Threads

Hello_World_Thread/cleaner.sh

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+rm *~ .*

Hello_World_Thread/compile.sh

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+gcc -g -c hello_world_thread.c -o hello_world_thread.o
+gcc -g hello_world_thread.o -o hello_world_thread.exe -lpthread
+rm *.o

Hello_World_Thread/hello_world_thread.c

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+/*
+ * =====================================================================================
+ *
+ *       Filename:  hello_world_thread.c
+ *
+ *    Description:  
+ *
+ *        Version:  1.0
+ *        Created:  06/03/24 08:38:10 PM IST
+ *       Revision:  none
+ *       Compiler:  gcc
+ *
+ *         Author:  YOUR NAME (), 
+ *   Organization:  
+ *
+ * =====================================================================================
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h> /* For working with POSIX threads */
+#include <unistd.h>  /* For pause() and sleep() */
+
+
+/*Note: pthread_exit(0) API can be used to terminate a thread
+ * , be it child thread or parent thread */
+
+
+/* A thread callback fn must have following prototypes
+ * void *(*thread_fn)(void *)
+ * */
+static void *
+thread_fn_callback(void *arg){
+    char *input = (char *)arg;
+    while(1){
+        printf("Input is : %s\n",input);
+        sleep(1);
+    }
+}
+
+/* Note that this function is not
+ * main thread, rather it just a function
+ * which create a thread and return to main()
+ * function, which is actually the main thread of this
+ * process */
+void
+thread1_create(){
+
+    /* opaque object, don't bother about its internal
+     * members */
+    pthread_t pthread; /* Thread handler: This is like a variable which is used
+                        * handle the thread processed */
+
+    /* Take some argument to be passed to the thread fn,
+     * Look after that you always pass the persistant memory
+     * as an argument to the thread, do not pass caller's
+     * local variables Or stack Memory */
+    static char *thread_input1 = "I am thread 1, child thread of main thread";
+    
+    /* Return 0 on success, otherwise returns error-code, all
+     * pthread functions return -ve error-code on failure, they
+     * do not set global 'errno' variable */
+    int rc = pthread_create(&pthread,
+                            NULL,
+                            thread_fn_callback,
+                            (void *)thread_input1);
+
+    if( rc != 0 ){
+        printf("Error occured, thread could not be created, errno = %d\n",rc);
+        exit(0);
+    }
+}
+
+int
+main(int argc , char **argv){
+    
+   thread1_create();
+   printf("The execution of main function( or main thread ) is paused\n");
+   //pause();
+   /* Main thread, if complete its execution and return normally
+    * by returning 0 then all the child thread of main thread terminates
+    * but, if we use pthread_exit(0) to terminate main thread then the 
+    * child threads can continue to exit without any obstruction. */
+
+   pthread_exit(0);
+   return 0;
+}