Replace ArrayBlockingQueue with jctools queue.

dependencyManagement/build.gradle.kts

@@ -92,6 +92,7 @@ val DEPENDENCIES = listOf(
         "org.awaitility:awaitility:4.0.3",
         "org.codehaus.mojo:animal-sniffer-annotations:1.20",
         "org.curioswitch.curiostack:protobuf-jackson:1.2.0",
+        "org.jctools:jctools-core:3.3.0",
         "org.junit-pioneer:junit-pioneer:1.3.8",
         "org.skyscreamer:jsonassert:1.5.0",
         "org.slf4j:slf4j-simple:1.7.30"

sdk-extensions/autoconfigure/build.gradle.kts

@@ -35,6 +35,8 @@ dependencies {
     compileOnly("io.prometheus:simpleclient_httpserver")
     compileOnly(project(":exporters:zipkin"))
 
+    testImplementation(project(path=":sdk:trace-shaded-deps"))
+
     testImplementation(project(":proto"))
     testImplementation(project(":sdk:testing"))
     testImplementation("com.linecorp.armeria:armeria-junit5")

sdk-extensions/autoconfigure/src/test/java/io/opentelemetry/sdk/autoconfigure/TracerProviderConfigurationTest.java

@@ -17,11 +17,12 @@
 import io.opentelemetry.sdk.trace.SpanProcessor;
 import io.opentelemetry.sdk.trace.export.BatchSpanProcessor;
 import io.opentelemetry.sdk.trace.export.SpanExporter;
+import io.opentelemetry.sdk.trace.internal.JcTools;
 import io.opentelemetry.sdk.trace.samplers.Sampler;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.concurrent.ArrayBlockingQueue;
+import java.util.Queue;
 import java.util.concurrent.TimeUnit;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -97,8 +98,7 @@ void configureSpanProcessor_empty() {
                 assertThat(worker)
                     .extracting("queue")
                     .isInstanceOfSatisfying(
-                        ArrayBlockingQueue.class,
-                        queue -> assertThat(queue.remainingCapacity()).isEqualTo(2048));
+                        Queue.class, queue -> assertThat(JcTools.capacity(queue)).isEqualTo(2048));
                 assertThat(worker).extracting("spanExporter").isEqualTo(mockSpanExporter);
               });
     } finally {
@@ -133,8 +133,7 @@ void configureSpanProcessor_configured() {
                 assertThat(worker)
                     .extracting("queue")
                     .isInstanceOfSatisfying(
-                        ArrayBlockingQueue.class,
-                        queue -> assertThat(queue.remainingCapacity()).isEqualTo(2));
+                        Queue.class, queue -> assertThat(JcTools.capacity(queue)).isEqualTo(2));
                 assertThat(worker).extracting("spanExporter").isEqualTo(mockSpanExporter);
               });
     } finally {

sdk/trace-shaded-deps/build.gradle.kts

@@ -0,0 +1,22 @@
+plugins {
+    `java-library`
+
+    id("com.github.johnrengelman.shadow")
+}
+
+// This project is not published, it is bundled into :sdk:trace
+
+description = "Internal use only - shaded dependencies of OpenTelemetry SDK for Tracing"
+extra["moduleName"] = "io.opentelemetry.sdk.trace.internal"
+
+dependencies {
+    implementation("org.jctools:jctools-core")
+}
+
+tasks {
+    shadowJar {
+        minimize()
+
+        relocate("org.jctools", "io.opentelemetry.internal.shaded.jctools")
+    }
+}

sdk/trace-shaded-deps/src/main/java/io/opentelemetry/sdk/trace/internal/JcTools.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.trace.internal;
+
+import java.util.Queue;
+import org.jctools.queues.MessagePassingQueue;
+import org.jctools.queues.MpscArrayQueue;
+
+/** Internal accessor of JCTools package for fast queues. */
+public final class JcTools {
+
+  /**
+   * Returns a new {@link Queue} appropriate for use with multiple producers and a single consumer.
+   */
+  public static <T> Queue<T> newMpscArrayQueue(int capacity) {
+    return new MpscArrayQueue<>(capacity);
+  }
+
+  /**
+   * Returns the capacity of the {@link Queue}, which must be a JcTools queue. We cast to the
+   * implementation so callers do not need to use the shaded classes.
+   */
+  public static long capacity(Queue<?> queue) {
+    return ((MessagePassingQueue<?>) queue).capacity();
+  }
+
+  private JcTools() {}
+}

sdk/trace/build.gradle.kts

@@ -9,10 +9,14 @@ plugins {
 description = "OpenTelemetry SDK For Tracing"
 extra["moduleName"] = "io.opentelemetry.sdk.trace"
 
+evaluationDependsOn(":sdk:trace-shaded-deps")
+
 dependencies {
     api(project(":api:all"))
     api(project(":sdk:common"))
 
+    compileOnly(project(":sdk:trace-shaded-deps"))
+
     implementation(project(":api:metrics"))
     implementation(project(":semconv"))
 
