Repro #2, surface regression.

gcrepro/gcrepro.go

@@ -3,6 +3,7 @@ package main
 import (
 	"bytes"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"runtime"
 
@@ -24,14 +25,52 @@ func random(length int) []byte {
 
 func main() {
 	data := random(256 * 1024 * 1024)
-
 	run(data, 1)
 	run(data, 1)
 	run(data, 1)
 	fmt.Println()
 	run(data, 8)
 	run(data, 8)
 	run(data, 8)
+
+	fmt.Println()
+	fmt.Println()
+
+	iter := 256 * 1024
+	burst(iter, 1)
+	burst(iter, 1)
+	burst(iter, 1)
+	fmt.Println()
+	burst(iter, 8)
+	burst(iter, 8)
+	burst(iter, 8)
+}
+
+func burst(iters int, threads int) {
+	runtime.GOMAXPROCS(threads)
+
+	ir, iw := io.Pipe()
+	or, ow := io.Pipe()
+
+	// Gather memory stats
+	start := new(runtime.MemStats)
+	runtime.ReadMemStats(start)
+
+	// Run the operation
+	go bufioprop.Copy(ow, ir, 1024)
+
+	input, output := []byte{0xff}, make([]byte, 1)
+	for i := 0; i < iters; i++ {
+		iw.Write(input)
+		or.Read(output)
+	}
+	ow.Close()
+
+	// Gather memory stats and report
+	end := new(runtime.MemStats)
+	runtime.ReadMemStats(end)
+
+	fmt.Printf("short bursts: gomaxprocs %d, allocs: %d, bytes: %d\n", runtime.GOMAXPROCS(0), end.Mallocs-start.Mallocs, end.TotalAlloc-start.TotalAlloc)
 }
 
 func run(data []byte, threads int) {
@@ -48,5 +87,5 @@ func run(data []byte, threads int) {
 	end := new(runtime.MemStats)
 	runtime.ReadMemStats(end)
 
-	fmt.Printf("Gomaxprocs %d, allocs: %d, bytes: %d\n", runtime.GOMAXPROCS(0), end.Mallocs-start.Mallocs, end.TotalAlloc-start.TotalAlloc)
+	fmt.Printf("long run: gomaxprocs %d, allocs: %d, bytes: %d\n", runtime.GOMAXPROCS(0), end.Mallocs-start.Mallocs, end.TotalAlloc-start.TotalAlloc)
 }