fix(otel): Avoid deadlock in SentryContextStorage.root() with virtual threads

[adinauer]

📜 Description

SentryContextStorage.root() no longer calls SentryContextWrapper.wrap(). Instead it returns the default OTel root context directly.

wrap() triggers forkCurrentScope() → scope.clone() which acquires locks on SynchronizedQueue (breadcrumbs). Under virtual threads, ReentrantLock.unlock() can schedule a virtual thread continuation via ForkJoinPool.execute(), which OpenTelemetry's executor instrumentation intercepts. That instrumentation calls Context.current() which falls back to Context.root() → SentryContextStorage.root(), re-entering scope cloning and attempting to acquire the same lock. This causes a deadlock.

Sentry scopes are resolved later via attach() (when a context is actually used) or Sentry.getCurrentScopes().

💡 Motivation and Context

Fixes #5226 — customer-reported deadlock with virtual threads + OTel agent (Java 25, Spring Boot, Redisson/Netty).

The OTel ContextStorage.root() contract requires it to be trivially cheap, idempotent, and lock-free. Our implementation violated that contract by triggering scope cloning.

💚 How did you test it?

• Verified the change compiles and passes formatting (spotlessApply, apiDump)

📝 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

• Audit attach() for similar re-entrancy risk from auto-instrumented executor paths
• Replace SynchronizedQueue with lock-free ConcurrentLinkedQueue + AtomicInteger (defense-in-depth)
• Fix Scope copy constructor thread-safety issues (fingerprint, session, propagationContext races)

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

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Bug Fixes 🐛

• (otel) Avoid deadlock in SentryContextStorage.root() with virtual threads by adinauer in #5234

Internal Changes 🔧

• Pin GitHub Actions to full-length commit SHAs by joshuarli in #5229

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

[sentry]

Sentry Build Distribution

App Name	App ID	Version	Configuration	Install Page
SDK Size	io.sentry.tests.size	8.37.0 (1)	release	Install Build

[adinauer]

cursor review

[adinauer]

@sentry review

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	340.96 ms	416.90 ms	75.94 ms
Size	0 B	0 B	0 B

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
6405ec5	310.88 ms	354.56 ms	43.69 ms
d5a29b6	298.62 ms	391.78 ms	93.16 ms
f064536	329.00 ms	395.62 ms	66.62 ms
fcec2f2	357.47 ms	447.32 ms	89.85 ms
bbc35bb	324.88 ms	425.73 ms	100.85 ms
694d587	312.37 ms	402.77 ms	90.41 ms
b8bd880	314.56 ms	336.50 ms	21.94 ms
889ecea	367.58 ms	437.52 ms	69.94 ms
e2dce0b	308.96 ms	360.10 ms	51.14 ms
83884a0	334.46 ms	400.92 ms	66.46 ms

App size

Revision	Plain	With Sentry	Diff
6405ec5	1.58 MiB	2.12 MiB	552.23 KiB
d5a29b6	1.58 MiB	2.12 MiB	549.37 KiB
f064536	1.58 MiB	2.20 MiB	633.90 KiB
fcec2f2	1.58 MiB	2.12 MiB	551.50 KiB
bbc35bb	1.58 MiB	2.12 MiB	553.01 KiB
694d587	1.58 MiB	2.19 MiB	620.06 KiB
b8bd880	1.58 MiB	2.29 MiB	722.92 KiB
889ecea	1.58 MiB	2.11 MiB	539.75 KiB
e2dce0b	0 B	0 B	0 B
83884a0	1.58 MiB	2.29 MiB	722.97 KiB

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