Dining Philosopher Problem in C (Operating Systems)

Dining Philosopher Problem in C (Operating Systems)

20:10

Description: The following C code solves the Dining Philosopher problem using semaphore. It’s a simple Dining Philosopher problem solution often taught in Operating Systems.

#include<stdlib.h>

#include <stdio.h>

#include <unistd.h>

#include <semaphore.h>

#define SIZE 5

sem_t chopsticks[SIZE];

sem_t isEating[SIZE];

void *Philosopher(void *param){

   int i,s;

   while(1){

      i=rand()%5;

      sem_wait(&isEating[i]);

      printf("\n\n\t--> Philosopher#%d Turn\n\n",i);

      if(i%2){

          sem_wait(&chopsticks[i]);

          sem_wait(&chopsticks[(i+1)%5]);

      }

      else{

          sem_wait(&chopsticks[(i+1)%5]);

          sem_wait(&chopsticks[i]);

      }

      printf("--> Philosopher#%d has STARTED Eating\n",i);

      s=rand()%4+1;

      sleep(s);

      printf("--> Philosopher#%d has FINISHED Eating\n",i);

      sem_post(&chopsticks[i]);

      sem_post(&chopsticks[(i+1)%5]);

      sem_post(&isEating[i]);

   }

}

int main(){

   int i;

   for(i=0;i<SIZE;i++)

      sem_init(&chopsticks[i], 2, 1);

   for(i=0;i<SIZE;i++)

      sem_init(&isEating[i], 2, 1);

   pthread_t threadID;

   pthread_attr_t attributes;

   pthread_attr_init (&attributes);

   for(i=0;i<4;i++)

      pthread_create(&threadID,&attributes,Philosopher,NULL);

   sleep(30);

   exit(0);

}