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package sysinfo // import "github.com/docker/docker/pkg/sysinfo"
import (
"runtime"
"golang.org/x/sys/unix"
)
// numCPU queries the system for the count of threads available
// for use to this process.
//
// Issues two syscalls.
// Returns 0 on errors. Use |runtime.NumCPU| in that case.
func numCPU() int {
// Gets the affinity mask for a process: The very one invoking this function.
pid := unix.Getpid()
var mask unix.CPUSet
err := unix.SchedGetaffinity(pid, &mask)
if err != nil {
return 0
}
return mask.Count()
}
// NumCPU returns the number of CPUs which are currently online
func NumCPU() int {
if ncpu := numCPU(); ncpu > 0 {
return ncpu
}
return runtime.NumCPU()
}
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