Initialise bytebuddy instrumentation in a new thread at bootstrap

Author: amarziali

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

@@ -206,7 +206,11 @@ public static void start(
       remoteConfigEnabled = false;
       telemetryEnabled = false;
       // apply trace instrumentation, but skip other products at native-image build time
-      startDatadogAgent(initTelemetry, inst);
+      try {
+        startDatadogAgent(initTelemetry, inst).join();
+      } catch (InterruptedException e) {
+        Thread.currentThread().interrupt();
+      }
       StaticEventLogger.end("Agent.start");
       return;
     }
@@ -301,7 +305,7 @@ 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 +388,12 @@ public static void start(
       StaticEventLogger.end("Profiling");
     }
 
+    try {
+      agentLoadThread.join();
+    } catch (InterruptedException e) {
+      Thread.currentThread().interrupt();
+    }
+
     StaticEventLogger.end("Agent.start");
   }
 
@@ -722,7 +732,7 @@ 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");
@@ -732,14 +742,15 @@ private static synchronized void startDatadogAgent(
             AGENT_CLASSLOADER.loadClass(AGENT_INSTALLER_CLASS_NAME);
         final Method agentInstallerMethod =
             agentInstallerClass.getMethod("installBytebuddyAgent", Instrumentation.class);
-        agentInstallerMethod.invoke(null, inst);
+        return (Thread) agentInstallerMethod.invoke(null, inst);
       } 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;
@@ -71,29 +73,36 @@ private static void circularityErrorWorkaround() {
     }
   }
 
-  public static void installBytebuddyAgent(final Instrumentation inst) {
+  public static Thread installBytebuddyAgent(final Instrumentation inst) {
     /*
      * 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,
+            () -> {
+              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.");
+              }
+            });
+    ret.start();
+    return ret;
   }
 
   /**

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");