test: modernize benchmarks with b.Loop

element_create_benchmark_test.go

@@ -27,14 +27,14 @@ func (benchCreateUI) JawsUpdate(elem *Element) {}
 //
 // Batching is deliberate: b.StopTimer and b.StartTimer each call runtime.ReadMemStats, so
 // toggling around a single sub-microsecond creation would leave the timed section tiny,
-// calibration would pick an enormous b.N, and the excluded setup would run for minutes.
+// calibration would pick an enormous iteration count, and the excluded setup would run
+// for minutes.
 // Amortising both calls over the batch keeps that honest, and deleting the batch keeps the
 // Request registry bounded instead of growing across iterations. The reported figure is per
 // batch of 64 Elements.
 //
-// The Jaws and Request are built before b.ResetTimer, and the final b.StopTimer excludes the
-// deferred Close: both would otherwise be divided into every reported figure, time and
-// allocations alike, making the result depend on b.N rather than on the Element.
+// [testing.B.Loop] excludes construction and the deferred Close from the measurement,
+// while the explicit timer calls exclude per-batch deletion.
 func BenchmarkElementCreateBatch(b *testing.B) {
 	b.ReportAllocs()
 	const batch = 64
@@ -51,8 +51,7 @@ func BenchmarkElementCreateBatch(b *testing.B) {
 	var ui benchCreateUI
 	elems := make([]*Element, 0, batch)
 
-	b.ResetTimer()
-	for range b.N {
+	for b.Loop() {
 		elems = elems[:0]
 		for range batch {
 			elem := rq.NewElement(ui)
@@ -65,5 +64,4 @@ func BenchmarkElementCreateBatch(b *testing.B) {
 		rq.DeleteElements(elems)
 		b.StartTimer()
 	}
-	b.StopTimer()
 }

examples/minesweeper/main_benchmark_test.go

@@ -49,8 +49,7 @@ func BenchmarkSingleCellDirtyFanout(b *testing.B) {
 
 	cell := g.cells[0][0]
 	b.ReportAllocs()
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for b.Loop() {
 		// Mirror the framework's dirty dispatch: expand the toggle's tags and
 		// resolve each to its registered elements (Request.GetElements is the same
 		// tagMap lookup makeUpdateList performs). The sum is the number of element

jaws_test.go

@@ -3137,8 +3137,7 @@ func BenchmarkRequestLifecyclePooling(b *testing.B) {
 						jw := newBenchPoolJaws(b)
 						cycleBenchRequest(jw, impl.newRq, impl.recycle, tags) // warm the pool and backing arrays
 						b.ReportAllocs()
-						b.ResetTimer()
-						for i := 0; i < b.N; i++ {
+						for b.Loop() {
 							cycleBenchRequest(jw, impl.newRq, impl.recycle, tags)
 						}
 					})
@@ -3204,8 +3203,7 @@ func BenchmarkRequestRecycleAfterHighWater(b *testing.B) {
 			}
 			jw.recycle(big)
 			b.ReportAllocs()
-			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				rq := jw.NewRequest(nil)
 				jw.recycle(rq)
 				runtime.KeepAlive(rq)
@@ -3223,8 +3221,7 @@ func BenchmarkRequestClaimStartFinish(b *testing.B) {
 	jw := newBenchPoolJaws(b)
 	r := httptest.NewRequest(http.MethodGet, "/", nil)
 	b.ReportAllocs()
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for b.Loop() {
 		rq := jw.NewRequest(r)
 		if jw.UseRequest(rq.JawsKey, r) != rq {
 			b.Fatal("claim failed")
@@ -3292,8 +3289,7 @@ func BenchmarkSubscriptionChannels(b *testing.B) {
 			rq := jw.NewRequest(nil)
 			defer jw.recycle(rq)
 			b.ReportAllocs()
-			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				msgCh := jw.subscribe(rq, 1)
 				if msgCh == nil {
 					b.Fatal("subscribe returned nil")
@@ -3353,8 +3349,7 @@ func BenchmarkDistributeDirt(b *testing.B) {
 			}
 
