golang pprof 代码
文件路径：/src/cmd/compile/internal/gc/pprof.go
/ Copyright 2017 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.
/go:build go1.8
/ +build go1.8
package gc
import "runtime"
func startMutexProfiling() {
runtime.SetMutexProfileFraction(1)
}