperMetrics;
@@ -181,6 +182,7 @@ public final class IndexModule {
     private final MapperMetrics mapperMetrics;
     private final IndexingStatsSettings indexingStatsSettings;
     private final SearchStatsSettings searchStatsSettings;
+    private final MergeMetrics mergeMetrics;
 
     /**
      * Construct the index module for the index with the specified index settings. The index module contains extension points for plugins
@@ -190,6 +192,7 @@ public final class IndexModule {
      * @param analysisRegistry   the analysis registry
      * @param engineFactory      the engine factory
      * @param directoryFactories the available store types
+     * @param mergeMetrics
      */
     public IndexModule(
         final IndexSettings indexSettings,
@@ -203,7 +206,8 @@ public final class IndexModule {
         final MapperMetrics mapperMetrics,
         final List<SearchOperationListener> searchOperationListeners,
         final IndexingStatsSettings indexingStatsSettings,
-        final SearchStatsSettings searchStatsSettings
+        final SearchStatsSettings searchStatsSettings,
+        final MergeMetrics mergeMetrics
     ) {
         this.indexSettings = indexSettings;
         this.analysisRegistry = analysisRegistry;
@@ -220,6 +224,7 @@ public final class IndexModule {
         this.mapperMetrics = mapperMetrics;
         this.indexingStatsSettings = indexingStatsSettings;
         this.searchStatsSettings = searchStatsSettings;
+        this.mergeMetrics = mergeMetrics;
     }
 
     /**
@@ -557,7 +562,8 @@ public final class IndexModule {
                 mapperMetrics,
                 queryRewriteInterceptor,
                 indexingStatsSettings,
-                searchStatsSettings
+                searchStatsSettings,
+                mergeMetrics
             );
             success = true;
             return indexService;

server/src/main/java/org/elasticsearch/index/IndexService.java

@@ -49,6 +49,7 @@ import org.elasticsearch.index.cache.bitset.BitsetFilterCache;
 import org.elasticsearch.index.cache.query.QueryCache;
 import org.elasticsearch.index.engine.Engine;
 import org.elasticsearch.index.engine.EngineFactory;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.engine.ThreadPoolMergeExecutorService;
 import org.elasticsearch.index.fielddata.FieldDataContext;
 import org.elasticsearch.index.fielddata.IndexFieldData;
@@ -172,6 +173,7 @@ public class IndexService extends AbstractIndexComponent implements IndicesClust
     private final QueryRewriteInterceptor queryRewriteInterceptor;
     private final IndexingStatsSettings indexingStatsSettings;
     private final SearchStatsSettings searchStatsSettings;
+    private final MergeMetrics mergeMetrics;
 
     @SuppressWarnings("this-escape")
     public IndexService(
@@ -210,7 +212,8 @@ public class IndexService extends AbstractIndexComponent implements IndicesClust
         MapperMetrics mapperMetrics,
         QueryRewriteInterceptor queryRewriteInterceptor,
         IndexingStatsSettings indexingStatsSettings,
-        SearchStatsSettings searchStatsSettings
+        SearchStatsSettings searchStatsSettings,
+        MergeMetrics mergeMetrics
     ) {
         super(indexSettings);
         assert indexCreationContext != IndexCreationContext.RELOAD_ANALYZERS
@@ -297,6 +300,7 @@ public class IndexService extends AbstractIndexComponent implements IndicesClust
         }
         this.indexingStatsSettings = indexingStatsSettings;
         this.searchStatsSettings = searchStatsSettings;
+        this.mergeMetrics = mergeMetrics;
         updateFsyncTaskIfNecessary();
     }
 
@@ -588,7 +592,8 @@ public class IndexService extends AbstractIndexComponent implements IndicesClust
                 indexCommitListener,
                 mapperMetrics,
                 indexingStatsSettings,
-                searchStatsSettings
+                searchStatsSettings,
+                mergeMetrics
             );
             eventListener.indexShardStateChanged(indexShard, null, indexShard.state(), "shard created");
             eventListener.afterIndexShardCreated(indexShard);

server/src/main/java/org/elasticsearch/index/engine/EngineConfig.java

@@ -149,6 +149,8 @@ public final class EngineConfig {
 
     private final EngineResetLock engineResetLock;
 
+    private final MergeMetrics mergeMetrics;
+
     /**
      * Creates a new {@link org.elasticsearch.index.engine.EngineConfig}
      */
@@ -181,7 +183,8 @@ public final class EngineConfig {
         Engine.IndexCommitListener indexCommitListener,
         boolean promotableToPrimary,
         MapperService mapperService,
-        EngineResetLock engineResetLock
+        EngineResetLock engineResetLock,
+        MergeMetrics mergeMetrics
     ) {
         this.shardId = shardId;
         this.indexSettings = indexSettings;
@@ -229,6 +232,7 @@ public final class EngineConfig {
         // always use compound on flush - reduces # of file-handles on refresh
         this.useCompoundFile = indexSettings.getSettings().getAsBoolean(USE_COMPOUND_FILE, true);
         this.engineResetLock = engineResetLock;
+        this.mergeMetrics = mergeMetrics;
     }
 
     /**
@@ -477,4 +481,8 @@ public final class EngineConfig {
     public EngineResetLock getEngineResetLock() {
         return engineResetLock;
     }
+
+    public MergeMetrics getMergeMetrics() {
+        return mergeMetrics;
+    }
 }

server/src/main/java/org/elasticsearch/index/engine/InternalEngine.java

@@ -257,7 +257,8 @@ public class InternalEngine extends Engine {
             mergeScheduler = createMergeScheduler(
                 engineConfig.getShardId(),
                 engineConfig.getIndexSettings(),
-                engineConfig.getThreadPoolMergeExecutorService()
+                engineConfig.getThreadPoolMergeExecutorService(),
+                engineConfig.getMergeMetrics()
             );
             scheduler = mergeScheduler.getMergeScheduler();
             throttle = new IndexThrottle(pauseIndexingOnThrottle);
@@ -2908,10 +2909,11 @@ public class InternalEngine extends Engine {
     protected ElasticsearchMergeScheduler createMergeScheduler(
         ShardId shardId,
         IndexSettings indexSettings,
-        @Nullable ThreadPoolMergeExecutorService threadPoolMergeExecutorService
+        @Nullable ThreadPoolMergeExecutorService threadPoolMergeExecutorService,
+        MergeMetrics mergeMetrics
     ) {
         if (threadPoolMergeExecutorService != null) {
-            return new EngineThreadPoolMergeScheduler(shardId, indexSettings, threadPoolMergeExecutorService);
+            return new EngineThreadPoolMergeScheduler(shardId, indexSettings, threadPoolMergeExecutorService, mergeMetrics);
         } else {
             return new EngineConcurrentMergeScheduler(shardId, indexSettings);
         }
@@ -2921,9 +2923,10 @@ public class InternalEngine extends Engine {
         EngineThreadPoolMergeScheduler(
             ShardId shardId,
             IndexSettings indexSettings,
-            ThreadPoolMergeExecutorService threadPoolMergeExecutorService
+            ThreadPoolMergeExecutorService threadPoolMergeExecutorService,
+            MergeMetrics mergeMetrics
         ) {
-            super(shardId, indexSettings, threadPoolMergeExecutorService, InternalEngine.this::estimateMergeBytes);
+            super(shardId, indexSettings, threadPoolMergeExecutorService, InternalEngine.this::estimateMergeBytes, mergeMetrics);
         }
 