 			b.ReportAllocs()
-			b.ResetTimer()
-			for n := 0; n < b.N; n++ {
+			for b.Loop() {
 				b.StopTimer()
 				jw.setDirty(tags)
 				for _, rq := range reqs {
@@ -3387,14 +3382,14 @@ func BenchmarkRequestWantMessage(b *testing.B) {
 	b.Run("single-tag", func(b *testing.B) {
 		msg := wire.Message{Dest: hit, What: what.Update}
 		b.ReportAllocs()
-		for n := 0; n < b.N; n++ {
+		for b.Loop() {
 			_ = rq.wantMessage(&msg)
 		}
 	})
 	b.Run("multi-tag", func(b *testing.B) {
 		msg := wire.Message{Dest: []any{tag.Tag("nope"), hit}, What: what.Update}
 		b.ReportAllocs()
-		for n := 0; n < b.N; n++ {
+		for b.Loop() {
 			_ = rq.wantMessage(&msg)
 		}
 	})
@@ -3409,7 +3404,7 @@ func BenchmarkGetSendMsgs(b *testing.B) {
 		b.Run("idle/elems="+strconv.Itoa(n), func(b *testing.B) {
 			rq := newBenchRequest(b, n)
 			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				_ = rq.getSendMsgs()
 			}
 		})
@@ -3427,13 +3422,13 @@ func BenchmarkGetElementByJid(b *testing.B) {
 		miss := Jid(n + 1)
 		b.Run("last/elems="+strconv.Itoa(n), func(b *testing.B) {
 			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				_ = rq.getElementByJidLocked(last)
 			}
 		})
 		b.Run("miss/elems="+strconv.Itoa(n), func(b *testing.B) {
 			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				_ = rq.getElementByJidLocked(miss)
 			}
 		})
@@ -3460,8 +3455,7 @@ func BenchmarkRequestHandleBroadcastCall(b *testing.B) {
 			}
 			msg := wire.Message{Dest: tc.dest, What: what.Call, Data: `app.refresh={"source":"server"}`}
 			b.ReportAllocs()
-			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				rq.handleBroadcast(msg, nil)
 				rq.muQueue.Lock()
 				rq.wsQueue = rq.wsQueue[:0]
@@ -3515,8 +3509,7 @@ func BenchmarkRequestEventDispatch(b *testing.B) {
 
 			var err error
 			b.ReportAllocs()
-			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				err = rq.callAllEventHandlers(elem.Jid(), what.Input, "value")
 			}
 			if err != nil {
@@ -3545,8 +3538,7 @@ func BenchmarkRequestEventDispatch(b *testing.B) {
 
 		var err error
 		b.ReportAllocs()
-		b.ResetTimer()
-		for i := 0; i < b.N; i++ {
+		for b.Loop() {
 			err = rq.callAllEventHandlers(0, what.Click, clickValue)
 		}
 		if err != nil {
@@ -3566,7 +3558,7 @@ func BenchmarkAppendJSQuote(b *testing.B) {
 		b.Run(c.name, func(b *testing.B) {
 			buf := make([]byte, 0, 256)
 			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				buf = appendJSQuote(buf[:0], c.s)
 			}
 			_ = buf
@@ -3598,8 +3590,7 @@ func BenchmarkSendQueue(b *testing.B) {
 			}
 			ch := make(chan wire.WsMsg, k)
 			b.ReportAllocs()
-			b.ResetTimer()
-			for n := 0; n < b.N; n++ {
+			for b.Loop() {
 				rq.muQueue.Lock()
 				rq.wsQueue = append(rq.wsQueue[:0], msgs...)
 				rq.muQueue.Unlock()
@@ -3627,7 +3618,7 @@ func BenchmarkDistributeDirtSort(b *testing.B) {
 		}
 		b.Run("tags="+strconv.Itoa(n), func(b *testing.B) {
 			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				benchDirtSink = sortedDirtTags(m)
 			}
 		})

