Producer-Consumer Problem with Multithreading

Producer-Consumer Problem with Multithreading

#define BUFFER_SIZE 10
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <semaphore.h>
#define TRUE 1
pthread_mutex_t mutex; //The mutex lock
sem_t full,empty; //semaphores
int buffer[BUFFER_SIZE];
int counter; //buffer counter

pthread_t tid;//ThreadID

void *consumer(void *param);
void *producer(void *param); //The producer thread
void insert_item(int);
int remove_item();
void initialize()
 {
  pthread_mutex_init(&mutex,NULL); //Create the mutex lock
  sem_init(&full,1,0); //Initialize full semaphore to 0
  sem_init(&empty,1,BUFFER_SIZE); //Initialize emty semaphore to BUFFER_SIZE
  counter=0;
 }

/*Producer Thread */

void *producer(void *param)
 {
    int item;
    int waittime;//Next item is produced after waittime
    waittime=rand()% 5;
    sleep(waittime);
    item=rand()%10; //Generate an item to insert in the buffer
    sem_wait(&empty);//wait for queue to become emtpty,using semaphore
    pthread_mutex_lock(&mutex);//Acquire the buffer
    printf("Producer produced %d\n",item);
    insert_item(item);//Insert in the queue
    pthread_mutex_unlock(&mutex); //Release the buffer
    sem_post(&full);//Signal the semaphore full
 }    

/*Consumer thread */

void *consumer(void *param)
 {
  int item;
  int waittime;//Next item is consumed after waittime
  waittime=rand() % 3;
  sleep(waittime);
  sem_wait(&full);//wait if the buffer is full
  pthread_mutex_lock(&mutex);//Acquire the buffer
  item=remove_item();
  printf("Consumer Consumed : %d\n",item);
  pthread_mutex_unlock(&mutex);//Release the buffer
  sem_post(&empty); // Signal empty
 }
 
//Add item to buffer
void insert_item(int item)
 {
   buffer[counter++]=item;
 } 

//Remove an item from the buffer
int remove_item()
 {
    return(buffer[--counter]);
 }

int main()
 {
     int n1;//No. of producers
     int n2;//No. of consumers
     int i;
     printf("Enter no. of producers :\n");
         scanf("%d",&n1);
         printf("Enter no. of consumers :\n");
     scanf("%d",&n2);
     initialize();
   //Create producers threads
        for(i=0;i<n1;i++)
        pthread_create(&tid,NULL,producer,NULL);
  //Create consumer threads            
         for(i=0;i<n2;i++)
         pthread_create(&tid,NULL,consumer,NULL);
      sleep(50);
         exit(0);
 }     

 -----------------------------------------------------------------O/P---------------------------------------------------

guest-stEO95@computer-OptiPlex-745:~$ gedit 1234.c

guest-stEO95@computer-OptiPlex-745:~$ cc 1234.c -lpthread

guest-stEO95@computer-OptiPlex-745:~$ ./a.out

Enter no. of producers :

5

Enter no. of consumers :

4

Producer produced 6

Consumer Consumed : 6

Producer produced 2

Consumer Consumed : 2

Producer produced 7

Consumer Consumed : 7

Producer produced 0

Consumer Consumed : 0

Producer produced 9

guest-stEO95@computer-OptiPlex-745:~$