perf(flutter): Optimize Android scope sync by buenaflor · Pull Request #3708 · getsentry/sentry-dart

buenaflor · 2026-05-19T08:52:31Z

📜 Description

Optimize Android scope sync by sending breadcrumb, user, and context payloads over JNI as UTF-8 JSON bytes instead of recursively constructing Java Map/List objects from Dart.

This keeps primitive JNI calls direct, preserves structured nested user data through native deserialization, and reduces per-entry JNI object churn for large user-controlled scope payloads.

💡 Motivation and Context

Large arbitrary maps in breadcrumbs, contexts, or user data can be expensive on lower-end Android devices when each nested value crosses JNI as an object. Passing the serialized payload once and deserializing on the Kotlin/Java side keeps the bridge coarse-grained and aligns with the existing byte-based native context/debug-image paths.

This lead to ANRs or even crashes in lower end devices.

Fixes #3709

💚 How did you test it?

fvm flutter analyze lib/src/native/utils/utf8_json.dart lib/src/native/java/sentry_native_java.dart example/integration_test/native_jni_utils_test.dart
JAVA_HOME="$(/usr/libexec/java_home -v 17)" PATH="$(/usr/libexec/java_home -v 17)/bin:$PATH" ./gradlew :sentry_flutter:compileReleaseKotlin
fvm flutter test test/native/sentry_native_java_test.dart
fvm flutter test -d emulator-5554 integration_test/native_jni_utils_test.dart
fvm flutter test -d emulator-5554 integration_test/integration_test.dart --plain-name "syncs large scope maps to native on Android"
fvm flutter test -d emulator-5554 integration_test/integration_test.dart --plain-name "setUser syncs to native"
Full fvm flutter test -d emulator-5554 integration_test was also run locally; the token-gated e2e captureException test failed because SENTRY_AUTH_TOKEN_E2E was unset.

📝 Checklist

I reviewed submitted code
I added tests to verify changes
No new PII added or SDK only sends newly added PII if sendDefaultPii is enabled
I updated the docs if needed
All tests passing
No breaking changes

🔮 Next steps

github-actions · 2026-05-19T08:52:49Z

🚨 Detected changes in high risk code 🚨

High-risk code has higher potential to break the SDK and may be hard to test. To prevent severe bugs, apply the rollout process for releasing such changes and be extra careful when changing and reviewing these files:

packages/flutter/android/src/main/kotlin/io/sentry/flutter/SentryFlutterPlugin.kt

github-actions · 2026-05-19T08:52:54Z

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

This is how your changes will appear in the changelog.
Entries from this PR are highlighted with a left border (blockquote style).

Fixes

Dart

Make sentryOnError synchronous in runZonedGuarded by theprantadutta in #3697
Route SDK diagnostic logs to browser console on web by theprantadutta in #3698

Other

(flutter) Release replay JNI refs by buenaflor in #3699

Enhancements

(flutter) Optimize Android scope sync by buenaflor in #3708

Internal Changes

(flutter) Align CI with stable SwiftPM defaults by buenaflor in #3710

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

codecov · 2026-05-19T08:55:25Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.91%. Comparing base (2e4277e) to head (8551b07).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3708      +/-   ##
==========================================
+ Coverage   87.19%   91.91%   +4.72%     
==========================================
  Files         149      105      -44     
  Lines        5513     3737    -1776     
==========================================
- Hits         4807     3435    -1372     
+ Misses        706      302     -404

Flag	Coverage Δ
sentry_dio	`?`
sentry_drift	`?`
sentry_file	`?`
sentry_firebase_remote_config	`100.00% <ø> (ø)`
sentry_flutter	`91.53% <100.00%> (+<0.01%)`	⬆️
sentry_hive	`?`
sentry_isar	`?`
sentry_link	`?`
sentry_logging	`?`
sentry_sqflite	`?`
sentry_supabase	`97.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
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github-actions · 2026-05-19T09:01:32Z

Android Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	383.65 ms	382.90 ms	-0.75 ms
Size	14.55 MiB	15.87 MiB	1.31 MiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
`c5cf749`	379.18 ms	360.60 ms	-18.58 ms
`3ddf010`	431.14 ms	438.10 ms	6.96 ms
`6e7d494`	397.35 ms	378.91 ms	-18.43 ms
`dbd526b`	504.88 ms	569.02 ms	64.15 ms
`753d4ac`	426.28 ms	423.45 ms	-2.83 ms
`575ebaa`	478.00 ms	585.76 ms	107.76 ms
`f3771ea`	379.02 ms	363.91 ms	-15.11 ms
`c58ce03`	469.42 ms	472.40 ms	2.98 ms
`38a22c2`	418.68 ms	436.54 ms	17.86 ms
`c1e775e`	482.36 ms	608.98 ms	126.62 ms