         @Override

server/src/main/java/org/elasticsearch/index/engine/MergeMetrics.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.index.engine;
+
+import org.apache.lucene.index.MergePolicy;
+import org.elasticsearch.index.merge.OnGoingMerge;
+import org.elasticsearch.telemetry.TelemetryProvider;
+import org.elasticsearch.telemetry.metric.LongCounter;
+import org.elasticsearch.telemetry.metric.LongHistogram;
+import org.elasticsearch.telemetry.metric.LongWithAttributes;
+import org.elasticsearch.telemetry.metric.MeterRegistry;
+
+import java.util.concurrent.atomic.AtomicLong;
+
+public class MergeMetrics {
+
+    public static final String MERGE_SEGMENTS_SIZE = "es.merge.segments.size";
+    public static final String MERGE_DOCS_TOTAL = "es.merge.docs.total";
+    public static final String MERGE_SEGMENTS_QUEUED_USAGE = "es.merge.segments.queued.usage";
+    public static final String MERGE_SEGMENTS_RUNNING_USAGE = "es.merge.segments.running.usage";
+    public static final String MERGE_SEGMENTS_MERGED_SIZE = "es.merge.segments.merged.size";
+    public static final String MERGE_QUEUED_ESTIMATED_MEMORY_SIZE = "es.merge.segments.memory.size";
+    public static final String MERGE_TIME_IN_SECONDS = "es.merge.time";
+    public static MergeMetrics NOOP = new MergeMetrics(TelemetryProvider.NOOP.getMeterRegistry());
+
+    private final LongCounter mergeSizeInBytes;
+    private final LongCounter mergeMergedSegmentSizeInBytes;
+    private final LongCounter mergeNumDocs;
+    private final LongHistogram mergeTimeInSeconds;
+
+    private final AtomicLong runningMergeSizeInBytes = new AtomicLong();
+    private final AtomicLong queuedMergeSizeInBytes = new AtomicLong();
+    private final AtomicLong queuedEstimatedMergeMemoryInBytes = new AtomicLong();
+
+    public MergeMetrics(MeterRegistry meterRegistry) {
+        mergeSizeInBytes = meterRegistry.registerLongCounter(MERGE_SEGMENTS_SIZE, "Total size of segments merged", "bytes");
+        meterRegistry.registerLongGauge(
+            MERGE_SEGMENTS_QUEUED_USAGE,
+            "Total usage of segments queued to be merged",
+            "bytes",
+            () -> new LongWithAttributes(queuedMergeSizeInBytes.get())
+        );
+        meterRegistry.registerLongGauge(
+            MERGE_SEGMENTS_RUNNING_USAGE,
+            "Total usage of segments currently being merged",
+            "bytes",
+            () -> new LongWithAttributes(runningMergeSizeInBytes.get())
+        );
+        mergeMergedSegmentSizeInBytes = meterRegistry.registerLongCounter(
+            MERGE_SEGMENTS_MERGED_SIZE,
+            "Total size of the new merged segments",
+            "bytes"
+        );
+        mergeNumDocs = meterRegistry.registerLongCounter(MERGE_DOCS_TOTAL, "Total number of documents merged", "documents");
+        mergeTimeInSeconds = meterRegistry.registerLongHistogram(MERGE_TIME_IN_SECONDS, "Merge time in seconds", "seconds");
+        meterRegistry.registerLongGauge(
+            MERGE_QUEUED_ESTIMATED_MEMORY_SIZE,
+            "Estimated memory usage for queued merges",
+            "bytes",
+            () -> new LongWithAttributes(queuedEstimatedMergeMemoryInBytes.get())
+        );
+    }
+
+    public void incrementQueuedMergeBytes(OnGoingMerge currentMerge, long estimatedMemorySize) {
+        queuedMergeSizeInBytes.getAndAdd(currentMerge.getTotalBytesSize());
+        queuedEstimatedMergeMemoryInBytes.getAndAdd(estimatedMemorySize);
+    }
+
+    public void moveQueuedMergeBytesToRunning(OnGoingMerge currentMerge, long estimatedMemorySize) {
+        long totalSize = currentMerge.getTotalBytesSize();
+        queuedMergeSizeInBytes.getAndAdd(-totalSize);
+        runningMergeSizeInBytes.getAndAdd(totalSize);
+        queuedEstimatedMergeMemoryInBytes.getAndAdd(-estimatedMemorySize);
+    }
+
+    public void decrementRunningMergeBytes(OnGoingMerge currentMerge) {
+        runningMergeSizeInBytes.getAndAdd(-currentMerge.getTotalBytesSize());
+    }
+
+    public void markMergeMetrics(MergePolicy.OneMerge currentMerge, long mergedSegmentSize, long tookMillis) {
+        mergeSizeInBytes.incrementBy(currentMerge.totalBytesSize());
+        mergeMergedSegmentSizeInBytes.incrementBy(mergedSegmentSize);
+        mergeNumDocs.incrementBy(currentMerge.totalNumDocs());
+        mergeTimeInSeconds.record(tookMillis / 1000);
+    }
+
+    public long getQueuedMergeSizeInBytes() {
+        return queuedMergeSizeInBytes.get();
+    }
+
+    public long getRunningMergeSizeInBytes() {
+        return runningMergeSizeInBytes.get();
+    }
+}

server/src/main/java/org/elasticsearch/index/engine/ThreadPoolMergeScheduler.java

