Before we go any further, we should make sure that we have a good understanding of what a std::thread object really represents and in what states it can be. We haven't yet talked about what sort of threads there normally are in a system executing a C++ program. In the following figure, we have captured a snapshot of a hypothetical running system:
Snapshot of a hypothetical running system
Starting from the bottom, the figure shows the CPU and its hardware threads. Those are the execution units on the CPU. In this example, the CPU provides four hardware threads; usually that means it has four cores, but it could be some other configuration. ...
