From 1284103b98c2b00ba6ac811e3977c68e08999bb3 Mon Sep 17 00:00:00 2001
From: Alex Fabijanic <alex@pocoproject.org>
Date: Thu, 6 Nov 2025 20:39:34 +0100
Subject: [PATCH] fix(AsyncNotificationCenter): hang on stop() #5059

---
 Foundation/include/Poco/AsyncNotificationCenter.h | 5 +++++
 Foundation/src/AsyncNotificationCenter.cpp        | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/Foundation/include/Poco/AsyncNotificationCenter.h b/Foundation/include/Poco/AsyncNotificationCenter.h
index 27358fcab..a63f63dcc 100644
--- a/Foundation/include/Poco/AsyncNotificationCenter.h
+++ b/Foundation/include/Poco/AsyncNotificationCenter.h
@@ -120,6 +120,11 @@ private:
 
 	using Adapter = RunnableAdapter<AsyncNotificationCenter>;
 
+	class ShutdownNotification: public Notification
+		/// Internal notification used to signal the dequeue loop to stop.
+	{
+	};
+
 	const AsyncMode _mode { AsyncMode::ENQUEUE };
 
 	// Async enqueue for notifications
diff --git a/Foundation/src/AsyncNotificationCenter.cpp b/Foundation/src/AsyncNotificationCenter.cpp
index 0458d41d3..4adb54261 100644
--- a/Foundation/src/AsyncNotificationCenter.cpp
+++ b/Foundation/src/AsyncNotificationCenter.cpp
@@ -180,6 +180,7 @@ void AsyncNotificationCenter::stop()
 	{
 		if (_enqueueThreadStarted.exchange(false))
 		{
+			_nq.enqueueUrgentNotification(new ShutdownNotification);
 			_nq.wakeUpAll();
 			while (!_enqueueThreadDone) Thread::sleep(100);
 			_enqueueThread.join();
@@ -207,8 +208,11 @@ void AsyncNotificationCenter::dequeue()
 	Notification::Ptr pNf;
 	_enqueueThreadStarted = true;
 	_enqueueThreadDone = false;
-	while ((pNf = _nq.waitDequeueNotification()))
+	while (true)
 	{
+		pNf = _nq.waitDequeueNotification();
+		if (!pNf) break;
+		if (pNf.cast<ShutdownNotification>()) break;
 		try
 		{
 			notifyObservers(pNf);