JuanVqz · Sep 30, 2026 · Sep 30, 2026 · Sep 30, 2026 · Sep 30, 2026
diff --git a/.github/workflows/benchmarks.yml b/.github/workflows/benchmarks.yml
@@ -99,6 +99,99 @@ jobs:
           path: results/
           if-no-files-found: warn
 
+  # Builds the results site from every job's results, also when some jobs
+  # failed, so a PR gets a preview (the site-preview artifact, named outside
+  # the results-* pattern so a re-run never downloads it). Skipped when the
+  # benchmark jobs did not run (a lint failure). Only a push to
+  # main where every job passed publishes it, so a partial run never replaces
+  # the live site. Not required: a Pages problem never blocks a merge.
+  site:
+    needs: [changes, rake]
+    if: ${{ !cancelled() && needs.changes.outputs.run == 'true' && needs.rake.result != 'skipped' }}
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/download-artifact@v4
+        with:
+          pattern: results-*
+          path: results/
+          merge-multiple: true
+      - name: Build the results site
+        # A failed benchmark job leaves no result file, like a benchmark that needs a newer Ruby, so the page says missing results may be crashes.
+        env:
+          RESULTS_INCOMPLETE: ${{ needs.rake.result != 'success' && '1' || '' }}
+        run: docker compose run --rm -T -e RESULTS_INCOMPLETE --entrypoint ruby ruby_4.0 script/build_results_site.rb results _site
+      - name: Upload the site preview
+        id: preview
+        uses: actions/upload-artifact@v4
+        with:
+          name: site-preview
+          path: _site/
+          # A re-run replaces the earlier attempt's preview.
+          overwrite: true
+      # A one-click link on the run's Summary page; it needs no extra permissions, so it works for PRs from forks too.
+      - name: Link the site preview in the run summary
+        env:
+          PREVIEW_URL: ${{ steps.preview.outputs.artifact-url }}
+        run: |
+          {
+            echo "### Results site preview"
+            echo ""
+            echo "[Download the site preview]($PREVIEW_URL) (a zip, needs a GitHub login), unzip it and open \`index.html\` in a browser."
+          } >> "$GITHUB_STEP_SUMMARY"
+      - name: Upload the site for GitHub Pages
+        if: github.event_name == 'push' && github.ref_name == 'main' && needs.rake.result == 'success'
+        uses: actions/upload-pages-artifact@v5
+        with:
+          path: _site/
+
+  deploy:
+    needs: [rake, site]
+    if: github.event_name == 'push' && github.ref_name == 'main' && needs.rake.result == 'success' && needs.site.result == 'success'
+    runs-on: ubuntu-latest
+    # Only this job can publish; the rest of the workflow keeps the default
+    # token permissions.
+    permissions:
+      pages: write
+      id-token: write
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    # One deploy at a time; a newer merge waits instead of cancelling one that
+    # is halfway through.
+    concurrency:
+      group: pages
+      cancel-in-progress: false
+
+    steps:
+      # Runs can finish out of order, so an older run must not put its results back over a newer one.
+      # When main moved on, ask pick-benchmarks.sh (the same rule CI uses) whether the newer commits run benchmarks.
+      # If they do, their own run deploys newer results; if not (a README-only merge), this run's results are still the newest.
+      - uses: actions/checkout@v4
+        with:
+          ref: main
+          fetch-depth: 0
+      - name: Check no newer run on main will deploy
+        id: newest
+        run: |
+          if [ "$(git rev-parse HEAD)" = "$GITHUB_SHA" ]; then
+            echo "deploy=true" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+          GITHUB_EVENT_NAME=push GITHUB_OUTPUT=newer.txt .github/scripts/pick-benchmarks.sh "$GITHUB_SHA"
+          if grep -q '^run=true' newer.txt; then
+            echo "main moved on and its newer commits run benchmarks, so their run deploys; skipping."
+            echo "deploy=false" >> "$GITHUB_OUTPUT"
+          else
+            echo "main moved on, but nothing since this run affects benchmarks; deploying."
+            echo "deploy=true" >> "$GITHUB_OUTPUT"
+          fi
+      - name: Deploy to GitHub Pages
+        id: deployment
+        if: steps.newest.outputs.deploy == 'true'
+        uses: actions/deploy-pages@v5
+
   # The check to require on main. Passes when every benchmark job passed, or
   # when there was nothing to benchmark.
   benchmarks-ok:

diff --git a/.gitignore b/.gitignore
@@ -2,3 +2,4 @@
 *.bundle
 /Gemfile.lock
 /results/
+/_site/
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -112,6 +112,16 @@ it ran on:
 RESULTS_DIR=results RESULTS_LABEL=ruby_3.4 docker compose run --rm ruby_3.4 code/your-new/entry.rb
 ```
 
+To see those results the way the results site shows them, build the site
+into `_site/`, then open `_site/index.html` in a browser:
+
+```
+docker compose run --rm -T --entrypoint ruby ruby_4.0 script/build_results_site.rb results _site
+```
+
+CI does the same after every run: the site is attached to the run as the
+`site-preview` artifact, and published to GitHub Pages from `main`.
