perf(android): [SDK Overhead Reduction 4] Use default timezone directly by adinauer · Pull Request #5587 · getsentry/sentry-java · GitHub

PR Stack (SDK Overhead Reduction)

perf(core): SDK Overhead Reduction #5499
perf(core): [SDK Overhead Reduction 1] Skip java.specification.version lookup on Android #5500
perf(android): [SDK Overhead Reduction 2] Replace reflective OptionsContainer with direct subclass #5501
perf(android): [SDK Overhead Reduction 3] Reuse SentryExecutorService for DeviceInfoUtil pre-caching #5502
perf(android): [SDK Overhead Reduction 4] Use default timezone directly #5587
perf(core): [SDK Overhead Reduction 5] Replace Calendar with Date in DateUtils #5589
perf(core): [SDK Overhead Reduction 6] Reduce JsonWriter stack allocation #5591
perf(core): [SDK Overhead Reduction 7] Lazily allocate Breadcrumb data #5598
perf(core): [SDK Overhead Reduction 8] Reduce context serialization allocations #5599
perf(core): [SDK Overhead Reduction 9] Lazily allocate reflection serializer state #5600
perf(core): [SDK Overhead Reduction 10] Lazily create reflection JSON serializer #5601
perf(core): [SDK Overhead Reduction 11] Replace ISO8601 timestamp handling #5602
perf(core): [SDK Overhead Reduction 12] Avoid cloning Date getters #5603
fix(core): [SDK Overhead Reduction 13] Preserve ISO8601 utility compatibility #5609

📜 Description

Replace the normal Android device timezone path with TimeZone.getDefault() instead of constructing a Calendar just to read its timezone.

One compatibility detail is preserved: Android 13+ Calendar.getInstance(locale) can honor a locale Unicode tz extension (for example en-US-u-tz-usnyc). For those rare locales, the code keeps the Calendar path so the SDK continues reporting the same timezone as before. On Android N through Android 12, and for normal locales without a tz extension, the locale did not affect the timezone value.

💡 Motivation and Context

Part of the SDK Overhead Reduction stack. In the common case, device context collection only needs the process default timezone. TimeZone.getDefault() is available on Android API 21 and Java 8, and avoids constructing a Calendar and reading locale configuration just to retrieve the same timezone.

The previous API 24+ branch used the first Configuration locale, but Android N through Android 12 did not use that locale to select the timezone. Android 13 added tz Unicode extension support to Calendar.getInstance(locale), so this PR preserves that behavior with a narrow fallback while keeping the fast direct-default path for all other cases.

💚 How did you test it?

./gradlew :sentry-android-core:testDebugUnitTest --tests io.sentry.android.core.DeviceInfoUtilTest — all tests pass
- includes regression coverage for an Android 13+ locale with a Unicode tz extension (en-US-u-tz-usnyc)
./gradlew spotlessApply apiDump — no API surface changes

📝 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

More SDK overhead reduction PRs in this stack.

⚠️ Merge this PR using a merge commit (not squash). Only the collection branch is squash-merged into main.

Avoid constructing a Calendar only to read the default device timezone. The locale passed to Calendar does not affect the timezone value, so TimeZone.getDefault returns the same value with less work during device context collection. Co-Authored-By: Claude <noreply@anthropic.com>

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.45.0 (1)	release

⚙️ sentry-android Build Distribution Settings

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	310.74 ms	338.59 ms	27.85 ms
Size	0 B	0 B	0 B

Baseline results on branch: perf/sdk-overhead-reduction

Startup times

Revision	Plain	With Sentry	Diff
57376d3	309.80 ms	368.60 ms	58.80 ms

App size

Revision	Plain	With Sentry	Diff
57376d3	0 B	0 B	0 B

Previous results on branch: perf/sdk-overhead-reduction-timezone-default

Startup times

Revision	Plain	With Sentry	Diff
c5c9ee6	325.41 ms	385.38 ms	59.97 ms
c8b80df	351.04 ms	416.90 ms	65.85 ms
c83d67b	310.10 ms	358.83 ms	48.73 ms

App size

Revision	Plain	With Sentry	Diff
c5c9ee6	0 B	0 B	0 B
c8b80df	0 B	0 B	0 B
c83d67b	0 B	0 B	0 B

Keep the Calendar-based timezone path for Android 13+ locales that carry a Unicode tz extension. This preserves the existing device timezone behavior while keeping the direct default timezone fast path for normal locales. Co-Authored-By: Claude <noreply@anthropic.com>

LGTM 👍

Cursor review

@sentry review

✅ Bugbot reviewed your changes and found no new issues!

Comment @cursor review or bugbot run to trigger another review on this PR

Reviewed by Cursor Bugbot for commit 2bcedec. Configure here.

This one is a bit confusing and I'm not sure about the edge cases. Do we have an idea what the performance benefit is here?

