Fix race condition of GlobalOpenTelemetry initialization with AutoConfiguredOpenTelemetrySdkBuilder

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/AutoConfiguredOpenTelemetrySdkBuilder.java

@@ -36,6 +36,7 @@
 import io.opentelemetry.sdk.trace.samplers.Sampler;
 import java.io.Closeable;
 import java.io.IOException;
+import java.lang.reflect.Field;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -424,6 +425,10 @@
    * the settings of this {@link AutoConfiguredOpenTelemetrySdkBuilder}.
    */
   public AutoConfiguredOpenTelemetrySdk build() {
+    return maybeRunWithGlobalOpenTelemetryLock(this::buildImpl);
+  }
+
+  private AutoConfiguredOpenTelemetrySdk buildImpl() {
     SpiHelper spiHelper = SpiHelper.create(componentLoader);
     if (!customized) {
       customized = true;
@@ -572,6 +577,35 @@
     Runtime.getRuntime().addShutdownHook(shutdownHook(openTelemetrySdk));
   }
 
+  private <T> T maybeRunWithGlobalOpenTelemetryLock(Supplier<T> supplier) {
+    Object mutex;
+    if (!setResultAsGlobal || (mutex = getGlobalOpenTelemetryLock()) == null) {
+      return supplier.get();
+    }
+    synchronized (mutex) {
+      return supplier.get();
+    }
+  }
+
+  // Visible for testing
+  @Nullable
+  static Object getGlobalOpenTelemetryLock() {
+    Object mutex = null;
+    try {
+      Field mutexField = GlobalOpenTelemetry.class.getDeclaredField("mutex");
+      mutexField.setAccessible(true);
+      mutex = mutexField.get(null);
+      if (mutex == null) {
+        logger.log(
+            Level.SEVERE,
+            "Found a null Global OpenTelemetry mutex, this is a bug in the opentelemetry-java SDK and should be reported");
+      }
+    } catch (Exception exception) {
+      logger.log(Level.WARNING, "Could not acquire Global OpenTelemetry mutex", exception);
+    }
+    return mutex;
+  }
+
   private void maybeSetAsGlobal(
       OpenTelemetrySdk openTelemetrySdk, @Nullable Object configProvider) {
     if (!setResultAsGlobal) {

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

@@ -0,0 +1,18 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.autoconfigure;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class AutoConfiguredOpenTelemetrySdkBuilderTest {
+
+  @Test
+  void getGlobalOpenTelemetryLock_findsLock() {
+    assertThat(AutoConfiguredOpenTelemetrySdkBuilder.getGlobalOpenTelemetryLock()).isNotNull();
+  }
+}