Skip to content

fix(ddtrace/tracer): avoid race on TestTracerPrioritySampler#4490

Merged
gh-worker-dd-mergequeue-cf854d[bot] merged 6 commits into
mainfrom
dario.castane/ktlo/flaky-testtracer-prioritysampler
Mar 12, 2026
Merged

fix(ddtrace/tracer): avoid race on TestTracerPrioritySampler#4490
gh-worker-dd-mergequeue-cf854d[bot] merged 6 commits into
mainfrom
dario.castane/ktlo/flaky-testtracer-prioritysampler

Conversation

@darccio

@darccio darccio commented Mar 2, 2026

Copy link
Copy Markdown
Member

What does this PR do?

Adds a loop to check if priority sampler is updated on TestTracerPrioritySampler as we emulate the rate_by_service of the agent on response.

Motivation

Avoid flakiness like https://github.com/DataDog/dd-trace-go/actions/runs/22556129490/job/65333714361#step:8:302

Reviewer's Checklist

  • Changed code has unit tests for its functionality at or near 100% coverage.
  • New code is free of linting errors. You can check this by running make lint locally.
  • New code doesn't break existing tests. You can check this by running make test locally.
  • Add an appropriate team label so this PR gets put in the right place for the release notes.

Unsure? Have a question? Request a review!

@darccio
darccio requested a review from a team as a code owner March 2, 2026 21:03
@codecov

codecov Bot commented Mar 2, 2026 •
edited
Loading

Copy link
Copy Markdown

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.05%. Comparing base (1ebb74b) to head (92ae805).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files
Files with missing lines Coverage Δ
ddtrace/tracer/sampler.go 95.04% <100.00%> (ø)

... and 433 files with indirect coverage changes

🚀 New features to boost your workflow:
  • ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
  • 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

@pr-commenter

pr-commenter Bot commented Mar 2, 2026 •
edited
Loading

Copy link
Copy Markdown

Benchmarks

Benchmark execution time: 2026-03-12 16:44:16

Comparing candidate commit 92ae805 in PR branch dario.castane/ktlo/flaky-testtracer-prioritysampler with baseline commit 1ebb74b in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 156 metrics, 8 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

  • 🟩 = significantly better candidate vs. baseline
  • 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

kakkoyun
kakkoyun reviewed Mar 10, 2026
View reviewed changes
Comment thread ddtrace/tracer/tracer_test.go Outdated
// response asynchronously, so we must poll rather than use a fixed sleep.
timeout := time.After(time.Second * timeMultiplicator)
for {
tr.prioritySampling.mu.RLock()

@kakkoyun kakkoyun Mar 10, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

nit: Maybe we should consider adding a prioritySampling.getDefaultRate() function where we guard with mutex.

@darccio darccio Mar 10, 2026

Copy link
Copy Markdown
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Done in f65d0f8

@darccio
darccio requested a review from a team as a code owner March 10, 2026 10:15
@datadog-prod-us1-4

datadog-prod-us1-4 Bot commented Mar 10, 2026 •
edited by datadog-prod-us1-6 Bot
Loading

Copy link
Copy Markdown

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 59.29%

This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 92ae805 | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!

@darccio

darccio commented Mar 11, 2026

Copy link
Copy Markdown
Member Author

/merge

@gh-worker-devflow-routing-ef8351

gh-worker-devflow-routing-ef8351 Bot commented Mar 11, 2026 •
edited
Loading

Copy link
Copy Markdown

View all feedbacks in Devflow UI.

2026-03-11 16:08:42 UTC ℹ️ Start processing command /merge

2026-03-11 16:08:52 UTC ℹ️ MergeQueue: waiting for PR to be ready

This pull request is not mergeable according to GitHub. Common reasons include pending required checks, missing approvals, or merge conflicts — but it could also be blocked by other repository rules or settings.
It will be added to the queue as soon as checks pass and/or get approvals. View in MergeQueue UI.
Note: if you pushed new commits since the last approval, you may need additional approval.
You can remove it from the waiting list with /remove command.

2026-03-11 21:04:10 UTC ⚠️ MergeQueue: This merge request was unqueued

devflow unqueued this merge request: It did not become mergeable within the expected time

@gh-worker-dd-mergequeue-cf854d
gh-worker-dd-mergequeue-cf854d Bot merged commit 2d3f643 into main Mar 12, 2026
207 checks passed
@gh-worker-dd-mergequeue-cf854d
gh-worker-dd-mergequeue-cf854d Bot deleted the dario.castane/ktlo/flaky-testtracer-prioritysampler branch March 12, 2026 17:31
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@kakkoyun kakkoyun kakkoyun approved these changes
@genesor genesor genesor approved these changes

Assignees

No one assigned

Labels

mergequeue-status: done team:apm-go

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

3 participants

@darccio @kakkoyun @genesor