github.com/yukk001/go1.10.8@v0.0.0-20190813125351-6df2d3982e20/src/runtime/debug.go (about)

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime
     6  
     7  import (
     8  	"runtime/internal/atomic"
     9  	"unsafe"
    10  )
    11  
    12  // GOMAXPROCS sets the maximum number of CPUs that can be executing
    13  // simultaneously and returns the previous setting. If n < 1, it does not
    14  // change the current setting.
    15  // The number of logical CPUs on the local machine can be queried with NumCPU.
    16  // This call will go away when the scheduler improves.
    17  func GOMAXPROCS(n int) int {
    18  	lock(&sched.lock)
    19  	ret := int(gomaxprocs)
    20  	unlock(&sched.lock)
    21  	if n <= 0 || n == ret {
    22  		return ret
    23  	}
    24  
    25  	stopTheWorld("GOMAXPROCS")
    26  
    27  	// newprocs will be processed by startTheWorld
    28  	newprocs = int32(n)
    29  
    30  	startTheWorld()
    31  	return ret
    32  }
    33  
    34  // NumCPU returns the number of logical CPUs usable by the current process.
    35  //
    36  // The set of available CPUs is checked by querying the operating system
    37  // at process startup. Changes to operating system CPU allocation after
    38  // process startup are not reflected.
    39  func NumCPU() int {
    40  	return int(ncpu)
    41  }
    42  
    43  // NumCgoCall returns the number of cgo calls made by the current process.
    44  func NumCgoCall() int64 {
    45  	var n int64
    46  	for mp := (*m)(atomic.Loadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink {
    47  		n += int64(mp.ncgocall)
    48  	}
    49  	return n
    50  }
    51  
    52  // NumGoroutine returns the number of goroutines that currently exist.
    53  func NumGoroutine() int {
    54  	return int(gcount())
    55  }