CPU - Raspberry Pi Hardware Reference - page 50

At this point, the main thread and the function my_thread() execute in parallel.
Since there is only one CPU on the Raspberry Pi, only one executes at any instant of time.
But they both execute concurrently, trading blocks of execution time in a preemptive
manner. Each, of course, runs using its own stack.
Thread my_thread() terminates gracefully, by returning.

pthread_attr_t
There are several thread attributes that can be fetched and set. You'll look only at perhaps
the most important attribute (stack size) to keep this crash course brief. For the full list of
attributes and functions, you can view the man pages for it:

$ man pthread_attr_init

To initialize a new attribute, or to release a previously initialized pthread attribute,
use this pair of routines:

int pthread_attr_init(pthread_attr_t attr);

int pthread_attr_destroy(pthread_attr_t

∗

attr);

∗

attr : Address of the pthread_attr_t variable to initialize/
destroy
returns : Zero upon success, or an error code when it fails
(not in errno )

Error Description

ENOMEM Insufficient resources (memory)

The Linux implementation of pthread_attr_init(3) may never return the ENOMEM
error, but other Unix platforms might.
The following is a simple example of creating and destroying an attribute object:

pthread_attr_t attr;

pthread_attr_init(&attr); // Initialize attr
...
pthread_attr_destroy(&attr); // Destroy attr

Perhaps one of the most important attributes of a thread is the stack size attribute:

int pthread_attr_setstacksize(
pthread_attr_t *attr,
size_t stacksize
);