Add experiment to bypass bridgeless background executor (#44797)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/44797

Noticed when profiling bridgeless that  that every call into JS would be passed via a (default priority) background thread first. This is inefficient from a scheduling perspective. Instead use the Task's default/immediate executor to immediately execute the success callback on the current thread and avoid a thread change.

This diff adds a new feature flag, to use the immediate executor for any ReactInstance method that doesn't require further synchronization within ReactInstance. For most methods, this is indeed unnecessary as ReactInstance will synchronize internally by scheduling work on the JS thread.

Changelog: [Android][Added] Added featureflag to avoid additional background threads during execution

Reviewed By: cortinico

Differential Revision: D58186090

fbshipit-source-id: 67ffed2d34083a6b6e7871160a2f3d6f1967d630

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -3848,6 +3848,7 @@ public abstract interface class com/facebook/react/runtime/internal/bolts/Contin
 }
 
 public class com/facebook/react/runtime/internal/bolts/Task : com/facebook/react/interfaces/TaskInterface {
+	public static final field IMMEDIATE_EXECUTOR Ljava/util/concurrent/Executor;
 	public static final field UI_THREAD_EXECUTOR Ljava/util/concurrent/Executor;
 	public static fun call (Ljava/util/concurrent/Callable;)Lcom/facebook/react/runtime/internal/bolts/Task;
 	public static fun call (Ljava/util/concurrent/Callable;Ljava/util/concurrent/Executor;)Lcom/facebook/react/runtime/internal/bolts/Task;

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<bc03d88b59af436b2db4f9048184a881>>
+ * @generated SignedSource<<177f05d7b2fadcfffa32cb5a7a21c76b>>
  */
 
 /**
@@ -136,6 +136,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun setAndroidLayoutDirection(): Boolean = accessor.setAndroidLayoutDirection()
 
+  /**
+   * Invoke callbacks immediately on the ReactInstance rather than going through a background thread for synchronization
+   */
+  @JvmStatic
+  public fun useImmediateExecutorInAndroidBridgeless(): Boolean = accessor.useImmediateExecutorInAndroidBridgeless()
+
   /**
    * When enabled, it uses the modern fork of RuntimeScheduler that allows scheduling tasks with priorities from any thread.
    */

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<546c981f0b56bb022ad4e96e6a6ddb17>>
+ * @generated SignedSource<<492902f307361b8f7b7d42973561a3b4>>
  */
 
 /**
@@ -38,6 +38,7 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
   private var lazyAnimationCallbacksCache: Boolean? = null
   private var preventDoubleTextMeasureCache: Boolean? = null
   private var setAndroidLayoutDirectionCache: Boolean? = null
+  private var useImmediateExecutorInAndroidBridgelessCache: Boolean? = null
   private var useModernRuntimeSchedulerCache: Boolean? = null
   private var useNativeViewConfigsInBridgelessModeCache: Boolean? = null
   private var useRuntimeShadowNodeReferenceUpdateCache: Boolean? = null
@@ -206,6 +207,15 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
     return cached
   }
 
+  override fun useImmediateExecutorInAndroidBridgeless(): Boolean {
+    var cached = useImmediateExecutorInAndroidBridgelessCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.useImmediateExecutorInAndroidBridgeless()
+      useImmediateExecutorInAndroidBridgelessCache = cached
+    }
+    return cached
+  }
+
   override fun useModernRuntimeScheduler(): Boolean {
     var cached = useModernRuntimeSchedulerCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<d3e722e1630002aee16eaf33b60c8a8f>>
+ * @generated SignedSource<<05bf91e1b2a64cdc48615137deec627a>>
  */
 
 /**
@@ -64,6 +64,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun setAndroidLayoutDirection(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun useImmediateExecutorInAndroidBridgeless(): Boolean
+
   @DoNotStrip @JvmStatic public external fun useModernRuntimeScheduler(): Boolean
 
   @DoNotStrip @JvmStatic public external fun useNativeViewConfigsInBridgelessMode(): Boolean

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<8cb9343bf5aa9a7ec1940720ce253c5b>>
+ * @generated SignedSource<<7c95ebf976344317cd8904d71ea22fe5>>
  */
 
 /**
@@ -59,6 +59,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun setAndroidLayoutDirection(): Boolean = false
 
