code: func MaximizeOpenFileLimit() (int, error) {
  	// Get the current limit on number of open files.
  	var lim syscall.Rlimit
  	if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim); err != nil {
  		return 0, err
  	}
  
  	// If we're already at max, there's no need to try to raise the limit.
  	if lim.Cur >= lim.Max {
  		return int(lim.Cur), nil
  	}
  
  	// Try to increase the limit to the max.
  	oldLimit := lim.Cur
  	lim.Cur = lim.Max
  	if err := syscall.Setrlimit(syscall.RLIMIT_NOFILE, &lim); err != nil {
  		return int(oldLimit), err
  	}
  
  	// If the set succeeded, perform a new get to see what happened. We might
  	// have gotten a value lower than the one in lim.Max, if lim.Max was
  	// something that indicated "unlimited" (i.e. intmax).
  	if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim); err != nil {
  		// We don't really know the correct value here since Getrlimit
  		// mysteriously failed after working once... Shouldn't ever happen, I
  		// think.
  		return 0, err
  	}
  
  	return int(lim.Cur), nil
  }
docs: // MaximizeOpenFileLimit tries to set the resource limit RLIMIT_NOFILE (number
  // of open file descriptors) to the max (hard limit), if the current (soft
  // limit) is below the max. Returns the new (though possibly unchanged) limit,
  // or an error if it could not be changed.