App size

Revision	Plain	With Sentry	Diff
`c5cf749`	14.31 MiB	15.49 MiB	1.19 MiB
`3ddf010`	13.93 MiB	15.18 MiB	1.25 MiB
`6e7d494`	13.93 MiB	15.06 MiB	1.13 MiB
`dbd526b`	6.54 MiB	7.69 MiB	1.15 MiB
`753d4ac`	14.31 MiB	15.49 MiB	1.19 MiB
`575ebaa`	6.54 MiB	7.69 MiB	1.15 MiB
`f3771ea`	14.31 MiB	15.49 MiB	1.19 MiB
`c58ce03`	14.31 MiB	15.49 MiB	1.19 MiB
`38a22c2`	14.31 MiB	15.49 MiB	1.19 MiB
`c1e775e`	6.54 MiB	7.70 MiB	1.17 MiB

Previous results on branch: perf/android-scope-sync-json

Startup times

Revision	Plain	With Sentry	Diff
`e15b49d`	441.27 ms	432.31 ms	-8.95 ms
`c666afd`	394.31 ms	398.04 ms	3.73 ms
`b85800e`	382.05 ms	371.26 ms	-10.78 ms
`a713631`	378.04 ms	366.07 ms	-11.98 ms
`7d8ec5f`	378.61 ms	382.80 ms	4.19 ms
`e2bd84b`	354.40 ms	350.51 ms	-3.89 ms
`04f26dc`	369.18 ms	357.13 ms	-12.05 ms
`f9a84b1`	356.82 ms	358.37 ms	1.55 ms
`0c34206`	394.20 ms	385.98 ms	-8.22 ms
`b43bb60`	375.35 ms	371.24 ms	-4.11 ms

App size

Revision	Plain	With Sentry	Diff
`e15b49d`	14.31 MiB	15.49 MiB	1.19 MiB
`c666afd`	14.31 MiB	15.49 MiB	1.19 MiB
`b85800e`	14.31 MiB	15.49 MiB	1.19 MiB
`a713631`	14.31 MiB	15.49 MiB	1.19 MiB
`7d8ec5f`	14.31 MiB	15.49 MiB	1.19 MiB
`e2bd84b`	14.55 MiB	15.87 MiB	1.31 MiB
`04f26dc`	14.31 MiB	15.49 MiB	1.19 MiB
`f9a84b1`	14.55 MiB	15.87 MiB	1.31 MiB
`0c34206`	14.55 MiB	15.87 MiB	1.31 MiB
`b43bb60`	14.31 MiB	15.49 MiB	1.19 MiB

Send large Android scope payloads as JSON bytes instead of recursively constructing Java maps and lists through JNI. This keeps nested user data structured while reducing per-entry JNI object churn. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

Clarify that large or arbitrary Dart collection payloads should cross JNI as JSON bytes, while primitives and small controlled payloads can use direct conversion. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

github-actions · 2026-05-19T09:07:28Z

iOS Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1253.71 ms	1259.55 ms	5.84 ms
Size	5.83 MiB	6.28 MiB	461.20 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
`c58ce03`	1245.18 ms	1247.00 ms	1.82 ms
`101a9c7`	1225.80 ms	1236.04 ms	10.25 ms
`67de70c`	1260.09 ms	1266.79 ms	6.71 ms
`ea06d23`	1254.02 ms	1252.60 ms	-1.42 ms
`29e8ebe`	1260.46 ms	1262.60 ms	2.14 ms
`93b7728`	1247.23 ms	1264.87 ms	17.64 ms
`cdf371b`	1246.24 ms	1251.10 ms	4.86 ms
`2cb90b9`	1272.90 ms	1285.55 ms	12.66 ms
`6b69699`	1254.80 ms	1273.31 ms	18.52 ms
`e5ae2a6`	1240.48 ms	1253.26 ms	12.78 ms

App size

Revision	Plain	With Sentry	Diff
`c58ce03`	5.73 MiB	6.17 MiB	455.86 KiB
`101a9c7`	5.73 MiB	6.17 MiB	455.47 KiB
`67de70c`	5.73 MiB	6.17 MiB	455.45 KiB
`ea06d23`	5.53 MiB	5.96 MiB	443.26 KiB
`29e8ebe`	5.53 MiB	6.01 MiB	488.12 KiB
`93b7728`	7.86 MiB	9.44 MiB	1.58 MiB
`cdf371b`	5.53 MiB	6.02 MiB	501.23 KiB
`2cb90b9`	7.86 MiB	9.54 MiB	1.69 MiB
`6b69699`	7.86 MiB	9.44 MiB	1.58 MiB
`e5ae2a6`	5.65 MiB	6.09 MiB	446.96 KiB