+  override fun useImmediateExecutorInAndroidBridgeless(): Boolean = false
+
   override fun useModernRuntimeScheduler(): Boolean = false
 
   override fun useNativeViewConfigsInBridgelessMode(): Boolean = false

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<3b6ad9b32518e319bb7d11da4eaa262c>>
+ * @generated SignedSource<<d23d2a5f44f2b2068dde9e85e5b1ce9f>>
  */
 
 /**
@@ -42,6 +42,7 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
   private var lazyAnimationCallbacksCache: Boolean? = null
   private var preventDoubleTextMeasureCache: Boolean? = null
   private var setAndroidLayoutDirectionCache: Boolean? = null
+  private var useImmediateExecutorInAndroidBridgelessCache: Boolean? = null
   private var useModernRuntimeSchedulerCache: Boolean? = null
   private var useNativeViewConfigsInBridgelessModeCache: Boolean? = null
   private var useRuntimeShadowNodeReferenceUpdateCache: Boolean? = null
@@ -228,6 +229,16 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun useImmediateExecutorInAndroidBridgeless(): Boolean {
+    var cached = useImmediateExecutorInAndroidBridgelessCache
+    if (cached == null) {
+      cached = currentProvider.useImmediateExecutorInAndroidBridgeless()
+      accessedFeatureFlags.add("useImmediateExecutorInAndroidBridgeless")
+      useImmediateExecutorInAndroidBridgelessCache = cached
+    }
+    return cached
+  }
+
   override fun useModernRuntimeScheduler(): Boolean {
     var cached = useModernRuntimeSchedulerCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<af167f52f81a78ac200159717eb55e8e>>
+ * @generated SignedSource<<d84816a13ad49b6e1c69c968a8503385>>
  */
 
 /**
@@ -59,6 +59,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun setAndroidLayoutDirection(): Boolean
 
+  @DoNotStrip public fun useImmediateExecutorInAndroidBridgeless(): Boolean
+
   @DoNotStrip public fun useModernRuntimeScheduler(): Boolean
 
   @DoNotStrip public fun useNativeViewConfigsInBridgelessMode(): Boolean

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactHostImpl.java

@@ -59,6 +59,7 @@ import com.facebook.react.fabric.FabricUIManager;
 import com.facebook.react.interfaces.TaskInterface;
 import com.facebook.react.interfaces.exceptionmanager.ReactJsExceptionHandler;
 import com.facebook.react.interfaces.fabric.ReactSurface;
+import com.facebook.react.internal.featureflags.ReactNativeFeatureFlags;
 import com.facebook.react.modules.appearance.AppearanceModule;
 import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
 import com.facebook.react.modules.core.DeviceEventManagerModule;
@@ -215,7 +216,8 @@ public class ReactHostImpl implements ReactHost {
         reactInstance -> {
           log(method, "Execute");
           reactInstance.prerenderSurface(surface);
-        });
+        },
+        mBGExecutor);
   }
 
   /**
@@ -235,7 +237,8 @@ public class ReactHostImpl implements ReactHost {
         reactInstance -> {
           log(method, "Execute");
           reactInstance.startSurface(surface);
-        });
+        },
+        mBGExecutor);
   }
 
   /**
@@ -255,7 +258,8 @@ public class ReactHostImpl implements ReactHost {
             reactInstance -> {
               log(method, "Execute");
               reactInstance.stopSurface(surface);
-            })
+            },
+            mBGExecutor)
         .makeVoid();
   }
 
@@ -756,7 +760,8 @@ public class ReactHostImpl implements ReactHost {
         reactInstance -> {
           log(method, "Execute");
           reactInstance.loadJSBundle(bundleLoader);
-        });
+        },
+        null);
   }
 
   /* package */ Task<Boolean> registerSegment(
@@ -771,7 +776,8 @@ public class ReactHostImpl implements ReactHost {
           log(method, "Execute");
           reactInstance.registerSegment(segmentId, path);
           assertNotNull(callback).invoke();
-        });
+        },
+        null);
   }
 
   /* package */ void handleHostException(Exception e) {
@@ -800,7 +806,8 @@ public class ReactHostImpl implements ReactHost {
         method,
         reactInstance -> {
           reactInstance.callFunctionOnModule(moduleName, methodName, args);
-        });
+        },
+        null);
   }
 
   /* package */ void attachSurface(ReactSurfaceImpl surface) {
@@ -852,8 +859,8 @@ public class ReactHostImpl implements ReactHost {
     }
   }
 
