29.1. Overview

Like processes, threads are a mechanism that permits an application to perform multiple tasks concurrently. A single process can contain multiple threads, as illustrated in Figure 29-1. All of these threads are independently executing the same program, and they all share the same global memory, including the initialized data, uninitialized data, and heap segments. (A traditional UNIX process is simply a special case of a multithreaded processes; it is a process that contains just one thread.)

Note:

We have simplified things somewhat in Figure 29-1. In particular, the location of the per-thread stacks may be intermingled with shared libraries and shared memory regions, depending on the order in which threads are created, shared libraries loaded, and shared memory regions attached. Furthermore, the location of the per-thread stacks can vary depending on the Linux distribution.