+
 ## Benchmarks that need a newer Ruby
 
 CI runs every benchmark on every Ruby in `compose.yaml`, back to Ruby 2.1, and

diff --git a/script/build_results_site.rb b/script/build_results_site.rb
@@ -0,0 +1,179 @@
+# Builds the results site from the JSON written by docker/collect_results.rb:
+#
+#   ruby script/build_results_site.rb [results_dir] [output_dir]
+#
+# results_dir defaults to results/ and output_dir to _site/. Result files are
+# found at any depth, so both a local results/<label>/ folder and CI's merged
+# artifacts work. The site answers one question per benchmark: does the
+# report the file claims is fastest win on this Ruby and build? Every verdict
+# compares reports inside one run, never one Ruby or build against another:
+# each build ran as its own CI job, often on a different CPU model.
+require "fileutils"
+require "json"
+
+module ResultsSite
+  REPO_URL = "https://github.com/fastruby/fast-ruby".freeze
+  ENGINES = %w[ruby jruby truffleruby].freeze
+  TEMPLATE = File.expand_path("results_site.html", __dir__)
+
+  # Over a billion iterations per second is under 1 ns per iteration: the JIT
+  # most likely removed the work (TruffleRuby reports hundreds of billions).
+  SUSPECT_IPS = 1e9
+
+  # Sections come from the folder under code/, in this order.
+  # A folder not listed here is shown after these, with its name capitalized.
+  SECTIONS = {
+    "general"        => "General",
+    "method"         => "Method Invocation",
+    "array"          => "Array",
+    "enumerable"     => "Enumerable",
+    "date"           => "Date",
+    "hash"           => "Hash",
+    "proc-and-block" => "Proc & Block",
+    "string"         => "String",
+    "time"           => "Time",
+    "range"          => "Range",
+    "bigdecimal"     => "BigDecimal"
+  }.freeze
+
+  module_function
+
+  def build(results_dir, output_dir)
+    # Only result files: anything else under results_dir
+    # (a site built there earlier, another artifact) has no "entries".
+    reports = Dir[File.join(results_dir, "**", "*.json")].sort.map { |path| JSON.parse(File.read(path)) }
+    reports.select! { |r| r.is_a?(Hash) && r["entries"].is_a?(Array) && r["label"] }
+    abort "No results found in #{results_dir}" if reports.empty?
+
+    data = site_data(reports)
+    FileUtils.rm_rf(output_dir)
+    FileUtils.mkdir_p(output_dir)
+    File.write(File.join(output_dir, "index.html"), render(data))
+    File.write(File.join(output_dir, "results.json"), JSON.generate(data))
+    puts "Built #{data[:benchmarks].size} benchmarks on #{data[:meta][:labels].size} builds into #{output_dir}"
+  end
+
+  # The claim is the first report: the lint guarantees the claimed one (the
+  # report calling `fastest`, `faster` or `fast`) is listed first. A tie is
+  # benchmark-ips' "same-ish": the i/s +- error ranges overlap, with the same
+  # comparison as Benchmark::IPS::Stats::StatsMetric#overlaps?.
+  def verdict(entries, claim)
+    sorted = entries.sort_by { |e| -e["ips"] }
+    top = sorted.first
+    claimed = entries.find { |e| e["name"] == claim }
+    suspect = entries.any? { |e| e["ips"] > SUSPECT_IPS }
+    return { state: "na", suspect: suspect } unless claimed
+
+    if claimed.equal?(top)
+      second = sorted[1]
+      if second.nil? || overlaps?(top, second)
+        { state: "eq", suspect: suspect }
+      else
+        { state: "ok", ratio: top["ips"] / second["ips"], suspect: suspect }
+      end
+    elsif overlaps?(claimed, top)
+      { state: "eq", suspect: suspect }
+    else
+      { state: "no", ratio: top["ips"] / claimed["ips"], winner: top["name"], suspect: suspect }
+    end
+  end
+
+  def overlaps?(a, b)
+    a["ips"] + a["error"] > b["ips"] - b["error"] && a["ips"] - a["error"] < b["ips"] + b["error"]
+  end
+
+  def site_data(reports)
+    labels = reports.map { |r| r["label"] }.uniq.sort_by { |l| label_sort_key(l) }
+    grouped = reports.group_by { |r| [r["benchmark"], r["part"]] }
+    multi_part = grouped.keys.group_by(&:first).select { |_, parts| parts.size > 1 }.keys
+
+    benchmarks = grouped.map do |(file, part), runs|
+      # The run with the most reports has them all; older Rubies can skip a
+      # report guarded by RUBY_VERSION.