-  /* package */ interface VeniceThenable<T> {
-    void then(T t);
+  private interface ReactInstanceCalback {
+    void then(ReactInstance reactInstance);
   }
 
   @ThreadConfined("ReactHost")
@@ -911,11 +918,23 @@ public class ReactHostImpl implements ReactHost {
         TAG, new ReactNoCrashSoftException(method + ": " + message));
   }
 
+  private Executor getDefaultReactInstanceExecutor() {
+    return ReactNativeFeatureFlags.useImmediateExecutorInAndroidBridgeless()
+        ? Task.IMMEDIATE_EXECUTOR
+        : mBGExecutor;
+  }
+
   /** Schedule work on a ReactInstance that is already created. */
   private Task<Boolean> callWithExistingReactInstance(
-      final String callingMethod, final VeniceThenable<ReactInstance> continuation) {
+      final String callingMethod,
+      final ReactInstanceCalback continuation,
+      @Nullable Executor executor) {
     final String method = "callWithExistingReactInstance(" + callingMethod + ")";
 
+    if (executor == null) {
+      executor = getDefaultReactInstanceExecutor();
+    }
+
     return mReactInstanceTaskRef
         .get()
         .onSuccess(
@@ -929,14 +948,20 @@ public class ReactHostImpl implements ReactHost {
               continuation.then(reactInstance);
               return TRUE;
             },
-            mBGExecutor);
+            executor);
   }
 
   /** Create a ReactInstance if it doesn't exist already, and schedule work on it. */
   private Task<Void> callAfterGetOrCreateReactInstance(
-      final String callingMethod, final VeniceThenable<ReactInstance> runnable) {
+      final String callingMethod,
+      final ReactInstanceCalback runnable,
+      @Nullable Executor executor) {
     final String method = "callAfterGetOrCreateReactInstance(" + callingMethod + ")";
 
+    if (executor == null) {
+      executor = getDefaultReactInstanceExecutor();
+    }
+
     return getOrCreateReactInstance()
         .onSuccess(
             task -> {
@@ -949,15 +974,14 @@ public class ReactHostImpl implements ReactHost {
               runnable.then(reactInstance);
               return null;
             },
-            mBGExecutor)
+            executor)
         .continueWith(
             task -> {
               if (task.isFaulted()) {
                 handleHostException(task.getError());
               }
               return null;
-            },
-            mBGExecutor);
+            });
   }
 
   private BridgelessReactContext getOrCreateReactContext() {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactInstance.java

@@ -369,6 +369,7 @@ final class ReactInstance {
     }
   }
 
+  @ThreadConfined("ReactHost")
   /* package */ void prerenderSurface(ReactSurfaceImpl surface) {
     Systrace.beginSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE, "ReactInstance.prerenderSurface");
     FLog.d(TAG, "call prerenderSurface with surface: " + surface.getModuleName());

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/internal/bolts/Task.java

@@ -27,7 +27,7 @@ public class Task<TResult> implements TaskInterface<TResult> {
    * stack runs too deep, at which point it will delegate to {@link Task#BACKGROUND_EXECUTOR} in
    * order to trim the stack.
    */
-  private static final Executor IMMEDIATE_EXECUTOR = Executors.IMMEDIATE;
+  public static final Executor IMMEDIATE_EXECUTOR = Executors.IMMEDIATE;
 
   /** An {@link java.util.concurrent.Executor} that executes tasks on the UI thread. */
   public static final Executor UI_THREAD_EXECUTOR = Executors.UI_THREAD;

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<43b256d5f58743df52f579dc69721083>>
+ * @generated SignedSource<<2af7a8ae4860f81b46e48afb17ee54b6>>
  */
 
 /**
@@ -147,6 +147,12 @@ class ReactNativeFeatureFlagsProviderHolder
     return method(javaProvider_);
   }
 
