fix(gestures): Replace GestureDetectorCompat with lightweight detector to fix ANR by romtsn · Pull Request #5138 · getsentry/sentry-java

romtsn · 2026-03-02T20:05:02Z

Summary

Replace GestureDetectorCompat with a custom lightweight SentryGestureDetector in SentryWindowCallback to fix ANR SDK-CRASHES-JAVA-596 (175K+ occurrences, 574 users)
GestureDetectorCompat internally uses Handler.sendMessage/removeMessages which acquires a synchronized lock on the main thread's MessageQueue, plus recordGestureClassification() triggers IPC/binder calls — both cause contention under load
The new detector only implements click, scroll, and fling detection (the only gestures SentryGestureListener uses), eliminating all Handler scheduling, MessageQueue lock contention, and IPC overhead

Test plan

Added SentryGestureDetectorTest with 7 test cases: tap, no-tap, scroll with deltas, fling, slow release, cancel cleanup, sequential gesture reset
Existing SentryWindowCallbackTest (4 tests) passes
Existing SentryGestureListenerTest suite passes
./gradlew :sentry-android-core:testDebugUnitTest passes
Manual testing on Android device

🤖 Generated with Claude Code

github-actions · 2026-03-02T20:05:41Z

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

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Entries from this PR are highlighted with a left border (blockquote style).

Bug Fixes 🐛

(gestures) Replace GestureDetectorCompat with lightweight detector to fix ANR by romtsn in #5138

Internal Changes 🔧

Deps

Update Gradle to v9.4.1 by github-actions in #5063
Bump actions/github-script from 8.0.0 to 9.0.0 by dependabot in #5285
Bump actions/create-github-app-token from 3.0.0 to 3.1.1 by dependabot in #5287
Bump actions/upload-artifact from 7.0.0 to 7.0.1 by dependabot in #5286
Update Native SDK to v0.13.6 by github-actions in #5277

_{🤖 This preview updates automatically when you update the PR.}

github-actions · 2026-03-02T20:17:20Z

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	412.58 ms	464.67 ms	52.09 ms
Size	0 B	0 B	0 B

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
`d15471f`	310.66 ms	368.19 ms	57.53 ms
`9054d65`	330.94 ms	403.24 ms	72.30 ms
`b77456b`	393.26 ms	441.10 ms	47.84 ms
`96449e8`	361.30 ms	423.39 ms	62.09 ms
`ee747ae`	357.79 ms	421.84 ms	64.05 ms
`a416a65`	295.53 ms	373.74 ms	78.21 ms
`ab8a72d`	316.24 ms	356.38 ms	40.14 ms
`1564554`	323.06 ms	336.68 ms	13.62 ms
`b3d8889`	371.69 ms	432.96 ms	61.26 ms
`d15471f`	315.20 ms	370.22 ms	55.02 ms

App size

Revision	Plain	With Sentry	Diff
`d15471f`	1.58 MiB	2.13 MiB	559.54 KiB
`9054d65`	1.58 MiB	2.29 MiB	723.38 KiB
`b77456b`	1.58 MiB	2.12 MiB	548.11 KiB
`96449e8`	1.58 MiB	2.11 MiB	539.35 KiB
`ee747ae`	1.58 MiB	2.10 MiB	530.95 KiB
`a416a65`	1.58 MiB	2.12 MiB	555.26 KiB
`ab8a72d`	1.58 MiB	2.12 MiB	551.55 KiB
`1564554`	1.58 MiB	2.20 MiB	635.33 KiB
`b3d8889`	1.58 MiB	2.10 MiB	535.06 KiB
`d15471f`	1.58 MiB	2.13 MiB	559.54 KiB

Previous results on branch: rz/fix/anr-gesture-detector

Startup times

Revision	Plain	With Sentry	Diff
`85a0af4`	312.65 ms	356.14 ms	43.49 ms
`d7d285a`	324.00 ms	357.96 ms	33.96 ms
`fdd395a`	304.87 ms	340.11 ms	35.24 ms

App size

Revision	Plain	With Sentry	Diff
`85a0af4`	0 B	0 B	0 B
`d7d285a`	0 B	0 B	0 B
`fdd395a`	0 B	0 B	0 B

