From 434562ae0e0d25e7d89b31980b4c84b8de79edb0 Mon Sep 17 00:00:00 2001
From: Josh Newman <3987603+josh-newman@users.noreply.github.com>
Date: Fri, 6 Nov 2020 03:31:38 +0000
Subject: [PATCH] Comparative benchmark

---
 push_read_test.go | 105 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)

diff --git a/push_read_test.go b/push_read_test.go
index 3f80c53..5505255 100644
--- a/push_read_test.go
+++ b/push_read_test.go
@@ -1,10 +1,17 @@
 package bigslice_test
 
 import (
+	"context"
+	"math"
+	"math/rand"
+	"strconv"
 	"testing"
 
 	fuzz "github.com/google/gofuzz"
+	"github.com/grailbio/base/must"
 	"github.com/grailbio/bigslice"
+	"github.com/grailbio/bigslice/exec"
+	"github.com/grailbio/bigslice/sliceio"
 )
 
 func TestPushReader(t *testing.T) {
@@ -29,3 +36,101 @@ func TestPushReader(t *testing.T) {
 	slice = bigslice.Fold(slice, func(a, e int) int { return a + e })
 	assertEqual(t, slice, false, []string{""}, []int{N * Nshard})
 }
+
+// On an m5d.2xlarge on EC2:
+//   goos: linux
+//   goarch: amd64
+//   pkg: github.com/grailbio/bigslice
+//   BenchmarkReaders/10/pushreader-8                     110          10705539 ns/op
+//   BenchmarkReaders/10/readerfunc-8                     100          10036689 ns/op
+//   BenchmarkReaders/1000/pushreader-8                     8         131828675 ns/op
+//   BenchmarkReaders/1000/readerfunc-8                    12          97414219 ns/op
+//   BenchmarkReaders/100000/pushreader-8                   1        11181803529 ns/op
+//   BenchmarkReaders/100000/readerfunc-8                   1        8714653324 ns/op
+//   PASS
+//   ok      github.com/grailbio/bigslice    26.135s
+func BenchmarkReaders(b *testing.B) {
+	ctx := context.Background()
+	sess := exec.Start(exec.Local)
+	for _, rowsPerShard := range []int{10, 1000, 100000} {
+		lastResult := -1
+		checkResult := func(sliceResult *exec.Result) {
+			scanner := sliceResult.Scanner()
+			var result int
+			must.True(scanner.Scan(ctx, &result))
+			if lastResult < 0 {
+				lastResult = result
+			}
+			must.True(lastResult == result)
+		}
+
+		b.Run(strconv.Itoa(rowsPerShard), func(b *testing.B) {
+			b.Run("pushreader", func(b *testing.B) {
+				for i := 0; i < b.N; i++ {
+					checkResult(sess.Must(ctx, benchmarkPushReader, int64(1), rowsPerShard, true))
+				}
+			})
+			b.Run("readerfunc", func(b *testing.B) {
+				for i := 0; i < b.N; i++ {
+					checkResult(sess.Must(ctx, benchmarkPushReader, int64(1), rowsPerShard, false))
+				}
+			})
+		})
+	}
+	sess.Shutdown()
+}
+
+var benchmarkPushReader = bigslice.Func(func(
+	seed int64,
+	rowsPerShard int,
+	usePush bool,
+) bigslice.Slice {
+	const nShards = 100
+	shardSeeds := make([]int64, nShards)
+	rnd := rand.New(rand.NewSource(seed))
+	for i := range shardSeeds {
+		shardSeeds[i] = rnd.Int63()
+	}
+	var slice bigslice.Slice
+	if usePush {
+		slice = bigslice.PushReader(nShards, func(shard int, row func(int32)) error {
+			shardRnd := rand.New(rand.NewSource(shardSeeds[shard]))
+			for i := 0; i < rowsPerShard; i++ {
+				row(shardRnd.Int31())
+			}
+			return nil
+		})
+	} else {
+		type state struct {
+			*rand.Rand
+			doneRows int
+		}
+		slice = bigslice.ReaderFunc(nShards, func(shard int, state *state, nums []int32) (int, error) {
+			if state.Rand == nil {
+				state.Rand = rand.New(rand.NewSource(shardSeeds[shard]))
+			}
+			if state.doneRows == rowsPerShard {
+				return 0, sliceio.EOF
+			}
+			var i int
+			for state.doneRows < rowsPerShard && i < len(nums) {
+				nums[i] = state.Rand.Int31()
+				state.doneRows++
+				i++
+			}
+			return i, nil
+		})
+	}
+	slice = bigslice.Map(slice, func(num int32) (joinKey int, _ int32) {
+		return 0, num
+	})
+	slice = bigslice.Fold(slice, func(accum int, num int32) int {
+		if num < math.MaxInt32/2 {
+			return accum
+		}
+		return accum + 1
+	})
+	return bigslice.Map(slice, func(joinKey, accum int) int {
+		return accum
+	})
+})