OpenMP in Small Bites/Tasking and Data Scoping

This video deepens the knowledge of OpenMP Tasking and Data Scoping by using an example which includes typical scenarios. Furthermore, aspects of the lifetime of a variable are discussed.

Video

( Slides as pdf)

Quiz

1. Consider the following code snippet

int x = 42;
#pragma omp parallel private(x)
{

#pragma omp task

{

x = 3;

}

}
printf("x=%d\n", x);

What is the data scope of x in the task region and what is printed at the end?

	firstprivate, x=42
	firstprivate, x=3
	shared, x=3

2. Consider the following code snippet

int x = 42;
int y = 0;
#pragma omp parallel num_threads(4)
{

#pragma omp task

{

#pragma omp critical

{

y += x;

}

}

}
printf("y=%d\n", y);

What is the data scope of x in the task region and what is printed out at the end?

	shared, y=42
	shared, y=168
	firstprivate, y=168

3. Consider the following code snippet

int x = 42;
int y = 0;
#pragma omp parallel num_threads(4)
{

#pragma omp single

{

#pragma omp task

{

#pragma omp critical

{

y += x;

}

}

}

}
printf("y=%d\n", y);

What is the data scope of x in the task region and what is printed out at the end?

	shared, y=42
	shared, y=168
	firstprivate, y=168