Benchmark results invoking the util on a newer Android version (API level 34) that does not enter the inner if regarding "tz":

 ┌─────────────────────────────────────────┬─────────────┬─────────────┬────────┐
 │ Metric                                  │ Old/base    │ New/head    │ Delta  │
 ├─────────────────────────────────────────┼─────────────┼─────────────┼────────┤
 │ Benchmark thread wall time              │ 6803.058 ms │ 1624.340 ms │ -76.1% │
 ├─────────────────────────────────────────┼─────────────┼─────────────┼────────┤
 │ Benchmark thread CPU time               │ 6421.307 ms │ 1532.483 ms │ -76.1% │
 ├─────────────────────────────────────────┼─────────────┼─────────────┼────────┤
 │ CPU per call                            │ 0.3211 ms   │ 0.0766 ms   │ -76.1% │
 ├─────────────────────────────────────────┼─────────────┼─────────────┼────────┤
 │ App process CPU during benchmark window │ 9187.463 ms │ 2716.467 ms │ -70.4% │
 ├─────────────────────────────────────────┼─────────────┼─────────────┼────────┤
 │ Scheduler slices                        │ 1037        │ 223         │ -78.5% │
 └─────────────────────────────────────────┴─────────────┴─────────────┴────────┘

Results for inner code triggered, e.g. by "en-US-u-tz-usnyc":

 ┌─────────────────────────────────────────┬───────────────┬───────────────┬───────┐
 │ Metric                                  │ Old/base rare │ New/head rare │ Delta │
 ├─────────────────────────────────────────┼───────────────┼───────────────┼───────┤
 │ Benchmark thread wall time              │ 14359.059 ms  │ 15315.136 ms  │ +6.7% │
 ├─────────────────────────────────────────┼───────────────┼───────────────┼───────┤
 │ Benchmark thread CPU time               │ 13549.090 ms  │ 14585.745 ms  │ +7.7% │
 ├─────────────────────────────────────────┼───────────────┼───────────────┼───────┤
 │ CPU per call                            │ 0.6775 ms     │ 0.7293 ms     │ +7.7% │
 ├─────────────────────────────────────────┼───────────────┼───────────────┼───────┤
 │ App process CPU during benchmark window │ 19780.192 ms  │ 20366.205 ms  │ +3.0% │
 └─────────────────────────────────────────┴───────────────┴───────────────┴───────┘

Both benchmarks ran 20k iterations on the util.

Some more info on the "tz":

tz is a Unicode locale extension key meaning timezone.

 Example:

 `en-US-u-tz-usnyc`

 Breakdown:

 - en-US = English, United States
 - u = start of Unicode locale extensions
 - tz = timezone extension key
 - usnyc = timezone type, here New York

 So en-US-u-tz-usnyc roughly means: “English (US), with preferred timezone New York.”

 It’s different from the device/system timezone. It’s metadata embedded in the locale tag, mainly for APIs that format calendars/dates according to locale preferences. Android 13+ Calendar.getInstance(locale) can honor this extension, which is why PR #5587 keeps the Calendar path when
 locale.getUnicodeLocaleType("tz") != null.

Document why Android 13+ locales with Unicode timezone extensions keep using Calendar while normal locales use the default timezone directly for performance. Co-Authored-By: Claude <noreply@anthropic.com>

…o perf/sdk-overhead-reduction-timezone-default # Conflicts: # CHANGELOG.md

This was referenced Jun 23, 2026

perf(core): [SDK Overhead Reduction 11] Replace ISO8601 timestamp handling #5602

Merged

perf(core): [SDK Overhead Reduction 12] Avoid cloning Date getters #5603

Merged

lbloder approved these changes Jun 23, 2026

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adinauer mentioned this pull request Jun 23, 2026

fix(core): [SDK Overhead Reduction 13] Preserve ISO8601 utility compatibility #5609

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cursor Bot reviewed Jun 24, 2026

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adinauer marked this pull request as ready for review June 24, 2026 08:09

adinauer requested review from 0xadam-brown, markushi, romtsn and runningcode as code owners June 24, 2026 08:09

runningcode reviewed Jun 24, 2026

View reviewed changes

Comment thread sentry-android-core/src/main/java/io/sentry/android/core/DeviceInfoUtil.java

Comment thread sentry-android-core/src/main/java/io/sentry/android/core/DeviceInfoUtil.java

docs(android): Explain timezone Calendar fallback

9ac735a

Document why Android 13+ locales with Unicode timezone extensions keep using Calendar while normal locales use the default timezone directly for performance. Co-Authored-By: Claude <noreply@anthropic.com>

adinauer added 2 commits June 24, 2026 17:14

docs(core): Add timezone changelog entry

92262a2

Merge remote-tracking branch 'origin/perf/sdk-overhead-reduction' int…

4d4cafd

…o perf/sdk-overhead-reduction-timezone-default # Conflicts: # CHANGELOG.md

adinauer merged commit cd17726 into perf/sdk-overhead-reduction Jun 25, 2026
61 of 62 checks passed

adinauer deleted the perf/sdk-overhead-reduction-timezone-default branch June 25, 2026 07:26

sentry-release-bot Bot mentioned this pull request Jun 25, 2026

publish: getsentry/sentry-java@8.46.0 getsentry/publish#8701

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perf(android): [SDK Overhead Reduction 4] Use default timezone directly by adinauer · Pull Request #5587 · getsentry/sentry-java · GitHub

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perf(android): [SDK Overhead Reduction 4] Use default timezone directly - #5587

perf(android): [SDK Overhead Reduction 4] Use default timezone directly#5587
adinauer merged 5 commits into
perf/sdk-overhead-reductionfrom
perf/sdk-overhead-reduction-timezone-default

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PR Stack (SDK Overhead Reduction)

📜 Description

💡 Motivation and Context

💚 How did you test it?

📝 Checklist

🔮 Next steps

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📲 Install Builds

Android

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Performance metrics 🚀

Baseline results on branch: perf/sdk-overhead-reduction

Startup times

App size

Previous results on branch: perf/sdk-overhead-reduction-timezone-default

Startup times

App size

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