No need to do any deadlock check here

transport/src/main/java/io/netty/channel/group/ImmediateEventExecutor.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2013 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.channel.group;
+
+import io.netty.util.concurrent.AbstractEventExecutorWithoutScheduler;
+import io.netty.util.concurrent.DefaultPromise;
+import io.netty.util.concurrent.EventExecutor;
+import io.netty.util.concurrent.EventExecutorGroup;
+import io.netty.util.concurrent.Promise;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+final class ImmediateEventExecutor extends AbstractEventExecutorWithoutScheduler {
+
+    @Override
+    public EventExecutorGroup parent() {
+        return null;
+    }
+
+    @Override
+    public boolean inEventLoop() {
+        return true;
+    }
+
+    @Override
+    public boolean inEventLoop(Thread thread) {
+        return true;
+    }
+
+    @Override
+    public void shutdown() {
+    }
+
+    @Override
+    public boolean isShutdown() {
+        return false;
+    }
+
+    @Override
+    public boolean isTerminated() {
+        return false;
+    }
+
+    @Override
+    public boolean awaitTermination(long timeout, TimeUnit unit) {
+        return false;
+    }
+
+    @Override
+    public List<Runnable> shutdownNow() {
+        return Collections.emptyList();
+    }
+
+    @Override
+    public void execute(Runnable command) {
+        if (command == null) {
+            throw new NullPointerException("command");
+        }
+        command.run();
+    }
+
+    @Override
+    public <V> Promise<V> newPromise() {
+        return new ImmediatePromise<V>(this);
+    }
+
+    static class ImmediatePromise<V> extends DefaultPromise<V> {
+        ImmediatePromise(EventExecutor executor) {
+            super(executor);
+        }
+
+        @Override
+        protected void checkDeadLock() {
+            // No check
+        }
+    }
+}