Part 3: Devise an OpenMP solution for the Queue Scheduling problem described in
ID: 3911763 • Letter: P
Question
Part 3: Devise an OpenMP solution for the Queue Scheduling problem described in Task 1.3
Please use OpenMP directives and OpenMP synchronization primitives ONLY as appropriate
Task 1.3 Code listed below:
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <pthread.h>
#include <semaphore.h>
int num_students;
int office_capacity;
int current_student_id;
sem_t OfficeSpots;
sem_t StudentCanAskQuestion;
sem_t ProfessorCanSpeak;
sem_t StudentCanSpeak;
void * Professor();
void * Student(void *id);
void AnswerStart(int student_id);
void AnswerDone(int student_id);
void EnterOffice(int id);
void LeaveOffice(int id);
void QuestionStart(int id);
void QuestionDone(int id);
int main(int argc, char *argv[])
{
// Input Validation
if (argc <= 2)
{
printf("Error: Please specify a number of students and office capacity. ");
return 0;
}
num_students = atoi(argv[1]);
office_capacity = atoi(argv[2]);
if (!num_students || !office_capacity)
{
printf("Arguments are not valid. ");
return 0;
}
printf("num_students: %d, capacity: %d ", num_students, office_capacity);
sem_init(&OfficeSpots, 0, office_capacity);
sem_init(&StudentCanAskQuestion, 0, 1);
sem_init(&ProfessorCanSpeak, 0, 0);
sem_init(&StudentCanSpeak, 0, 0);
pthread_t professor_thread;
pthread_create(&professor_thread, NULL, Professor, NULL);
int student_num;
pthread_t student_threads[num_students];
int student_ids[num_students];
for (student_num = 0; student_num < num_students; student_num++) {
student_ids[student_num] = student_num;
pthread_create(&student_threads[student_num], NULL, Student, (void *)&student_ids[student_num]);
}
for (student_num = 0; student_num < num_students; student_num++) {
pthread_join(student_threads[student_num], NULL);
}
printf("Simulation completed. No more students left. ");
return 0;
}
void * Professor() {
while(1) {
sem_post(&StudentCanSpeak);
sem_wait(&ProfessorCanSpeak);
AnswerStart(current_student_id);
AnswerDone(current_student_id);
sem_post(&StudentCanSpeak);
}
}
void * Student(void *id) {
int student_id = *((int *) id);
int n_questions = (student_id % 4) + 1;
int quest;
sem_wait(&OfficeSpots); // Wait for a spot in the office
EnterOffice(student_id);
for(quest = 0; quest < n_questions; quest++) {
sem_wait(&StudentCanAskQuestion); // Wait for turn
current_student_id = student_id;
sem_wait(&StudentCanSpeak);
QuestionStart(student_id);
sem_post(&ProfessorCanSpeak); // Let professor answer
sem_wait(&StudentCanSpeak);
QuestionDone(student_id);
sem_post(&StudentCanAskQuestion); // Let another student ask
}
sem_post(&OfficeSpots); // Let another student in the office
LeaveOffice(student_id);
}
// Professor Actions
void AnswerStart(int student_id) {
printf("Professor starts to answer question for student %d. ", student_id);
}
void AnswerDone(int student_id) {
printf("Professor is done with answer for student %d. ", student_id);
}
// Student Actions
void EnterOffice(int id) {
printf("Student %d enters the office. ", id);
}
void LeaveOffice(int id) {
printf("Student %d leaves the office. ", id);
}
void QuestionStart(int id) {
printf("Student %d asks a question. ", id);
}
void QuestionDone(int id) {
printf("Student %d is satisfied. ", id);
}
Explanation / Answer
#include <stdio.h>
#include <omp.h>
#include <stdlib.h>
#include <stdint.h>
#include <pthread.h>
#include <;.h>
int num_students;
int office_capacity;
int current_student_id;
sem_t OfficeSpots;
sem_t StudentCanAskQuestion;
sem_t ProfessorCanSpeak;
sem_t StudentCanSpeak;
void * Professor();
void * Student(void *id);
void AnswerStart(int student_id);
void AnswerDone(int student_id);
void EnterOffice(int id);
void LeaveOffice(int id);
void QuestionStart(int id);
void QuestionDone(int id);
int main(int argc, char *argv[])
{
// Input Validation
if (argc <= 2)
{
printf("Error: Please specify a number of students and office capacity. ");
return 0;
}
num_students = atoi(argv[1]);
office_capacity = atoi(argv[2]);
if (!num_students || !office_capacity)
{
printf("Arguments are not valid. ");
return 0;
}
printf("num_students: %d, capacity: %d ", num_students, office_capacity);
sem_init(&OfficeSpots, 0, office_capacity);
sem_init(&StudentCanAskQuestion, 0, 1);
sem_init(&ProfessorCanSpeak, 0, 0);
sem_init(&StudentCanSpeak, 0, 0);
pthread_t professor_thread;
pthread_create(&professor_thread, NULL, Professor, NULL);
int student_num;
pthread_t student_threads[num_students];
int student_ids[num_students];
for (student_num = 0; student_num < num_students; student_num++) {
student_ids[student_num] = student_num;
pthread_create(&student_threads[student_num], NULL, Student, (void *)&student_ids[student_num]);
}
for (student_num = 0; student_num < num_students; student_num++) {
pthread_join(student_threads[student_num], NULL);
}
printf("Simulation completed. No more students left. ");
return 0;
}
void * Professor() {
while(1) {
sem_post(&StudentCanSpeak);
sem_wait(&ProfessorCanSpeak);
AnswerStart(current_student_id);
AnswerDone(current_student_id);
sem_post(&StudentCanSpeak);
}
}
void * Student(void *id) {
int student_id = *((int *) id);
int n_questions = (student_id % 4) + 1;
int quest;
sem_wait(&OfficeSpots); // Wait for a spot in the office
EnterOffice(student_id);
for(quest = 0; quest < n_questions; quest++) {
sem_wait(&StudentCanAskQuestion); // Wait for turn
current_student_id = student_id;
sem_wait(&StudentCanSpeak);
QuestionStart(student_id);
sem_post(&ProfessorCanSpeak); // Let professor answer
sem_wait(&StudentCanSpeak);
QuestionDone(student_id);
sem_post(&StudentCanAskQuestion); // Let another student ask
}
sem_post(&OfficeSpots); // Let another student in the office
LeaveOffice(student_id);
}
// Professor Actions
void AnswerStart(int student_id) {
printf("Professor starts to answer question for student %d. ", student_id);
}
void AnswerDone(int student_id) {
printf("Professor is done with answer for student %d. ", student_id);
}
// Student Actions
void EnterOffice(int id) {
printf("Student %d enters the office. ", id);
}
void LeaveOffice(int id) {
printf("Student %d leaves the office. ", id);
}
void QuestionStart(int id) {
printf("Student %d asks a question. ", id);
}
void QuestionDone(int id) {
printf("Student %d is satisfied. ", id);
}