Corrections diverses.

ex2/T2.c

@@ -13,6 +13,8 @@ void sort(int arr[], int size);
 
 // Function prototypes for thread tasks
 void* mean(void* arr) {
+    printf("Mean TID: %ld\n", pthread_self());
+
     float sum = 0;
     for (int i = 0 ; i < SIZE ; i++) {
         sum += ((int*) arr)[i];
@@ -23,6 +25,8 @@ void* mean(void* arr) {
 
 // Side effect: sorts the array in ascending order
 void* median(void* arr) {
+    printf("Median TID: %ld\n", pthread_self());
+
     sort((int*) arr, SIZE);
     medianval = ((int*) arr)[SIZE/2];
     pthread_exit(0);
@@ -35,21 +39,18 @@ int main() {
 
     // Mean thread:
     pthread_t tid1;
-    pthread_attr_t attr1;
-    pthread_attr_init(&attr1);
-    pthread_create(&tid1, &attr1, mean, arr);
+
+    pthread_create(&tid1, NULL, mean, arr);
 
     // Median thread:
     pthread_t tid2;
-    pthread_attr_t attr2;
-    pthread_attr_init(&attr2);
-    pthread_create(&tid2, &attr2, median, arr);
+
+    pthread_create(&tid2, NULL, median, arr);
 
     pthread_join(tid1, NULL);
     pthread_join(tid2, NULL);
 
     printf("Mean = %f\nMedian = %d\n", meanval, medianval);
-    printf("Mean thread PID: %ld\nMedian thread PID: %ld\n", tid1, tid2);
 
     return 0;
 }

ex2/T3.c

@@ -12,9 +12,7 @@ void* runner(void* arg) {
 
 pthread_t thread_gen() {
     pthread_t tid;
-    pthread_attr_t attr;
-    pthread_attr_init(&attr);
-    pthread_create(&tid, &attr, runner, NULL);
+    pthread_create(&tid, NULL, runner, NULL);
     return tid;
 }
 

ex2/T4.c

@@ -16,12 +16,17 @@ struct args
 
 void * accumulate(void * in)
 {
+	int reslocal = 0;
 	int* arr = ((struct args*) in)->arr;
 	int start = ((struct args*) in)->start;
 	int end = ((struct args*) in)->end;
 	for (int i = start ; i < end ; i++) {
-		result += arr[i];
+		reslocal += arr[i];
 	}
+	pthread_mutex_lock(&lock);
+	result += reslocal;
+	pthread_mutex_unlock(&lock);
+
 	return NULL;
 }
 
@@ -32,19 +37,17 @@ int main ()
 	for(int i=0;i<SIZE;i++)
 		arr[i]=1;
 
+	pthread_mutex_init(&lock, NULL);
+
 	pthread_t threads[NUM_THREADS-1];
 	struct args thread_args[NUM_THREADS-1];
-	pthread_t tid;
-	pthread_attr_t attr;
 
 	int i;
 	for (i = 0 ; i < NUM_THREADS-1 ; i++) {
-		threads[i] = tid;
 		thread_args[i].arr = arr;
 		thread_args[i].start = i * (SIZE/NUM_THREADS);
 		thread_args[i].end = i * (SIZE/NUM_THREADS) + SIZE/NUM_THREADS;
-		pthread_attr_init(&attr);
-		pthread_create(&tid, &attr, accumulate, (void*) (thread_args + i));
+		pthread_create((threads + i), NULL, accumulate, (void*) (thread_args + i));
 	}
 
 	int main_start = i;
@@ -60,5 +63,6 @@ int main ()
 	accumulate(&main_arg);
 
 	printf("Sum is: %d\n", result);
-}
 
+	pthread_mutex_destroy(&lock);
+}

ex2/T5.c

 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
 
 #define SIZE 5
 struct process{