[devicelab] Fix memory benchmark tap synchronization and swipe flakes by bkonyi · Pull Request #194457 · flutter/flutter

bkonyi · 2026-10-15T16:42:20Z

Fixes synchronization and timeout flakes in Devicelab memory benchmarks:

Replaces the Future.any race in MemoryTest.tapNotification() (which fired adb shell input tap 100 100 every 100ms and could leave an unawaited tap in flight after TAPPED was received, causing stray taps or duplicate Completer.complete() throws in flutter_gallery__memory_nav and complex_layout_scroll_perf__memory) with a sequential retry loop (up to 10 attempts, 1s timeout per tap).
Guards Completer.complete() in MemoryTest.handleLogcatLine(), ReportedDurationTest.run(), memory_nav.dart, and scroll_perf.dart against duplicate benchmark markers.
Updates fast_scroll_heavy_gridview__memory and fast_scroll_large_images__memory to drive scrolling deterministically in-process with LiveWidgetController(WidgetsBinding.instance).fling(...) + endOfAnimation() and ==== MEMORY BENCHMARK ==== DONE ==== via the standard MemoryTest.useMemory() flow instead of blind adb shell input swipe coordinates and fixed delays.
Adds bounded 60-second timeouts (MemoryTest.nextMessageTimeout and ReportedDurationTest.durationTimeout) to READY, DONE, AppLifecycleState.paused, and durationCompleter.future logcat waits so missed log lines fail fast instead of hanging the LUCI builder for 30 minutes.

Pre-launch Checklist

Replaces the unawaited `Future.any` tap loop in `MemoryTest.tapNotification()` with sequential tap-and-wait retries so in-flight `adb shell input tap` commands do not leak into the benchmark after `TAPPED` is received, and guards `Completer.complete()` against duplicate `TAPPED` logcat markers. Updates `fast_scroll_heavy_gridview__memory` and `fast_scroll_large_images__memory` to drive scrolling deterministically in-process with `LiveWidgetController.fling` and `endOfAnimation()` instead of blind `adb shell input swipe` commands and fixed sleeps, and adds bounded 60-second timeouts to `MemoryTest` and `ReportedDurationTest` logcat waits. Fixes flutter#149901

gemini-code-assist

Code Review

This pull request refactors memory benchmark tests to perform automated flinging internally within the test apps rather than using external ADB swipe commands, and improves tap synchronization with sequential retries and timeouts. Feedback on these changes suggests simplifying the widget tree in the benchmark apps by removing redundant GestureDetector and IgnorePointer wrappers, and replacing null-aware operators (?.) with null-assertions (!) on receivedNextMessage to prevent silent test bypasses and ensure fast failures.

gemini-code-assist · 2026-10-15T16:45:33Z

+  runApp(
+    GestureDetector(
+      child: const IgnorePointer(
+        ignoring: false,
+        child: MacrobenchmarksApp(initialRoute: kHeavyGridViewRouteName),
+      ),
+    ),
+  );


Since runApp completely replaces the widget tree, wrapping the app in a redundant GestureDetector (with no callbacks) and IgnorePointer(ignoring: false) is unnecessary. We can simplify this by directly calling runApp with the MacrobenchmarksApp widget.

Suggested change

runApp(

GestureDetector(

child: const IgnorePointer(

ignoring: false,

child: MacrobenchmarksApp(initialRoute: kHeavyGridViewRouteName),

),

),

);

runApp(const MacrobenchmarksApp(initialRoute: kHeavyGridViewRouteName));

References

Suggest simplification and refactoring: Assess whether the code can be made simpler or refactored to enhance readability and maintainability. ^(link)

gemini-code-assist · 2026-10-15T16:45:33Z

+  runApp(
+    GestureDetector(
+      child: const IgnorePointer(
+        ignoring: false,
+        child: MacrobenchmarksApp(initialRoute: kLargeImagesRouteName),
+      ),
+    ),
+  );


Since runApp completely replaces the widget tree, wrapping the app in a redundant GestureDetector (with no callbacks) and IgnorePointer(ignoring: false) is unnecessary. We can simplify this by directly calling runApp with the MacrobenchmarksApp widget.

Suggested change

runApp(

GestureDetector(

child: const IgnorePointer(

ignoring: false,

child: MacrobenchmarksApp(initialRoute: kLargeImagesRouteName),

),

),

);

runApp(const MacrobenchmarksApp(initialRoute: kLargeImagesRouteName));

References

Suggest simplification and refactoring: Assess whether the code can be made simpler or refactored to enhance readability and maintainability. ^(link)

gemini-code-assist · 2026-10-15T16:45:33Z

      prepareForNextMessage('AppLifecycleState.paused');
      await device!.shellExec('input', <String>['keyevent', 'KEYCODE_BACK']);
-      await receivedNextMessage;
+      await receivedNextMessage?.timeout(MemoryTest.nextMessageTimeout);


Using the null-aware operator ?. on receivedNextMessage means that if receivedNextMessage is null (e.g., due to a developer error where prepareForNextMessage was not called), the expression will silently evaluate to null and await null will complete immediately without waiting. Using the null-assertion operator ! instead ensures that the test fails fast with a clear error if receivedNextMessage is null, preventing silent test bypasses.

