CST 352 - Threads

Write a program using threads and mutexes by building on the program listing primes.c This program demonstrates basic pthread usage as well as the passing of parameters to and from a thread. In this case, main() generates a single thread that calculates the n'th prime and then returns it.

What you should do is generate 5 threads that share in the calculation of all the primes up to some limit. Please do the following:

• Modify the program so that 5 threads are generated. See the file “thread-create.c” for an example of how to create a thread.
• Each thread is passed a data structure that contains the thread's ID (0,1,2...) and a value for the maximum prime to calculate. See the file “thread-create2.c” for an example of how to pass a parameter to a thread.
• Each thread should read the global integer 'master_list' for the prime to be calculated and then increment it for the next thread so that no prime is calculated more than once ('master_list' should have been previously initialized to 1). Since there are 5 threads, you will need to use mutexes when accessing master_list. See the “condvar.c” file for an example of using a mutex.
• The subroutine compute_prime() is the function executed by the thread. Instead, write your own routine called void *prime_job(void *arg) (or whatever you want to call it) that is executed by the thread. Modify compute_prime() so that it is passed an integer (prime to calculate) and returns an integer ( the value of the prime).
• Prime_job() should extract its ID and max prime value and then enter an endless loop that reads the master_list for a number, increments master_list, compares the number with the maximum value, and breaks out of the loop if the maximum is exceeded. Otherwise, it calls compute_prime(). Each thread should print its ID, the prime #, and the value of the prime. See the “thread-pid.c” program as an example for retrieving a thread’s PID value.
• Each thread should keep a local counter of how many primes it actually got to calculate and return this value to main(). These count statistics should be printed out at the end of the program.