+  bool useImmediateExecutorInAndroidBridgeless() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("useImmediateExecutorInAndroidBridgeless");
+    return method(javaProvider_);
+  }
+
   bool useModernRuntimeScheduler() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("useModernRuntimeScheduler");
@@ -271,6 +277,11 @@ bool JReactNativeFeatureFlagsCxxInterop::setAndroidLayoutDirection(
   return ReactNativeFeatureFlags::setAndroidLayoutDirection();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::useImmediateExecutorInAndroidBridgeless(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::useImmediateExecutorInAndroidBridgeless();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::useModernRuntimeScheduler(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::useModernRuntimeScheduler();
@@ -367,6 +378,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "setAndroidLayoutDirection",
         JReactNativeFeatureFlagsCxxInterop::setAndroidLayoutDirection),
+      makeNativeMethod(
+        "useImmediateExecutorInAndroidBridgeless",
+        JReactNativeFeatureFlagsCxxInterop::useImmediateExecutorInAndroidBridgeless),
       makeNativeMethod(
         "useModernRuntimeScheduler",
         JReactNativeFeatureFlagsCxxInterop::useModernRuntimeScheduler),

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<19fe3642ec462c23d361e0f036da887a>>
+ * @generated SignedSource<<1d1422d073ae40ee4bbc788dc222cc28>>
  */
 
 /**
@@ -84,6 +84,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool setAndroidLayoutDirection(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool useImmediateExecutorInAndroidBridgeless(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool useModernRuntimeScheduler(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<b7969efd5890b7be7be5fd8e6b0bf301>>
+ * @generated SignedSource<<ec12fd62d1dc2109e52a95094d7ad167>>
  */
 
 /**
@@ -93,6 +93,10 @@ bool ReactNativeFeatureFlags::setAndroidLayoutDirection() {
   return getAccessor().setAndroidLayoutDirection();
 }
 
+bool ReactNativeFeatureFlags::useImmediateExecutorInAndroidBridgeless() {
+  return getAccessor().useImmediateExecutorInAndroidBridgeless();
+}
+
 bool ReactNativeFeatureFlags::useModernRuntimeScheduler() {
   return getAccessor().useModernRuntimeScheduler();
 }

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<c4d88f9d9b8c6d5ca917d1ba9e53d9e8>>
+ * @generated SignedSource<<5f1ae3edfe01ee0545bd89137c5cb3e9>>
  */
 
 /**
@@ -127,6 +127,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool setAndroidLayoutDirection();
 
+  /**
+   * Invoke callbacks immediately on the ReactInstance rather than going through a background thread for synchronization
+   */
+  RN_EXPORT static bool useImmediateExecutorInAndroidBridgeless();
+
   /**
    * When enabled, it uses the modern fork of RuntimeScheduler that allows scheduling tasks with priorities from any thread.
    */

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<5f27dd10824706ea065dc0340d46c409>>
+ * @generated SignedSource<<6d08fc8ff31f1db50cb4b14edb6b690f>>
  */
 
 /**
@@ -353,6 +353,24 @@ bool ReactNativeFeatureFlagsAccessor::setAndroidLayoutDirection() {
   return flagValue.value();
 }
 
+bool ReactNativeFeatureFlagsAccessor::useImmediateExecutorInAndroidBridgeless() {
+  auto flagValue = useImmediateExecutorInAndroidBridgeless_.load();
+
+  if (!flagValue.has_value()) {
+    // This block is not exclusive but it is not necessary.
+    // If multiple threads try to initialize the feature flag, we would only
+    // be accessing the provider multiple times but the end state of this
+    // instance and the returned flag value would be the same.
+
+    markFlagAsAccessed(18, "useImmediateExecutorInAndroidBridgeless");
+
+    flagValue = currentProvider_->useImmediateExecutorInAndroidBridgeless();
+    useImmediateExecutorInAndroidBridgeless_ = flagValue;
+  }
+
+  return flagValue.value();
+}
+
 bool ReactNativeFeatureFlagsAccessor::useModernRuntimeScheduler() {
   auto flagValue = useModernRuntimeScheduler_.load();
 
@@ -362,7 +380,7 @@ bool ReactNativeFeatureFlagsAccessor::useModernRuntimeScheduler() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(18, "useModernRuntimeScheduler");
+    markFlagAsAccessed(19, "useModernRuntimeScheduler");
 
     flagValue = currentProvider_->useModernRuntimeScheduler();
     useModernRuntimeScheduler_ = flagValue;
@@ -380,7 +398,7 @@ bool ReactNativeFeatureFlagsAccessor::useNativeViewConfigsInBridgelessMode() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(19, "useNativeViewConfigsInBridgelessMode");
+    markFlagAsAccessed(20, "useNativeViewConfigsInBridgelessMode");
 