@@ -64,6 +64,7 @@ public class ThreadPoolMergeScheduler extends MergeScheduler implements Elastics
     private final MergeSchedulerConfig config;
     protected final Logger logger;
     private final MergeTracking mergeTracking;
+    private final MergeMetrics mergeMetrics;
     private final ThreadPoolMergeExecutorService threadPoolMergeExecutorService;
     private final PriorityQueue<MergeTask> backloggedMergeTasks = new PriorityQueue<>(
         16,
@@ -86,16 +87,19 @@ public class ThreadPoolMergeScheduler extends MergeScheduler implements Elastics
      * @param indexSettings                  used to obtain the {@link MergeSchedulerConfig}
      * @param threadPoolMergeExecutorService the executor service used to execute merge tasks from this scheduler
      * @param mergeMemoryEstimateProvider    provides an estimate for how much memory a merge will take
+     * @param mergeMetrics metrics related to merges
      */
     public ThreadPoolMergeScheduler(
         ShardId shardId,
         IndexSettings indexSettings,
         ThreadPoolMergeExecutorService threadPoolMergeExecutorService,
-        MergeMemoryEstimateProvider mergeMemoryEstimateProvider
+        MergeMemoryEstimateProvider mergeMemoryEstimateProvider,
+        MergeMetrics mergeMetrics
     ) {
         this.shardId = shardId;
         this.config = indexSettings.getMergeSchedulerConfig();
         this.logger = Loggers.getLogger(getClass(), shardId);
+        this.mergeMetrics = mergeMetrics;
         this.mergeTracking = new MergeTracking(
             logger,
             () -> this.config.isAutoThrottle()
@@ -226,6 +230,7 @@ public class ThreadPoolMergeScheduler extends MergeScheduler implements Elastics
     boolean submitNewMergeTask(MergeSource mergeSource, MergePolicy.OneMerge merge, MergeTrigger mergeTrigger) {
         try {
             MergeTask mergeTask = newMergeTask(mergeSource, merge, mergeTrigger);
+            mergeMetrics.incrementQueuedMergeBytes(mergeTask.getOnGoingMerge(), mergeTask.getMergeMemoryEstimateBytes());
             mergeQueued(mergeTask.onGoingMerge);
             return threadPoolMergeExecutorService.submitMergeTask(mergeTask);
         } finally {
@@ -310,6 +315,7 @@ public class ThreadPoolMergeScheduler extends MergeScheduler implements Elastics
 
     private void mergeTaskDone(OnGoingMerge merge) {
         doneMergeTaskCount.incrementAndGet();
+        mergeMetrics.decrementRunningMergeBytes(merge);
         mergeExecutedOrAborted(merge);
         checkMergeTaskThrottling();
     }
@@ -437,6 +443,7 @@ public class ThreadPoolMergeScheduler extends MergeScheduler implements Elastics
             assert hasStartedRunning() == false;
             assert ThreadPoolMergeScheduler.this.runningMergeTasks.containsKey(onGoingMerge.getMerge())
                 : "runNowOrBacklog must be invoked before actually running the merge task";
+            boolean success = false;
             try {
                 beforeMerge(onGoingMerge);
                 try {
@@ -444,11 +451,13 @@ public class ThreadPoolMergeScheduler extends MergeScheduler implements Elastics
                         throw new IllegalStateException("The merge task is already started or aborted");
                     }
                     mergeTracking.mergeStarted(onGoingMerge);
+                    mergeMetrics.moveQueuedMergeBytesToRunning(onGoingMerge, mergeMemoryEstimateBytes);
                     if (verbose()) {
                         message(String.format(Locale.ROOT, "merge task %s start", this));
                     }
                     try {
                         doMerge(mergeSource, onGoingMerge.getMerge());
+                        success = onGoingMerge.getMerge().isAborted() == false;
                         if (verbose()) {
                             message(
                                 String.format(
@@ -468,6 +477,10 @@ public class ThreadPoolMergeScheduler extends MergeScheduler implements Elastics
                         }
                     } finally {
                         long tookMS = TimeValue.nsecToMSec(System.nanoTime() - mergeStartTimeNS.get());
+                        if (success) {
+                            long newSegmentSize = getNewSegmentSize(onGoingMerge.getMerge());
+                            mergeMetrics.markMergeMetrics(onGoingMerge.getMerge(), newSegmentSize, tookMS);
+                        }
                         mergeTracking.mergeFinished(onGoingMerge.getMerge(), onGoingMerge, tookMS);
                     }
                 } finally {
@@ -508,6 +521,8 @@ public class ThreadPoolMergeScheduler extends MergeScheduler implements Elastics
             // {@code IndexWriter} checks the abort flag internally, while running the merge.
             // The segments of an aborted merge become available to subsequent merges.
             onGoingMerge.getMerge().setAborted();
+
+            mergeMetrics.moveQueuedMergeBytesToRunning(onGoingMerge, mergeMemoryEstimateBytes);
             try {
                 if (verbose()) {
                     message(String.format(Locale.ROOT, "merge task %s start abort", this));
@@ -554,6 +569,21 @@ public class ThreadPoolMergeScheduler extends MergeScheduler implements Elastics
             return onGoingMerge;
         }
 
+        private static long getNewSegmentSize(MergePolicy.OneMerge currentMerge) {
+            try {
+                return currentMerge.getMergeInfo() != null ? currentMerge.getMergeInfo().sizeInBytes() : currentMerge.estimatedMergeBytes;
+            } catch (IOException e) {
+                // For stateless only: It is (rarely) possible that the merged segment could be merged away by the IndexWriter prior to
+                // reaching this point. Once the IW creates the new segment, it could be exposed to be included in a new merge. That
+                // merge can be executed concurrently if more than 1 merge threads are configured. That new merge allows this IW to
+                // delete segment created by this merge. Although the files may still be available in the object store for executing
+                // searches, the IndexDirectory will no longer have references to the underlying segment files and will throw file not
+                // found if we try to read them. In this case, we will ignore that exception (which would otherwise fail the shard) and
+                // use the originally estimated merge size for metrics.
+                return currentMerge.estimatedMergeBytes;
+            }
+        }
+
         @Override
         public String toString() {
             return name + (onGoingMerge.getMerge().isAborted() ? " (aborted)" : "");

server/src/main/java/org/elasticsearch/index/shard/IndexShard.java

@@ -91,6 +91,7 @@ import org.elasticsearch.index.engine.Engine.GetResult;
 import org.elasticsearch.index.engine.EngineConfig;
 import org.elasticsearch.index.engine.EngineException;
 import org.elasticsearch.index.engine.EngineFactory;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.engine.ReadOnlyEngine;
 import org.elasticsearch.index.engine.RefreshFailedEngineException;
 import org.elasticsearch.index.engine.SafeCommitInfo;
@@ -269,6 +270,7 @@ public class IndexShard extends AbstractIndexShardComponent implements IndicesCl
     private final MeanMetric externalRefreshMetric = new MeanMetric();
     private final MeanMetric flushMetric = new MeanMetric();
     private final CounterMetric periodicFlushMetric = new CounterMetric();
+    private final MergeMetrics mergeMetrics;
 
     private final ShardEventListener shardEventListener = new ShardEventListener();
 
