dining philosophers problem code code example
Example: dining philosophers problem in c
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#define NUM_PHILOSOPHERS 5
int chopsticks[NUM_PHILOSOPHERS];
void *philosopher_behaviour(void* id)
{
int philosopher_number = *((int*)id);
while(1)
{
printf("PID : (%ld) Philosopher %d is THINKING\n", pthread_self(), philosopher_number+1);
sleep(1);
printf("PID : (%ld) Philosopher %d is Hungry\n", pthread_self(), philosopher_number+1);
while(1)
{
if(chopsticks[philosopher_number] == 1)
continue;
if(chopsticks[(philosopher_number+1)%NUM_PHILOSOPHERS] == 1)
continue;
chopsticks[philosopher_number] = 1;
chopsticks[(philosopher_number+1)%NUM_PHILOSOPHERS] = 1;
printf("PID : (%ld) Philosopher %d picks #%d and #%d chopsticks up\n", pthread_self(), philosopher_number+1, philosopher_number+1, 1 + ((philosopher_number+1)%NUM_PHILOSOPHERS));
printf("PID : (%ld) Philosopher %d is Eating Noodles\n", pthread_self(), philosopher_number+1);
sleep(1);
chopsticks[philosopher_number] = 0;
chopsticks[(philosopher_number+1)%NUM_PHILOSOPHERS] = 0;
printf("PID : (%ld) Philosopher %d puts #%d and #%d chopsticks down\n", pthread_self(), philosopher_number+1, philosopher_number+1, 1 + ((philosopher_number+1)%NUM_PHILOSOPHERS));
break;
}
}
}
void *philosopher_behaviour_rev(void* id)
{
int philosopher_number = *((int*)id);
while(1)
{
printf("PID : (%ld) Philosopher %d is THINKING\n", pthread_self(), philosopher_number+1);
sleep(1);
printf("PID : (%ld) Philosopher %d is Hungry\n", pthread_self(), philosopher_number+1);
while(1)
{
if(chopsticks[(philosopher_number+1)%NUM_PHILOSOPHERS] == 1)
continue;
if(chopsticks[philosopher_number] == 1)
continue;
chopsticks[(philosopher_number+1)%NUM_PHILOSOPHERS] = 1;
chopsticks[philosopher_number] = 1;
printf("PID : (%ld) Philosopher %d picks #%d and #%d chopsticks up\n", pthread_self(), philosopher_number+1, philosopher_number+1, 1 + ((philosopher_number+1)%NUM_PHILOSOPHERS));
printf("PID : (%ld) Philosopher %d is Eating Noodles\n", pthread_self(), philosopher_number+1);
sleep(1);
chopsticks[philosopher_number] = 0;
chopsticks[(philosopher_number+1)%NUM_PHILOSOPHERS] = 0;
printf("PID : (%ld) Philosopher %d puts #%d and #%d chopsticks down\n", pthread_self(), philosopher_number+1, philosopher_number+1, 1 + ((philosopher_number+1)%NUM_PHILOSOPHERS));
break;
}
}
}
int main(int argc, char const *argv[])
{
pthread_t thread_ids[NUM_PHILOSOPHERS];
int philosopher_numbers[NUM_PHILOSOPHERS];
for (int i = 0; i < NUM_PHILOSOPHERS; i++)
{
philosopher_numbers[i] = i;
}
for (int i = 0; i < NUM_PHILOSOPHERS; i++)
{
chopsticks[i] = 0;
}
for (int i = 0; i < NUM_PHILOSOPHERS-1; i++)
{
pthread_create(&thread_ids[i], NULL, philosopher_behaviour, (void*)&philosopher_numbers[i]);
}
pthread_create(&thread_ids[NUM_PHILOSOPHERS-1], NULL, philosopher_behaviour_rev,(void*) &philosopher_numbers[NUM_PHILOSOPHERS-1]);
for (int i = 0; i < NUM_PHILOSOPHERS; i++)
{
pthread_join(thread_ids[i], NULL);
}
exit(0);
}