Check the DBM comment region in place, dropping the duplicate-comment substring by dougqh · Pull Request #11737 · DataDog/dd-trace-java

dougqh · 2026-06-24T22:57:47Z

What Does This Do

Replaces the per-call sql.substring used by SQLCommenter.hasDDComment.
In place of a sub-string, the code now uses a SubSequence which has lower overhead

Motivation

SubSequence avoids the allocation and copying of a regular sub-string.
And frequently, SubSequence is completely optimized away by escape analysis.

For this code path, the net effect is zero allocation and a modest ~12% improvement in throughput.

Additional Notes

Measured — SQLCommenterDuplicateCommentBenchmark (JDK 17, @Threads(8), @Fork(5), -prof gc)

	throughput	`gc.alloc.rate.norm`
before (substring)	23.5M ± 1.1M ops/s	140 B/op
after (range/view)	26.2M ± 1.5M ops/s	~0 (10⁻⁵)

The allocation delta (140 → 0 B/op) is the win and is exact/fork-stable. This path is scan-CPU-dominated, so the ~12% throughput is a modest bonus — the real, compounding win is the per-inject allocation removed across comment-bearing queries.

🤖 Generated with Claude Code

dd-octo-sts · 2026-06-24T23:20:45Z

🟢 Java Benchmark SLOs — All performance SLOs passed

Suite	Status
Startup	🟢 pass

SLO thresholds are defined here based on automatically generated metrics. A warning is raised when results are within 5% of the threshold.

PR vs. master results

Scenario	Candidate	master	Δ (95% CI of mean)
startup:insecure-bank:iast:Agent	13.96 s	14.05 s	[-1.3%; +0.0%] (no difference)
startup:insecure-bank:tracing:Agent	12.94 s	13.02 s	[-1.4%; +0.2%] (no difference)
startup:petclinic:appsec:Agent	16.37 s	16.70 s	[-6.4%; +2.4%] (no difference)
startup:petclinic:iast:Agent	16.40 s	16.91 s	[-7.2%; +1.2%] (no difference)
startup:petclinic:profiling:Agent	16.85 s	16.33 s	[-1.1%; +7.4%] (no difference)
startup:petclinic:sca:Agent	16.81 s	16.59 s	[+0.2%; +2.5%] (maybe worse)
startup:petclinic:tracing:Agent	15.59 s	16.09 s	[-7.1%; +1.0%] (no difference)

Commit:2eeff802 · CI Pipeline · Benchmarking Platform UI

Load and DaCapo benchmarks can be triggered manually in the GitLab pipeline. Results will appear in the Benchmarking Platform UI after completion.

dougqh · 2026-06-25T11:35:29Z

Benchmark results (zulu-17, JDK 17.0.7, @Threads(8), @Fork(5), -prof gc)

SQLCommenterDuplicateCommentBenchmark.alreadyCommented:

	throughput	gc.alloc.rate.norm
before (substring)	23.5M ± 1.1M ops/s	140 B/op
after (range/view)	26.2M ± 1.5M ops/s	~0 B/op (10⁻⁵)

The extractCommentContent substring (140 B/op) is gone — the in-place range scan and the SubSequence view it flows through are both EA-elided. The headline win is the allocation: this path is dominated by the nine indexOf scans (CPU the alloc-removal doesn't touch), so throughput is a modest ~1.1× uplift, now resolved at @Fork(5). Benchmark Javadoc refreshed in bd0983f.

…ld the view Per review on #11737: move SubSequence.of to the call sites (SQLCommenter builds the comment-region view; the String overload wraps the whole content) and make SharedDBCommenter.containsTraceComment take a SubSequence instead of (String, from, to). Behavior unchanged (SubSequence.contains -> Strings.regionContains); test + dup-comment-benchmark Javadoc updated to the new shape. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

…tent substring SQLCommenter.hasDDComment materialized sql.substring(commentStart, commentEnd) on every duplicate-comment check just to feed containsTraceComment. Add a SharedDBCommenter.containsTraceComment(sql, from, to) range overload that scans the comment body in place, and a Strings.regionContains primitive it (and the String delegate) build on -- no per-call substring. The String overload now delegates to the range form, so Mongo behavior is unchanged. regionContains is the allocation-free, copy-free primitive; the natural-reading SubSequence.contains layer can delegate to it later. Boundary semantics unit- tested on Strings.regionContains; DB needle behavior on the overloads; existing SQLCommenter/SharedDBCommenter suites unchanged and green. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

…diom) Add SubSequence.contains (delegating to the Strings.regionContains primitive) and rewrite containsTraceComment(sql, from, to) as SubSequence.of(sql, from, to).contains(...) -- a 1-to-1 substitution for what you'd idiomatically write on a substring, with no copy. EA elides the view in the transient consumption; even if it doesn't, the string copy is still avoided. Couples this branch to the SubSequence base (#10640); regionContains stays as the allocation-free primitive the view delegates to. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