@@ -343,7 +345,8 @@ public class IndexShard extends AbstractIndexShardComponent implements IndicesCl
         final Engine.IndexCommitListener indexCommitListener,
         final MapperMetrics mapperMetrics,
         final IndexingStatsSettings indexingStatsSettings,
-        final SearchStatsSettings searchStatsSettings
+        final SearchStatsSettings searchStatsSettings,
+        final MergeMetrics mergeMetrics
     ) throws IOException {
         super(shardRouting.shardId(), indexSettings);
         assert shardRouting.initializing();
@@ -432,6 +435,7 @@ public class IndexShard extends AbstractIndexShardComponent implements IndicesCl
         this.refreshFieldHasValueListener = new RefreshFieldHasValueListener();
         this.relativeTimeInNanosSupplier = relativeTimeInNanosSupplier;
         this.indexCommitListener = indexCommitListener;
+        this.mergeMetrics = mergeMetrics;
     }
 
     public ThreadPool getThreadPool() {
@@ -3755,7 +3759,8 @@ public class IndexShard extends AbstractIndexShardComponent implements IndicesCl
             indexCommitListener,
             routingEntry().isPromotableToPrimary(),
             mapperService(),
-            engineResetLock
+            engineResetLock,
+            mergeMetrics
         );
     }
 

server/src/main/java/org/elasticsearch/indices/IndicesService.java

@@ -98,6 +98,7 @@ import org.elasticsearch.index.cache.request.ShardRequestCache;
 import org.elasticsearch.index.engine.CommitStats;
 import org.elasticsearch.index.engine.EngineFactory;
 import org.elasticsearch.index.engine.InternalEngineFactory;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.engine.NoOpEngine;
 import org.elasticsearch.index.engine.ReadOnlyEngine;
 import org.elasticsearch.index.engine.ThreadPoolMergeExecutorService;
@@ -283,6 +284,7 @@ public class IndicesService extends AbstractLifecycleComponent
     final SlowLogFieldProvider slowLogFieldProvider; // pkg-private for testingå
     private final IndexingStatsSettings indexStatsSettings;
     private final SearchStatsSettings searchStatsSettings;
+    private final MergeMetrics mergeMetrics;
 
     @Override
     protected void doStart() {
@@ -358,6 +360,7 @@ public class IndicesService extends AbstractLifecycleComponent
         this.requestCacheKeyDifferentiator = builder.requestCacheKeyDifferentiator;
         this.queryRewriteInterceptor = builder.queryRewriteInterceptor;
         this.mapperMetrics = builder.mapperMetrics;
+        this.mergeMetrics = builder.mergeMetrics;
         // doClose() is called when shutting down a node, yet there might still be ongoing requests
         // that we need to wait for before closing some resources such as the caches. In order to
         // avoid closing these resources while ongoing requests are still being processed, we use a
@@ -801,7 +804,8 @@ public class IndicesService extends AbstractLifecycleComponent
             mapperMetrics,
             searchOperationListeners,
             indexStatsSettings,
-            searchStatsSettings
+            searchStatsSettings,
+            mergeMetrics
         );
         for (IndexingOperationListener operationListener : indexingOperationListeners) {
             indexModule.addIndexOperationListener(operationListener);
@@ -900,7 +904,8 @@ public class IndicesService extends AbstractLifecycleComponent
             mapperMetrics,
             searchOperationListeners,
             indexStatsSettings,
-            searchStatsSettings
+            searchStatsSettings,
+            mergeMetrics
         );
         pluginsService.forEach(p -> p.onIndexModule(indexModule));
         return indexModule.newIndexMapperService(clusterService, parserConfig, mapperRegistry, scriptService);

server/src/main/java/org/elasticsearch/indices/IndicesServiceBuilder.java

@@ -27,6 +27,7 @@ import org.elasticsearch.index.SlowLogFieldProvider;
 import org.elasticsearch.index.SlowLogFields;
 import org.elasticsearch.index.analysis.AnalysisRegistry;
 import org.elasticsearch.index.engine.EngineFactory;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.mapper.MapperMetrics;
 import org.elasticsearch.index.mapper.MapperRegistry;
 import org.elasticsearch.index.shard.SearchOperationListener;
@@ -79,6 +80,7 @@ public class IndicesServiceBuilder {
     @Nullable
     CheckedBiConsumer<ShardSearchRequest, StreamOutput, IOException> requestCacheKeyDifferentiator;
     MapperMetrics mapperMetrics;
+    MergeMetrics mergeMetrics;
     List<SearchOperationListener> searchOperationListener = List.of();
     QueryRewriteInterceptor queryRewriteInterceptor = null;
     SlowLogFieldProvider slowLogFieldProvider = new SlowLogFieldProvider() {
@@ -206,6 +208,11 @@ public class IndicesServiceBuilder {
         return this;
     }
 
+    public IndicesServiceBuilder mergeMetrics(MergeMetrics mergeMetrics) {
+        this.mergeMetrics = mergeMetrics;
+        return this;
+    }
+
     public List<SearchOperationListener> searchOperationListeners() {
         return searchOperationListener;
     }
@@ -244,6 +251,7 @@ public class IndicesServiceBuilder {
         Objects.requireNonNull(indexFoldersDeletionListeners);
         Objects.requireNonNull(snapshotCommitSuppliers);
         Objects.requireNonNull(mapperMetrics);
+        Objects.requireNonNull(mergeMetrics);
         Objects.requireNonNull(searchOperationListener);
         Objects.requireNonNull(slowLogFieldProvider);
 