sentry · 2026-03-11T13:27:23Z

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.38.0 (1)	release

⚙️ sentry-android Build Distribution Settings

…stureDetector to fix ANR GestureDetectorCompat internally uses Handler.sendMessage/removeMessages which acquires a synchronized lock on the main thread MessageQueue, plus recordGestureClassification triggers IPC calls. This caused ANRs under load (SDK-CRASHES-JAVA-596, 175K+ occurrences). Replace with a minimal custom detector that only detects click, scroll, and fling without any Handler scheduling, MessageQueue contention, or IPC overhead. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…velocity data Matches GestureDetector behavior: if consecutive ACTION_DOWN events arrive without an intervening ACTION_UP/ACTION_CANCEL, stale motion data could bleed into fling detection. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…check UserInteractionIntegration gated itself on GestureDetectorCompat being available via classloader check, but SentryGestureDetector only uses Android SDK classes. Remove the check so the integration works without androidx.core. Also remove the stale proguard -keep rule. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Keep VelocityTracker alive across gesture cycles instead of obtain/recycle churn on every gesture. Add release() method called from SentryWindowCallback.stopTracking() to prevent native resource leaks when activity is destroyed mid-gesture. Also fix broken Javadoc @link to removed dependency, change onTouchEvent return to void, and remove redundant null check. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

When a second finger touches the screen (ACTION_POINTER_DOWN), cancel tap detection by setting isInTapRegion to false. Previously, pinch-to-zoom gestures where the first finger stayed still would incorrectly trigger onSingleTapUp, producing false click breadcrumbs. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Add local btrace-perfetto skill for capturing and comparing Perfetto traces on Android devices using btrace 3.0. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Workflow skill that automates capturing and comparing Perfetto traces using btrace 3.0 on Android devices. Includes a Perfetto UI viewer template with SQL query deep-linking via postMessage API. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cursor

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 76e9b72. Configure here.}

Use release builds for accurate profiling, add ProGuard keep rules for btrace and Sentry class names, increase trace duration to 30s, and play a Ping sound synced to the actual trace start. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…rison Prefer debug builds for richer tracing instrumentation (Handler, MessageQueue, Lock slices). Add trace_processor prerequisite for local querying. Add Step 6 with SQL queries and comparison table generation. Include sampling rate reference and additional troubleshooting entries. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

romtsn · 2026-04-16T11:46:28Z

Ran some tests with perfetto in the sample app and this is the result (although the diff will have been much more significant in a real production app on a device under pressure). Tested on an HMD Pulse, Android 15, 4GB RAM, T606 CPU

other calls were too fast for the profiling sample rate to catch them

…ied swipes The ACTION_POINTER_DOWN handler suppressed taps but not flings. When the last finger lifts quickly after a pinch-to-zoom, the velocity check in ACTION_UP could fire onFling, causing SentryGestureListener to misclassify the gesture as a swipe breadcrumb. Add ignoreUpEvent flag mirroring GestureDetector's mIgnoreNextUpEvent to skip the entire UP handler after multi-touch. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

romtsn requested review from adinauer, lcian and markushi as code owners March 2, 2026 20:05

sentry bot reviewed Mar 2, 2026

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Comment thread ...droid-core/src/main/java/io/sentry/android/core/internal/gestures/SentryGestureDetector.java

cursor bot reviewed Mar 2, 2026

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Comment thread ...droid-core/src/main/java/io/sentry/android/core/internal/gestures/SentryGestureDetector.java

cursor bot reviewed Mar 2, 2026

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Comment thread ...ndroid-core/src/main/java/io/sentry/android/core/internal/gestures/SentryWindowCallback.java

sentry bot reviewed Mar 11, 2026

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Comment thread ...droid-core/src/main/java/io/sentry/android/core/internal/gestures/SentryGestureDetector.java

markushi approved these changes Mar 11, 2026

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romtsn and others added 7 commits April 15, 2026 12:23

test(android): Add unit tests for SentryGestureDetector

06a26ed

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

changelog

7ef8b55

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Move changelog entry

47117f4

romtsn force-pushed the rz/fix/anr-gesture-detector branch from 1a7624e to e9db3cb Compare April 15, 2026 11:06

romtsn and others added 3 commits April 15, 2026 21:08

chore: Register btrace-perfetto skill in agents.toml

5726ea7

Add local btrace-perfetto skill for capturing and comparing Perfetto traces on Android devices using btrace 3.0. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cursor bot reviewed Apr 16, 2026

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Comment thread ...droid-core/src/main/java/io/sentry/android/core/internal/gestures/SentryGestureDetector.java

romtsn and others added 2 commits April 16, 2026 13:06

romtsn merged commit de6a178 into main Apr 16, 2026
67 of 69 checks passed

romtsn deleted the rz/fix/anr-gesture-detector branch April 16, 2026 12:35

sentry-release-bot bot mentioned this pull request Apr 16, 2026

publish: getsentry/sentry-java@8.39.0 getsentry/publish#7828

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romtsn commented Mar 2, 2026

Summary

Test plan

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Semver Impact of This PR

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Deps

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Performance metrics 🚀

Baseline results on branch: main

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App size

Previous results on branch: rz/fix/anr-gesture-detector

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