In this section you will learn how to create threads using the Pthreads $($POSIX standard$)$

API.

$1.$ The C program shown on the next page demonstrates the basic Pthreads API for

constructing a multithreaded program that calculates the summation of a non$-$

negative integer in a separate thread.

$2.$ In a Pthreads program, separate threads begin execution in a specified function. In

the code on the next page, this is the runner$()$ function.

$3.$ When this program begins, a single thread of control begins in main$().$

$4.$ After some initialization, main$()$ creates a second thread that begins control in the

runner$()$ function. Both threads share the global data sum.

$5.$ All Pthreads programs must include the pthread.h header file.

$6.$ The statement pthread$\_$t tid declares the identifier for the thread we will create.

Each thread has a set of attributes, including stack size and scheduling information.

The pthread$\_$attr$\_$t attr declaration represents the attributes for the thread.

We set the attributes in the function call pthread$\_$attr$\_$init$($&attr$).$ Because

we did not explicitly set any attributes, we use the default attributes provided.

$7.$ A separate thread is created with the pthread$\_$create$()$ function call. In addition

to passing the thread identifier and the attributes for the thread, we also pass the

name of the function where the new thread will begin execution$$in this case, the

runner$()$ function. Last, we pass the integer parameter that was provided on the

command line, argv$[1].$