     flagValue = currentProvider_->useNativeViewConfigsInBridgelessMode();
     useNativeViewConfigsInBridgelessMode_ = flagValue;
@@ -398,7 +416,7 @@ bool ReactNativeFeatureFlagsAccessor::useRuntimeShadowNodeReferenceUpdate() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(20, "useRuntimeShadowNodeReferenceUpdate");
+    markFlagAsAccessed(21, "useRuntimeShadowNodeReferenceUpdate");
 
     flagValue = currentProvider_->useRuntimeShadowNodeReferenceUpdate();
     useRuntimeShadowNodeReferenceUpdate_ = flagValue;
@@ -416,7 +434,7 @@ bool ReactNativeFeatureFlagsAccessor::useRuntimeShadowNodeReferenceUpdateOnLayou
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(21, "useRuntimeShadowNodeReferenceUpdateOnLayout");
+    markFlagAsAccessed(22, "useRuntimeShadowNodeReferenceUpdateOnLayout");
 
     flagValue = currentProvider_->useRuntimeShadowNodeReferenceUpdateOnLayout();
     useRuntimeShadowNodeReferenceUpdateOnLayout_ = flagValue;
@@ -434,7 +452,7 @@ bool ReactNativeFeatureFlagsAccessor::useStateAlignmentMechanism() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(22, "useStateAlignmentMechanism");
+    markFlagAsAccessed(23, "useStateAlignmentMechanism");
 
     flagValue = currentProvider_->useStateAlignmentMechanism();
     useStateAlignmentMechanism_ = flagValue;

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<8837dd1578561f205e6f682afd98c450>>
+ * @generated SignedSource<<3be4d7eb8694603de9fb5885562d5a78>>
  */
 
 /**
@@ -49,6 +49,7 @@ class ReactNativeFeatureFlagsAccessor {
   bool lazyAnimationCallbacks();
   bool preventDoubleTextMeasure();
   bool setAndroidLayoutDirection();
+  bool useImmediateExecutorInAndroidBridgeless();
   bool useModernRuntimeScheduler();
   bool useNativeViewConfigsInBridgelessMode();
   bool useRuntimeShadowNodeReferenceUpdate();
@@ -64,7 +65,7 @@ class ReactNativeFeatureFlagsAccessor {
   std::unique_ptr<ReactNativeFeatureFlagsProvider> currentProvider_;
   bool wasOverridden_;
 
-  std::array<std::atomic<const char*>, 23> accessedFeatureFlags_;
+  std::array<std::atomic<const char*>, 24> accessedFeatureFlags_;
 
   std::atomic<std::optional<bool>> commonTestFlag_;
   std::atomic<std::optional<bool>> allowCollapsableChildren_;
@@ -84,6 +85,7 @@ class ReactNativeFeatureFlagsAccessor {
   std::atomic<std::optional<bool>> lazyAnimationCallbacks_;
   std::atomic<std::optional<bool>> preventDoubleTextMeasure_;
   std::atomic<std::optional<bool>> setAndroidLayoutDirection_;
+  std::atomic<std::optional<bool>> useImmediateExecutorInAndroidBridgeless_;
   std::atomic<std::optional<bool>> useModernRuntimeScheduler_;
   std::atomic<std::optional<bool>> useNativeViewConfigsInBridgelessMode_;
   std::atomic<std::optional<bool>> useRuntimeShadowNodeReferenceUpdate_;

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDefaults.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<2a0324c7b8009e906b18db11c5d2beb9>>
+ * @generated SignedSource<<97c824bb63734389fae8eea61b92d440>>
  */
 
 /**
@@ -99,6 +99,10 @@ class ReactNativeFeatureFlagsDefaults : public ReactNativeFeatureFlagsProvider {
     return false;
   }
 
+  bool useImmediateExecutorInAndroidBridgeless() override {
+    return false;
+  }
+
   bool useModernRuntimeScheduler() override {
     return false;
   }

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsProvider.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<7cd3889fcccc029925651f7ef406ff40>>
+ * @generated SignedSource<<454a55db4c97f9c28c0a8427d4c0bd57>>
  */
 
 /**
@@ -43,6 +43,7 @@ class ReactNativeFeatureFlagsProvider {
   virtual bool lazyAnimationCallbacks() = 0;
   virtual bool preventDoubleTextMeasure() = 0;
   virtual bool setAndroidLayoutDirection() = 0;
+  virtual bool useImmediateExecutorInAndroidBridgeless() = 0;
   virtual bool useModernRuntimeScheduler() = 0;
   virtual bool useNativeViewConfigsInBridgelessMode() = 0;
   virtual bool useRuntimeShadowNodeReferenceUpdate() = 0;

packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<914fa03d71af61b82f05f005d3f3973d>>
+ * @generated SignedSource<<81d9543c4231939f31dc5c9bb06c942c>>
  */
 
