Android: stop re-arming the idle TIMERS_EVENTS Choreographer frame callback (behind feature flag)

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<<b7ef80c2c39c734ae511fe6457b89ce7>>
+ * @generated SignedSource<<d2d65cecfe7e05e7d4d04fc54c904e60>>
  */
 
 /**
@@ -60,6 +60,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun disableEarlyViewCommandExecution(): Boolean = accessor.disableEarlyViewCommandExecution()
 
+  /**
+   * Stop re-arming the TIMERS_EVENTS Choreographer frame callback at vsync rate while the timer queue is empty on Android; createTimer re-arms it lazily
+   */
+  @JvmStatic
+  public fun disableIdleTimersFrameCallbackRearmAndroid(): Boolean = accessor.disableIdleTimersFrameCallbackRearmAndroid()
+
   /**
    * Force disable view preallocation for images triggered from createNode off the main thread on Android
    */

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<<68aefd0293540d56f57e8badc0de04c8>>
+ * @generated SignedSource<<e601df5e10547f5a92e005f57c09a1b3>>
  */
 
 /**
@@ -25,6 +25,7 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
   private var cxxNativeAnimatedEnabledCache: Boolean? = null
   private var defaultTextToOverflowHiddenCache: Boolean? = null
   private var disableEarlyViewCommandExecutionCache: Boolean? = null
+  private var disableIdleTimersFrameCallbackRearmAndroidCache: Boolean? = null
   private var disableImageViewPreallocationAndroidCache: Boolean? = null
   private var disableMountItemReorderingAndroidCache: Boolean? = null
   private var disableSubviewClippingAndroidCache: Boolean? = null
@@ -152,6 +153,15 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun disableIdleTimersFrameCallbackRearmAndroid(): Boolean {
+    var cached = disableIdleTimersFrameCallbackRearmAndroidCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.disableIdleTimersFrameCallbackRearmAndroid()
+      disableIdleTimersFrameCallbackRearmAndroidCache = cached
+    }
+    return cached
+  }
+
   override fun disableImageViewPreallocationAndroid(): Boolean {
     var cached = disableImageViewPreallocationAndroidCache
     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<<247f721796621af8615014477518bcd9>>
+ * @generated SignedSource<<e83d4ef1dff441f096e0e05f0762f47b>>
  */
 
 /**
@@ -38,6 +38,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun disableEarlyViewCommandExecution(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun disableIdleTimersFrameCallbackRearmAndroid(): Boolean
+
   @DoNotStrip @JvmStatic public external fun disableImageViewPreallocationAndroid(): Boolean
 
   @DoNotStrip @JvmStatic public external fun disableMountItemReorderingAndroid(): 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<<33071257f9c96a8664c9af429e387061>>
+ * @generated SignedSource<<d329c4772411b7a603e4e106cac3b516>>
  */
 
 /**
@@ -33,6 +33,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun disableEarlyViewCommandExecution(): Boolean = false
 
+  override fun disableIdleTimersFrameCallbackRearmAndroid(): Boolean = false
+
   override fun disableImageViewPreallocationAndroid(): Boolean = false
 
   override fun disableMountItemReorderingAndroid(): 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<<f218220c66b8367211cae49adba46afc>>
+ * @generated SignedSource<<8c79cf348cdf6e6705d6b8dac2c8482a>>
  */
 
 /**
@@ -29,6 +29,7 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private var cxxNativeAnimatedEnabledCache: Boolean? = null
   private var defaultTextToOverflowHiddenCache: Boolean? = null
   private var disableEarlyViewCommandExecutionCache: Boolean? = null
+  private var disableIdleTimersFrameCallbackRearmAndroidCache: Boolean? = null
   private var disableImageViewPreallocationAndroidCache: Boolean? = null
   private var disableMountItemReorderingAndroidCache: Boolean? = null
   private var disableSubviewClippingAndroidCache: Boolean? = null
@@ -161,6 +162,16 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
     return cached
   }
 
