cmd/swarm-bench: replace go-metrics with local statistics by thaJeztah · Pull Request #3281 · moby/swarmkit

thaJeztah · 2026-08-01T18:22:51Z

relates to swarm-bench: Benchmarking tool with phone-home stats collector. #163

The go-metrics repository is archived, and swarm-bench only uses a small part of its timer implementation.

Replace it with a local collector that records task startup durations and calculates count, min, max, mean, standard deviation, and percentiles using the standard library. Preserve the percentile interpolation used by go-metrics, and replace its EWMA rates with the overall task completion rate.

Protect collection and snapshots with a mutex so that periodic statistics can still be reported safely while tasks are connecting.

Also make Collector's zero value usable and keep it local to Benchmark.Run, removing the now-unnecessary constructor and Benchmark field.

- What I did

- How I did it

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- Description for the changelog

thaJeztah · 2026-08-01T18:23:45Z

-	fmt.Fprintf(w, "  1-min rate:  %12.2f\n", t.Rate1())
-	fmt.Fprintf(w, "  5-min rate:  %12.2f\n", t.Rate5())
-	fmt.Fprintf(w, "  15-min rate: %12.2f\n", t.Rate15())


I can add these back if we care deeply (not sure if this utility is even used by anyone though, so kept it minimal).

Copilot

Pull request overview

This PR removes the archived github.com/rcrowley/go-metrics dependency from cmd/swarm-bench and replaces it with a local, mutex-protected statistics collector that computes basic distribution stats and percentiles using the standard library.

Changes:

Drop go-metrics from go.mod/go.sum and remove its vendored sources.
Rework swarm-bench’s Collector to record per-task connection latencies and compute min/max/mean/stddev/percentiles and an overall completion rate.
Simplify Benchmark by making Collector a local variable in Benchmark.Run and removing the constructor/field.

Reviewed changes

Copilot reviewed 3 out of 34 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
vendor/modules.txt	Remove go-metrics from vendored module list
vendor/github.com/rcrowley/go-metrics/writer.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/validate.sh	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/timer.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/syslog.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/sample.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/runtime.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/runtime_no_gccpufraction.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/runtime_no_cgo.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/runtime_gccpufraction.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/runtime_cgo.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/registry.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/README.md	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/opentsdb.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/metrics.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/meter.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/memory.md	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/log.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/LICENSE	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/json.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/histogram.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/healthcheck.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/graphite.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/gauge.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/gauge_float64.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/ewma.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/debug.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/counter.go	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/.travis.yml	Remove vendored go-metrics file
vendor/github.com/rcrowley/go-metrics/.gitignore	Remove vendored go-metrics file
go.sum	Remove go-metrics checksums
go.mod	Remove go-metrics dependency
cmd/swarm-bench/collector.go	Add local statistics collector implementation
cmd/swarm-bench/benchmark.go	Use local collector; remove Benchmark field/ctor usage

Suppressed comments (1)

cmd/swarm-bench/benchmark.go:66

Benchmark.Run hard-codes the final stats display unit to time.Second, ignoring Config.Unit. Use b.cfg.Unit here as well for consistency with periodic reports.

	fmt.Printf("\n%s: Benchmark completed\n", time.Now())
	collector.Stats(os.Stdout, time.Second)

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codecov-commenter · 2026-08-01T18:31:34Z

Codecov Report

❌ Patch coverage is 0% with 58 lines in your changes missing coverage. Please review.
✅ Project coverage is 14.68%. Comparing base (6e9e7b8) to head (40c4014).
⚠️ Report is 60 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3281      +/-   ##
==========================================
- Coverage   14.73%   14.68%   -0.05%     
==========================================
  Files         200      200              
  Lines       93077    93055      -22     
==========================================
- Hits        13712    13667      -45     
- Misses      78019    78047      +28     
+ Partials     1346     1341       -5

🚀 New features to boost your workflow:

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Copilot

Pull request overview

Copilot reviewed 3 out of 34 changed files in this pull request and generated 1 comment.

Copilot

Pull request overview

Copilot reviewed 3 out of 34 changed files in this pull request and generated 1 comment.

The go-metrics repository is archived, and swarm-bench only uses a small part of its timer implementation. Replace it with a local collector that records task startup durations and calculates count, min, max, mean, standard deviation, and percentiles using the standard library. Preserve the percentile interpolation used by go-metrics, and replace its EWMA rates with the overall task completion rate. Protect collection and snapshots with a mutex so that periodic statistics can still be reported safely while tasks are connecting. Also make Collector's zero value usable and keep it local to Benchmark.Run, removing the now-unnecessary constructor and Benchmark field. Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Copilot

Pull request overview

Copilot reviewed 3 out of 34 changed files in this pull request and generated 1 comment.

Suppressed comments (1)

cmd/swarm-bench/collector.go:51

Collect can spin indefinitely if Accept() starts returning a persistent error (e.g., listener closed) because it logs and continues without an exit path, and it also doesn't honor ctx cancellation to stop collection. Consider unblocking Accept() on ctx.Done() and returning on net.ErrClosed to avoid a tight error loop during shutdown/cancellation.

		conn, err := c.ln.Accept()
		if err != nil {
			log.G(ctx).WithError(err).Error("failure accepting connection")
			continue
		}

thaJeztah · 2026-08-01T21:22:19Z

 import (
 	"context"
 	"fmt"
 	"io"
+	"math"


you're dreaming?

thaJeztah commented Aug 1, 2026

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thaJeztah marked this pull request as ready for review August 1, 2026 18:23

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Comment thread cmd/swarm-bench/collector.go Outdated

Comment thread cmd/swarm-bench/benchmark.go

thaJeztah force-pushed the remove_go_metrics branch from c76cedb to a16cc47 Compare August 1, 2026 19:17

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Comment thread cmd/swarm-bench/collector.go

thaJeztah force-pushed the remove_go_metrics branch from a16cc47 to 515f1ec Compare August 1, 2026 19:47

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Comment thread cmd/swarm-bench/collector.go

thaJeztah force-pushed the remove_go_metrics branch from 515f1ec to db84341 Compare August 1, 2026 20:04

thaJeztah force-pushed the remove_go_metrics branch from db84341 to 40c4014 Compare August 1, 2026 20:07

thaJeztah requested a review from Copilot August 1, 2026 20:07

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thaJeztah requested review from corhere and vvoland August 1, 2026 21:23

thaJeztah mentioned this pull request Aug 3, 2026

remove direct dependency on github.com/spf13/cobra #3280

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cmd/swarm-bench: replace go-metrics with local statistics - #3281

cmd/swarm-bench: replace go-metrics with local statistics#3281
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thaJeztah:remove_go_metrics

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