First commit

content/progsys/TDM_5-threads/index.md

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+---
+title : "TDM : Les processus légers"
+category: Programmation système
+date: 2018-09-25
+---
+[télécharger les questions](./files/tdm5.pdf)
+
+## Question 1
+
+Comme vu en TD, les résultats ne sont pas ceux attendu du fait de l'absence de
+mutex. Je constate aussi qu'ils varient aussi d'une execution sur l'autre.
+
+### avec un mutex
+
+J'obtiens la valeur attendue pour blob.
+
+[Voir mon code dans mutex](./src/td5/q1.c)
+[Voir mon code avec mutex](./src/td5/q1_mutex.c)
+
+## Question 2
+
+[Voir mon code](./src/td5/q2.c)

content/progsys/TDM_5-threads/src/q1.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+//define
+#define THREADS 2
+#define ITERATIONS 1000000
+
+static long glob = 0;
+
+void *tmain( void *arg){
+    long tmp;
+    for (int i=0; i < ITERATIONS; i++){
+        tmp = glob;
+        tmp++;
+        glob = tmp;
+
+    }
+    return NULL;
+}
+
+int main(int argc, char **argv) {
+    pthread_t *t;
+    void *res;
+    // memory allocation for threads
+    if ( (t=calloc(THREADS, sizeof(pthread_t))) == NULL) {
+        perror("Unable ro allocate memory for pthread");
+    }
+    for (int i=0; i < THREADS; i++){
+        if (pthread_create(&t[i],NULL, tmain, &"") != 0){ 
+            perror("unable to create thread\n");
+        }
+    }
+    // Need to block parent thread until brother thread are finished
+    for (int j=0;j < THREADS; j++){
+        // bloc main thread exec with pthread_join()
+        if (pthread_join(t[j], &res) != 0){
+            perror ("Unable to join process");
+        }
+    }
+    printf("glob is %ld, should be 2000000\n", glob);
+    free(t);
+    exit (EXIT_SUCCESS);
+}

content/progsys/TDM_5-threads/src/q1_mutex.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+//define
+#define THREADS 2
+#define ITERATIONS 1000000
+
+static long glob = 0;
+static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+
+void *tmain( void *arg){
+    long tmp;
+    for (int i=0; i < ITERATIONS; i++){
+        if (pthread_mutex_lock(&mutex) != 0) {
+            perror("Mutex lock failed");
+            exit(EXIT_FAILURE);
+        }
+        tmp = glob;
+        tmp++;
+        glob = tmp;
+        if (pthread_mutex_unlock(&mutex) != 0) {
+            perror("Mutex lock failed");
+            exit(EXIT_FAILURE);
+        }
+    }
+    return NULL;
+}
+
+int main(int argc, char **argv) {
+    pthread_t *t;
+    void *res;
+    // memory allocation for threads
+    if ( (t=calloc(THREADS, sizeof(pthread_t))) == NULL) {
+        perror("Unable ro allocate memory for pthread");
+    }
+    for (int i=0; i < THREADS; i++){
+        if (pthread_create(&t[i],NULL, tmain, &"") != 0){ 
+            perror("unable to create thread\n");
+        }
+    }
+    // Need to block parent thread until brother thread are finished
+    for (int j=0;j < THREADS; j++){
+        // bloc main thread exec with pthread_join()
+        if (pthread_join(t[j], &res) != 0){
+            perror ("Unable to join process");
+        }
+    }
+    printf("glob is %ld, should be 2000000\n", glob);
+    free(t);
+    exit (EXIT_SUCCESS);
+}

content/progsys/TDM_5-threads/src/q2.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <pthread.h>
+
+//define
+#define THREADS 5
+#define ITERATIONS 5
+#define SLEEP 2
+
+void *tmain( void *arg){
+    for (int i=0; i < ITERATIONS; i++){
+        sleep(SLEEP);
+        printf("I'm alive : %i\n",(int) pthread_self());
+    }
+    return NULL;
+}
+
+int main(int argc, char **argv) {
+    pthread_t *t;
+    void *res;
+    // memory allocation for threads
+    if ( (t=calloc(THREADS, sizeof(pthread_t))) == NULL) {
+        perror("Unable ro allocate memory for pthread");
+    }
+    for (int i=0; i < THREADS; i++){
+        if (pthread_create(&t[i],NULL, tmain, &"") != 0){ 
+            perror("unable to create thread\n");
+        }
+    }
+    // Need to block parent thread until brother thread are finished
+    for (int j=0;j < THREADS; j++){
+        // bloc main thread exec with pthread_join()
+        if (pthread_join(t[j], &res) != 0){
+            perror ("Unable to join process");
+        }
+    }
+    free(t);
+    exit (EXIT_SUCCESS);
+}