feat(anr): Profile main thread when ANR and report ANR profiles to Sentry

[markushi]

📜 Description

Adds ANR (Application Not Responding) profiling integration that profiles the main thread when an ANR is detected and reports the captured profiles to Sentry.

Key Changes:

• New AnrProfilingIntegration to capture profiles during ANR events
• AnrV2Integration now takes care of matching and capturing the profile on the next start
• If the captured ANR event only contains system frames, a static fingerprint will get set, effectively changing the grouping behavior to group all noisy ANRs into a single issue

💡 Motivation and Context

This feature enables better ANR diagnostics by capturing profiling data at the time of ANR detection, allowing developers to identify performance bottlenecks and problematic code paths causing application hangs.

💚 How did you test it?

• Added tests

📝 Checklist

• I added GH Issue ID & Linear ID
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

[github-actions]

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 4c95292

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	304.53 ms	351.20 ms	46.67 ms
Size	1.58 MiB	2.13 MiB	563.71 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
3d205d0	352.15 ms	432.53 ms	80.38 ms
fc5ccaf	256.80 ms	322.36 ms	65.56 ms
ee747ae	374.71 ms	455.18 ms	80.47 ms
6edfca2	314.02 ms	383.20 ms	69.18 ms
674d437	355.28 ms	504.18 ms	148.90 ms
6405ec5	310.88 ms	354.56 ms	43.69 ms
bbc35bb	324.88 ms	425.73 ms	100.85 ms
dba088c	321.78 ms	364.59 ms	42.82 ms
fc5ccaf	279.11 ms	353.34 ms	74.23 ms
3699cd5	423.60 ms	495.52 ms	71.92 ms

App size

Revision	Plain	With Sentry	Diff
3d205d0	1.58 MiB	2.10 MiB	532.97 KiB
fc5ccaf	1.58 MiB	2.13 MiB	557.54 KiB
ee747ae	1.58 MiB	2.10 MiB	530.95 KiB
6edfca2	1.58 MiB	2.13 MiB	559.07 KiB
674d437	1.58 MiB	2.10 MiB	530.94 KiB
6405ec5	1.58 MiB	2.12 MiB	552.23 KiB
bbc35bb	1.58 MiB	2.12 MiB	553.01 KiB
dba088c	1.58 MiB	2.13 MiB	558.99 KiB
fc5ccaf	1.58 MiB	2.13 MiB	557.54 KiB
3699cd5	1.58 MiB	2.10 MiB	533.45 KiB

Previous results on branch: markushi/feat/anr-profiling

Startup times

Revision	Plain	With Sentry	Diff
be4960b	322.67 ms	380.85 ms	58.18 ms
184b846	276.09 ms	351.65 ms	75.56 ms
b238cff	332.00 ms	401.47 ms	69.47 ms
c22421f	331.24 ms	367.91 ms	36.67 ms
a4af52f	304.52 ms	364.92 ms	60.40 ms

App size

Revision	Plain	With Sentry	Diff
be4960b	1.58 MiB	2.13 MiB	562.64 KiB
184b846	1.58 MiB	2.13 MiB	558.70 KiB
b238cff	1.58 MiB	2.13 MiB	562.66 KiB
c22421f	1.58 MiB	2.13 MiB	563.53 KiB
a4af52f	1.58 MiB	2.13 MiB	563.53 KiB

[markushi]

@sentry review

[markushi]

Addressing bot comments:

Concurrent QueueFile Access (Comments on AnrV2Integration.java:327, :367):
✅ Working as designed. The reader uses AnrProfileRotationHelper.getLastFile() which reads from a rotated/archived file, while the writer writes to the current file. They access different files.

AnrProfileManager file descriptor leak (AnrProfileManager.java:50):
✅ Already fixed. The code uses try-with-resources: try (final AnrProfileManager provider = new AnrProfileManager(options, lastFile))

lowQualityPackages initialization (AnrCulpritIdentifier.java:85):
✅ Already fixed. The field uses a static initializer block.

Stack depth calculation (AggregatedStackTrace.java:38):
✅ Already fixed.

Incomplete stack trace handling (AnrCulpritIdentifier.java:138):
✅ Already fixed. Code has if (stackTraceMap.isEmpty()) return null; guard at line 140.

Empty debug log (AnrV2Integration.java:346):
✅ Already fixed.

Missing rotate() call (AnrV2Integration.java:424):
✅ Working as designed. Rotation should only happen once after app start, not on every ANR event read.

Stack trace serialization (AnrStackTrace.java:35):
✅ Already fixed.

Missing listener removal (AnrProfilingIntegration.java:79):
✅ Already fixed.

Profile ID mismatch (AnrV2Integration.java:418):
✅ Working as designed. We intentionally return chunk.getProfilerId() to reference the chunk_id as profiler_id.

hasOnlySystemFrames() fingerprinting (AnrV2Integration.java:321, :497):
✅ FIXED in this update. Modified to return false when exceptions list is null/empty, preventing incorrect fingerprinting when profiling fails.

[linear]

ANDROID-229 Capture main thread stack traces if main thread is blocked

ANDROID-230 Associate captured ANR stacktraces with events

[cursor]

Cursor Bugbot has reviewed your changes and found 3 potential issues.

^{Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.}

[cursor]

Missing null check for cacheDirPath causes NPE

Medium Severity

When opts.getCacheDirPath() returns null, new File(null) throws a NullPointerException. Unlike AnrV2Integration which checks for null cacheDirPath before using it (line 94 and 236), AnrProfilingIntegration has no such validation. If ANR profiling is enabled but cacheDirPath is null, the integration will register itself as a listener, and upon the first ANR suspicion, calling clearStacks() or addStackTrace() will crash.

 

[cursor]

Dead code due to requireNonNull throwing before null check

Low Severity

The if (this.options == null) return; check is unreachable dead code. Objects.requireNonNull on line 51-54 throws an IllegalArgumentException when the ternary expression evaluates to null (i.e., when options is not a SentryAndroidOptions). The null check can never execute because the exception is thrown first.

 

[cursor]

Profile file deleted prematurely when reporting historical ANRs

Medium Severity

The ANR profile file is deleted in a finally block on every call to applyAnrProfile, regardless of whether the profile was actually matched and used. When reportHistoricalAnrs is enabled, historical ANRs are processed before the latest ANR. Each historical ANR triggers applyAnrProfile, which deletes the profile file even though the timestamp doesn't match. By the time the latest ANR (which should match the profile) is processed, the file is already deleted and the profile is lost.