Metrics to account for time spent waiting for next chunk

server/src/main/java/org/elasticsearch/action/bulk/IncrementalBulkService.java

@@ -22,6 +22,8 @@
 import org.elasticsearch.core.Releasables;
 import org.elasticsearch.core.TimeValue;
 import org.elasticsearch.index.IndexingPressure;
+import org.elasticsearch.telemetry.metric.LongHistogram;
+import org.elasticsearch.telemetry.metric.MeterRegistry;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -33,6 +35,7 @@
 import static org.elasticsearch.common.settings.Setting.boolSetting;
 
 public class IncrementalBulkService {
+    public static final String CHUNK_WAIT_TIME_HISTOGRAM_NAME = "es.rest.incremental_bulk.wait_for_next_chunk.duration.histogram";
 
     public static final Setting<Boolean> INCREMENTAL_BULK = boolSetting(
         "rest.incremental_bulk",
@@ -44,9 +47,17 @@ public class IncrementalBulkService {
     private final AtomicBoolean enabledForTests = new AtomicBoolean(true);
     private final IndexingPressure indexingPressure;
 
-    public IncrementalBulkService(Client client, IndexingPressure indexingPressure) {
+    /* Capture in milliseconds because the APM histogram only has a range of 100,000 */
+    private final LongHistogram chunkWaitTimeMillisHistogram;
+
+    public IncrementalBulkService(Client client, IndexingPressure indexingPressure, MeterRegistry meterRegistry) {
         this.client = client;
         this.indexingPressure = indexingPressure;
+        this.chunkWaitTimeMillisHistogram = meterRegistry.registerLongHistogram(
+            CHUNK_WAIT_TIME_HISTOGRAM_NAME,
+            "Total time in millis spent waiting for next chunk of a bulk request",
+            "ms"
+        );
     }
 
     public Handler newBulkRequest() {
@@ -56,7 +67,7 @@ public Handler newBulkRequest() {
 
     public Handler newBulkRequest(@Nullable String waitForActiveShards, @Nullable TimeValue timeout, @Nullable String refresh) {
         ensureEnabled();
-        return new Handler(client, indexingPressure, waitForActiveShards, timeout, refresh);
+        return new Handler(client, indexingPressure, waitForActiveShards, timeout, refresh, chunkWaitTimeMillisHistogram);
     }
 
     private void ensureEnabled() {
@@ -99,6 +110,8 @@ public static class Handler implements Releasable {
         private final ArrayList<Releasable> releasables = new ArrayList<>(4);
         private final ArrayList<BulkResponse> responses = new ArrayList<>(2);
         private final IndexingPressure.Incremental incrementalOperation;
+        // Ideally this should be in RestBulkAction, but it's harder to inject the metric registry there
+        private final LongHistogram chunkWaitTimeMillisHistogram;
         private boolean closed = false;
         private boolean globalFailure = false;
         private boolean incrementalRequestSubmitted = false;
@@ -111,20 +124,26 @@ protected Handler(
             IndexingPressure indexingPressure,
             @Nullable String waitForActiveShards,
             @Nullable TimeValue timeout,
-            @Nullable String refresh
+            @Nullable String refresh,
+            LongHistogram chunkWaitTimeMillisHistogram
         ) {
             this.client = client;
             this.waitForActiveShards = waitForActiveShards != null ? ActiveShardCount.parseString(waitForActiveShards) : null;
             this.timeout = timeout;
             this.refresh = refresh;
             this.incrementalOperation = indexingPressure.startIncrementalCoordinating(0, 0, false);
+            this.chunkWaitTimeMillisHistogram = chunkWaitTimeMillisHistogram;
             createNewBulkRequest(EMPTY_STATE);
         }
 
         public IndexingPressure.Incremental getIncrementalOperation() {
             return incrementalOperation;
         }
 
+        public void updateWaitForChunkMetrics(long chunkWaitTimeInMillis) {
+            chunkWaitTimeMillisHistogram.record(chunkWaitTimeInMillis);
+        }
+
         public void addItems(List<DocWriteRequest<?>> items, Releasable releasable, Runnable nextItems) {
             assert closed == false;
             assert bulkInProgress == false;

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

@@ -997,7 +997,11 @@ public Map<String, String> queryFields() {
             .map(TerminationHandlerProvider::handler);
         terminationHandler = getSinglePlugin(terminationHandlers, TerminationHandler.class).orElse(null);
 
-        final IncrementalBulkService incrementalBulkService = new IncrementalBulkService(client, indexingLimits);
+        final IncrementalBulkService incrementalBulkService = new IncrementalBulkService(
+            client,
+            indexingLimits,
+            telemetryProvider.getMeterRegistry()
+        );
 
         final ResponseCollectorService responseCollectorService = new ResponseCollectorService(clusterService);
         modules.bindToInstance(ResponseCollectorService.class, responseCollectorService);

server/src/main/java/org/elasticsearch/rest/action/document/RestBulkAction.java

@@ -42,6 +42,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Supplier;
 
 import static org.elasticsearch.rest.RestRequest.Method.POST;
@@ -165,6 +166,9 @@ static class ChunkHandler implements BaseRestHandler.RequestBodyChunkConsumer {
         private final ArrayDeque<ReleasableBytesReference> unParsedChunks = new ArrayDeque<>(4);
         private final ArrayList<DocWriteRequest<?>> items = new ArrayList<>(4);
 
