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// Copyright 2009 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 runtime
import (
// GOMAXPROCS sets the maximum number of CPUs that can be executing
// simultaneously and returns the previous setting. If n < 1, it does not
// change the current setting.
// The number of logical CPUs on the local machine can be queried with NumCPU.
// This call will go away when the scheduler improves.
func GOMAXPROCS(n int) int {
if n > _MaxGomaxprocs {
n = _MaxGomaxprocs
ret := int(gomaxprocs)
if n <= 0 || n == ret {
return ret
// newprocs will be processed by startTheWorld
newprocs = int32(n)
return ret
// NumCPU returns the number of logical CPUs usable by the current process.
// The set of available CPUs is checked by querying the operating system
// at process startup. Changes to operating system CPU allocation after
// process startup are not reflected.
func NumCPU() int {
return int(ncpu)
// NumCgoCall returns the number of cgo calls made by the current process.
func NumCgoCall() int64 {
var n int64
for mp := (*m)(atomic.Loadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink {
n += int64(mp.ncgocall)
return n
// NumGoroutine returns the number of goroutines that currently exist.
func NumGoroutine() int {
return int(gcount())