COP 4600, Fall 2006 Extra Credit Assignment
Due: Monday, September 18, 2006, at the beginning of class.
Assignment description:
Consider the multithreaded program below:
#include <pthread.h>
#include <stdio.h>
#define N 2
void *printSi(void *threadid) {
printf("%d: Si\n", threadid);
pthread_exit(0);
}
int main (int argc, char *argv[]) {
pthread_t threads[N];
pthread_attr_t attr[N];
int t;
for(t=0; t<N; t++){
printf("Creating thread %d\n", t);
pthread_attr_init(&attr[t]);
pthread_create(&threads[t], &attr[t], printSi, (void *)t);
}
pthread_exit(0);
}
When N is 2, as above, there are three possible outputs from running this program:
Creating thread 0 Creating thread 0 Creating thread 0
0: Si Creating thread 1 Creating thread 1
Creating thread 1 0: Si 1: Si
1: Si 1: Si 0: Si
Question: In general, how many possible outputs are there for a given N? In other
words, what is the function F(N) that returns the number of possible outputs for any
positive integer N? (F(1) should equal 1, F(2) should equal 3, etc.)
Simplify your answer as much as possible.