+      names = runs.max_by { |r| r["entries"].size }["entries"].map { |e| e["name"] }
+      title = title_for(names)
+      title += " (part #{part})" if multi_part.include?(file)
+      {
+        file: file,
+        part: part,
+        title: title,
+        section: section_for(file),
+        names: names,
+        runs: runs.to_h { |r| [r["label"], run_data(r, names)] }
+      }
+    end
+
+    order = SECTIONS.values
+    benchmarks.sort_by! { |b| [order.index(b[:section]) || order.size, b[:section], b[:file], b[:part]] }
+    # Two files with the same report labels get their file name added.
+    benchmarks.group_by { |b| b[:title] }.each_value do |same|
+      same.each { |b| b[:title] += " (#{File.basename(b[:file])})" } if same.size > 1
+    end
+
+    { meta: meta(reports, labels), benchmarks: benchmarks }
+  end
+
+  # Per build: the verdict, and ips/error per report in the order of `names`
+  # (nil where that report did not run).
+  def run_data(report, names)
+    entries = report["entries"]
+    v = verdict(entries, names.first)
+    by_name = entries.to_h { |e| [e["name"], e] }
+    v[:ratio] = v[:ratio].round(4) if v[:ratio]
+    v[:winner] = names.index(v[:winner]) if v[:winner]
+    v.merge(entries: names.map { |n| (e = by_name[n]) && [e["ips"].round(3), e["error"].to_f.round(1)] })
+  end
+
+  def meta(reports, labels)
+    first = reports.first
+    by_label = reports.group_by { |r| r["label"] }.transform_values(&:first)
+    {
+      commit: first["commit"],
+      run_id: first["run_id"],
+      pr: first["pr"],
+      # Set by CI when a benchmark job failed: its results are missing, which looks like a skip.
+      incomplete: ENV["RESULTS_INCOMPLETE"] == "1",
+      built_at: Time.now.utc.strftime("%Y-%m-%d %H:%M UTC"),
+      repo: REPO_URL,
+      labels: labels,
+      default: default_label(labels),
+      descriptions: by_label.transform_values { |r| r["ruby_description"] },
+      cpus: by_label.transform_values { |r| r.dig("environment", "cpu") }
+    }
+  end
+
+  # The newest released MRI: head builds and JIT variants are left out.
+  def default_label(labels)
+    labels.select { |l| l.match?(/\Aruby_\d[\d.]*\z/) }.max_by { |l| Gem::Version.new(l.delete_prefix("ruby_")) } || labels.first
+  end
+
+  # ruby, then jruby, then truffleruby; oldest to newest, head last; the plain
+  # build before its JIT variants.
+  def label_sort_key(label)
+    base, variant = label.split("+", 2)
+    engine, version = base.match(/\A([a-z]+)_(.+)\z/)&.captures || [base, ""]
+    head = version == "head" ? 1 : 0
+    [ENGINES.index(engine) || ENGINES.size, head, version.scan(/\d+/).map(&:to_i), variant.to_s]
+  end
+
+  # The title is the report labels, claimed report first: "`String#tr` vs `String#gsub`".
+  # A label with a backtick in it is left as plain text, so it cannot break the code style.
+  def title_for(names)
+    names.map { |n| n.include?("`") ? n : "`#{n}`" }.join(" vs ")
+  end
+
+  # code/proc-and-block/proc-call-vs-yield.rb is in "Proc & Block".
+  def section_for(file)
+    folder = file.split("/")[1].to_s
+    SECTIONS.fetch(folder) { folder.split("-").map(&:capitalize).join(" ") }
+  end
+
+  # The data goes inline so the page also works opened from disk. "</" is
+  # escaped so a report name can never close the script tag.
+  def render(data)
+    json = JSON.generate(data).gsub("</", "<\\/").gsub("\u2028", "\\u2028").gsub("\u2029", "\\u2029")
+    File.read(TEMPLATE).sub("/*RESULTS_DATA*/") { "window.RESULTS = #{json};" }
+  end
+end
+
+ResultsSite.build(ARGV[0] || "results", ARGV[1] || "_site") if $PROGRAM_NAME == __FILE__