package numcpus

Import Path
	github.com/tklauser/numcpus (on go.dev)

Dependency Relation
	imports 7 packages, and imported by one package


Involved Source Files

	
		Package numcpus provides information about the number of CPUs in the system.
		
		It gets the number of CPUs (online, offline, present, possible or kernel
		maximum) on Linux, Darwin, FreeBSD, NetBSD, OpenBSD, DragonflyBSD,
		Solaris/Illumos or Windows systems.
		
		On Linux, the information is retrieved by reading the corresponding CPU
		topology files in /sys/devices/system/cpu.
		
		On BSD systems, the information is retrieved using the hw.ncpu and
		hw.ncpuonline sysctls, if supported.
		
		On Windows systems, the information is retrieved using the
		GetActiveProcessorCount and GetMaximumProcessorCount functions, respectively.
		
		Not all functions are supported on Darwin, FreeBSD, NetBSD, OpenBSD,
		DragonflyBSD, Solaris/Illumos and Windows. ErrNotSupported is returned in
		case a function is not supported on a particular platform.

	    numcpus_linux.go


Code Examples

	
		package main
		
		import (
			"fmt"
			"os"
		
			"github.com/tklauser/numcpus"
		)
		
		func main() {
			offline, err := numcpus.GetOffline()
			if err != nil {
				fmt.Fprintf(os.Stderr, "GetOffline: %v\n", err)
			}
			fmt.Printf("# of offline CPUs: %v\n", offline)
		}

	
		package main
		
		import (
			"fmt"
			"os"
		
			"github.com/tklauser/numcpus"
		)
		
		func main() {
			online, err := numcpus.GetOnline()
			if err != nil {
				fmt.Fprintf(os.Stderr, "GetOnline: %v\n", err)
			}
			fmt.Printf("# of online CPUs: %v\n", online)
		}

	
		package main
		
		import (
			"fmt"
			"os"
		
			"github.com/tklauser/numcpus"
		)
		
		func main() {
			possible, err := numcpus.GetPossible()
			if err != nil {
				fmt.Fprintf(os.Stderr, "GetPossible: %v\n", err)
			}
			fmt.Printf("# of possible CPUs: %v\n", possible)
		}

	
		package main
		
		import (
			"fmt"
			"os"
		
			"github.com/tklauser/numcpus"
		)
		
		func main() {
			present, err := numcpus.GetPresent()
			if err != nil {
				fmt.Fprintf(os.Stderr, "GetPresent: %v\n", err)
			}
			fmt.Printf("# of present CPUs: %v\n", present)
		}




Package-Level Functions (total 6)


	
		GetConfigured returns the number of CPUs configured on the system. This
		function should return the same value as `getconf _SC_NPROCESSORS_CONF` on a
		unix system.


	
		GetKernelMax returns the maximum number of CPUs allowed by the kernel
		configuration. This function is only supported on Linux and Windows systems.


	
		GetOffline returns the number of offline CPUs, i.e. CPUs that are not online
		because they have been hotplugged off or exceed the limit of CPUs allowed by
		the kernel configuration (see GetKernelMax). This function is only supported
		on Linux systems.


	
		GetOnline returns the number of CPUs that are online and being scheduled.


	
		GetPossible returns the number of possible CPUs, i.e. CPUs that
		have been allocated resources and can be brought online if they are present.


	
		GetPresent returns the number of CPUs present in the system.




Package-Level Variables (only one)


	
		ErrNotSupported is the error returned when the function is not supported.