https://blog.toright.com/posts/3534/apache-%e9%80%8f%e9%81%8e-itk-multi-processing-module-%e8%ae%93%e8%99%9b%e6%93%ac%e4%b8%bb%e6%a9%9fu3%e4%b8%8d%e5%90%8c%e4%bd%bf%e7%94%a8%e8%80%85%e5%9f%b7%e8%a1%8c