fix(anr): extend main thread detection from thread dump by markushi · Pull Request #5733 · getsentry/sentry-java · GitHub

📜 Description

Not every main thread has a name="main" set, so we ended up not correctly identifying it (on some Android versions/OEMs, native threads, etc...).

To solve this we now rely on a common Linux/Android convention: The main thread kernel id (sysTid) is the same as the process id (pid). For managed Java threads, a fallback for the "main" thread name remains.

Changes

Parses the process id from the thread dump header (----- pid <pid> at ... -----) and marks the thread whose sysTid equals it as the main thread.
The main thread's name is normalized back to "main" so downstream consumers see a consistent name even when the OS renamed it.
Threads without a stacktrace are skipped, as they are not actionable.

No public API change.

💡 Motivation and Context

When the OS names the main thread after the process, ANRs were not attributed to the main thread and were reported without a stack trace. Matching on sysTid == pid is robust and does not depend on the (truncatable) process name.

Fixes JAVA-635
Fixes #5731

💚 How did you test it?

Added tests to ThreadDumpParserTest
Updated existing 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

--

View Junior Session in Sentry

On some Android versions/OEMs, AppExitInfo's thread dump names the main thread after the process name (e.g. 'com.example.app') instead of 'main'. ThreadDumpParser previously only matched on 'main', causing the thread to not be flagged as main/crashed and resulting in ANR events with no usable stack trace. Pass the process name from ApplicationExitInfo.getProcessName() to ThreadDumpParser and treat a thread as main if its name equals 'main' OR the process name. Fixes JAVA-635 Co-Authored-By: sentry-junior[bot] <264270552+sentry-junior[bot]@users.noreply.github.com>

JAVA-635

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.47.0 (1)	release

⚙️ sentry-android Build Distribution Settings

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	466.78 ms	513.84 ms	47.06 ms
Size	0 B	0 B	0 B

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
d364ace	382.77 ms	443.21 ms	60.44 ms
4c04bb8	333.16 ms	408.16 ms	75.00 ms
bb0ff41	344.70 ms	413.82 ms	69.12 ms
91bb874	314.47 ms	440.00 ms	125.53 ms
bdbe1f4	380.66 ms	464.44 ms	83.78 ms
8687935	294.00 ms	304.02 ms	10.02 ms
eb95ded	317.51 ms	369.08 ms	51.57 ms
b936425	302.69 ms	372.86 ms	70.17 ms
d15471f	342.08 ms	415.44 ms	73.35 ms
5b66efd	308.67 ms	363.85 ms	55.18 ms

App size

Revision	Plain	With Sentry	Diff
d364ace	1.58 MiB	2.11 MiB	539.75 KiB
4c04bb8	0 B	0 B	0 B
bb0ff41	0 B	0 B	0 B
91bb874	1.58 MiB	2.13 MiB	559.07 KiB
bdbe1f4	1.58 MiB	2.11 MiB	538.88 KiB
8687935	1.58 MiB	2.19 MiB	619.17 KiB
eb95ded	0 B	0 B	0 B
b936425	0 B	0 B	0 B
d15471f	1.58 MiB	2.13 MiB	559.54 KiB
5b66efd	1.58 MiB	2.13 MiB	559.07 KiB

Previous results on branch: fix/anrv2-main-thread-process-name

Startup times

Revision	Plain	With Sentry	Diff
14ba103	320.87 ms	362.88 ms	42.01 ms
420f794	314.27 ms	377.56 ms	63.29 ms
b6ecc1e	311.13 ms	366.86 ms	55.73 ms
2a331f8	341.76 ms	424.69 ms	82.93 ms

App size

Revision	Plain	With Sentry	Diff
14ba103	0 B	0 B	0 B
420f794	0 B	0 B	0 B
b6ecc1e	0 B	0 B	0 B
2a331f8	0 B	0 B	0 B

The main thread can be renamed by the OS to the (potentially truncated) process name, so relying on the process name is fragile. On Linux/Android the main thread's kernel thread id (sysTid) always equals the process id, so use that as the authoritative signal instead. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

this looks good! shall we also address the second part which is not to attach a thread if its stacktrace has no frames? Could be addressed in a separate PR ofc

…trace Normalize the main thread's name back to "main" once it is identified (the OS may have renamed it to the process name), and drop threads that have no stacktrace as they are not actionable. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Identify the main thread by matching the thread whose kernel thread id (sysTid) equals the process id, falling back to the conventional "main" thread name, and skip threads that have no stacktrace as they are not actionable. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-authored-by: Roman Zavarnitsyn <rom4ek93@gmail.com>

Format code

afcbab4

markushi and others added 3 commits July 7, 2026 12:17

changelog

b3f6ab0

Simplify changelog entry

e62aea4

romtsn approved these changes Jul 7, 2026

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markushi changed the title fix(anr): detect main thread when OS names it after the process fix(anr): extend main thread detection from thread dump Jul 7, 2026

markushi and others added 3 commits July 7, 2026 14:45

ref(anr): Clean up ThreadDumpParser

99cc520

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

markushi marked this pull request as ready for review July 7, 2026 14:08

markushi requested review from 0xadam-brown, adinauer and runningcode as code owners July 7, 2026 14:08

markushi requested a review from romtsn July 7, 2026 14:08

romtsn reviewed Jul 7, 2026

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Comment thread CHANGELOG.md

romtsn approved these changes Jul 7, 2026

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Co-authored-by: Roman Zavarnitsyn <rom4ek93@gmail.com>

markushi merged commit e3bd612 into main Jul 8, 2026
70 checks passed

markushi deleted the fix/anrv2-main-thread-process-name branch July 8, 2026 07:42

markushi mentioned this pull request Jul 8, 2026

fix(anr): Detect main thread from tombstone via pid matching thread id #5742

Merged

8 tasks

sentry-release-bot Bot mentioned this pull request Jul 8, 2026

publish: getsentry/sentry-java@8.48.0 getsentry/publish#8822

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3 tasks

github-actions Bot mentioned this pull request Jul 8, 2026

ANRv2 (AppExitInfo): main thread not detected when the OS thread dump names it after the process → ANR reported with no stack trace #5731

Closed

fix(anr): extend main thread detection from thread dump by markushi · Pull Request #5733 · getsentry/sentry-java · GitHub

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fix(anr): extend main thread detection from thread dump - #5733

fix(anr): extend main thread detection from thread dump#5733
markushi merged 9 commits into
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fix/anrv2-main-thread-process-name

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fix(anr): extend main thread detection from thread dump by markushi · Pull Request #5733 · getsentry/sentry-java · GitHub

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fix(anr): extend main thread detection from thread dump - #5733

fix(anr): extend main thread detection from thread dump#5733markushi merged 9 commits intomaingetsentry/sentry-java:mainfrom fix/anrv2-main-thread-process-namegetsentry/sentry-java:fix/anrv2-main-thread-process-nameCopy head branch name to clipboard

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markushi commented Jul 7, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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📜 Description

💡 Motivation and Context

💚 How did you test it?

📝 Checklist

🔮 Next steps

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linear-code Bot commented Jul 7, 2026

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📲 Install Builds

Android

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Performance metrics 🚀

Baseline results on branch: main

Startup times

App size

Previous results on branch: fix/anrv2-main-thread-process-name

Startup times

App size

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fix(anr): extend main thread detection from thread dump#5733
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fix/anrv2-main-thread-process-name

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