[camera_android] Use WeakReference to prevent startImageStream OOM error when main thread hangs (flutter#166533) #9571

kwikwag · 2025-07-07T11:26:39Z

This is an alternative solution to the pull request #8998

When streaming images using CameraController.startImageStream(), images are being post()-ed to the main looper in the Android implementation, even if it's hanging or paused. This will happen, for instance, when the Flutter debugger is paused or when the main thread is very busy. This can quickly result in an OOM (out-of-memory) error due to many images pending in queue, and the Android OS will kill the app abruptly.

This version of the fix is done by keep the frames (except for the latest one) as WeakReferences. When memory pressur is on, the runtime can free weak references, therefore dropping frames. A log message is emitted for each dropped frame. As opposed to the back-pressure solution, there is no hard limit to how many frames are kept in queue - this means that if the main thread is delayed in processing frames for some reason, they will pile up as long as the memory can sustain them.

Fixes flutter/flutter#166533 That issue also provides a demo program for testing the behavior.

Some more data and considerations are listed in the original pull request.

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…read paused (flutter#166533) When streaming images using CameraController.startImageStream(), images are being post()-ed to the main looper even if it's halted. This is common when debugging. This quickly results in an OOM and the app crashes abruptly. The fix is done by counting the number of images that have been posted to the main thread but have not yet arrived. If too many images are in transit (I arbitrarily chose 3 as the maximum allowable amount) subsequent frames are dropped, until the main thread receives the pending images. A log message is emitted for each dropped frame. Fixes flutter/flutter#166533 That issue also provides a demo program.

…read paused (flutter#166533) When streaming images using CameraController.startImageStream(), images are being `post()`-ed to the main looper even if it's hanging or paused. This will happen, for instance, if the debugger is paused or the main thread is busy. This can quickly result in the OS killing the app abruptly with an OOM (out-of-memory) error. This fixes it by using a `WeakReference` rather than a hard reference to the image data. If too much memory is used up, the runtime may release image frames that have not yet been processed. A log message is emitted for each frame that was evicted before it was processed.

reidbaker

@camsim99 can you spend extra time validating that you are happy with the test coverage of this new behavior. Async testing is tricky and we dont want to regress this feature.

reidbaker · 2025-07-08T18:50:19Z

...ndroid/android/src/test/java/io/flutter/plugins/camera/media/ImageStreamReaderTestUtils.java

+import java.nio.ByteBuffer;
+
+public class ImageStreamReaderTestUtils {
+  public static Image getImage(int imageWidth, int imageHeight, int padding, int imageFormat) {


Please add java doc for this method

reidbaker · 2025-07-08T19:23:48Z

.../camera_android/android/src/main/java/io/flutter/plugins/camera/media/ImageStreamReader.java

+    boolean postResult =
+        handler.post(
+            new Runnable() {
+              // a public field is required in order to test this code


nit: This comment can be removed it does not add anything over the @visibleForTesing annotation.

reidbaker · 2025-07-08T19:25:48Z

.../camera_android/android/src/main/java/io/flutter/plugins/camera/media/ImageStreamReader.java

+              @Override
+              public void run() {
+                final Map<String, Object> imageBuffer = weakImageBuffer.get();
+                if (imageBuffer == null) {


I think it is correct but can you add a comment here about why garbage collected image buffer is neither and error or success?

I hope the comment I added is sufficient?

kwikwag · 2025-07-08T23:08:32Z

Hey @reidbaker thanks for the review. I've addressed the comments, hopefully correctly. I also merged main. Let me know if there's anything else.

camsim99

As far as I can tell, the test covers the cases well. LGTM!

…eam OOM error when main thread hangs (flutter#166533) (flutter/packages#9571)