 /**
@@ -127,6 +127,11 @@ bool NativeReactNativeFeatureFlags::setAndroidLayoutDirection(
   return ReactNativeFeatureFlags::setAndroidLayoutDirection();
 }
 
+bool NativeReactNativeFeatureFlags::useImmediateExecutorInAndroidBridgeless(
+    jsi::Runtime& /*runtime*/) {
+  return ReactNativeFeatureFlags::useImmediateExecutorInAndroidBridgeless();
+}
+
 bool NativeReactNativeFeatureFlags::useModernRuntimeScheduler(
     jsi::Runtime& /*runtime*/) {
   return ReactNativeFeatureFlags::useModernRuntimeScheduler();

packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<1458397650db55d5a985685fa4998e41>>
+ * @generated SignedSource<<e13caa80ac317feb98cf4db5ac89be79>>
  */
 
 /**
@@ -71,6 +71,8 @@ class NativeReactNativeFeatureFlags
 
   bool setAndroidLayoutDirection(jsi::Runtime& runtime);
 
+  bool useImmediateExecutorInAndroidBridgeless(jsi::Runtime& runtime);
+
   bool useModernRuntimeScheduler(jsi::Runtime& runtime);
 
   bool useNativeViewConfigsInBridgelessMode(jsi::Runtime& runtime);

packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js

@@ -122,6 +122,11 @@ const definitions: FeatureFlagDefinitions = {
       defaultValue: false,
       description: 'Propagate layout direction to Android views.',
     },
+    useImmediateExecutorInAndroidBridgeless: {
+      defaultValue: false,
+      description:
+        'Invoke callbacks immediately on the ReactInstance rather than going through a background thread for synchronization',
+    },
     useModernRuntimeScheduler: {
       defaultValue: false,
       description:

packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<c3b421b10f05f33a9830fbd730a3786a>>
+ * @generated SignedSource<<870e25c844e692bb04ee49fe20cd3baf>>
  * @flow strict-local
  */
 
@@ -58,6 +58,7 @@ export type ReactNativeFeatureFlags = {
   lazyAnimationCallbacks: Getter<boolean>,
   preventDoubleTextMeasure: Getter<boolean>,
   setAndroidLayoutDirection: Getter<boolean>,
+  useImmediateExecutorInAndroidBridgeless: Getter<boolean>,
   useModernRuntimeScheduler: Getter<boolean>,
   useNativeViewConfigsInBridgelessMode: Getter<boolean>,
   useRuntimeShadowNodeReferenceUpdate: Getter<boolean>,
@@ -177,6 +178,10 @@ export const preventDoubleTextMeasure: Getter<boolean> = createNativeFlagGetter(
  * Propagate layout direction to Android views.
  */
 export const setAndroidLayoutDirection: Getter<boolean> = createNativeFlagGetter('setAndroidLayoutDirection', false);
+/**
+ * Invoke callbacks immediately on the ReactInstance rather than going through a background thread for synchronization
+ */
+export const useImmediateExecutorInAndroidBridgeless: Getter<boolean> = createNativeFlagGetter('useImmediateExecutorInAndroidBridgeless', false);
 /**
  * When enabled, it uses the modern fork of RuntimeScheduler that allows scheduling tasks with priorities from any thread.
  */

packages/react-native/src/private/featureflags/specs/NativeReactNativeFeatureFlags.js

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<4a30969e69164b149af42698f94c3b28>>
+ * @generated SignedSource<<6922b452333fc62a263bd77d42afbbbe>>
  * @flow strict-local
  */
 
@@ -41,6 +41,7 @@ export interface Spec extends TurboModule {
   +lazyAnimationCallbacks?: () => boolean;
   +preventDoubleTextMeasure?: () => boolean;
   +setAndroidLayoutDirection?: () => boolean;
+  +useImmediateExecutorInAndroidBridgeless?: () => boolean;
   +useModernRuntimeScheduler?: () => boolean;
   +useNativeViewConfigsInBridgelessMode?: () => boolean;
   +useRuntimeShadowNodeReferenceUpdate?: () => boolean;