Detect number of CPUs installed

Question

I already found a solution for \"Most unixes\" via cat /proc/cpuinfo, but a pure-Ruby solution would be nicer.

Answer 1

Here is an implementation for Linux, OSX, Windows and BSD: https://gist.github.com/1009994

Source code:

module System
  extend self
  def cpu_count
    return Java::Java.lang.Runtime.getRuntime.availableProcessors if defined? Java::Java
    return File.read('/proc/cpuinfo').scan(/^processor\s*:/).size if File.exist? '/proc/cpuinfo'
    require 'win32ole'
    WIN32OLE.connect("winmgmts://").ExecQuery("select * from Win32_ComputerSystem").NumberOfProcessors
  rescue LoadError
    Integer `sysctl -n hw.ncpu 2>/dev/null` rescue 1
  end
end

System.cpu_count # => 2