server/src/main/java/org/elasticsearch/node/NodeConstruction.java

@@ -116,6 +116,7 @@ import org.elasticsearch.index.IndexingPressure;
 import org.elasticsearch.index.SlowLogFieldProvider;
 import org.elasticsearch.index.SlowLogFields;
 import org.elasticsearch.index.analysis.AnalysisRegistry;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.mapper.MapperMetrics;
 import org.elasticsearch.index.mapper.SourceFieldMetrics;
 import org.elasticsearch.index.search.stats.ShardSearchPhaseAPMMetrics;
@@ -806,6 +807,9 @@ class NodeConstruction {
             threadPool::relativeTimeInMillis
         );
         MapperMetrics mapperMetrics = new MapperMetrics(sourceFieldMetrics);
+
+        MergeMetrics mergeMetrics = new MergeMetrics(telemetryProvider.getMeterRegistry());
+
         final List<SearchOperationListener> searchOperationListeners = List.of(
             new ShardSearchPhaseAPMMetrics(telemetryProvider.getMeterRegistry())
         );
@@ -894,6 +898,7 @@ class NodeConstruction {
             .valuesSourceRegistry(searchModule.getValuesSourceRegistry())
             .requestCacheKeyDifferentiator(searchModule.getRequestCacheKeyDifferentiator())
             .mapperMetrics(mapperMetrics)
+            .mergeMetrics(mergeMetrics)
             .searchOperationListeners(searchOperationListeners)
             .slowLogFieldProvider(slowLogFieldProvider)
             .build();
@@ -1290,6 +1295,7 @@ class NodeConstruction {
             b.bind(FailureStoreMetrics.class).toInstance(failureStoreMetrics);
             b.bind(ShutdownPrepareService.class).toInstance(shutdownPrepareService);
             b.bind(OnlinePrewarmingService.class).toInstance(onlinePrewarmingService);
+            b.bind(MergeMetrics.class).toInstance(mergeMetrics);
         });
 
         if (ReadinessService.enabled(environment)) {

server/src/test/java/org/elasticsearch/index/IndexModuleTests.java

@@ -60,6 +60,7 @@ import org.elasticsearch.index.engine.Engine;
 import org.elasticsearch.index.engine.EngineTestCase;
 import org.elasticsearch.index.engine.InternalEngine;
 import org.elasticsearch.index.engine.InternalEngineFactory;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.engine.ThreadPoolMergeExecutorService;
 import org.elasticsearch.index.engine.ThreadPoolMergeScheduler;
 import org.elasticsearch.index.fielddata.IndexFieldDataCache;
@@ -256,7 +257,8 @@ public class IndexModuleTests extends ESTestCase {
             MapperMetrics.NOOP,
             emptyList(),
             new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+            MergeMetrics.NOOP
         );
         module.setReaderWrapper(s -> new Wrapper());
 
@@ -286,7 +288,8 @@ public class IndexModuleTests extends ESTestCase {
             MapperMetrics.NOOP,
             emptyList(),
             new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+            MergeMetrics.NOOP
         );
 
         final IndexService indexService = newIndexService(module);
@@ -314,7 +317,8 @@ public class IndexModuleTests extends ESTestCase {
             MapperMetrics.NOOP,
             emptyList(),
             new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+            MergeMetrics.NOOP
         );
 
         module.setDirectoryWrapper(new TestDirectoryWrapper());
@@ -670,7 +674,8 @@ public class IndexModuleTests extends ESTestCase {
             MapperMetrics.NOOP,
             emptyList(),
             new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+            MergeMetrics.NOOP
         );
 
         final IndexService indexService = newIndexService(module);
@@ -695,7 +700,8 @@ public class IndexModuleTests extends ESTestCase {
             MapperMetrics.NOOP,
             emptyList(),
             new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+            MergeMetrics.NOOP
         );
 
         final AtomicLong lastAcquiredPrimaryTerm = new AtomicLong();
@@ -800,7 +806,8 @@ public class IndexModuleTests extends ESTestCase {
             MapperMetrics.NOOP,
             emptyList(),
             new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+            MergeMetrics.NOOP
         );
     }
 

server/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java

@@ -3635,7 +3635,8 @@ public class InternalEngineTests extends EngineTestCase {
             null,
             true,
             config.getMapperService(),
-            config.getEngineResetLock()
+            config.getEngineResetLock(),
+            config.getMergeMetrics()
         );
         expectThrows(EngineCreationFailureException.class, () -> new InternalEngine(brokenConfig));
 
@@ -7243,7 +7244,8 @@ public class InternalEngineTests extends EngineTestCase {
                 config.getIndexCommitListener(),
                 config.isPromotableToPrimary(),
                 config.getMapperService(),
-                config.getEngineResetLock()
+                config.getEngineResetLock(),
+                config.getMergeMetrics()
             );
             try (InternalEngine engine = createEngine(configWithWarmer)) {
                 assertThat(warmedUpReaders, empty());

server/src/test/java/org/elasticsearch/index/engine/ThreadPoolMergeSchedulerTests.java

@@ -46,6 +46,7 @@ import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.lessThanOrEqualTo;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
@@ -74,12 +75,14 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
         nodeEnvironment = newNodeEnvironment(settings);
         ThreadPoolMergeExecutorService threadPoolMergeExecutorService = ThreadPoolMergeExecutorServiceTests
             .getThreadPoolMergeExecutorService(threadPoolTaskQueue.getThreadPool(), settings, nodeEnvironment);
+        var mergeMetrics = mock(MergeMetrics.class);
         try (
             ThreadPoolMergeScheduler threadPoolMergeScheduler = new ThreadPoolMergeScheduler(
                 new ShardId("index", "_na_", 1),
                 IndexSettingsModule.newIndexSettings("index", Settings.EMPTY),
                 threadPoolMergeExecutorService,
-                merge -> 0
+                merge -> 0,
+                mergeMetrics
             )
         ) {
             List<OneMerge> executedMergesList = new ArrayList<>();
@@ -97,9 +100,19 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                     return null;
                 }).when(mergeSource).merge(any(OneMerge.class));
                 threadPoolMergeScheduler.merge(mergeSource, randomFrom(MergeTrigger.values()));
+
+                // verify queued byte metric is recorded for each merge
+                verify(mergeMetrics, times(i + 1)).incrementQueuedMergeBytes(any(), anyLong());
             }
+
             threadPoolTaskQueue.runAllTasks();
             assertThat(executedMergesList.size(), is(mergeCount));
+
+            // verify metrics are reported for each merge
+            verify(mergeMetrics, times(mergeCount)).moveQueuedMergeBytesToRunning(any(), anyLong());
+            verify(mergeMetrics, times(mergeCount)).decrementRunningMergeBytes(any());
+            verify(mergeMetrics, times(mergeCount)).markMergeMetrics(any(), anyLong(), anyLong());
+
             // assert merges are executed in ascending size order
             for (int i = 1; i < mergeCount; i++) {
                 assertThat(
@@ -113,6 +126,7 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
 