+        private long requestNextChunkTime;
+        private long totalChunkWaitTimeInNanos = 0L;
+
         ChunkHandler(boolean allowExplicitIndex, RestRequest request, Supplier<IncrementalBulkService.Handler> handlerSupplier) {
             this.request = request;
             this.handlerSupplier = handlerSupplier;
@@ -189,13 +193,20 @@ static class ChunkHandler implements BaseRestHandler.RequestBodyChunkConsumer {
         public void accept(RestChannel restChannel) {
             this.restChannel = restChannel;
             this.handler = handlerSupplier.get();
+            requestNextChunkTime = System.nanoTime();
             request.contentStream().next();
         }
 
         @Override
         public void handleChunk(RestChannel channel, ReleasableBytesReference chunk, boolean isLast) {
             assert handler != null;
             assert channel == restChannel;
+            long now = System.nanoTime();
+            long elapsedTime = now - requestNextChunkTime;
+            if (elapsedTime > 0) {
+                totalChunkWaitTimeInNanos += elapsedTime;
+                requestNextChunkTime = now;
+            }
             if (shortCircuited) {
                 chunk.close();
                 return;
@@ -239,12 +250,18 @@ public void handleChunk(RestChannel channel, ReleasableBytesReference chunk, boo
                     items.clear();
                     handler.lastItems(toPass, () -> Releasables.close(releasables), new RestRefCountedChunkedToXContentListener<>(channel));
                 }
+                handler.updateWaitForChunkMetrics(TimeUnit.NANOSECONDS.toMillis(totalChunkWaitTimeInNanos));
+                totalChunkWaitTimeInNanos = 0L;
             } else if (items.isEmpty() == false) {
                 ArrayList<DocWriteRequest<?>> toPass = new ArrayList<>(items);
                 items.clear();
-                handler.addItems(toPass, () -> Releasables.close(releasables), () -> request.contentStream().next());
+                handler.addItems(toPass, () -> Releasables.close(releasables), () -> {
+                    requestNextChunkTime = System.nanoTime();
+                    request.contentStream().next();
+                });
             } else {
                 Releasables.close(releasables);
+                requestNextChunkTime = System.nanoTime();
                 request.contentStream().next();
             }
         }

server/src/test/java/org/elasticsearch/action/ActionModuleTests.java

@@ -42,6 +42,7 @@
 import org.elasticsearch.tasks.Task;
 import org.elasticsearch.tasks.TaskManager;
 import org.elasticsearch.telemetry.TelemetryProvider;
+import org.elasticsearch.telemetry.metric.MeterRegistry;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.threadpool.TestThreadPool;
 import org.elasticsearch.threadpool.ThreadPool;
@@ -130,7 +131,7 @@ public void testSetupRestHandlerContainsKnownBuiltin() {
             List.of(),
             List.of(),
             RestExtension.allowAll(),
-            new IncrementalBulkService(null, null),
+            new IncrementalBulkService(null, null, MeterRegistry.NOOP),
             TestProjectResolvers.alwaysThrow()
         );
         actionModule.initRestHandlers(null, null);
@@ -197,7 +198,7 @@ public String getName() {
                 List.of(),
                 List.of(),
                 RestExtension.allowAll(),
-                new IncrementalBulkService(null, null),
+                new IncrementalBulkService(null, null, MeterRegistry.NOOP),
                 TestProjectResolvers.alwaysThrow()
             );
             Exception e = expectThrows(IllegalArgumentException.class, () -> actionModule.initRestHandlers(null, null));
@@ -257,7 +258,7 @@ public List<RestHandler> getRestHandlers(
                 List.of(),
                 List.of(),
                 RestExtension.allowAll(),
-                new IncrementalBulkService(null, null),
+                new IncrementalBulkService(null, null, MeterRegistry.NOOP),
                 TestProjectResolvers.alwaysThrow()
             );
             actionModule.initRestHandlers(null, null);
@@ -310,7 +311,7 @@ public void test3rdPartyHandlerIsNotInstalled() {
                     List.of(),
                     List.of(),
                     RestExtension.allowAll(),
-                    new IncrementalBulkService(null, null),
+                    new IncrementalBulkService(null, null, MeterRegistry.NOOP),
                     TestProjectResolvers.alwaysThrow()
                 )
             );
@@ -354,7 +355,7 @@ public void test3rdPartyRestControllerIsNotInstalled() {
                     List.of(),
                     List.of(),
                     RestExtension.allowAll(),
-                    new IncrementalBulkService(null, null),
+                    new IncrementalBulkService(null, null, MeterRegistry.NOOP),
                     TestProjectResolvers.alwaysThrow()
                 )
             );

server/src/test/java/org/elasticsearch/http/AbstractHttpServerTransportTests.java

