This post discuss the limits on the maximum number of threads and processes supported on Windows. Unlike some UNIX variants, most resources in Windows have no fixed upper bound compiled into the operating system, but rather derive their limits based on basic operating system resources. Process and threads, for example, require physical memory, virtual memory, and pool memory, so the number of processes or threads that can be created on a given Windows system is ultimately determined by one of these resources, depending on the way that the processes or threads are created and which constraint is hit first. A Windows process is essentially container that hosts the execution of an executable image file. It is represented with a kernel process object and Windows uses the process object and its associated data structures to store and track information about the image’s execution.

Full Article: Marks' Blog