Revert "Avoid performing blocking I/O operation on application thread (#8120)"

communication/src/main/java/datadog/communication/ddagent/SharedCommunicationObjects.java

@@ -1,7 +1,6 @@
 package datadog.communication.ddagent;
 
 import static datadog.communication.ddagent.TracerVersion.TRACER_VERSION;
-import static datadog.trace.util.AgentThreadFactory.AGENT_THREAD_GROUP;
 
 import datadog.common.container.ContainerInfo;
 import datadog.common.socket.SocketUtils;
@@ -10,7 +9,6 @@
 import datadog.remoteconfig.ConfigurationPoller;
 import datadog.remoteconfig.DefaultConfigurationPoller;
 import datadog.trace.api.Config;
-import datadog.trace.util.AgentTaskScheduler;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Supplier;
 import okhttp3.HttpUrl;
@@ -100,11 +98,8 @@ public DDAgentFeaturesDiscovery featuresDiscovery(Config config) {
               agentUrl,
               config.isTraceAgentV05Enabled(),
               config.isTracerMetricsEnabled());
-      if (AGENT_THREAD_GROUP.equals(Thread.currentThread().getThreadGroup())) {
-        featuresDiscovery.discover(); // safe to run on same thread
-      } else {
-        // avoid performing blocking I/O operation on application thread
-        AgentTaskScheduler.INSTANCE.execute(featuresDiscovery::discover);
+      if (!"true".equalsIgnoreCase(System.getProperty("dd.test.no.early.discovery"))) {
+        featuresDiscovery.discover();
       }
     }
     return featuresDiscovery;

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/agent/DebuggerAgentTest.java

@@ -122,11 +122,11 @@ public void runEnabledWithDatadogAgent() throws InterruptedException, IOExceptio
     ConfigurationPoller configurationPoller =
         (ConfigurationPoller) sharedCommunicationObjects.configurationPoller(Config.get());
     configurationPoller.start();
-    RecordedRequest request;
-    do {
-      request = datadogAgentServer.takeRequest(5, TimeUnit.SECONDS);
-      assertNotNull(request);
-    } while ("/info".equals(request.getPath()));
+    RecordedRequest request = datadogAgentServer.takeRequest(5, TimeUnit.SECONDS);
+    assertNotNull(request);
+    assertEquals("/info", request.getPath());
+    request = datadogAgentServer.takeRequest(5, TimeUnit.SECONDS);
+    assertNotNull(request);
     assertEquals("/v0.7/config", request.getPath());
     DebuggerAgent.stop();
     datadogAgentServer.shutdown();

dd-trace-core/src/main/java/datadog/trace/core/datastreams/DefaultDataStreamsMonitoring.java

@@ -136,7 +136,21 @@ public DefaultDataStreamsMonitoring(
 
   @Override
   public void start() {
+    if (features.getDataStreamsEndpoint() == null) {
+      features.discoverIfOutdated();
+    }
+
+    agentSupportsDataStreams = features.supportsDataStreams();
     checkDynamicConfig();
+
+    if (!configSupportsDataStreams) {
+      log.debug("Data streams is disabled");
+    } else if (!agentSupportsDataStreams) {
+      log.debug("Data streams is disabled or not supported by agent");
+    }
+
+    nextFeatureCheck = timeSource.getCurrentTimeNanos() + FEATURE_CHECK_INTERVAL_NANOS;
+
     cancellation =
         AgentTaskScheduler.INSTANCE.scheduleAtFixedRate(
             new ReportTask(), this, bucketDurationNanos, bucketDurationNanos, TimeUnit.NANOSECONDS);
@@ -327,22 +341,6 @@ private StatsBucket getStatsBucket(final long timestamp, final String serviceNam
 
     @Override
     public void run() {
-
-      if (features.getDataStreamsEndpoint() == null) {
-        features.discoverIfOutdated();
-      }
-
-      agentSupportsDataStreams = features.supportsDataStreams();
-      checkDynamicConfig();
-
-      if (!configSupportsDataStreams) {
-        log.debug("Data streams is disabled");
-      } else if (!agentSupportsDataStreams) {
-        log.debug("Data streams is disabled or not supported by agent");
-      }
-
-      nextFeatureCheck = timeSource.getCurrentTimeNanos() + FEATURE_CHECK_INTERVAL_NANOS;
-
       Thread currentThread = Thread.currentThread();
       while (!currentThread.isInterrupted()) {
         try {

dd-trace-core/src/test/groovy/datadog/trace/core/propagation/XRayHttpInjectorTest.groovy

@@ -6,7 +6,6 @@ import datadog.trace.api.DDTraceId
 import datadog.trace.api.DynamicConfig
 import datadog.trace.api.time.TimeSource
 import datadog.trace.bootstrap.instrumentation.api.AgentTracer.NoopPathwayContext
-import datadog.trace.core.datastreams.DataStreamsMonitoring
 
 import static datadog.trace.api.sampling.PrioritySampling.*
 import static datadog.trace.api.sampling.SamplingMechanism.*
@@ -26,11 +25,7 @@ class XRayHttpInjectorTest extends DDCoreSpecification {
     setup:
     def writer = new ListWriter()
     def timeSource = Mock(TimeSource)
-    def tracer = tracerBuilder()
-      .dataStreamsMonitoring(Mock(DataStreamsMonitoring))
-      .writer(writer)
-      .timeSource(timeSource)
-      .build()
+    def tracer = tracerBuilder().writer(writer).timeSource(timeSource).build()
     final DDSpanContext mockedContext =
       new DDSpanContext(
       DDTraceId.from("$traceId"),
@@ -81,11 +76,7 @@ class XRayHttpInjectorTest extends DDCoreSpecification {
     setup:
     def writer = new ListWriter()
     def timeSource = Mock(TimeSource)
-    def tracer = tracerBuilder()
-      .dataStreamsMonitoring(Mock(DataStreamsMonitoring))
-      .writer(writer)
-      .timeSource(timeSource)
-      .build()
+    def tracer = tracerBuilder().writer(writer).timeSource(timeSource).build()
     def headers = [
       'X-Amzn-Trace-Id' : "Root=1-00000000-00000000${traceId.padLeft(16, '0')};Parent=${spanId.padLeft(16, '0')}"
     ]
@@ -145,11 +136,7 @@ class XRayHttpInjectorTest extends DDCoreSpecification {
     setup:
     def writer = new ListWriter()
     def timeSource = Mock(TimeSource)
-    def tracer = tracerBuilder()
-      .dataStreamsMonitoring(Mock(DataStreamsMonitoring))
-      .writer(writer)
-      .timeSource(timeSource)
-      .build()
+    def tracer = tracerBuilder().writer(writer).timeSource(timeSource).build()
     final DDSpanContext mockedContext =
       new DDSpanContext(
       DDTraceId.from("1"),