@@ -43,6 +43,7 @@
 import org.elasticsearch.rest.RestStatus;
 import org.elasticsearch.tasks.Task;
 import org.elasticsearch.telemetry.TelemetryProvider;
+import org.elasticsearch.telemetry.metric.MeterRegistry;
 import org.elasticsearch.telemetry.tracing.Tracer;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.test.MockLog;
@@ -1182,7 +1183,7 @@ public Collection<RestHeaderDefinition> getRestHeaders() {
             List.of(),
             List.of(),
             RestExtension.allowAll(),
-            new IncrementalBulkService(null, null),
+            new IncrementalBulkService(null, null, MeterRegistry.NOOP),
             TestProjectResolvers.alwaysThrow()
         );
     }

server/src/test/java/org/elasticsearch/rest/action/document/RestBulkActionTests.java

@@ -28,6 +28,7 @@
 import org.elasticsearch.index.IndexingPressure;
 import org.elasticsearch.rest.RestChannel;
 import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.telemetry.metric.MeterRegistry;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.test.client.NoOpNodeClient;
 import org.elasticsearch.test.rest.FakeRestChannel;
@@ -68,7 +69,7 @@ public void bulk(BulkRequest request, ActionListener<BulkResponse> listener) {
             new RestBulkAction(
                 settings(IndexVersion.current()).build(),
                 ClusterSettings.createBuiltInClusterSettings(),
-                new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class))
+                new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class), MeterRegistry.NOOP)
             ).handleRequest(
                 new FakeRestRequest.Builder(xContentRegistry()).withPath("my_index/_bulk").withParams(params).withContent(new BytesArray("""
                     {"index":{"_id":"1"}}
@@ -104,7 +105,7 @@ public void bulk(BulkRequest request, ActionListener<BulkResponse> listener) {
                 new RestBulkAction(
                     settings(IndexVersion.current()).build(),
                     ClusterSettings.createBuiltInClusterSettings(),
-                    new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class))
+                    new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class), MeterRegistry.NOOP)
                 ).handleRequest(
                     new FakeRestRequest.Builder(xContentRegistry()).withPath("my_index/_bulk")
                         .withParams(params)
@@ -129,7 +130,7 @@ public void bulk(BulkRequest request, ActionListener<BulkResponse> listener) {
                 new RestBulkAction(
                     settings(IndexVersion.current()).build(),
                     ClusterSettings.createBuiltInClusterSettings(),
-                    new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class))
+                    new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class), MeterRegistry.NOOP)
                 ).handleRequest(
                     new FakeRestRequest.Builder(xContentRegistry()).withPath("my_index/_bulk")
                         .withParams(params)
@@ -153,7 +154,7 @@ public void bulk(BulkRequest request, ActionListener<BulkResponse> listener) {
                 new RestBulkAction(
                     settings(IndexVersion.current()).build(),
                     ClusterSettings.createBuiltInClusterSettings(),
-                    new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class))
+                    new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class), MeterRegistry.NOOP)
                 ).handleRequest(
                     new FakeRestRequest.Builder(xContentRegistry()).withPath("my_index/_bulk")
                         .withParams(params)
@@ -178,7 +179,7 @@ public void bulk(BulkRequest request, ActionListener<BulkResponse> listener) {
                 new RestBulkAction(
                     settings(IndexVersion.current()).build(),
                     ClusterSettings.createBuiltInClusterSettings(),
-                    new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class))
+                    new IncrementalBulkService(mock(Client.class), mock(IndexingPressure.class), MeterRegistry.NOOP)
                 ).handleRequest(
                     new FakeRestRequest.Builder(xContentRegistry()).withPath("my_index/_bulk")
                         .withParams(params)
@@ -233,7 +234,14 @@ public void next() {
 
         IndexingPressure indexingPressure = new IndexingPressure(Settings.EMPTY);
         RestBulkAction.ChunkHandler chunkHandler = new RestBulkAction.ChunkHandler(true, request, () -> {
-            return new IncrementalBulkService.Handler(null, indexingPressure, null, null, null) {
+            return new IncrementalBulkService.Handler(
+                null,
+                indexingPressure,
+                null,
+                null,
+                null,
+                MeterRegistry.NOOP.getLongHistogram(IncrementalBulkService.CHUNK_WAIT_TIME_HISTOGRAM_NAME)
+            ) {
 
                 @Override
                 public void addItems(List<DocWriteRequest<?>> items, Releasable releasable, Runnable nextItems) {

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

@@ -63,6 +63,7 @@
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.script.ScriptService;
 import org.elasticsearch.telemetry.TelemetryProvider;
+import org.elasticsearch.telemetry.metric.MeterRegistry;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.test.IndexSettingsModule;
 import org.elasticsearch.test.MockLog;
@@ -947,7 +948,7 @@ public void testSecurityRestHandlerInterceptorCanBeInstalled() throws IllegalAcc
                 List.of(),
                 List.of(),
                 RestExtension.allowAll(),
-                new IncrementalBulkService(null, null),
+                new IncrementalBulkService(null, null, MeterRegistry.NOOP),
                 TestProjectResolvers.alwaysThrow()
             );
             actionModule.initRestHandlers(null, null);