From cc71f9c550864000dad148dfd2d72fe3e0fc6075 Mon Sep 17 00:00:00 2001
From: Nick Lefever <lefever@meta.com>
Date: Mon, 11 Aug 2025 14:45:36 -0700
Subject: [PATCH] Create tryDispatchMountItems runnable only when needed
 (#53196)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/53196

In the FabricUIManager, the runnable created for scheduled mounts is only used if currently running on the UI thread.

With this diff the runnable only gets created when needed.

Changelog: [Internal]

Reviewed By: christophpurrer

Differential Revision: D79969412

fbshipit-source-id: ee78890322af8580357389aad8357f7c0d18490f
---
 .../com/facebook/react/fabric/FabricUIManager.java | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java
index cb16e0b0ca2..078cc64ac7c 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java
@@ -935,14 +935,14 @@ public class FabricUIManager
     if (shouldSchedule) {
       Assertions.assertNotNull(mountItem, "MountItem is null");
       mMountItemDispatcher.addMountItem(mountItem);
-      Runnable runnable =
-          new GuardedRunnable(mReactApplicationContext) {
-            @Override
-            public void runGuarded() {
-              mMountItemDispatcher.tryDispatchMountItems();
-            }
-          };
       if (UiThreadUtil.isOnUiThread()) {
+        Runnable runnable =
+            new GuardedRunnable(mReactApplicationContext) {
+              @Override
+              public void runGuarded() {
+                mMountItemDispatcher.tryDispatchMountItems();
+              }
+            };
         runnable.run();
       }
     }