+  override fun disableIdleTimersFrameCallbackRearmAndroid(): Boolean {
+    var cached = disableIdleTimersFrameCallbackRearmAndroidCache
+    if (cached == null) {
+      cached = currentProvider.disableIdleTimersFrameCallbackRearmAndroid()
+      accessedFeatureFlags.add("disableIdleTimersFrameCallbackRearmAndroid")
+      disableIdleTimersFrameCallbackRearmAndroidCache = cached
+    }
+    return cached
+  }
+
   override fun disableImageViewPreallocationAndroid(): Boolean {
     var cached = disableImageViewPreallocationAndroidCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsOverrides_RNOSS_Experimental_Android.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<<bad3dbaf92a0a869dfb91523ef4904f9>>
+ * @generated SignedSource<<a3427f1f1d9939d368b781e251cb8d03>>
  */
 
 /**
@@ -23,6 +23,8 @@ public open class ReactNativeFeatureFlagsOverrides_RNOSS_Experimental_Android :
   // We could use JNI to get the defaults from C++,
   // but that is more expensive than just duplicating the defaults here.
 
+  override fun disableIdleTimersFrameCallbackRearmAndroid(): Boolean = true
+
   override fun enableFlexboxAutoMinSizeInStrictMode(): Boolean = true
 
   override fun preventShadowTreeCommitExhaustion(): Boolean = true

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<<915bf918212b9898319de61d4cadaa13>>
+ * @generated SignedSource<<2b86c6b4f9923a97602642ac2b11a58d>>
  */
 
 /**
@@ -33,6 +33,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun disableEarlyViewCommandExecution(): Boolean
 
+  @DoNotStrip public fun disableIdleTimersFrameCallbackRearmAndroid(): Boolean
+
   @DoNotStrip public fun disableImageViewPreallocationAndroid(): Boolean
 
   @DoNotStrip public fun disableMountItemReorderingAndroid(): Boolean

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/core/JavaTimerManager.kt

@@ -20,6 +20,7 @@ import com.facebook.react.common.SystemClock.nanoTime
 import com.facebook.react.common.SystemClock.uptimeMillis
 import com.facebook.react.common.annotations.internal.LegacyArchitecture
 import com.facebook.react.devsupport.interfaces.DevSupportManager
+import com.facebook.react.internal.featureflags.ReactNativeFeatureFlags
 import com.facebook.react.jstasks.HeadlessJsTaskContext
 import com.facebook.react.jstasks.HeadlessJsTaskEventListener
 import java.util.PriorityQueue
@@ -186,6 +187,16 @@ public open class JavaTimerManager(
       timers.add(timer)
       timerIdsToTimers.put(timerId, timer)
     }
+    if (ReactNativeFeatureFlags.disableIdleTimersFrameCallbackRearmAndroid() &&
+        !frameCallbackPosted &&
+        (!isPaused.get() || isRunningTasks.get())) {
+      // The timers frame callback disarms itself once the queue drains (see TimerFrameCallback);
+      // re-arm it lazily when a new timer arrives. setChoreographerCallback is UI-confined
+      // (ReactChoreographer must be driven from the UI looper) and idempotent, so hop to the UI
+      // thread. While the host is paused, only headless JS task execution may run timers —
+      // mirroring the guard in clearFrameCallback.
+      UiThreadUtil.runOnUiThread { setChoreographerCallback() }
+    }
   }
 
