Create 2 thread and print ping and pong multiple time.
There are 2 ways/method to synchronise threads:
- mutex with conditional variable
- semaphore
Source code of multi threading c with semaphore:
#include <stdio.h>
#include<pthread.h>
#include <semaphore.h>
#include <unistd.h>
//using namespace std;
int i = 0;
sem_t sR;
sem_t sW;
void* Writer(void*)
{
printf("In Writer\n");
while(i!= 10)
{
++i;
printf("Writer: %d\n",i);
sem_post(&sW);
sem_wait(&sR);
}
}
void* Reader(void*)
{
printf("In Reader\n");
while(i!= 10)
{
sem_wait(&sW);
printf("Reader: %d\n",i);
sem_post(&sR);
}
}
int main()
{
pthread_t t1, t2;
printf("In Main\n");
sem_init(&sR, 0, 0);
sem_init(&sW, 0, 0);
pthread_create(&t1, 0, Writer, 0);
pthread_create(&t2, 0, Reader, 0);
pthread_join(t1, 0);
pthread_join(t2, 0);
sem_destroy(&sW);
sem_destroy(&sR);
return 0;
}
Source code of multi threading c with mutex:
#include <stdio.h>
#include<pthread.h>
#include <semaphore.h>
#include <unistd.h>
int i = 0;
pthread_mutex_t m1;
pthread_cond_t condR;
pthread_cond_t condW;
void* MyWriter(void*)
{
printf("In Writer\n");
sleep(1);
pthread_mutex_lock(&m1);
while(i!= 10)
{
++i;
printf("Writer: %d\n",i);
pthread_cond_signal( & condR);
pthread_cond_wait( & condW, & m1 );
}
pthread_mutex_unlock(&m1);
}
void* MyReader(void*)
{
printf("In Reader\n");
pthread_mutex_lock(&m1);
while(i!= 10)
{
pthread_cond_wait( & condR, & m1 );
printf("Reader: %d\n",i);
pthread_cond_signal( & condW);
}
pthread_mutex_unlock(&m1);
}
int main()
{
pthread_t t1, t2;
printf("In Main\n");
pthread_mutex_init(&m1, 0);
pthread_cond_init(&condR, NULL);
pthread_cond_init(&condW, NULL);
pthread_create(&t1, 0, MyWriter, 0);
pthread_create(&t2, 0, MyReader, 0);
pthread_join(t1, 0);
pthread_join(t2, 0);
return 0;
}
Output:
In Main In Writer Writer: 1 In Reader Reader: 1 Writer: 2 Reader: 2 Writer: 3 Reader: 3 Writer: 4 Reader: 4 Writer: 5 Reader: 5 Writer: 6 Reader: 6 Writer: 7 Reader: 7 Writer: 8 Reader: 8 Writer: 9 Reader: 9 Writer: 10 Reader: 10