lib/assets/js_benchmark_test.go

@@ -51,6 +51,8 @@ for (let i = 0; i < count; i++) {
 }
 `
 
+	// Keep b.N here so Node executes the calibrated message count in one process;
+	// starting a process per B.Loop iteration would measure process startup instead.
 	cmd := exec.CommandContext(b.Context(), node, "-e", script, jsPath, strconv.Itoa(b.N))
 	b.SetBytes(int64(len(frame)))
 	b.ResetTimer()

lib/key/key_benchmark_test.go

@@ -11,8 +11,12 @@ var appendBenchSink []byte
 // BenchmarkAppend guards the base-32 encode hot path; it must stay
 // allocation-light when appending into an existing buffer.
 func BenchmarkAppend(b *testing.B) {
+	const benchmarkKey key.Key = 0x1234abcd
 	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
-		appendBenchSink = key.Append(appendBenchSink[:0], key.Key(0x1234abcd))
+	// Seed the backing array before B.Loop resets the timer so every measured
+	// append uses an existing buffer, including fixed-iteration runs.
+	appendBenchSink = key.Append(appendBenchSink[:0], benchmarkKey)
+	for b.Loop() {
+		appendBenchSink = key.Append(appendBenchSink[:0], benchmarkKey)
 	}
 }

lib/tag/tag_benchmark_test.go

@@ -49,8 +49,7 @@ var tagExpandBenchSink []any
 func benchmarkTagExpandCase(b *testing.B, tag any) {
 	b.Helper()
 	b.ReportAllocs()
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for b.Loop() {
 		got, err := TagExpand(tag)
 		if err != nil {
 			b.Fatal(err)

lib/ui/container_nested_reorder_benchmark_test.go

@@ -36,6 +36,8 @@ func BenchmarkNestedContainersUpdate(b *testing.B) {
 
 			b.ReportAllocs()
 			b.ResetTimer()
+			// Keep b.N because validation crosses iterations with the timer stopped;
+			// B.Loop requires its condition to run while the timer is enabled.
 			for i := range b.N {
 				if benchmark.reorder {
 					tree.reverse()