Previous results on branch: perf/android-scope-sync-json

Startup times

Revision	Plain	With Sentry	Diff
`b43bb60`	1249.37 ms	1254.39 ms	5.02 ms
`0c34206`	1238.37 ms	1243.72 ms	5.35 ms
`7d8ec5f`	1244.50 ms	1248.21 ms	3.71 ms
`c666afd`	1251.53 ms	1258.02 ms	6.49 ms
`e15b49d`	1238.53 ms	1248.98 ms	10.45 ms
`f9a84b1`	1248.19 ms	1247.64 ms	-0.54 ms
`04f26dc`	1247.53 ms	1247.93 ms	0.40 ms
`e2bd84b`	1254.02 ms	1260.48 ms	6.45 ms
`a713631`	1255.24 ms	1250.47 ms	-4.77 ms
`b85800e`	1241.09 ms	1246.09 ms	5.00 ms

App size

Revision	Plain	With Sentry	Diff
`b43bb60`	5.73 MiB	6.18 MiB	461.67 KiB
`0c34206`	5.83 MiB	6.28 MiB	461.21 KiB
`7d8ec5f`	5.73 MiB	6.18 MiB	461.67 KiB
`c666afd`	5.73 MiB	6.18 MiB	461.66 KiB
`e15b49d`	5.73 MiB	6.18 MiB	461.76 KiB
`f9a84b1`	5.83 MiB	6.28 MiB	461.20 KiB
`04f26dc`	5.73 MiB	6.18 MiB	463.07 KiB
`e2bd84b`	5.83 MiB	6.28 MiB	461.20 KiB
`a713631`	5.73 MiB	6.18 MiB	461.66 KiB
`b85800e`	5.73 MiB	6.18 MiB	461.76 KiB

Keep the Android JSON reader helper within ktlint formatting limits after adding the scope sync byte-array bridge. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

Wrap all native JSON conversion when branches consistently so ktlint accepts the multiline Kotlin helper added for Android scope sync. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

Use the existing native boundary normalizer before encoding Android scope payloads as JSON bytes instead of maintaining a second normalization helper. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

Keep null values when converting JSON object and array payloads on Android so the bridge remains lossless before native model deserialization. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

Copilot

Pull request overview

Optimizes Android scope sync by passing breadcrumb, user, and context payloads across JNI as UTF-8 JSON byte arrays (deserialized on the Kotlin side via Sentry's JsonObjectReader / JSONTokener) instead of recursively constructing Java Map/List objects through per-entry JNI calls. This also fixes a previous limitation where nested Map/List values inside User.data were stringified.

Changes:

Added new addBreadcrumbFromJsonBytes / setUserFromJsonBytes / setContextFromJsonBytes entry points on the Kotlin SentryFlutterPlugin plus matching JNI bindings.
Updated SentryNativeJava to use the new byte-array path via a new jsonToJByteArray helper and encodeUtf8Json utility (which normalizes non-primitive values first).
Updated integration tests: added a "large scope maps" Android test and removed the Android-specific stringification branch in the existing setUser test now that nested structures round-trip correctly.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/flutter/lib/src/native/utils/utf8_json.dart	New `encodeUtf8Json` helper that JSON-encodes Dart data to UTF-8 bytes.
packages/flutter/lib/src/native/java/sentry_native_java.dart	Switches breadcrumb/user/context sync to JSON-byte JNI path; adds `jsonToJByteArray`.
packages/flutter/lib/src/native/java/binding.dart	Generated JNI bindings for new Kotlin static methods.
packages/flutter/android/src/main/kotlin/io/sentry/flutter/SentryFlutterPlugin.kt	Adds Kotlin entry points that deserialize JSON bytes via `JsonObjectReader`/`JSONTokener`.
packages/flutter/example/integration_test/native_jni_utils_test.dart	Tests for `normalize` and `jsonToJByteArray`.
packages/flutter/example/integration_test/integration_test.dart	Adds large-scope sync test; removes Android-specific stringified assertions.
packages/flutter/AGENTS.md	Documents the "JSON bytes for arbitrary payloads" JNI guideline.

