In C write a multithreadedpthread program that outputs prime

In C write a multithreaded(pthread) program that outputs prime numbers. This program should work as follows: The user will run the program and will enter a number on the command line. The program will then create a seperate thread that outputs all the prime numbers less than or equal to the numbers entered by the user.

Solution

#include #include #include #define MAX_N 100000000 #define MAX_THREADS 25 // global values int threadNumber; int largestNumber; int isPrime; int nthreads, // number of threads (not counting main()) prime[MAX_N + 1], n, // in the end, prime[i] = 1 if i prime, else 0 nextbase; // next sieve multiplier to be used // lock for the shared variable nextbase pthread_mutex_t nextbaselock = PTHREAD_MUTEX_INITIALIZER; void crossout(int a) { int i, j, check; for (i = 2; i < largestNumber; i++) prime[i] = 1; for (i = a; i < largestNumber;) if (prime[i]) for (j = i; i * j < largestNumber; j++) prime[i * j] = 0; } int checkPrime(int a) { int i; for (i = 2; i <= a; ++i) { if (a % i == 0) { isPrime = 1; return isPrime; break; } else isPrime = 2; crossout(a); return isPrime; } } void* workerThread(void* t) { int lim, base; long i, j; long tid; tid = (long)t; printf(\"Thread %ld starting...\ \", tid); while (1) { pthread_mutex_lock(&nextbaselock); base = nextbase; nextbase++; // unlock the lock pthread_mutex_unlock(&nextbaselock); if (base <= lim) { if (prime[base]) { checkPrime(base); // log work done by this thread } } if (checkPrime(base) == 2) printf(\"Thread %ld done. Prime = %d\ \", tid, base); pthread_exit((void*) t); } return NULL; } //main function with two parameters :argc and argv int main(int argc, char** argv) { threadNumber = argv[3]; largestNumber = argv[1]; int i; pthread_t thread[threadNumber]; int rc; long t; void* status; for (t = 0; t < threadNumber; t++) { printf(\"Main: creating thread %ld\ \", t); rc = pthread_create(&thread[t], NULL, workerThread, (void*)t); if (rc) { printf(\"ERROR; return code from pthread_create() is %d\ \", rc); exit(-1); } } for (t = 0; t < threadNumber; t++) { rc = pthread_join(thread[t], (void*)&t); if (rc) { printf(\"ERROR; return code from pthread_join() is %d\ \", rc); exit(-1); } printf(\"Main: completed join with thread %ld \ \", t); } }