perf(core): Skip Hint allocation in addBreadcrumb without callback - #5689
Merged
runningcode merged 1 commit intoJul 6, 2026
Merged
perf(core): Skip Hint allocation in addBreadcrumb without callback#5689runningcode merged 1 commit into
runningcode merged 1 commit into
Conversation
Copy link
Copy Markdown
Contributor
Sorry, something went wrong.
Copy link
Copy Markdown
Sorry, something went wrong.
runningcode
force-pushed
the
no/java-605-avoid-hint-allocation
branch
from
88119b9 to
3680ae4
Compare
July 2, 2026 16:50
Copy link
Copy Markdown
📲 Install BuildsAndroid
|
Sorry, something went wrong.
runningcode
marked this pull request as ready for review
July 2, 2026 16:53
runningcode
requested review from
0xadam-brown,
adinauer,
markushi and
romtsn
as code owners
July 2, 2026 16:53
runningcode
marked this pull request as draft
July 2, 2026 16:57
runningcode
marked this pull request as ready for review
July 2, 2026 17:05
Copy link
Copy Markdown
Contributor
Performance metrics 🚀
Baseline results on branch: mainStartup times
App size
Previous results on branch: no/java-605-avoid-hint-allocationStartup times
App size
|
Sorry, something went wrong.
romtsn
approved these changes
Jul 3, 2026
Only allocate a Hint when a beforeBreadcrumb callback is set. addBreadcrumb previously allocated a Hint (HashMap + ArrayList + lock) on every call even though the Hint is only ever passed to the callback, wasting allocations on the common no-callback path. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
runningcode
force-pushed
the
no/java-605-avoid-hint-allocation
branch
from
3680ae4 to
1916876
Compare
July 6, 2026 12:50
runningcode
enabled auto-merge (squash)
July 6, 2026 12:54
3 tasks
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Reviewers
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Resolves JAVA-605.
Description
Scope.addBreadcrumb(Breadcrumb, Hint) allocated a Hint unconditionally when the caller passed null, even though the Hint is only ever used to pass to the beforeBreadcrumb callback. When no callback is configured (the common case) the Hint — a HashMap + ArrayList + AutoClosableReentrantLock — was created and immediately discarded on every breadcrumb.
This moves the allocation inside the callback != null branch, so no Hint is allocated on the common path.
Pure allocation elimination, no behavior change.
Source
Found via on-device Perfetto method-trace analysis of the Android SDK (Scope#addBreadcrumb breadcrumb path). Part of Reduce SDK init time [Android].
🤖 Generated with Claude Code
Benchmark
Measured on-device with androidx Microbenchmark 1.4.1 (benchmark-junit4) on a Samsung Galaxy A55 (SM-A556B), Android API 36 (release build, non-minified).
The benchmark exercises the caller-side cost of a scope mutation with scope persistence enabled (enableScopePersistence = true, cacheDirPath set, no beforeBreadcrumb). The async serialize + disk write is dispatched to a no-op executor so it never runs on the measured thread — mirroring production, where it runs off-thread. Each branch is compared against its base commit (aab952b82e); the per-branch delta isolates this change. allocationCount is deterministic; timeNs has ~±10 ns run-to-run noise on a non-rooted device (unlocked clocks), so it is reported as a median and reproduced across 2 runs.
How it was done
A local, uncommitted androidx microbenchmark module (sentry-android-integration-tests/sentry-uitest-android-microbenchmark) depending on :sentry, with a BenchmarkRule looping the scope mutation. Run with:
Result — scope.addBreadcrumb()
The 4 eliminated allocations are the Hint plus its HashMap, ArrayList, and AutoClosableReentrantLock. The setTag control path (unaffected by this change) was unchanged at ~127 ns / 3 allocs.