feat: threads

scripts/bench-browser.ts

@@ -0,0 +1,93 @@
+import { chromium } from "playwright"
+
+// Start the Vite dev server (it serves the COOP/COEP headers needed for
+// SharedArrayBuffer), drive real headless Chromium through both bench modes, and
+// read the timings back. Real V8 + Web Workers + SAB + rAF -- the environment my
+// headless Bun benches can't see.
+
+const PORT = 5199
+const URL = `http://localhost:${PORT}`
+
+const vite = Bun.spawn(["bunx", "--bun", "vite", "--port", String(PORT), "--strictPort"], {
+  cwd: import.meta.dir + "/..",
+  stdout: "pipe",
+  stderr: "pipe",
+  env: { ...process.env, NO_COLOR: "1" },
+})
+
+async function waitForServer(): Promise<void> {
+  for (let i = 0; i < 150; i++) {
+    try {
+      const r = await fetch(URL + "/")
+      if (r.ok) {
+        return
+      }
+    } catch {
+      // not up yet
+    }
+    await Bun.sleep(200)
+  }
+  throw new Error("vite dev server did not start")
+}
+
+type Bench = {
+  mode: string
+  parallel: boolean
+  cores: number
+  coi: boolean
+  res: string
+  workMs: { median: number; p95: number; max: number; mean: number }
+  frameMs: { median: number; p95: number; max: number; mean: number }
+}
+
+async function main(): Promise<void> {
+  await waitForServer()
+  const browser = await chromium.launch({
+    headless: true,
+    args: [
+      "--enable-features=SharedArrayBuffer",
+      "--disable-background-timer-throttling",
+      "--disable-renderer-backgrounding",
+      "--disable-backgrounding-occluded-windows",
+    ],
+  })
+
+  async function run(mode: string): Promise<Bench> {
+    const page = await browser.newPage()
+    page.on("pageerror", (e) => console.log(`  [page error] ${e.message}`))
+    page.on("console", (m) => {
+      const t = m.text()
+      if (t.startsWith("BENCH") || m.type() === "error") {
+        console.log(`  [console] ${t}`)
+      }
+    })
+    await page.setViewportSize({ width: 800, height: 600 })
+    await page.goto(`${URL}/?bench=${mode}`, { waitUntil: "load" })
+    await page.waitForFunction("window.__BENCH__ !== undefined", null, { timeout: 120000 })
+    const result = (await page.evaluate("window.__BENCH__")) as Bench
+    await page.close()
+    return result
+  }
+
+  console.log("--- single-thread ---")
+  const st = await run("st")
+  console.log("--- workers ---")
+  const mt = await run("mt")
+  await browser.close()
+
+  const line = (b: Bench) =>
+    `parallel=${b.parallel} coi=${b.coi} cores=${b.cores} res=${b.res}  work med/p95/max = ${b.workMs.median}/${b.workMs.p95}/${b.workMs.max} ms  frame med/p95 = ${b.frameMs.median}/${b.frameMs.p95} ms`
+  console.log("")
+  console.log(`single-thread : ${line(st)}`)
+  console.log(`workers       : ${line(mt)}`)
+  console.log("")
+  console.log(`work median   : ${st.workMs.median} -> ${mt.workMs.median} ms  (${(st.workMs.median / mt.workMs.median).toFixed(2)}x)`)
+  console.log(`work p95      : ${st.workMs.p95} -> ${mt.workMs.p95} ms  (${(st.workMs.p95 / mt.workMs.p95).toFixed(2)}x)`)
+  console.log(`frame p95     : ${st.frameMs.p95} -> ${mt.frameMs.p95} ms   (jitter: lower p95/median = steadier)`)
+}
+
+try {
+  await main()
+} finally {
+  vite.kill()
+}