   /**
@@ -292,6 +303,7 @@ public open class JavaTimerManager(
         return
       }
       val frameTimeMillis = frameTimeNanos / 1000000
+      var shouldRepost = true
       synchronized(timerGuard) {
         while (!timers.isEmpty() && timers.peek()!!.targetTime < frameTimeMillis) {
           var timer = timers.poll()
@@ -309,12 +321,22 @@ public open class JavaTimerManager(
             timerIdsToTimers.remove(timer.timerId)
           }
         }
+        if (ReactNativeFeatureFlags.disableIdleTimersFrameCallbackRearmAndroid()) {
+          // The timer queue is empty: disarm instead of re-posting this callback at vsync rate.
+          // createTimer re-arms the callback when a new timer arrives.
+          shouldRepost = timers.isNotEmpty()
+          if (!shouldRepost) {
+            frameCallbackPosted = false
+          }
+        }
       }
       timersToCall?.let { timers ->
         javaScriptTimerExecutor.callTimers(timers)
         timersToCall = null
       }
-      reactChoreographer.postFrameCallback(ReactChoreographer.CallbackType.TIMERS_EVENTS, this)
+      if (shouldRepost) {
+        reactChoreographer.postFrameCallback(ReactChoreographer.CallbackType.TIMERS_EVENTS, this)
+      }
     }
   }
 

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<<177c5cc7f6e970a2d4454c32d7f777ef>>
+ * @generated SignedSource<<14d8d9fb09b9c47aa6efa35fd521699e>>
  */
 
 /**
@@ -69,6 +69,12 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
+  bool disableIdleTimersFrameCallbackRearmAndroid() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("disableIdleTimersFrameCallbackRearmAndroid");
+    return method(javaProvider_);
+  }
+
   bool disableImageViewPreallocationAndroid() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("disableImageViewPreallocationAndroid");
@@ -584,6 +590,11 @@ bool JReactNativeFeatureFlagsCxxInterop::disableEarlyViewCommandExecution(
   return ReactNativeFeatureFlags::disableEarlyViewCommandExecution();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::disableIdleTimersFrameCallbackRearmAndroid(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::disableIdleTimersFrameCallbackRearmAndroid();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::disableImageViewPreallocationAndroid(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::disableImageViewPreallocationAndroid();
@@ -1035,6 +1046,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "disableEarlyViewCommandExecution",
         JReactNativeFeatureFlagsCxxInterop::disableEarlyViewCommandExecution),
+      makeNativeMethod(
+        "disableIdleTimersFrameCallbackRearmAndroid",
+        JReactNativeFeatureFlagsCxxInterop::disableIdleTimersFrameCallbackRearmAndroid),
       makeNativeMethod(
         "disableImageViewPreallocationAndroid",
         JReactNativeFeatureFlagsCxxInterop::disableImageViewPreallocationAndroid),

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<<eab10e240a16c8ef3f659bd8ded290f0>>
+ * @generated SignedSource<<5cc6a0602af0ce7ae394f41adde13ee0>>
  */
 
 /**
@@ -45,6 +45,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool disableEarlyViewCommandExecution(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool disableIdleTimersFrameCallbackRearmAndroid(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool disableImageViewPreallocationAndroid(
     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<<7b726d7483bb35062b79e582323f0d7e>>
+ * @generated SignedSource<<27db13f91b9672274086048a7a970362>>
  */
 
 /**
@@ -46,6 +46,10 @@ bool ReactNativeFeatureFlags::disableEarlyViewCommandExecution() {
   return getAccessor().disableEarlyViewCommandExecution();
 }
 
+bool ReactNativeFeatureFlags::disableIdleTimersFrameCallbackRearmAndroid() {
+  return getAccessor().disableIdleTimersFrameCallbackRearmAndroid();
+}
+
 bool ReactNativeFeatureFlags::disableImageViewPreallocationAndroid() {
   return getAccessor().disableImageViewPreallocationAndroid();
 }

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<<1e9009301b79f977132c4fa5599aebdd>>
+ * @generated SignedSource<<4850b4600168e52a55b10165de7dca48>>
  */
 
 /**
@@ -66,6 +66,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool disableEarlyViewCommandExecution();
 
+  /**
+   * Stop re-arming the TIMERS_EVENTS Choreographer frame callback at vsync rate while the timer queue is empty on Android; createTimer re-arms it lazily
+   */
+  RN_EXPORT static bool disableIdleTimersFrameCallbackRearmAndroid();
+
   /**
    * Force disable view preallocation for images triggered from createNode off the main thread on Android
    */