fix: Fix UITouch background thread access in SentryTouchTracker#6584
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fix: Fix UITouch background thread access in SentryTouchTracker#6584
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Extract UITouch data on main thread before dispatching to background queue to prevent EXC_BAD_ACCESS crashes when accessing UIKit objects from background threads. - Added ExtractedTouchData struct to hold thread-safe touch information - Changed trackedTouches dictionary to use ObjectIdentifier as key instead of UITouch - Extract touch.location, touch.phase, and ObjectIdentifier on calling thread - Process only thread-safe data structures on background queue Fixes #6231
philprime
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itaybre,
noahsmartin and
philipphofmann
as code owners
philprime
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![sentry[bot]](https://avatars.githubusercontent.com/in/12637?s=60&v=4){kind=small}
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## v8.x #6584 +/- ##
=============================================
+ Coverage 85.196% 86.097% +0.901%
=============================================
Files 441 441
Lines 27426 27470 +44
Branches 10368 11933 +1565
=============================================
+ Hits 23366 23651 +285
+ Misses 4018 3773 -245
- Partials 42 46 +4
... and 33 files with indirect coverage changes Continue to review full report in Codecov by Sentry.
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- Added testObjectIdentifierCollision_NewTouchGetsNewId to demonstrate the bug - Fix prevents corrupted touch data when UITouch memory is reused - When .began phase is detected, always create new TouchInfo - Updated CHANGELOG.md with combined entry for both fixes
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- Removed trackedTouches dictionary entirely - Use single allTouchInfos array with O(n) lookup - Store ObjectIdentifier in TouchInfo for matching - Eliminates collision/orphaning complexity - Reduced cyclomatic complexity (no more linter warnings) - All 14 tests pass
Contributor
Performance metrics 🚀
|
| Revision | Plain | With Sentry | Diff |
|---|---|---|---|
| ab82dac | 1213.12 ms | 1240.92 ms | 27.80 ms |
| c11a8e0 | 1203.00 ms | 1223.23 ms | 20.23 ms |
| ab82dac | 1249.73 ms | 1272.69 ms | 22.96 ms |
| 41834f1 | 1235.15 ms | 1256.31 ms | 21.17 ms |
| f76f6bf | 1207.70 ms | 1233.27 ms | 25.57 ms |
| b66be9b | 1218.22 ms | 1244.19 ms | 25.96 ms |
| 5fce94f | 1226.31 ms | 1246.82 ms | 20.50 ms |
| a7a0a2b | 1218.61 ms | 1248.69 ms | 30.08 ms |
| e537c90 | 1226.22 ms | 1256.64 ms | 30.41 ms |
| 3af1ae9 | 1225.60 ms | 1252.65 ms | 27.05 ms |
App size
| Revision | Plain | With Sentry | Diff |
|---|---|---|---|
| ab82dac | 23.75 KiB | 991.86 KiB | 968.11 KiB |
| c11a8e0 | 23.75 KiB | 991.86 KiB | 968.12 KiB |
| ab82dac | 23.75 KiB | 991.85 KiB | 968.10 KiB |
| 41834f1 | 23.75 KiB | 991.88 KiB | 968.13 KiB |
| f76f6bf | 23.74 KiB | 981.30 KiB | 957.56 KiB |
| b66be9b | 23.75 KiB | 996.03 KiB | 972.28 KiB |
| 5fce94f | 23.75 KiB | 991.62 KiB | 967.87 KiB |
| a7a0a2b | 23.75 KiB | 996.04 KiB | 972.29 KiB |
| e537c90 | 23.75 KiB | 992.03 KiB | 968.28 KiB |
| 3af1ae9 | 23.74 KiB | 981.29 KiB | 957.55 KiB |
noahsmartin
reviewed
Oct 29, 2025
Sources/Swift/Integrations/SessionReplay/SentryTouchTracker.swift
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noahsmartin
reviewed
Oct 29, 2025
Address PR feedback - use dictionary for O(1) lookup instead of O(n) array search. - trackedTouches: O(1) dictionary lookup for active touches - orphanedTouches: array for collision-replaced touches - When .began collides, move old touch to orphanedTouches before replacing - Extract processTouchEvent method to reduce cyclomatic complexity - replayEvents returns both active + orphaned touches - Maintains performance while preserving all events - All 14 tests pass
Contributor
|
CI is being very slow, I am backporting some fixes on #6604 to help this PR and the later release |
itaybre
added a commit
that referenced
this pull request
Oct 30, 2025
* test: Ensure test is server running (#6300) Ensure that the test server is running with a retry mechanism to avoid flakiness in CI. * ci: Add v8.x branch to workflows (#6321) * chore: Explain v8 branch (#6323) Add decision log entry for v8 branch and explain how to release from it. * ci(v8): Bump Xcode from 26.0 to 26.0.1 (#6394) * docs: Add note to README with reference to v9 on main branch (#6402) * fix: Wrong Frame Delay when becoming active (#6393) The SDK reported false frame delay statistics when it moved from the background to the foreground, which also led to falsely reported app hangs. Fixes GH-6345 * fix(session-replay): Add detection for potential PII leaks disabling session replay (#6389) * release: 8.57.0 * chore: Bump simulators to 26.1 (#6578) * fix: Fix crash when last replay info is missing some keys (#6577) * fix: Fix crash when last replay info is missing keys * Update changelog * fix: Disable SessionSentryReplayIntegration if the environment is unsafe (#6573) * fix: Disable SessionSentryReplayIntegration if the environment is unsafe * Simplify shouldEnableSessionReplay * Rename test * Add log message * Update changelog * Safely unwrap SentryOptions * fix: Fix UITouch background thread access in SentryTouchTracker (#6584) * release: 8.57.1 * Fix merge issues * Fix another merge issue * More merge conflicts * Add SentryThreadInspector again * Fix tests on iOS 26 * Add `enableSessionReplayInUnreliableEnvironment` --------- Co-authored-by: Philipp Hofmann <[email protected]> Co-authored-by: Philip Niedertscheider <[email protected]> Co-authored-by: getsentry-bot <[email protected]> Co-authored-by: getsentry-bot <[email protected]>
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📜 Description
This PR fixes a crash caused by accessing UITouch instances from a background thread in . The fix extracts all necessary data from UITouch objects on the main thread before dispatching to the background queue, then processes only thread-safe data structures on the background thread.
Changes:
ExtractedTouchDatastruct to hold thread-safe touch informationtrackedTouchesdictionary to useObjectIdentifieras key instead ofUITouchtouch.location,touch.phase, andObjectIdentifieron calling thread (main thread)💡 Motivation and Context
Fixes #6231
The issue was that
trackTouchFrom(event:)dispatched to a background queue and then accessed UITouch properties (touch.location(in: nil)andtouch.phase) from that background thread. This violates UIKit's thread-safety requirements and causedEXC_BAD_ACCESScrashes.The stack trace from the issue showed:
💚 How did you test it?
SentryTouchTrackerTestspass successfully📝 Checklist
sendDefaultPIIis enabled.