lib/ui/container_reuse_benchmark_test.go

@@ -65,6 +65,7 @@ func benchReuseRequest(b *testing.B) (*jaws.Jaws, *jaws.Request) {
 func BenchmarkContainerOfTemplatesUpdate(b *testing.B) {
 	b.ReportAllocs()
 	const rows = 200
+	// Keep b.N because fixture cleanup leaves the timer stopped between iterations.
 	for range b.N {
 		b.StopTimer()
 		jw, rq := benchReuseRequest(b)
@@ -91,6 +92,7 @@ func BenchmarkContainerOfTemplatesUpdate(b *testing.B) {
 func BenchmarkContainerOfStableChildrenUpdate(b *testing.B) {
 	b.ReportAllocs()
 	const rows = 200
+	// Keep b.N because fixture cleanup leaves the timer stopped between iterations.
 	for range b.N {
 		b.StopTimer()
 		jw, rq := benchReuseRequest(b)
@@ -119,6 +121,7 @@ func BenchmarkContainerInitialRender(b *testing.B) {
 	container := NewContainer("div", bc)
 	b.ReportAllocs()
 	b.ResetTimer()
+	// Keep b.N to bound batches by the calibrated number of operations.
 	for completed := 0; completed < b.N; {
 		batchSize := min(benchmarkContainerBatchSize, b.N-completed)
 		elems := make([]*jaws.Element, batchSize)
@@ -149,7 +152,6 @@ func BenchmarkContainerInitialRender(b *testing.B) {
 // BenchmarkContainerUnchangedUpdate measures a small reconciliation that reuses every
 // child and emits no browser mutation.
 func BenchmarkContainerUnchangedUpdate(b *testing.B) {
-	b.StopTimer()
 	tr := newReuseRequest(b)
 	bc := &benchStableContainer{contents: benchChildren(0, 4)}
 	container := NewContainer("div", bc)
@@ -159,12 +161,9 @@ func BenchmarkContainerUnchangedUpdate(b *testing.B) {
 	}
 	before := benchmarkContainerElements(b, elem, 4)
 	b.ReportAllocs()
-	b.ResetTimer()
-	b.StartTimer()
-	for range b.N {
+	for b.Loop() {
 		container.JawsUpdate(elem)
 	}
-	b.StopTimer()
 	after := benchmarkContainerElements(b, elem, 4)
 	for i := range before {
 		if after[i] != before[i] {
@@ -192,6 +191,7 @@ func BenchmarkContainerAppendRemoveUpdate(b *testing.B) {
 	b.ReportAllocs()
 	b.ResetTimer()
 	expanded := false
+	// Keep b.N to bound batches by the calibrated number of operations.
 	for completed := 0; completed < b.N; {
 		batchSize := min(benchmarkContainerBatchSize, b.N-completed)
 		startedExpanded := expanded
@@ -227,6 +227,7 @@ func BenchmarkContainerRegisterFirstUpdate(b *testing.B) {
 	container := NewContainer("div", bc)
 	b.ReportAllocs()
 	b.ResetTimer()
+	// Keep b.N to bound batches by the calibrated number of operations.
 	for completed := 0; completed < b.N; {
 		batchSize := min(benchmarkContainerBatchSize, b.N-completed)
 		elems := make([]*jaws.Element, batchSize)

lib/ui/container_test.go

@@ -522,8 +522,7 @@ func benchChildren(start, count int) []jaws.UI {
 func BenchmarkContainerValidateChildren(b *testing.B) {
 	b.ReportAllocs()
 	children := benchChildren(0, 1000)
-	b.ResetTimer() // exclude the one-time fixture allocation so -benchtime=1x is honest
-	for range b.N {
+	for b.Loop() {
 		if _, ok := firstUnusableChild(children); ok {
 			b.Fatal("unexpected unusable child")
 		}
@@ -533,6 +532,7 @@ func BenchmarkContainerValidateChildren(b *testing.B) {
 func BenchmarkContainerUpdateAppendHeavy(b *testing.B) {
 	b.ReportAllocs()
 	const size = 1000
+	// Keep b.N because fixture cleanup leaves the timer stopped between iterations.
 	for range b.N {
 		b.StopTimer()
 		jw, rq := benchRequest(b)
@@ -553,6 +553,7 @@ func BenchmarkContainerUpdateAppendHeavy(b *testing.B) {
 func BenchmarkContainerUpdateMixed(b *testing.B) {
 	b.ReportAllocs()
 	const size = 1000
+	// Keep b.N because fixture cleanup leaves the timer stopped between iterations.
 	for range b.N {
 		b.StopTimer()
 		jw, rq := benchRequest(b)

lib/ui/http_request_benchmark_test.go

@@ -38,8 +38,7 @@ func BenchmarkHTTPPageRenderingByComplexity(b *testing.B) {
 
 			handler := bc.handler(b, jw)
 			b.ReportAllocs()
-			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				req := benchmarkPageRequest()
 				rr := httptest.NewRecorder()
 
@@ -52,7 +51,6 @@ func BenchmarkHTTPPageRenderingByComplexity(b *testing.B) {
 				benchmarkCleanupNoscript(b, jw, req.RemoteAddr, rr.Body.String())
 				b.StartTimer()
 			}
-			b.StopTimer()
 
 			if got := jw.RequestCount(); got != 0 {
 				b.Fatalf("request count after benchmark = %d, want 0", got)