@@ -24,6 +28,7 @@ dependencies {
     testImplementation("com.google.guava:guava")
 
     jmh(project(":sdk:metrics"))
+    jmh(project(":sdk:trace-shaded-deps"))
     jmh(project(":sdk:testing")) {
         // JMH doesn"t handle dependencies that are duplicated between the main and jmh
         // configurations properly, but luckily here it"s simple enough to just exclude transitive
@@ -62,4 +67,11 @@ tasks {
             File(propertiesDir, "version.properties").writeText("sdk.version=${project.version}")
         }
     }
+
+    jar {
+        inputs.files(project(":sdk:trace-shaded-deps").file("src"))
+        val shadowJar = project(":sdk:trace-shaded-deps").tasks.named<Jar>("shadowJar")
+        from(zipTree(shadowJar.get().archiveFile))
+        dependsOn(shadowJar)
+    }
 }

sdk/trace/src/jmh/java/io/opentelemetry/sdk/trace/export/BatchSpanProcessorMultiThreadBenchmark.java

@@ -57,10 +57,6 @@ public final void recordMetrics() {
           new BatchSpanProcessorMetrics(sdkMeterProvider.collectAllMetrics(), numThreads);
       exportedSpans = metrics.exportedSpans();
       droppedSpans = metrics.droppedSpans();
-    }
-
-    @TearDown(Level.Trial)
-    public final void tearDown() {
       processor.shutdown().join(10, TimeUnit.SECONDS);
     }
   }

sdk/trace/src/jmh/java/io/opentelemetry/sdk/trace/export/DelayingSpanExporter.java

@@ -38,6 +38,7 @@ public CompletableResultCode flush() {
 
   @Override
   public CompletableResultCode shutdown() {
+    executor.shutdown();
     return CompletableResultCode.ofSuccess();
   }
 }

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/export/BatchSpanProcessor.java

@@ -17,8 +17,10 @@
 import io.opentelemetry.sdk.trace.ReadableSpan;
 import io.opentelemetry.sdk.trace.SpanProcessor;
 import io.opentelemetry.sdk.trace.data.SpanData;
+import io.opentelemetry.sdk.trace.internal.JcTools;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Queue;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.TimeUnit;
@@ -36,9 +38,6 @@
  * {@code maxQueueSize} maximum size, if queue is full spans are dropped). Spans are exported either
  * when there are {@code maxExportBatchSize} pending spans or {@code scheduleDelayNanos} has passed
  * since the last export finished.
- *
- * <p>This batch {@link SpanProcessor} can cause high contention in a very high traffic service.
- * TODO: Add a link to the SpanProcessor that uses Disruptor as alternative with low contention.
  */
 public final class BatchSpanProcessor implements SpanProcessor {
 
@@ -73,7 +72,7 @@ public static BatchSpanProcessorBuilder builder(SpanExporter spanExporter) {
             scheduleDelayNanos,
             maxExportBatchSize,
             exporterTimeoutNanos,
-            new ArrayBlockingQueue<>(maxQueueSize));
+            JcTools.newMpscArrayQueue(maxQueueSize));
     Thread workerThread = new DaemonThreadFactory(WORKER_THREAD_NAME).newThread(worker);
     workerThread.start();
   }
@@ -131,7 +130,8 @@ private static final class Worker implements Runnable {
     private final long exporterTimeoutNanos;
 
     private long nextExportTime;
-    private final BlockingQueue<ReadableSpan> queue;
+
+    private final Queue<ReadableSpan> queue;
     // When waiting on the spans queue, exporter thread sets this atomic to the number of more
     // spans it needs before doing an export. Writer threads would then wait for the queue to reach
     // spansNeeded size before notifying the exporter thread about new entries.
@@ -149,7 +149,7 @@ private Worker(
         long scheduleDelayNanos,
         int maxExportBatchSize,
         long exporterTimeoutNanos,
-        BlockingQueue<ReadableSpan> queue) {
+        Queue<ReadableSpan> queue) {
       this.spanExporter = spanExporter;
       this.scheduleDelayNanos = scheduleDelayNanos;
       this.maxExportBatchSize = maxExportBatchSize;

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/export/BatchSpanProcessorBuilder.java

@@ -86,7 +86,8 @@ long getExporterTimeoutNanos() {
   }
 
   /**
-   * Sets the maximum number of Spans that are kept in the queue before start dropping.
+   * Sets the maximum number of Spans that are kept in the queue before start dropping. More memory
+   * than this value may be allocated to optimize queue access.
    *
    * <p>See the BatchSampledSpansProcessor class description for a high-level design description of
    * this class.

settings.gradle.kts

@@ -63,6 +63,7 @@ include(":sdk:common")
 include(":sdk:metrics")
 include(":sdk:testing")
 include(":sdk:trace")
+include(":sdk:trace-shaded-deps")
 include(":sdk-extensions:async-processor")
 include(":sdk-extensions:autoconfigure")
 include(":sdk-extensions:aws")