| Platform SDK: DLLs, Processes, and Threads |
Each process provides the resources needed to execute a program. A process has a virtual address space, executable code, data, object handles, environment variables, a base priority, and minimum and maximum working set sizes. Each process is started with a single thread, often called the primary thread, but can create additional threads from any of its threads.
All threads of a process share its virtual address space and system resources. In addition, each thread maintains exception handlers, a scheduling priority, and a set of structures the system will use to save the thread context until it is scheduled. The thread context includes the thread's set of machine registers, the kernel stack, a thread environment block, and a user stack in the address space of the thread's process.
Windows NT/2000 and Windows 95/98 support preemptive multitasking, which creates the effect of simultaneous execution of multiple threads from multiple processes. On a multiprocessor computer, Windows NT/2000 can simultaneously execute as many threads as there are processors on the computer.
This overview discusses the following topics: