1 files changed, 42 insertions, 0 deletions
diff --git a/src/cmd/go/init_test.go b/src/cmd/go/init_test.go
new file mode 100644
index 0000000..5a5cbe5
--- /dev/null
+++ b/src/cmd/go/init_test.go
@@ -0,0 +1,42 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main_test
+
+import (
+	"internal/testenv"
+	"os/exec"
+	"sync/atomic"
+	"testing"
+)
+
+// BenchmarkExecGoEnv measures how long it takes for 'go env GOARCH' to run.
+// Since 'go' is executed, remember to run 'go install cmd/go' before running
+// the benchmark if any changes were done.
+func BenchmarkExecGoEnv(b *testing.B) {
+	testenv.MustHaveExec(b)
+	gotool, err := testenv.GoTool()
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	// We collect extra metrics.
+	var n, userTime, systemTime int64
+
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			cmd := exec.Command(gotool, "env", "GOARCH")
+
+			if err := cmd.Run(); err != nil {
+				b.Fatal(err)
+			}
+			atomic.AddInt64(&n, 1)
+			atomic.AddInt64(&userTime, int64(cmd.ProcessState.UserTime()))
+			atomic.AddInt64(&systemTime, int64(cmd.ProcessState.SystemTime()))
+		}
+	})
+	b.ReportMetric(float64(userTime)/float64(n), "user-ns/op")
+	b.ReportMetric(float64(systemTime)/float64(n), "sys-ns/op")
+}