Finish Lab 3

Lab3/examples/1-no_join-fixed.c

@@ -0,0 +1,17 @@
+/**To compile, don't forget to add -lpthread. Might not work without that */
+#include<pthread.h>
+#include<stdio.h>
+
+void* run (void* arg){
+    printf("Hello from run\n");
+    return NULL;
+}
+
+int main(){
+    pthread_t thread; // variable to store the reference to the thread
+    pthread_create(&thread, NULL, &run, NULL);
+    printf("In main"); // This section will be executed in parallel
+    pthread_join(thread,NULL); // necessary for waiting for the thread to finish
+    printf("In main 2");
+    return 0;
+}

Lab3/examples/2-sleep no_join-fixed.c

@@ -0,0 +1,23 @@
+#include<pthread.h>
+#include<stdio.h>
+#include<stdlib.h>
+#include<unistd.h>
+#include<time.h>
+#include<sys/time.h>
+
+void* run (void* arg){
+    printf("Hello from run\n");
+    return NULL;
+}
+
+int main(){
+    pthread_t thread;
+    pthread_create(&thread, NULL, &run, NULL);
+    // While the sleep() function will appear to provide synchronization,
+    // it is incorrect, and if used for this purposes instead of join
+    // or synchronization mechanism - the grade for the assignment will be
+    // reduced
+    sleep(2);
+    printf("Back in main");
+    return 0;
+}

Lab3/examples/3-losing_track_of_threads-fixed.c

@@ -0,0 +1,24 @@
+#include<pthread.h>
+#include<stdio.h>
+#include<stdlib.h>
+#include<unistd.h>
+#include<time.h>
+#include<sys/time.h>
+
+void* run (void* arg){
+    sleep(10-(int)arg);
+    printf("Hello from run\n");
+}
+
+int main(){
+    pthread_t thread[10];
+    int i = 0;
+    for (i = 0 ; i < 10; ++i)
+        pthread_create(&thread[i], NULL, &run,(void*)i);
+
+    // If you plan to use the results of all the threads, consider
+    // using join for all of the threads
+    for (i = 0 ; i < 10; ++i)
+        pthread_join(thread[i],NULL);
+    printf("In main");
+}

Lab3/examples/4-passing_data_wrongly.c

@@ -0,0 +1,21 @@
+#include<pthread.h>
+#include<stdio.h>
+
+void* run (void* arg){
+    int i = (int) arg;
+    printf("Hello from run, arg is %i\n",i);
+}
+
+int main(){
+    pthread_t thread[10];
+    int i = 0;
+    for (i = 0 ; i < 10; ++i)
+        pthread_create(&thread, NULL, &run,(void*)i);
+    // Notice how warnings are generated. This can be resolved by properly
+    // allocating space for the thread parameters.
+    // Note, that if you are using stack variable, the values might be corrupted
+    for (i = 0 ; i < 10; i++){
+        pthread_join(thread[i],NULL);
+    }
+    printf("In main");
+}

Lab3/examples/4-passing_data_wrongly_fixed.c

@@ -0,0 +1,31 @@
+#include<pthread.h>
+#include<stdio.h>
+#include <stdlib.h>
+
+typedef struct thread_args{
+    char letter;
+    int id;
+}Args;
+void* run (void* arg){
+    Args* argg = (Args*) arg;
+    int i = argg->id;
+    printf("Hello from run %d\n", i);
+    return NULL;
+}
+
+int main(int argc, char** argv){
+    pthread_t thread[10];
+    int i = 0;
+    for (i = 0 ; i < 10; i++){
+        Args* argg = (Args*) (malloc(sizeof(Args)));
+        argg->letter = 'q';
+        argg->id = i;
+        pthread_create(&(thread[i]), NULL, &run,(void*)argg);
+    }
+    for (i = 0 ; i < 10; i++){
+        pthread_join(thread[i],NULL);
+    }
+    // Free the resources somewhere, for long running program. Or let the OS handle that
+    printf("In main");
+    return 0;
+}

Lab3/examples/5-pthread_detach.c

@@ -0,0 +1,19 @@
+#include<pthread.h>
+#include<stdio.h>
+
+void* run (void* arg){
+    printf("Hello from run\n");
+    return NULL;
+}
+
+int main(){
+    pthread_t thread;
+    pthread_create(&thread, NULL, &run, NULL);
+    pthread_detach(thread);
+    // This command will make thread detached. This means the resources will be released 
+    // upon the thread's completion - calling return
+    // However, detached threads cannot be joined, which means if you care about the result
+    // of the thread execution - you should not be using pthread_detach
+    printf("In main");
+    return 0;
+}