[camera_android_camerax] Fixes premature garbage collection of native objects when app is under memory pressure #9287

bparrishMines · 2025-05-19T16:00:10Z

Note: Waiting on #9264 to land and to regenerate baseline file with.

This bumps pigeon to 25.3.2 and regenerates the code to fix a bug where native objects were getting garbage collected prematurely. See flutter/flutter#168531

Fixes flutter/flutter#152763

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bparrishMines · 2025-05-19T16:12:45Z

packages/camera/camera_android_camerax/android/build.gradle

@@ -60,7 +60,7 @@ android {
    lintOptions {
        checkAllWarnings true
        warningsAsErrors true
-        disable 'AndroidGradlePluginVersion', 'GradleDependency', 'InvalidPackage', 'NewerVersionAvailable'
+        disable 'AndroidGradlePluginVersion', 'GradleDependency', 'InvalidPackage', 'NewerVersionAvailable', 'UnsafeOptInUsageError'


In #8618, I manually added this to the generated pigeon file CameraXLibrary.g.kt. To prevent the need to manually change generated code, I moved the disable here.

Working on another camera PR (#9264) and I created a baseline lint file for that same UnsafeOptInUsageError lint. I think that might be better just in case the lint is valid for non-generated files, but let me know what you think!

If you agree and these other lints are from CameraXLibrary.g.kt, maybe we should remove them and just regenerate the baseline file.

I'll wait for #9264 to land and then regen the baseline file for this PR

camsim99 · 2025-05-20T18:25:16Z

packages/camera/camera_android_camerax/android/build.gradle

@@ -60,7 +60,7 @@ android {
    lintOptions {
        checkAllWarnings true
        warningsAsErrors true
-        disable 'AndroidGradlePluginVersion', 'GradleDependency', 'InvalidPackage', 'NewerVersionAvailable'
+        disable 'AndroidGradlePluginVersion', 'GradleDependency', 'InvalidPackage', 'NewerVersionAvailable', 'UnsafeOptInUsageError'


Working on another camera PR (#9264) and I created a baseline lint file for that same UnsafeOptInUsageError lint. I think that might be better just in case the lint is valid for non-generated files, but let me know what you think!

If you agree and these other lints are from CameraXLibrary.g.kt, maybe we should remove them and just regenerate the baseline file.

camsim99 · 2025-05-20T18:27:39Z

packages/camera/camera_android_camerax/pubspec.yaml

@@ -31,7 +31,7 @@ dev_dependencies:
    sdk: flutter
  leak_tracker_flutter_testing: any
  mockito: ^5.4.4
-  pigeon: ^25.3.1
+  pigeon: ^25.3.2


Just to clarify: this is a guess at the fix for flutter/flutter#152763 or have you determined this is the cause?

It is a guess, but a very educated guess.

I haven't been able to reproduce the exact error from the camerax_issue, but I have been able to reproduce the issues from flutter/flutter#168531 and flutter/flutter#168306 on iOS. Both of these are similar to the camerax_issue because they are NullPointerExceptions caused by an instance that originates from the native side (e.g. ImageProxy). Both of these were solved by bumping pigeon to 25.3.2.

I think it is harder to reproduce the error on Android because garbage collection for Java is nondeterministic and it requires the ImageProxy to be garbage collected within a small time frame. But I did use a few debug logs to verify that the scenario described here does occur within the plugin. And that this change most likely prevents it. Although the scenario is pretty rare, so its not impossible that I was just lucky.

Ah gotcha makes sense! SGTM :)

bparrishMines · 2025-06-04T03:32:35Z

...mera_android_camerax/android/src/main/java/io/flutter/plugins/camerax/ProxyApiRegistrar.java

@@ -60,7 +60,7 @@ void onFailure(@NonNull String methodName, @NonNull Throwable throwable) {
  }

  // PreviewProxyApi maintains a state to track SurfaceProducers provided by the Flutter engine.
-  @NonNull private final PreviewProxyApi previewProxyApi = new PreviewProxyApi(this);


This was causing a lint error when building locally: https://wiki.sei.cmu.edu/confluence/display/java/TSM01-J.+Do+not+let+the+this+reference+escape+during+object+construction

Hmm what version of Java are you using with locally?

I tried building again on flutter stable and I don't get the lint error. Could it be caused by the flutter.compileSdkVersion in the example app build.gradle? I was building it on flutter main before. Regardless, the lint seems to be valid.

camsim99

Change LGTM :) curious about the lint error you got locally but non-blocking

camsim99 · 2025-06-05T16:44:45Z

...mera_android_camerax/android/src/main/java/io/flutter/plugins/camerax/ProxyApiRegistrar.java

@@ -60,7 +60,7 @@ void onFailure(@NonNull String methodName, @NonNull Throwable throwable) {
  }

  // PreviewProxyApi maintains a state to track SurfaceProducers provided by the Flutter engine.
-  @NonNull private final PreviewProxyApi previewProxyApi = new PreviewProxyApi(this);


Hmm what version of Java are you using with locally?

… of native objects when app is under memory pressure (flutter/packages#9287)

flutter/packages@ecba2db...974f152 2025-06-06 [email protected] [camera_avfoundation] Implementation swift migration - part 4 (flutter/packages#9219) 2025-06-05 [email protected] [go_router_builder] Use a mixin instead of an extension (flutter/packages#9275) 2025-06-05 [email protected] Roll Flutter master to 8b18dde (flutter/packages#9387) 2025-06-05 [email protected] [camera_android_camerax] Fixes premature garbage collection of native objects when app is under memory pressure (flutter/packages#9287) 2025-06-05 [email protected] [google_maps_flutter_platform_interface] Add a new zIndexInt param to marker and deprecate zIndex (flutter/packages#9372) 2025-06-05 [email protected] [camera_android_camerax] Java style improvements (flutter/packages#9234) 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

regen pigeon

eff7748

github-actions bot added p: camera platform-android labels May 19, 2025

bparrishMines changed the title ~~regen pigeon~~ [camera_android_camerax] Fixes premature garbage collection of native objects when app is under memory pressure May 19, 2025

bparrishMines commented May 19, 2025

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bparrishMines marked this pull request as ready for review May 19, 2025 21:11

bparrishMines requested a review from camsim99 as a code owner May 19, 2025 21:11

camsim99 reviewed May 20, 2025

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bparrishMines marked this pull request as draft May 21, 2025 20:08

bparrishMines added 3 commits June 3, 2025 23:01

Merge branch 'main' of github.com:flutter/packages into camera_premature

4e6616b

fix lint and update baseline

f757acc

lint using command line

4afa930

bparrishMines commented Jun 4, 2025

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bparrishMines marked this pull request as ready for review June 4, 2025 15:41

bparrishMines requested a review from camsim99 June 4, 2025 15:41

camsim99 approved these changes Jun 5, 2025

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bparrishMines added 2 commits June 5, 2025 14:33

Merge branch 'main' of github.com:flutter/packages into camera_premature

ec1c0df

version bump

d6547d9

bparrishMines added the autosubmit Merge PR when tree becomes green via auto submit App label Jun 5, 2025

auto-submit bot merged commit 610dcb7 into flutter:main Jun 5, 2025
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engine-flutter-autoroll added a commit to engine-flutter-autoroll/flutter that referenced this pull request Jun 6, 2025

610dcb7d3 [camera_android_camerax] Fixes premature garbage collection…

f596024

… of native objects when app is under memory pressure (flutter/packages#9287)

engine-flutter-autoroll mentioned this pull request Jun 6, 2025

Roll Packages from ecba2dbf07ee to 974f1522ee03 (6 revisions) flutter/flutter#170146

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