@threads

Isolates the duplicate-comment guard (dbType=null skips the first-word scan; already-DD-commented SQL makes inject return early). The extractCommentContent substring allocated 140 B/op; the in-place range/view scan is EA-elided (~0). @threads(8), @fork(2), -prof gc; numbers in the class Javadoc. Throughput is flat-to-slightly-up but within @fork(2) noise -- this path is scan-CPU-dominated, so the win is the allocation, not throughput. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

zulu-17 @fork(5), -prof gc: 23.5M -> 26.2M ops/s (~1.1x), 140 -> ~0 B/op. Headline win is the allocation; @fork(5) tightens the earlier bimodal spread. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

…scan-overload # Conflicts: # internal-api/src/main/java/datadog/trace/util/SubSequence.java # internal-api/src/test/java/datadog/trace/util/SubSequenceTest.java

datadog-official · 2026-06-30T21:40:18Z

🎯 Code Coverage (details)
• Patch Coverage: 57.14%
• Overall Coverage: 56.72% (-0.46%)

_{This comment will be updated automatically if new data arrives.

🔗 Commit SHA: 2eeff80 | Docs | Datadog PR Page | Give us feedback!}

mhlidd

Nice improvements!

dd-octo-sts · 2026-07-14T15:29:57Z

/merge

gh-worker-devflow-routing-ef8351 · 2026-07-14T15:30:01Z

View all feedbacks in Devflow UI.

2026-07-14 15:30:01 UTC ℹ️ Start processing command /merge

2026-07-14 15:30:07 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in master is approximately 2h (p90).

2026-07-14 16:31:49 UTC ℹ️ MergeQueue: This merge request was merged

dougqh added tag: performance Performance related changes tag: no release notes Changes to exclude from release notes inst: jdbc JDBC instrumentation comp: database Database Monitoring tag: ai generated Largely based on code generated by an AI or LLM labels Jun 24, 2026

dougqh force-pushed the dougqh/dbcommenter-scan-overload branch from bd0983f to 24d8ea0Compare June 29, 2026 18:16

dougqh commented Jun 29, 2026
View reviewed changes

Comment thread...gent/instrumentation/jdbc/src/main/java/datadog/trace/instrumentation/jdbc/SQLCommenter.java

dougqh commented Jun 29, 2026
View reviewed changes

Comment thread...t-bootstrap/src/main/java/datadog/trace/bootstrap/instrumentation/dbm/SharedDBCommenter.java

dougqh marked this pull request as ready for review June 29, 2026 19:53

dougqh requested review from a team as code owners June 29, 2026 19:53

dougqh requested review from jordan-wong and mhlidd and removed request for a teamJune 29, 2026 19:53

dougqhand others added 4 commits June 29, 2026 20:54

Refresh SQLCommenterDuplicateCommentBenchmark results to JDK 17@fork(5)
5904552
zulu-17 @fork(5), -prof gc: 23.5M -> 26.2M ops/s (~1.1x), 140 -> ~0 B/op. Headline win is the allocation; @fork(5) tightens the earlier bimodal spread. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

dougqh force-pushed the dougqh/dbcommenter-scan-overload branch from 71f3df8 to 5904552Compare June 30, 2026 00:56

dougqh mentioned this pull request Jun 30, 2026
Add window-bounded String and char overloads to SubSequence #11796
Merged

Merge remote-tracking branch 'origin/master' into dougqh/dbcommenter-…
3b96fdc
…scan-overload # Conflicts: # internal-api/src/main/java/datadog/trace/util/SubSequence.java # internal-api/src/test/java/datadog/trace/util/SubSequenceTest.java

na-ji approved these changes Jul 1, 2026
View reviewed changes

dougqh enabled auto-merge July 1, 2026 19:29

Merge branch 'master' into dougqh/dbcommenter-scan-overload
0e91753

mhlidd approved these changes Jul 9, 2026
View reviewed changes

Merge branch 'master' into dougqh/dbcommenter-scan-overload
2eeff80

dougqh added this pull request to the merge queue Jul 14, 2026

github-merge-queueBot removed this pull request from the merge queue due to failed status checks Jul 14, 2026

gh-worker-dd-mergequeue-cf854dBot merged commit 7e08161 into masterJul 14, 2026
587 checks passed

gh-worker-dd-mergequeue-cf854dBot deleted the dougqh/dbcommenter-scan-overload branch July 14, 2026 16:31

github-actionsBot added this to the 1.65.0 milestone Jul 14, 2026

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Check the DBM comment region in place, dropping the duplicate-comment substring - #11737

Check the DBM comment region in place, dropping the duplicate-comment substring#11737
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What Does This Do

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