flutter/packages@4a231ae...cb8fef6 2025-07-17 49699333+dependabot[bot]@users.noreply.github.com [dependabot]: Bump androidx.activity:activity from 1.9.3 to 1.10.1 in /packages/image_picker/image_picker_android/android (flutter/packages#8725) 2025-07-17 [email protected] [webview_flutter] Update androidx.webkit to 1.14.0 (flutter/packages#9638) 2025-07-17 [email protected] Roll Flutter from c2739f0 to 9c626d9 (18 revisions) (flutter/packages#9641) 2025-07-17 [email protected] Roll Flutter (stable) from 077b4a4 to d7b523b (3 revisions) (flutter/packages#9640) 2025-07-17 [email protected] Fix Gemini note wrapping (flutter/packages#9639) 2025-07-17 49699333+dependabot[bot]@users.noreply.github.com [dependabot]: Bump com.google.android.gms:play-services-maps from 18.2.0 to 19.2.0 in /packages/google_maps_flutter/google_maps_flutter_android/android (flutter/packages#9120) 2025-07-17 49699333+dependabot[bot]@users.noreply.github.com [dependabot]: Bump androidx.fragment:fragment from 1.6.2 to 1.8.8 in /packages/local_auth/local_auth_android/android (flutter/packages#9406) 2025-07-16 [email protected] [ci] Add Gemini Code Assist review config (flutter/packages#9632) 2025-07-16 [email protected] Roll Flutter from cc3110c to c2739f0 (15 revisions) (flutter/packages#9633) 2025-07-16 [email protected] [image_picker] redesign example app (flutter/packages#9625) 2025-07-16 [email protected] [camera_avfoundation] Implementation swift migration - part 7 (flutter/packages#9595) 2025-07-15 [email protected] [webview_flutter_wkwebview] Replace Flutter method failure assertion with nslog (flutter/packages#9587) 2025-07-15 [email protected] Roll Flutter from a930ec1 to cc3110c (24 revisions) (flutter/packages#9631) 2025-07-15 [email protected] [webview_flutter] Add setMixedContentMode for Android (flutter/packages#9586) 2025-07-15 [email protected] [google_sign_in] Add exception info to migration guide (flutter/packages#9574) 2025-07-14 [email protected] [camera_android] Use WeakReference to prevent startImageStream OOM error when main thread hangs (#166533) (flutter/packages#9571) 2025-07-14 [email protected] [quick_actions] Restore the appShortcutLaunchActivityAfterStarting test in quick_actions_android (flutter/packages#9508) 2025-07-14 [email protected] Roll Flutter from 35f197f to a930ec1 (3 revisions) (flutter/packages#9624) 2025-07-14 49699333+dependabot[bot]@users.noreply.github.com [dependabot]: Bump com.android.tools.build:gradle from 8.9.1 to 8.11.1 in /packages/pigeon/platform_tests/test_plugin/android (flutter/packages#9618) 2025-07-12 [email protected] Roll Flutter from 43657f3 to 35f197f (39 revisions) (flutter/packages#9602) 2025-07-11 [email protected] Replace popularity badges (flutter/packages#9594) 2025-07-11 [email protected] [rfw] Update test to not depend on toString() (flutter/packages#9590) 2025-07-11 [email protected] [camera_avfoundation] Implementation swift migration - part 6 (flutter/packages#9588) 2025-07-10 [email protected] [url_launcher] Fixes new unnecessary boolean operations warnings (flutter/packages#9409) 2025-07-10 [email protected] [google_sign_in] Add troubleshooting to Android README (flutter/packages#9581) 2025-07-10 [email protected] Roll Flutter from ac12f66 to 43657f3 (25 revisions) (flutter/packages#9589) 2025-07-10 [email protected] [go_router_builder] Update case sensitive test to `go_router` 16.0.0 (flutter/packages#9482) 2025-07-09 [email protected] [rfw] Remove the RFW WASM example (flutter/packages#9551) 2025-07-09 [email protected] Roll Flutter (stable) from fcf2c11 to 077b4a4 (5 revisions) (flutter/packages#9585) 2025-07-09 [email protected] Roll Flutter from adffe24 to ac12f66 (28 revisions) (flutter/packages#9584) 2025-07-09 [email protected] [video_player] Add html 5 video poster support (thumbnail) as a VideoPlayerWebOptions (flutter/packages#8940) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages-flutter-autoroll Please CC [email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

…er#172303) flutter/packages@4a231ae...cb8fef6 2025-07-17 49699333+dependabot[bot]@users.noreply.github.com [dependabot]: Bump androidx.activity:activity from 1.9.3 to 1.10.1 in /packages/image_picker/image_picker_android/android (flutter/packages#8725) 2025-07-17 [email protected] [webview_flutter] Update androidx.webkit to 1.14.0 (flutter/packages#9638) 2025-07-17 [email protected] Roll Flutter from c2739f0 to 9c626d9 (18 revisions) (flutter/packages#9641) 2025-07-17 [email protected] Roll Flutter (stable) from 077b4a4 to d7b523b (3 revisions) (flutter/packages#9640) 2025-07-17 [email protected] Fix Gemini note wrapping (flutter/packages#9639) 2025-07-17 49699333+dependabot[bot]@users.noreply.github.com [dependabot]: Bump com.google.android.gms:play-services-maps from 18.2.0 to 19.2.0 in /packages/google_maps_flutter/google_maps_flutter_android/android (flutter/packages#9120) 2025-07-17 49699333+dependabot[bot]@users.noreply.github.com [dependabot]: Bump androidx.fragment:fragment from 1.6.2 to 1.8.8 in /packages/local_auth/local_auth_android/android (flutter/packages#9406) 2025-07-16 [email protected] [ci] Add Gemini Code Assist review config (flutter/packages#9632) 2025-07-16 [email protected] Roll Flutter from cc3110c to c2739f0 (15 revisions) (flutter/packages#9633) 2025-07-16 [email protected] [image_picker] redesign example app (flutter/packages#9625) 2025-07-16 [email protected] [camera_avfoundation] Implementation swift migration - part 7 (flutter/packages#9595) 2025-07-15 [email protected] [webview_flutter_wkwebview] Replace Flutter method failure assertion with nslog (flutter/packages#9587) 2025-07-15 [email protected] Roll Flutter from a930ec1 to cc3110c (24 revisions) (flutter/packages#9631) 2025-07-15 [email protected] [webview_flutter] Add setMixedContentMode for Android (flutter/packages#9586) 2025-07-15 [email protected] [google_sign_in] Add exception info to migration guide (flutter/packages#9574) 2025-07-14 [email protected] [camera_android] Use WeakReference to prevent startImageStream OOM error when main thread hangs (flutter#166533) (flutter/packages#9571) 2025-07-14 [email protected] [quick_actions] Restore the appShortcutLaunchActivityAfterStarting test in quick_actions_android (flutter/packages#9508) 2025-07-14 [email protected] Roll Flutter from 35f197f to a930ec1 (3 revisions) (flutter/packages#9624) 2025-07-14 49699333+dependabot[bot]@users.noreply.github.com [dependabot]: Bump com.android.tools.build:gradle from 8.9.1 to 8.11.1 in /packages/pigeon/platform_tests/test_plugin/android (flutter/packages#9618) 2025-07-12 [email protected] Roll Flutter from 43657f3 to 35f197f (39 revisions) (flutter/packages#9602) 2025-07-11 [email protected] Replace popularity badges (flutter/packages#9594) 2025-07-11 [email protected] [rfw] Update test to not depend on toString() (flutter/packages#9590) 2025-07-11 [email protected] [camera_avfoundation] Implementation swift migration - part 6 (flutter/packages#9588) 2025-07-10 [email protected] [url_launcher] Fixes new unnecessary boolean operations warnings (flutter/packages#9409) 2025-07-10 [email protected] [google_sign_in] Add troubleshooting to Android README (flutter/packages#9581) 2025-07-10 [email protected] Roll Flutter from ac12f66 to 43657f3 (25 revisions) (flutter/packages#9589) 2025-07-10 [email protected] [go_router_builder] Update case sensitive test to `go_router` 16.0.0 (flutter/packages#9482) 2025-07-09 [email protected] [rfw] Remove the RFW WASM example (flutter/packages#9551) 2025-07-09 [email protected] Roll Flutter (stable) from fcf2c11 to 077b4a4 (5 revisions) (flutter/packages#9585) 2025-07-09 [email protected] Roll Flutter from adffe24 to ac12f66 (28 revisions) (flutter/packages#9584) 2025-07-09 [email protected] [video_player] Add html 5 video poster support (thumbnail) as a VideoPlayerWebOptions (flutter/packages#8940) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages-flutter-autoroll Please CC [email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

kwikwag added 11 commits April 4, 2025 02:10

update pubspec.yaml and CHANGELOG.md

71e9414

Merge branch 'main' into fix/issue_166533

f9db089

add test

ee845f4

fix formatting

97e98f2

fix: remove log message on each frame

bf15d0b

fix: move getImage to ImageStreamReaderTestUtils

cc61ef8

fix: separate exception handling from numImagesInTransit

229ccd4

fix: formatting

cad3010

fix: whoops, forgot to remove some constants

6ed20c9

kwikwag requested a review from camsim99 as a code owner July 7, 2025 11:26

github-actions bot added p: camera platform-android labels Jul 7, 2025

camsim99 requested a review from reidbaker July 7, 2025 16:30

reidbaker approved these changes Jul 8, 2025

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kwikwag added 2 commits July 9, 2025 02:01

fix: some comments

79deae1

Merge branch 'main' into fix/issue_166533_alt2

511e27f

camsim99 approved these changes Jul 14, 2025

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camsim99 added the autosubmit Merge PR when tree becomes green via auto submit App label Jul 14, 2025

auto-submit bot merged commit a86b6c9 into flutter:main Jul 14, 2025
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…eam OOM error when main thread hangs (flutter#166533) (flutter/packages#9571)

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…eam OOM error when main thread hangs (flutter#166533) (flutter/packages#9571)

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[camera_android] Use WeakReference to prevent startImageStream OOM error when main thread hangs (flutter#166533) #9571

[camera_android] Use WeakReference to prevent startImageStream OOM error when main thread hangs (flutter#166533) #9571

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[camera_android] Use WeakReference to prevent startImageStream OOM error when main thread hangs (flutter#166533) #9571

[camera_android] Use WeakReference to prevent startImageStream OOM error when main thread hangs (flutter#166533) #9571

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