Initialise bytebuddy instrumentation in a new thread at bootstrap

dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/Agent.java

@@ -206,7 +206,14 @@ public static void start(
       remoteConfigEnabled = false;
       telemetryEnabled = false;
       // apply trace instrumentation, but skip other products at native-image build time
-      startDatadogAgent(initTelemetry, inst);
+      final Thread t = startDatadogAgent(initTelemetry, inst);
+      if (t != null) {
+        try {
+          t.join();
+        } catch (InterruptedException e) {
+          Thread.currentThread().interrupt();
+        }
+      }
       StaticEventLogger.end("Agent.start");
       return;
     }
@@ -301,7 +308,7 @@ public static void start(
       startCrashTracking();
       StaticEventLogger.end("crashtracking");
     }
-    startDatadogAgent(initTelemetry, inst);
+    final Thread agentLoadThread = startDatadogAgent(initTelemetry, inst);
 
     final EnumSet<Library> libraries = detectLibraries(log);
 
@@ -384,6 +391,14 @@ public static void start(
       StaticEventLogger.end("Profiling");
     }
 
+    if (agentLoadThread != null) {
+      try {
+        agentLoadThread.join();
+      } catch (InterruptedException e) {
+        Thread.currentThread().interrupt();
+      }
+    }
+
     StaticEventLogger.end("Agent.start");
   }
 
@@ -722,7 +737,7 @@ private static void maybeStartRemoteConfig(Class<?> scoClass, Object sco) {
     StaticEventLogger.end("Remote Config");
   }
 
-  private static synchronized void startDatadogAgent(
+  private static synchronized Thread startDatadogAgent(
       final InitializationTelemetry initTelemetry, final Instrumentation inst) {
     if (null != inst) {
       StaticEventLogger.begin("BytebuddyAgent");
@@ -731,15 +746,16 @@ private static synchronized void startDatadogAgent(
         final Class<?> agentInstallerClass =
             AGENT_CLASSLOADER.loadClass(AGENT_INSTALLER_CLASS_NAME);
         final Method agentInstallerMethod =
-            agentInstallerClass.getMethod("installBytebuddyAgent", Instrumentation.class);
-        agentInstallerMethod.invoke(null, inst);
+            agentInstallerClass.getMethod(
+                "installBytebuddyAgent", Instrumentation.class, InitializationTelemetry.class);
+        return (Thread) agentInstallerMethod.invoke(null, inst, initTelemetry);
       } catch (final Throwable ex) {
         log.error("Throwable thrown while installing the Datadog Agent", ex);
         initTelemetry.onFatalError(ex);
-      } finally {
         StaticEventLogger.end("BytebuddyAgent");
       }
     }
+    return null;
   }
 
   private static synchronized void installDatadogTracer(

dd-java-agent/agent-builder/src/main/java/datadog/trace/agent/tooling/AgentInstaller.java

@@ -3,6 +3,8 @@
 import static datadog.trace.agent.tooling.ExtensionFinder.findExtensions;
 import static datadog.trace.agent.tooling.ExtensionLoader.loadExtensions;
 import static datadog.trace.agent.tooling.bytebuddy.matcher.GlobalIgnoresMatcher.globalIgnoresMatcher;
+import static datadog.trace.util.AgentThreadFactory.AgentThread.AGENT_INIT_INSTRUMENTATION;
+import static datadog.trace.util.AgentThreadFactory.newAgentThread;
 import static net.bytebuddy.matcher.ElementMatchers.isDefaultFinalizer;
 
 import datadog.environment.SystemProperties;
@@ -18,6 +20,8 @@
 import datadog.trace.api.ProductActivation;
 import datadog.trace.api.telemetry.IntegrationsCollector;
 import datadog.trace.bootstrap.FieldBackedContextAccessor;
+import datadog.trace.bootstrap.InitializationTelemetry;
+import datadog.trace.bootstrap.benchmark.StaticEventLogger;
 import datadog.trace.bootstrap.instrumentation.java.concurrent.ExcludeFilter;
 import datadog.trace.util.AgentTaskScheduler;
 import de.thetaphi.forbiddenapis.SuppressForbidden;
@@ -71,29 +75,44 @@ private static void circularityErrorWorkaround() {
     }
   }
 
-  public static void installBytebuddyAgent(final Instrumentation inst) {
+  public static Thread installBytebuddyAgent(
+      final Instrumentation inst, InitializationTelemetry initTelemetry) {
     /*
      * ByteBuddy agent is used by several systems which can be enabled independently;
      * we need to install the agent whenever any of them is active.
      */
-    Set<InstrumenterModule.TargetSystem> enabledSystems = getEnabledSystems();
-    if (!enabledSystems.isEmpty()) {
-      installBytebuddyAgent(inst, false, enabledSystems);
-      if (DEBUG) {
-        log.debug("Instrumentation installed for {}", enabledSystems);
-      }
-      int poolCleaningInterval = InstrumenterConfig.get().getResolverResetInterval();
-      if (poolCleaningInterval > 0) {
-        AgentTaskScheduler.get()
-            .scheduleAtFixedRate(
-                SharedTypePools::clear,
-                poolCleaningInterval,
-                Math.max(poolCleaningInterval, 10),
-                TimeUnit.SECONDS);
-      }
-    } else if (DEBUG) {
-      log.debug("No target systems enabled, skipping instrumentation.");
-    }
+    final Thread ret =
+        newAgentThread(
+            AGENT_INIT_INSTRUMENTATION,
+            () -> {
+              try {
+                Set<InstrumenterModule.TargetSystem> enabledSystems = getEnabledSystems();
+                if (!enabledSystems.isEmpty()) {
+                  installBytebuddyAgent(inst, false, enabledSystems);
+                  if (DEBUG) {
+                    log.debug("Instrumentation installed for {}", enabledSystems);
+                  }
+                  int poolCleaningInterval = InstrumenterConfig.get().getResolverResetInterval();
+                  if (poolCleaningInterval > 0) {
+                    AgentTaskScheduler.get()
+                        .scheduleAtFixedRate(
+                            SharedTypePools::clear,
+                            poolCleaningInterval,
+                            Math.max(poolCleaningInterval, 10),
+                            TimeUnit.SECONDS);
+                  }
+                } else if (DEBUG) {
+                  log.debug("No target systems enabled, skipping instrumentation.");
+                }
+              } catch (Throwable ex) {
+                log.error("Throwable thrown while installing the Datadog Agent", ex);
+                initTelemetry.onFatalError(ex);
+              } finally {
+                StaticEventLogger.end("BytebuddyAgent");
+              }
+            });
+    ret.start();
+    return ret;
   }
 
   /**

dd-java-agent/instrumentation/graal/native-image/src/main/java/datadog/trace/instrumentation/graal/nativeimage/NativeImageGeneratorRunnerInstrumentation.java

@@ -155,6 +155,7 @@ public static void onEnter(@Advice.Argument(value = 0, readOnly = false) String[
               + "datadog.trace.logging.PrintStreamWrapper:build_time,"
               + "datadog.trace.util.CollectionUtils:build_time,"
               + "datadog.trace.util.TempLocationManager$SingletonHolder:run_time,"
+              + "datadog.trace.util.AgentThreadFactory:build_time,"
               + "datadog.slf4j.helpers.NOPLoggerFactory:build_time,"
               + "datadog.slf4j.helpers.SubstituteLoggerFactory:build_time,"
               + "datadog.slf4j.impl.StaticLoggerBinder:build_time,"

internal-api/src/main/java/datadog/trace/util/AgentThreadFactory.java

@@ -57,6 +57,8 @@ public enum AgentThread {
 
     RETRANSFORMER("dd-retransformer"),
 
+    AGENT_INIT_INSTRUMENTATION("dd-agent-init-instrumentation"),
+
     LOGS_INTAKE("dd-logs-intake"),
 
     LLMOBS_EVALS_PROCESSOR("dd-llmobs-evals-processor");