Question

For the following multithreaded program, use system level scope for thread scheduling. Submit your program and screenshot of output in a single word/pdf file.

Write a multithreaded program (USING C PROGRAM) that calculates various statistical values for a list of numbers. This program will be passed a series of numbers on the command line and will then create three separate worker threads. One thread will determine the average of the numbers, the second will determine the maximum value, and the third will determine the minimum value. For example, suppose your program is passed the integers

90 81 78 95 79 72 85

The program will report

The average value is 82

The minimum value is 72

The maximum value is 95

The variables representing the average, minimum, and maximum values will be stored globally. The worker threads will set these values, and the parent thread will output the values once the workers have exited. (We could obviously expand this program by creating additional threads that determine other statistical values, such as median and standard deviation.)

Answer 1

Code :

#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>

int *list,list_size;
int maximum,minimum,average;

void *maximumValue(void *var);
void *minimumValue(void *var);
void *averageValue(void *var);

int main(int argc,char* argv[])
{   
   if (argc==1) printf("Please enter an array of numbers\n");
  
   else if (argc>2)
   {
      
       pthread_attr_t custom_sched_attr;      
pthread_attr_init(&custom_sched_attr);  
// use system level scope for thread scheduling
pthread_attr_setscope(&custom_sched_attr, PTHREAD_SCOPE_SYSTEM);
      
       pthread_t thread_max,thread_min,thread_avg;
       list_size = argc-1;
       list = (int *) malloc((list_size)*sizeof(int));
      
       for (int i=0;i<list_size;i++) list[i] = atoi(argv[i+1]);
      
       //creation of threads
       pthread_create(&thread_max, &custom_sched_attr, maximumValue,NULL);
       pthread_create(&thread_min, &custom_sched_attr, minimumValue,NULL);
       pthread_create(&thread_avg, &custom_sched_attr, averageValue,NULL);
      
       pthread_join(thread_max, NULL);
       pthread_join(thread_min, NULL);
       pthread_join(thread_avg, NULL);
      
       //all threads finish execution and then we print the values
       printf("The average value is %d\nThe minimum value is %d\nThe maximum value is %d",average,minimum,maximum);
       exit(0);
   }
}
void *maximumValue(void *var)
{
   maximum = list[0];
   for (int i=1;i<list_size;i++) if (maximum<list[i]) maximum = list[i];
   return NULL;
}
void *minimumValue(void *var)
{
   minimum = list[0];
   for (int i=1;i<list_size;i++) if (minimum>list[i]) minimum = list[i];
   return NULL;
}
void *averageValue(void *var)
{
   average = 0;
   for (int i=0;i<list_size;i++) average += list[i];
   average=average/list_size;
   return NULL;
}

Output :-