fix(ios): CVPixelBuffer race condition crash in captureOutput#1676
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harSofja wants to merge 1 commit intojuliansteenbakker:developfrom
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fix(ios): CVPixelBuffer race condition crash in captureOutput#1676harSofja wants to merge 1 commit intojuliansteenbakker:developfrom
harSofja wants to merge 1 commit intojuliansteenbakker:developfrom
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Capture a strong reference to latestBuffer before dispatching to background thread. Fixes juliansteenbakker#1545
harSofja
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navaronbracke
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Mar 23, 2026
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navaronbracke
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Good catch! Yeah, chances are that there's a threading issue, since there's stuff running on the global dispatch queue.
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| guard let buffer = self.latestBuffer else { | ||
| let bufferToProcess = latestBuffer |
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Is the formatting off here? (relative to the surrounding code)
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@harSofja I see that Github provides me with a warning on the pull request? Does the branch need to be renamed? Also, can you add an entry in the changelog + bump the patch version in the pubspec? |
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Since the GitHub web editor is getting messy with hidden characters I will close this PR and create a clean one. I will also look at the formatting and add an entry in the change log |
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Summary
Fixes a race condition in
captureOutputwhereself.latestBufferis read on a background thread (DispatchQueue.global(qos: .userInitiated)) after being deallocated or overwritten on the main thread by the next camera frame orreleaseCamera().The fix captures a strong reference to the buffer before dispatching to the background queue, ensuring the
CVPixelBufferis retained for the duration of the background processing.Crash Stack Trace (from Xcode Organizer)
Thread 1 Crashed:
0 CoreVideo CVPixelBufferGetWidth + 28
1 VideoToolbox VTCreateCGImageFromCVPixelBuffer
2 mobile_scanner closure #1 in MobileScannerPlugin.captureOutput(:didOutput:from:)
3 mobile_scanner MobileScannerPlugin.captureOutput(:didOutput:from:) (partial)
4 libdispatch _dispatch_call_block_and_release
5 libdispatch _dispatch_client_callout
Environment
Related Issue
Fixes #1545