     public void testSimpleMergeTaskBacklogging() {
         int mergeExecutorThreadCount = randomIntBetween(1, 5);
+        var mergeMetrics = mock(MergeMetrics.class);
         Settings mergeSchedulerSettings = Settings.builder()
             .put(MergeSchedulerConfig.MAX_THREAD_COUNT_SETTING.getKey(), mergeExecutorThreadCount)
             .build();
@@ -122,7 +136,8 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
             new ShardId("index", "_na_", 1),
             IndexSettingsModule.newIndexSettings("index", mergeSchedulerSettings),
             threadPoolMergeExecutorService,
-            merge -> 0
+            merge -> 0,
+            mergeMetrics
         );
         // more merge tasks than merge threads
         int mergeCount = mergeExecutorThreadCount + randomIntBetween(1, 5);
@@ -143,6 +158,9 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
         }
         assertThat(threadPoolMergeScheduler.getRunningMergeTasks().size(), is(mergeExecutorThreadCount));
         assertThat(threadPoolMergeScheduler.getBackloggedMergeTasks().size(), is(mergeCount - mergeExecutorThreadCount));
+
+        // verify no metrics are recorded as no merges have been queued or executed through the merge scheduler
+        verifyNoInteractions(mergeMetrics);
     }
 
     public void testSimpleMergeTaskReEnqueueingBySize() {
@@ -156,7 +174,8 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
             new ShardId("index", "_na_", 1),
             IndexSettingsModule.newIndexSettings("index", mergeSchedulerSettings),
             threadPoolMergeExecutorService,
-            merge -> 0
+            merge -> 0,
+            MergeMetrics.NOOP
         );
         // sort backlogged merges by size
         PriorityQueue<MergeTask> backloggedMergeTasks = new PriorityQueue<>(
@@ -388,7 +407,8 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                     new ShardId("index", "_na_", 1),
                     IndexSettingsModule.newIndexSettings("index", settings),
                     threadPoolMergeExecutorService,
-                    merge -> 0
+                    merge -> 0,
+                    MergeMetrics.NOOP
                 )
             ) {
                 MergeSource mergeSource = mock(MergeSource.class);
@@ -454,6 +474,7 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
             // disable fs available disk space feature for this test
             .put(ThreadPoolMergeExecutorService.INDICES_MERGE_DISK_CHECK_INTERVAL_SETTING.getKey(), "0s")
             .build();
+        var mergeMetrics = mock(MergeMetrics.class);
         nodeEnvironment = newNodeEnvironment(settings);
         try (TestThreadPool testThreadPool = new TestThreadPool("test", settings)) {
             ThreadPoolMergeExecutorService threadPoolMergeExecutorService = ThreadPoolMergeExecutorServiceTests
@@ -465,7 +486,8 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                     new ShardId("index", "_na_", 1),
                     IndexSettingsModule.newIndexSettings("index", settings),
                     threadPoolMergeExecutorService,
-                    merge -> 0
+                    merge -> 0,
+                    mergeMetrics
                 )
             ) {
                 // at least 1 extra merge than there are concurrently allowed
@@ -485,7 +507,11 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                         return null;
                     }).when(mergeSource).merge(any(OneMerge.class));
                     threadPoolMergeScheduler.merge(mergeSource, randomFrom(MergeTrigger.values()));
+
+                    // verify queued byte metric is recorded for each merge
+                    verify(mergeMetrics, times(i + 1)).incrementQueuedMergeBytes(any(), anyLong());
                 }
+
                 for (int completedMergesCount = 0; completedMergesCount < mergeCount
                     - mergeSchedulerMaxThreadCount; completedMergesCount++) {
                     int finalCompletedMergesCount = completedMergesCount;
@@ -530,6 +556,11 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                     runMergeSemaphore.release();
                 }
                 assertBusy(() -> assertTrue(threadPoolMergeExecutorService.allDone()));
+
+                // verify metrics are recorded for each merge
+                verify(mergeMetrics, times(mergeCount)).moveQueuedMergeBytesToRunning(any(), anyLong());
+                verify(mergeMetrics, times(mergeCount)).decrementRunningMergeBytes(any());
+                verify(mergeMetrics, times(mergeCount)).markMergeMetrics(any(), anyLong(), anyLong());
             }
         }
     }
@@ -553,7 +584,8 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                     new ShardId("index", "_na_", 1),
                     IndexSettingsModule.newIndexSettings("index", settings),
                     threadPoolMergeExecutorService,
-                    merge -> 0
+                    merge -> 0,
+                    MergeMetrics.NOOP
                 )
             ) {
                 CountDownLatch mergeDoneLatch = new CountDownLatch(1);
@@ -626,7 +658,8 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                 new ShardId("index", "_na_", 1),
                 indexSettings,
                 threadPoolMergeExecutorService,
-                merge -> 0
+                merge -> 0,
+                MergeMetrics.NOOP
             )
         ) {
             threadPoolMergeScheduler.merge(mergeSource, randomFrom(MergeTrigger.values()));
@@ -656,7 +689,8 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                 new ShardId("index", "_na_", 1),
                 indexSettings,
                 threadPoolMergeExecutorService,
-                merge -> 0
+                merge -> 0,
+                MergeMetrics.NOOP
             )
         ) {
             threadPoolMergeScheduler.merge(mergeSource, randomFrom(MergeTrigger.values()));
@@ -673,7 +707,8 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                 new ShardId("index", "_na_", 1),
                 indexSettings,
                 threadPoolMergeExecutorService,
-                merge -> 0
+                merge -> 0,
+                MergeMetrics.NOOP
             )
         ) {
             // merge submitted upon closing
@@ -690,7 +725,8 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
                 new ShardId("index", "_na_", 1),
                 indexSettings,
                 threadPoolMergeExecutorService,
-                merge -> 0
+                merge -> 0,
+                MergeMetrics.NOOP
             )
         ) {
             // merge submitted upon closing
@@ -705,29 +741,63 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
         }
     }
 