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Cache JSON deserializers for scope sync payloads and replace the broad Any extension with a private helper function for Kotlin JSON conversion. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

Use the Java SDK JSON reader for context payload parsing instead of a custom recursive org.json conversion helper. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

Document that the Android JSON reader accepts root-level primitives so future changes do not replace it with object-only parsing. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

cursor

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

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Route Android context values through sentry-java's typed overloads so primitive Dart context values are serialized as valid context objects. Regenerate JNI bindings after removing the unused object overload entrypoint. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

Update the native context sync test to match the Android bridge's valid serialized shape for primitive context values. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

buenaflor and others added 2 commits May 19, 2026 11:05

style(flutter): Wrap JNI JSON reader helper

b85800e

Keep the Android JSON reader helper within ktlint formatting limits after adding the scope sync byte-array bridge. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

buenaflor force-pushed the perf/android-scope-sync-json branch from 04f26dc to b85800e Compare May 19, 2026 09:08

sentry-warden Bot reviewed May 19, 2026

View reviewed changes

Comment thread packages/flutter/lib/src/native/utils/utf8_json.dart Outdated

style(flutter): Apply ktlint when-branch formatting

e15b49d

Wrap all native JSON conversion when branches consistently so ktlint accepts the multiline Kotlin helper added for Android scope sync. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

sentry-warden Bot reviewed May 19, 2026

View reviewed changes

Comment thread packages/flutter/android/src/main/kotlin/io/sentry/flutter/SentryFlutterPlugin.kt Outdated

ref(flutter): Reuse native data normalizer

7d8ec5f

Use the existing native boundary normalizer before encoding Android scope payloads as JSON bytes instead of maintaining a second normalization helper. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

sentry-warden Bot reviewed May 19, 2026

View reviewed changes

Comment thread packages/flutter/lib/src/native/utils/utf8_json.dart Outdated

fix(flutter): Preserve nulls in Android JSON bridge

b43bb60

Keep null values when converting JSON object and array payloads on Android so the bridge remains lossless before native model deserialization. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

sentry-warden Bot reviewed May 19, 2026

View reviewed changes

Comment thread packages/flutter/lib/src/native/java/sentry_native_java.dart

buenaflor marked this pull request as ready for review May 19, 2026 11:25

buenaflor requested a review from denrase as a code owner May 19, 2026 11:25

Copilot AI review requested due to automatic review settings May 19, 2026 11:25

Copilot started reviewing on behalf of buenaflor May 19, 2026 11:25 View session

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denrase requested changes May 19, 2026

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perf(flutter): Reuse Android JSON deserializers

a713631

Cache JSON deserializers for scope sync payloads and replace the broad Any extension with a private helper function for Kotlin JSON conversion. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

sentry Bot reviewed May 19, 2026

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Comment thread packages/flutter/android/src/main/kotlin/io/sentry/flutter/SentryFlutterPlugin.kt

sentry-warden Bot reviewed May 19, 2026

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Comment thread packages/flutter/android/src/main/kotlin/io/sentry/flutter/SentryFlutterPlugin.kt Outdated

buenaflor and others added 2 commits May 19, 2026 15:12

ref(flutter): Use SDK JSON object reader

c666afd

Use the Java SDK JSON reader for context payload parsing instead of a custom recursive org.json conversion helper. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

Merge branch 'main' into perf/android-scope-sync-json

ab3bce0

buenaflor requested a review from denrase May 19, 2026 13:15

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Comment thread packages/flutter/lib/src/native/java/sentry_native_java.dart

sentry Bot reviewed May 19, 2026

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Comment thread packages/flutter/android/src/main/kotlin/io/sentry/flutter/SentryFlutterPlugin.kt

docs(flutter): Clarify JSON reader parsing

f9a84b1

Document that the Android JSON reader accepts root-level primitives so future changes do not replace it with object-only parsing. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

cursor Bot reviewed May 19, 2026

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Comment thread packages/flutter/lib/src/native/utils/utf8_json.dart

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Comment thread packages/flutter/android/src/main/kotlin/io/sentry/flutter/SentryFlutterPlugin.kt

test(flutter): Expect wrapped Android contexts

e2bd84b

Update the native context sync test to match the Android bridge's valid serialized shape for primitive context values. Co-Authored-By: GPT-5.5 <[email protected]> Co-authored-by: Cursor <[email protected]>

denrase approved these changes May 19, 2026

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Merge branch 'main' into perf/android-scope-sync-json

8551b07

buenaflor merged commit 79df88f into main May 19, 2026
70 checks passed

buenaflor deleted the perf/android-scope-sync-json branch May 19, 2026 22:25

github-actions Bot mentioned this pull request May 29, 2026

Large Android scope payloads can cause JNI overhead #3709

Closed

aqrc mentioned this pull request Jul 6, 2026

fix(replay): Accept Double timestamps in Android network breadcrumb conversion #3859

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📜 Description

💡 Motivation and Context

💚 How did you test it?

📝 Checklist

🔮 Next steps

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🚨 Detected changes in high risk code 🚨

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Semver Impact of This PR

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Android Performance metrics 🚀

Baseline results on branch: main

Startup times

App size

Previous results on branch: perf/android-scope-sync-json

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App size

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iOS Performance metrics 🚀

Baseline results on branch: main

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Previous results on branch: perf/android-scope-sync-json

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App size

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