forkwait main

gistfile1.txt

main(int argc, char* argv[])
{
  //	Generate a random number between MINFORKS and MAXFORKS
	unsigned int seed = generateSeed(0);
	int n = rand_r(&seed) % MAXFORKS + MINFORKS;
	
	//	Time elapsed
	long time = 0;
	time = elapsedTime((int)time);
	
	// Hang on to the PIDs so we can wait for them after forking
	pid_t PIDs[n];
	
	//	Fork n times
	for (int i = 0; i < n ; i++)
	{
		//	Call fork() and retain the returned identifier
		pid_t processIdentifier = fork();

		// Randomize the child sleep time
		seed = generateSeed(0) % MAXPAUSE + MINPAUSE;
		int sleeptime = rand_r(&seed);
		
		//	Check for errors
		if (processIdentifier == -1) {
			printf("Error: %i", errno);
		}
		
		//	We're in the child process
		if (!processIdentifier)
		{

			//	sleep for timeslept seconds
			usleep(sleeptime);

			exit(i);
		}
		
		else
		{
			PIDs[i] = processIdentifier;
			printf("Child %i, pid = %i, forked, waits %i usec\n",  i, processIdentifier, sleeptime);
		}
	}
	
	for (int i = 0; i < n; i++)
	{
		
		int childid = waitpid(PIDs[i], &childid, 0);
		
		printf("Child %i, pid = %i, terminated\n",  childid, PIDs[i]);
	}
}