-    public void testMergeSchedulerAbortsMergeWhenShouldSkipMergeIsTrue() {
+    public void testMergeSchedulerAbortsMergeWhenShouldSkipMergeIsTrue() throws IOException {
-        ThreadPoolMergeExecutorService threadPoolMergeExecutorService = mock(ThreadPoolMergeExecutorService.class);
+        DeterministicTaskQueue threadPoolTaskQueue = new DeterministicTaskQueue();
+        Settings settings = Settings.builder()
+            // disable fs available disk space feature for this test
+            .put(ThreadPoolMergeExecutorService.INDICES_MERGE_DISK_CHECK_INTERVAL_SETTING.getKey(), "0s")
+            .build();
+        nodeEnvironment = newNodeEnvironment(settings);
+        ThreadPoolMergeExecutorService threadPoolMergeExecutorService = ThreadPoolMergeExecutorServiceTests
+            .getThreadPoolMergeExecutorService(threadPoolTaskQueue.getThreadPool(), settings, nodeEnvironment);
+        var mergeMetrics = mock(MergeMetrics.class);
+        try (
             // build a scheduler that always returns true for shouldSkipMerge
             ThreadPoolMergeScheduler threadPoolMergeScheduler = new ThreadPoolMergeScheduler(
                 new ShardId("index", "_na_", 1),
-            IndexSettingsModule.newIndexSettings("index", Settings.builder().build()),
+                IndexSettingsModule.newIndexSettings("index", Settings.EMPTY),
                 threadPoolMergeExecutorService,
-            merge -> 0
+                merge -> 0,
+                mergeMetrics
             ) {
                 @Override
                 protected boolean shouldSkipMerge() {
                     return true;
                 }
-        };
+            }
+        ) {
+            int mergeCount = randomIntBetween(2, 10);
+            for (int i = 0; i < mergeCount; i++) {
                 MergeSource mergeSource = mock(MergeSource.class);
                 OneMerge oneMerge = mock(OneMerge.class);
                 when(oneMerge.getStoreMergeInfo()).thenReturn(getNewMergeInfo(randomLongBetween(1L, 10L)));
                 when(oneMerge.getMergeProgress()).thenReturn(new MergePolicy.OneMergeProgress());
                 when(mergeSource.getNextMerge()).thenReturn(oneMerge, (OneMerge) null);
+
+                // create the merge task
                 MergeTask mergeTask = threadPoolMergeScheduler.newMergeTask(mergeSource, oneMerge, randomFrom(MergeTrigger.values()));
+
                 // verify that calling schedule on the merge task indicates the merge should be aborted
                 Schedule schedule = threadPoolMergeScheduler.schedule(mergeTask);
                 assertThat(schedule, is(Schedule.ABORT));
+
+                // run the merge through the scheduler
+                threadPoolMergeScheduler.merge(mergeSource, randomFrom(MergeTrigger.values()));
+
+                // verify queued merge byte metrics are still recorded for each merge
+                verify(mergeMetrics, times(i + 1)).incrementQueuedMergeBytes(any(), anyLong());
+            }
+
+            // run all merges; they should all be aborted
+            threadPoolTaskQueue.runAllTasks();
+
+            // verify queued bytes metrics are moved to running and decremented
+            verify(mergeMetrics, times(mergeCount)).moveQueuedMergeBytesToRunning(any(), anyLong());
+            verify(mergeMetrics, times(mergeCount)).decrementRunningMergeBytes(any());
+
+            // verify we did not mark the merges as merged
+            verify(mergeMetrics, times(0)).markMergeMetrics(any(), anyLong(), anyLong());
+        }
     }
 
     private static MergeInfo getNewMergeInfo(long estimatedMergeBytes) {
@@ -746,7 +816,7 @@ public class ThreadPoolMergeSchedulerTests extends ESTestCase {
             IndexSettings indexSettings,
             ThreadPoolMergeExecutorService threadPoolMergeExecutorService
         ) {
-            super(shardId, indexSettings, threadPoolMergeExecutorService, merge -> 0);
+            super(shardId, indexSettings, threadPoolMergeExecutorService, merge -> 0, MergeMetrics.NOOP);
         }
 
         @Override

server/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java

@@ -5064,7 +5064,8 @@ public class IndexShardTests extends IndexShardTestCase {
                 config.getIndexCommitListener(),
                 config.isPromotableToPrimary(),
                 config.getMapperService(),
-                config.getEngineResetLock()
+                config.getEngineResetLock(),
+                config.getMergeMetrics()
             );
             return new InternalEngine(configWithWarmer);
         });
@@ -5346,7 +5347,8 @@ public class IndexShardTests extends IndexShardTestCase {
                     config.getIndexCommitListener(),
                     config.isPromotableToPrimary(),
                     config.getMapperService(),
-                    config.getEngineResetLock()
+                    config.getEngineResetLock(),
+                    config.getMergeMetrics()
                 );
                 lazyEngineConfig.set(engineConfigWithBlockingRefreshListener);
                 return new InternalEngine(engineConfigWithBlockingRefreshListener) {

server/src/test/java/org/elasticsearch/index/shard/RefreshListenersTests.java

@@ -43,6 +43,7 @@ import org.elasticsearch.index.engine.Engine;
 import org.elasticsearch.index.engine.EngineConfig;
 import org.elasticsearch.index.engine.EngineTestCase;
 import org.elasticsearch.index.engine.InternalEngine;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.engine.ThreadPoolMergeExecutorService;
 import org.elasticsearch.index.engine.ThreadPoolMergeScheduler;
 import org.elasticsearch.index.mapper.IdFieldMapper;
@@ -175,7 +176,8 @@ public class RefreshListenersTests extends ESTestCase {
             null,
             true,
             EngineTestCase.createMapperService(),
-            new EngineResetLock()
+            new EngineResetLock(),
+            MergeMetrics.NOOP
         );
         engine = new InternalEngine(config);
         EngineTestCase.recoverFromTranslog(engine, (e, s) -> 0, Long.MAX_VALUE);

server/src/test/java/org/elasticsearch/snapshots/SnapshotResiliencyTests.java

@@ -145,6 +145,7 @@ import org.elasticsearch.index.IndexNotFoundException;
 import org.elasticsearch.index.IndexSettingProviders;
 import org.elasticsearch.index.IndexingPressure;
 import org.elasticsearch.index.analysis.AnalysisRegistry;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.mapper.MapperMetrics;
 import org.elasticsearch.index.mapper.MapperRegistry;
 import org.elasticsearch.index.seqno.GlobalCheckpointSyncAction;
@@ -2483,6 +2484,7 @@ public class SnapshotResiliencyTests extends ESTestCase {
                     .client(client)
                     .metaStateService(new MetaStateService(nodeEnv, namedXContentRegistry))
                     .mapperMetrics(MapperMetrics.NOOP)
+                    .mergeMetrics(MergeMetrics.NOOP)
                     .build();
                 final RecoverySettings recoverySettings = new RecoverySettings(settings, clusterSettings);
                 snapshotShardsService = new SnapshotShardsService(

test/framework/src/main/java/org/elasticsearch/index/engine/EngineTestCase.java

@@ -169,6 +169,7 @@ public abstract class EngineTestCase extends ESTestCase {
 
     protected InternalEngine engine;
     protected InternalEngine replicaEngine;
+    protected MergeMetrics mergeMetrics;
 
     protected IndexSettings defaultSettings;
     protected String codecName;
@@ -263,6 +264,7 @@ public abstract class EngineTestCase extends ESTestCase {
         primaryTranslogDir = createTempDir("translog-primary");
         mapperService = createMapperService(defaultSettings.getSettings(), defaultMapping(), extraMappers());
         translogHandler = createTranslogHandler(mapperService);
+        mergeMetrics = MergeMetrics.NOOP;
         engine = createEngine(defaultSettings, store, primaryTranslogDir, newMergePolicy());
         LiveIndexWriterConfig currentIndexWriterConfig = engine.getCurrentIndexWriterConfig();
 
@@ -313,7 +315,8 @@ public abstract class EngineTestCase extends ESTestCase {
             config.getIndexCommitListener(),
             config.isPromotableToPrimary(),
             config.getMapperService(),
-            config.getEngineResetLock()
+            config.getEngineResetLock(),
+            config.getMergeMetrics()
         );
     }
 
@@ -347,7 +350,8 @@ public abstract class EngineTestCase extends ESTestCase {
             config.getIndexCommitListener(),
             config.isPromotableToPrimary(),
             config.getMapperService(),
-            config.getEngineResetLock()
+            config.getEngineResetLock(),
+            config.getMergeMetrics()
         );
     }
 
@@ -381,7 +385,8 @@ public abstract class EngineTestCase extends ESTestCase {
             config.getIndexCommitListener(),
             config.isPromotableToPrimary(),
             config.getMapperService(),
-            config.getEngineResetLock()
+            config.getEngineResetLock(),
+            config.getMergeMetrics()
         );
     }
 
@@ -887,7 +892,8 @@ public abstract class EngineTestCase extends ESTestCase {
             indexCommitListener,
             true,
             mapperService,
-            new EngineResetLock()
+            new EngineResetLock(),
+            mergeMetrics
         );
     }
 
@@ -929,7 +935,8 @@ public abstract class EngineTestCase extends ESTestCase {
             config.getIndexCommitListener(),
             config.isPromotableToPrimary(),
             config.getMapperService(),
-            config.getEngineResetLock()
+            config.getEngineResetLock(),
+            config.getMergeMetrics()
         );
     }
 

test/framework/src/main/java/org/elasticsearch/index/shard/IndexShardTestCase.java

@@ -54,6 +54,7 @@ import org.elasticsearch.index.engine.Engine;
 import org.elasticsearch.index.engine.EngineFactory;
 import org.elasticsearch.index.engine.EngineTestCase;
 import org.elasticsearch.index.engine.InternalEngineFactory;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.engine.ThreadPoolMergeExecutorService;
 import org.elasticsearch.index.engine.ThreadPoolMergeScheduler;
 import org.elasticsearch.index.mapper.MapperMetrics;
@@ -562,7 +563,8 @@ public abstract class IndexShardTestCase extends ESTestCase {
                 null,
                 MapperMetrics.NOOP,
                 new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-                new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+                new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+                MergeMetrics.NOOP
             );
             indexShard.addShardFailureCallback(DEFAULT_SHARD_FAILURE_HANDLER);
             success = true;

x-pack/plugin/ccr/src/test/java/org/elasticsearch/xpack/ccr/index/engine/FollowingEngineTests.java

@@ -37,6 +37,7 @@ import org.elasticsearch.index.engine.Engine;
 import org.elasticsearch.index.engine.EngineConfig;
 import org.elasticsearch.index.engine.EngineTestCase;
 import org.elasticsearch.index.engine.InternalEngine;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.engine.ThreadPoolMergeExecutorService;
 import org.elasticsearch.index.engine.ThreadPoolMergeScheduler;
 import org.elasticsearch.index.engine.TranslogHandler;
@@ -284,7 +285,8 @@ public class FollowingEngineTests extends ESTestCase {
             null,
             true,
             mapperService,
-            new EngineResetLock()
+            new EngineResetLock(),
+            MergeMetrics.NOOP
         );
     }
 

x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/SecurityTests.java

@@ -44,6 +44,7 @@ import org.elasticsearch.index.IndexVersions;
 import org.elasticsearch.index.SlowLogFieldProvider;
 import org.elasticsearch.index.analysis.AnalysisRegistry;
 import org.elasticsearch.index.engine.InternalEngineFactory;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.mapper.MapperMetrics;
 import org.elasticsearch.index.search.stats.SearchStatsSettings;
 import org.elasticsearch.index.shard.IndexingStatsSettings;
@@ -464,7 +465,8 @@ public class SecurityTests extends ESTestCase {
             MapperMetrics.NOOP,
             List.of(),
             new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+            MergeMetrics.NOOP
         );
         security.onIndexModule(indexModule);
         // indexReaderWrapper is a SetOnce so if Security#onIndexModule had already set an ReaderWrapper we would get an exception here

x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/WatcherPluginTests.java

@@ -14,6 +14,7 @@ import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.SlowLogFieldProvider;
 import org.elasticsearch.index.analysis.AnalysisRegistry;
 import org.elasticsearch.index.engine.InternalEngineFactory;
+import org.elasticsearch.index.engine.MergeMetrics;
 import org.elasticsearch.index.mapper.MapperMetrics;
 import org.elasticsearch.index.search.stats.SearchStatsSettings;
 import org.elasticsearch.index.shard.IndexingStatsSettings;
@@ -76,7 +77,8 @@ public class WatcherPluginTests extends ESTestCase {
             MapperMetrics.NOOP,
             List.of(),
             new IndexingStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
-            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings())
+            new SearchStatsSettings(ClusterSettings.createBuiltInClusterSettings()),
+            MergeMetrics.NOOP
         );
         // this will trip an assertion if the watcher indexing operation listener is null (which it is) but we try to add it
         watcher.onIndexModule(indexModule);