How to do a pool?

A self-contained Pool in C++14

by Jens Weller

From the article:

During C++Now I started writing a small application, that plays around with dlibs face recognition features. More on this later, the program uses the QThreadPool, and some researched showed that calling dlib::get_frontal_face_detector() is a very expensive operation. So I decided to write a thread safe pool to share the face detection object between threads, only loading as many as needed. The main thread owns the pool which owns the detection objects...