From b1accced20f0b2fc011b32e1f1d9bb83385efa1d Mon Sep 17 00:00:00 2001 From: Brad Fitzpatrick Date: Sun, 25 Feb 2018 16:41:22 +0000 Subject: [PATCH] strings: add Builder benchmarks comparing bytes.Buffer and strings.Builder Despite the existing test that locks in the allocation behavior, people really want a benchmark. So: BenchmarkBuildString_Builder/1Write_NoGrow-4 20000000 60.4 ns/op 48 B/op 1 allocs/op BenchmarkBuildString_Builder/3Write_NoGrow-4 10000000 230 ns/op 336 B/op 3 allocs/op BenchmarkBuildString_Builder/3Write_Grow-4 20000000 102 ns/op 112 B/op 1 allocs/op BenchmarkBuildString_ByteBuffer/1Write_NoGrow-4 10000000 125 ns/op 160 B/op 2 allocs/op BenchmarkBuildString_ByteBuffer/3Write_NoGrow-4 5000000 339 ns/op 400 B/op 3 allocs/op BenchmarkBuildString_ByteBuffer/3Write_Grow-4 5000000 316 ns/op 336 B/op 3 allocs/op I don't think these allocate-as-fast-as-you-can benchmarks are very interesting because they're effectively just GC benchmarks, but sure. If one wants to see that there's 1 fewer allocation, there it is. The ns/op and B/op numbers will change as the built string size changes. Updates #18990 Change-Id: Ifccf535bd396217434a0e6989e195105f90132ae Reviewed-on: https://go-review.googlesource.com/96980 Run-TryBot: Brad Fitzpatrick TryBot-Result: Gobot Gobot Reviewed-by: Alan Donovan --- src/strings/builder_test.go | 49 +++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/src/strings/builder_test.go b/src/strings/builder_test.go index ecbaeaa5c1..29d49e98a7 100644 --- a/src/strings/builder_test.go +++ b/src/strings/builder_test.go @@ -302,3 +302,52 @@ func TestBuilderCopyPanic(t *testing.T) { } } } + +var someBytes = []byte("some bytes sdljlk jsklj3lkjlk djlkjw") + +var sinkS string + +func benchmarkBuilder(b *testing.B, f func(b *testing.B, numWrite int, grow bool)) { + b.Run("1Write_NoGrow", func(b *testing.B) { + b.ReportAllocs() + f(b, 1, false) + }) + b.Run("3Write_NoGrow", func(b *testing.B) { + b.ReportAllocs() + f(b, 3, false) + }) + b.Run("3Write_Grow", func(b *testing.B) { + b.ReportAllocs() + f(b, 3, true) + }) +} + +func BenchmarkBuildString_Builder(b *testing.B) { + benchmarkBuilder(b, func(b *testing.B, numWrite int, grow bool) { + for i := 0; i < b.N; i++ { + var buf Builder + if grow { + buf.Grow(len(someBytes) * numWrite) + } + for i := 0; i < numWrite; i++ { + buf.Write(someBytes) + } + sinkS = buf.String() + } + }) +} + +func BenchmarkBuildString_ByteBuffer(b *testing.B) { + benchmarkBuilder(b, func(b *testing.B, numWrite int, grow bool) { + for i := 0; i < b.N; i++ { + var buf bytes.Buffer + if grow { + buf.Grow(len(someBytes) * numWrite) + } + for i := 0; i < numWrite; i++ { + buf.Write(someBytes) + } + sinkS = buf.String() + } + }) +} -- 2.48.1