POLITECNICO DI TORINO III Facoltà di Ingegneria dell Informazione INDUSTRIAL NETWORKS AND REAL-TIME OPERATING SYSTEMS.

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1 POLITECNICO DI TORINO III Facoltà di Ingegneria dell Informazione INDUSTRIAL NETWORKS AND REAL-TIME OPERATING SYSTEMS LAB 3 All Team No delivery in the laboratory. Do the exercises at home and deliver them within 4 days. Send them in the Elaborati folder of Didactical Portal. 1) Compile, test, and understand the following codes. For compile and link program with Pthread you must use the flag -lpthread To compile and link, you must use GCC: gcc o program_name file.c -lpthread To run a program:./program_name a) pthread1.c Simple threads creation and join Use pthread_create() and pthread_join() #define NUM_THREADS 5 void *PrintHello(void *arg) printf("hello World! I am thread!\n"); pthread_exit(0); int main(int argc, char *argv[]) int rc, t; printf("in main: creating thread %d\n", t); //Threads creation rc = pthread_create(&threads[t], NULL, PrintHello, NULL); //Whait for thread finish rc = pthread_join (threads[t], NULL); printf("error; return code from pthread_join() is %d\n", rc); //All threads finish execution printf("in main: finish\n"); return(0);

2 b) pthread2.c Simple threads creation and join, passing paramiter (int) to thread Use pthread_create() and pthread_join() #define NUM_THREADS 5 void *PrintHello(void *arg) int data; data = *( (int*)arg ); printf("hello World! I am thread, data=%d\n",data); //Set 0 to passed arguments *( (int*)arg )=0; pthread_exit(null); int main(int argc, char *argv[]) int rc, t; int array[num_threads]; //Initialize the arrays printf("in main: Original Array\n"); array[t]=t; printf("%d\n",array[t]); //Threads creation printf("in main: creating thread %d\n", t); rc = pthread_create(&threads[t], NULL, PrintHello, (void *) &array[t]); //Whait for thread finish rc = pthread_join (threads[t], NULL); printf("error; return code from pthread_join() is %d\n", rc); //All threads finish execution printf("in main: finish, printing array...\n"); printf("%d\n",array[t]); return(0);

3 c) pthread3.c A Pthreads program which demonstrates a safe way to pass arguments to threads during thread creation. In this case, a structure is used to pass multiple arguments. #define NUM_THREADS 8 char *messages[num_threads]; struct thread_data int thread_id; int sum; char *message; ; struct thread_data thread_data_array[num_threads]; void *PrintHello(void *threadarg) int taskid, sum; char *hello_msg; struct thread_data *my_data; sleep(1); my_data = (struct thread_data *) threadarg; taskid = my_data->thread_id; sum = my_data->sum; hello_msg = my_data->message; printf("thread %d: %s Sum=%d\n", taskid, hello_msg, sum); pthread_exit(null); int main(int argc, char *argv[]) int *taskids[num_threads]; int rc, t, sum; sum=0; messages[0] = "English: Hello World!"; messages[1] = "French: Bonjour, le monde!"; messages[2] = "Spanish: Hola al mundo"; messages[3] = "Klingon: Nuq neh!"; messages[4] = "German: Guten Tag, Welt!"; messages[5] = "Russian: Zdravstvytye, mir!"; messages[6] = "Japan: Sekai e konnichiwa!"; messages[7] = "Latin: Orbis, te saluto!"; sum = sum + t; thread_data_array[t].thread_id = t; thread_data_array[t].sum = sum; thread_data_array[t].message = messages[t]; printf("creating thread %d\n", t); rc = pthread_create(&threads[t], NULL, PrintHello, (void *) &thread_data_array[t]); exit(-1); sleep(3);

4 2) Write a C program to test the pthread library. Starting from a father process, the father must generate 3 sons. Two of these sons generate other two sons and the third one generate 0 sons. (see the diagram). Print to console the process family tree (i.e father, sons, grandson). The father ends when each thread is terminated and print a message. level: 0 father son 1 son 2 son son 1 son 2 son 1 son 2 3) The Fibonacci sequence is the series of numbers 0,1,1,2,3,5,8,... Formally, it can be expressed as: fib0 = 0 fib1 = 1 fibn = finn-1 + fibn-2 Write a multithreaded program that generates the Fibonaccci series using the Pthreads thread library. This program should work as follows: The user will enter on the command line the numbers that the programs is to generate. The program will then create one separate thread that will generate the Fibonacci numbers, placing the sequence in data that is shared by the threads (an array is probably the most convenient data structure). When the thread finishes execution, the parent thread will output the sequence generated by the child thread. Because the parent thread cannot begin outputting the Fibonacci sequence until the child thread finishes, this will require having the parent thread wait for the child to finish.

5 4) Write a C program according to the following requirements: 1. A main program create 5 threads (thread1, thread2, thread3 thread4 and threadmaster) 2. ThreadMaster generates a shared array of 400 random numbers between [ ]. 3. When ThreadMaster finishes the other threads perform the sorting of the array. Each thread sorts 100 elements of the array at the same time. (Thread1 sort elements from position 0 to 99, thread2 from position 100 to 199, etc). After sorting each thread terminates. 4. After the termination of all threads, the main sorts the array using merge-sort algorithm on the four parts previously ordered and print the array. 5. Only two functions must be used in all threads, one for threadmaster and one for thread1, thread2,thread3 and thread4 (pool of thread). Example Array of 16 elements At the same time: Thread1 sort > Thread2 sort > Thread3 sort > Thread4 sort > Next the main merge the block: