From 8b131bd1923fcc5e31657e77f2d05291894d9ecc Mon Sep 17 00:00:00 2001
From: Julien Lebosquain <julien@lebosquain.net>
Date: Thu, 27 Nov 2025 10:01:10 +0100
Subject: [PATCH] Fix headless race condition (#20143)

---
 .../HeadlessWindowExtensions.cs               | 22 +++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/Headless/Avalonia.Headless/HeadlessWindowExtensions.cs b/src/Headless/Avalonia.Headless/HeadlessWindowExtensions.cs
index 9909f053fa..7f33490caf 100644
--- a/src/Headless/Avalonia.Headless/HeadlessWindowExtensions.cs
+++ b/src/Headless/Avalonia.Headless/HeadlessWindowExtensions.cs
@@ -138,11 +138,25 @@ public static class HeadlessWindowExtensions
 
     private static void RunJobsOnImpl(this TopLevel topLevel, Action<IHeadlessWindow> action)
     {
-        Dispatcher.UIThread.RunJobs();
-        AvaloniaHeadlessPlatform.ForceRenderTimerTick();
-        Dispatcher.UIThread.RunJobs();
+        RunJobsAndRender();
         action(GetImpl(topLevel));
-        Dispatcher.UIThread.RunJobs();
+        RunJobsAndRender();
+
+        void RunJobsAndRender()
+        {
+            var count = 0;
+            var dispatcher = Dispatcher.UIThread;
+
+            while (dispatcher.HasJobsWithPriority(DispatcherPriority.MinimumActiveValue))
+            {
+                if (count >= 10)
+                    throw new InvalidOperationException("Dispatcher job loop detected");
+
+                dispatcher.RunJobs();
+                AvaloniaHeadlessPlatform.ForceRenderTimerTick();
+                ++count;
+            }
+        }
     }
 
     private static IHeadlessWindow GetImpl(this TopLevel topLevel)