github.com/panjjo/go@v0.0.0-20161104043856-d62b31386338/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  	if n > _MaxGomaxprocs {
    19  		n = _MaxGomaxprocs
    20  	}
    21  	lock(&sched.lock)
    22  	ret := int(gomaxprocs)
    23  	unlock(&sched.lock)
    24  	if n <= 0 || n == ret {
    25  		return ret
    26  	}
    27  
    28  	stopTheWorld("GOMAXPROCS")
    29  
    30  	// newprocs will be processed by startTheWorld
    31  	newprocs = int32(n)
    32  
    33  	startTheWorld()
    34  	return ret
    35  }
    36  
    37  // NumCPU returns the number of logical CPUs usable by the current process.
    38  //
    39  // The set of available CPUs is checked by querying the operating system
    40  // at process startup. Changes to operating system CPU allocation after
    41  // process startup are not reflected.
    42  func NumCPU() int {
    43  	return int(ncpu)
    44  }
    45  
    46  // NumCgoCall returns the number of cgo calls made by the current process.
    47  func NumCgoCall() int64 {
    48  	var n int64
    49  	for mp := (*m)(atomic.Loadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink {
    50  		n += int64(mp.ncgocall)
    51  	}
    52  	return n
    53  }
    54  
    55  // NumGoroutine returns the number of goroutines that currently exist.
    56  func NumGoroutine() int {
    57  	return int(gcount())
    58  }