From 07550cf4c68ca364798f8d46622a5a4e75ca0339 Mon Sep 17 00:00:00 2001
From: Andrea Marziali <andrea.marziali@datadoghq.com>
Date: Tue, 15 Sep 2026 10:57:12 +0200
Subject: [PATCH 1/2] Prevent Netty startup tasks from inheriting context

---
 ...entExecutorStartThreadInstrumentation.java | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 dd-java-agent/instrumentation/netty/netty-concurrent-4.0/src/main/java/datadog/trace/instrumentation/netty40/concurrent/SingleThreadEventExecutorStartThreadInstrumentation.java

diff --git a/dd-java-agent/instrumentation/netty/netty-concurrent-4.0/src/main/java/datadog/trace/instrumentation/netty40/concurrent/SingleThreadEventExecutorStartThreadInstrumentation.java b/dd-java-agent/instrumentation/netty/netty-concurrent-4.0/src/main/java/datadog/trace/instrumentation/netty40/concurrent/SingleThreadEventExecutorStartThreadInstrumentation.java
new file mode 100644
index 00000000000..14f558bfd25
--- /dev/null
+++ b/dd-java-agent/instrumentation/netty/netty-concurrent-4.0/src/main/java/datadog/trace/instrumentation/netty40/concurrent/SingleThreadEventExecutorStartThreadInstrumentation.java
@@ -0,0 +1,57 @@
+package datadog.trace.instrumentation.netty40.concurrent;
+
+import static datadog.trace.agent.tooling.bytebuddy.matcher.NameMatchers.named;
+import static datadog.trace.bootstrap.instrumentation.api.AgentTracer.isAsyncPropagationEnabled;
+import static datadog.trace.bootstrap.instrumentation.api.AgentTracer.setAsyncPropagationEnabled;
+import static net.bytebuddy.matcher.ElementMatchers.isPrivate;
+import static net.bytebuddy.matcher.ElementMatchers.returns;
+import static net.bytebuddy.matcher.ElementMatchers.takesNoArguments;
+
+import com.google.auto.service.AutoService;
+import datadog.trace.agent.tooling.Instrumenter;
+import datadog.trace.agent.tooling.InstrumenterModule;
+import net.bytebuddy.asm.Advice;
+
+/** Prevents Netty's lazily created event-loop maintenance tasks from inheriting user context. */
+@AutoService(InstrumenterModule.class)
+public final class SingleThreadEventExecutorStartThreadInstrumentation
+    extends InstrumenterModule.ContextTracking
+    implements Instrumenter.ForKnownTypes, Instrumenter.HasMethodAdvice {
+
+  public SingleThreadEventExecutorStartThreadInstrumentation() {
+    super("netty-concurrent", "netty-event-executor");
+  }
+
+  @Override
+  public String[] knownMatchingTypes() {
+    return new String[] {
+      "io.netty.util.concurrent.SingleThreadEventExecutor",
+      "io.grpc.netty.shaded.io.netty.util.concurrent.SingleThreadEventExecutor",
+    };
+  }
+
+  @Override
+  public void methodAdvice(MethodTransformer transformer) {
+    transformer.applyAdvice(
+        named("startThread").and(takesNoArguments()).and(returns(void.class)).and(isPrivate()),
+        getClass().getName() + "$DisableAsyncPropagation");
+  }
+
+  public static final class DisableAsyncPropagation {
+    @Advice.OnMethodEnter(suppress = Throwable.class)
+    public static boolean before() {
+      if (isAsyncPropagationEnabled()) {
+        setAsyncPropagationEnabled(false);
+        return true;
+      }
+      return false;
+    }
+
+    @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
+    public static void after(@Advice.Enter boolean wasDisabled) {
+      if (wasDisabled) {
+        setAsyncPropagationEnabled(true);
+      }
+    }
+  }
+}

From acbd49df68d779af8af5633c530d5a44e22f6f19 Mon Sep 17 00:00:00 2001
From: Andrea Marziali <andrea.marziali@datadoghq.com>
Date: Tue, 15 Sep 2026 12:51:03 +0200
Subject: [PATCH 2/2] Cover shaded Netty event executors

---
 .../SingleThreadEventExecutorStartThreadInstrumentation.java    | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/dd-java-agent/instrumentation/netty/netty-concurrent-4.0/src/main/java/datadog/trace/instrumentation/netty40/concurrent/SingleThreadEventExecutorStartThreadInstrumentation.java b/dd-java-agent/instrumentation/netty/netty-concurrent-4.0/src/main/java/datadog/trace/instrumentation/netty40/concurrent/SingleThreadEventExecutorStartThreadInstrumentation.java
index 14f558bfd25..826b37103f7 100644
--- a/dd-java-agent/instrumentation/netty/netty-concurrent-4.0/src/main/java/datadog/trace/instrumentation/netty40/concurrent/SingleThreadEventExecutorStartThreadInstrumentation.java
+++ b/dd-java-agent/instrumentation/netty/netty-concurrent-4.0/src/main/java/datadog/trace/instrumentation/netty40/concurrent/SingleThreadEventExecutorStartThreadInstrumentation.java
@@ -27,6 +27,8 @@ public String[] knownMatchingTypes() {
     return new String[] {
       "io.netty.util.concurrent.SingleThreadEventExecutor",
       "io.grpc.netty.shaded.io.netty.util.concurrent.SingleThreadEventExecutor",
+      "com.couchbase.client.deps.io.netty.util.concurrent.SingleThreadEventExecutor",
+      "play.shaded.ahc.io.netty.util.concurrent.SingleThreadEventExecutor",
     };
   }