Suggested change

await receivedNextMessage?.timeout(MemoryTest.nextMessageTimeout);

await receivedNextMessage!.timeout(MemoryTest.nextMessageTimeout);

gemini-code-assist · 2026-10-15T16:45:33Z

        fail('unable to launch activity');
      }
-      await receivedNextMessage;
+      await receivedNextMessage?.timeout(MemoryTest.nextMessageTimeout);


Using the null-aware operator ?. on receivedNextMessage means that if receivedNextMessage is null (e.g., due to a developer error where prepareForNextMessage was not called), the expression will silently evaluate to null and await null will complete immediately without waiting. Using the null-assertion operator ! instead ensures that the test fails fast with a clear error if receivedNextMessage is null, preventing silent test bypasses.

Suggested change

await receivedNextMessage?.timeout(MemoryTest.nextMessageTimeout);

await receivedNextMessage!.timeout(MemoryTest.nextMessageTimeout);

gemini-code-assist · 2026-10-15T16:45:33Z

-    print('awaiting "ready" message...');
-    await receivedNextMessage;
+    print('awaiting "ready" message... (timeout: $nextMessageTimeout)');
+    await receivedNextMessage?.timeout(nextMessageTimeout);


Using the null-aware operator ?. on receivedNextMessage means that if receivedNextMessage is null (e.g., due to a developer error where prepareForNextMessage was not called), the expression will silently evaluate to null and await null will complete immediately without waiting. Using the null-assertion operator ! instead ensures that the test fails fast with a clear error if receivedNextMessage is null, preventing silent test bypasses.

Suggested change

await receivedNextMessage?.timeout(nextMessageTimeout);

await receivedNextMessage!.timeout(nextMessageTimeout);

gemini-code-assist · 2026-10-15T16:45:33Z

+      await device!.tap(_tapCoordinate, _tapCoordinate);
+      print('awaiting "tapped" message... (timeout: $_tapRetryTimeout)');
+      try {
+        await receivedNextMessage?.timeout(_tapRetryTimeout);


Using the null-aware operator ?. on receivedNextMessage means that if receivedNextMessage is null (e.g., due to a developer error where prepareForNextMessage was not called), the expression will silently evaluate to null and await null will complete immediately without waiting. Using the null-assertion operator ! instead ensures that the test fails fast with a clear error if receivedNextMessage is null, preventing silent test bypasses.

Suggested change

await receivedNextMessage?.timeout(_tapRetryTimeout);

await receivedNextMessage!.timeout(_tapRetryTimeout);

gemini-code-assist · 2026-10-15T16:45:33Z

-    print('awaiting "done" message...');
-    await receivedNextMessage;
+    print('awaiting "done" message... (timeout: $nextMessageTimeout)');
+    await receivedNextMessage?.timeout(nextMessageTimeout);


Using the null-aware operator ?. on receivedNextMessage means that if receivedNextMessage is null (e.g., due to a developer error where prepareForNextMessage was not called), the expression will silently evaluate to null and await null will complete immediately without waiting. Using the null-assertion operator ! instead ensures that the test fails fast with a clear error if receivedNextMessage is null, preventing silent test bypasses.

Suggested change

await receivedNextMessage?.timeout(nextMessageTimeout);

await receivedNextMessage!.timeout(nextMessageTimeout);

…k-flakes

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bkonyi added the CICD Run CI/CD label Oct 15, 2026

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Piinks added the team-infra Owned by Infrastructure team label Oct 19, 2026

Merge remote-tracking branch 'origin/master' into fix-memory-benchmar…

1320c62

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bkonyi requested a review from chingjun November 6, 2026 17:45

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Merged via the queue into flutter:master with commit cf854df Nov 11, 2026
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Roll Flutter from fffd8c22ae64 to b98afb524077 (31 revisions) flutter/packages#13623

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[devicelab] Fix memory benchmark tap synchronization and swipe flakes - #194457

[devicelab] Fix memory benchmark tap synchronization and swipe flakes#194457
auto-submit[bot] merged 2 commits into
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	await receivedNextMessage?.timeout(MemoryTest.nextMessageTimeout);
	await receivedNextMessage!.timeout(MemoryTest.nextMessageTimeout);

	await receivedNextMessage?.timeout(nextMessageTimeout);
	await receivedNextMessage!.timeout(nextMessageTimeout);

	await receivedNextMessage?.timeout(_tapRetryTimeout);
	await receivedNextMessage!.timeout(_tapRetryTimeout);

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bkonyi commented Oct 15, 2026

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