One of the easiest ways to split your program into a parallel executing part is using threads. However, what is a thread's cost for the operating system and CPU? What number of threads is optimal?

In Windows and in the 32-bit mode, the maximum number of threads in your process is restricted by the virtual address space available, which is two gigabytes. A thread stack's size is one megabyte, so we can have maximum 2,048 threads. In a 64-bit OS for a 32-bit process, it should be 4,096. However in practice, the address space will be fragmented and occupied by some other data, and there are other reasons why the maximum number of threads can be significantly different.

The best way to find out what's going on is to write a code that checks our assumptions. Here we will print the current size of a handle, giving us a way to detect whether we are in 32-bit or 64-bit mode. Then the code will start new threads until we get any exception, and it will print out the number of threads...