Bug#23035296: MAIN.MYSQLDUMP FAILS BECUASE OF UNEXPECTED

              ERROR MESSAGE

Description:- Mtr test, "main.mysqldump" is failing with an
assert when "mysqlimport" client utility is executed with
the option "--use_threads".

Analysis:- "mysqlimport" uses the option, "--use_threads",
to spawn worker threads to complete its job in parallel. But
currently the main thread is not waiting for the worker
threads to complete its cleanup, rather just wait for the
worker threads to say its done doing its job. So the cleanup
is done in a race between the worker threads and the main
thread. This lead to an assertion failure.

Fix:- "my_thread_join()" is introduced in the main thread to
join all the worker threads it have spawned. This will let
the main thread to wait for all the worker threads to
complete its cleanup before calling "my_end()".

client/mysqlimport.c

@@ -592,7 +592,7 @@ pthread_handler_t worker_thread(void *arg)
   pthread_cond_signal(&count_threshhold);
   pthread_mutex_unlock(&counter_mutex);
   mysql_thread_end();
-
+  pthread_exit(0);
   return 0;
 }
 
@@ -615,15 +615,30 @@ int main(int argc, char **argv)
 
   if (opt_use_threads && !lock_tables)
   {
-    pthread_t mainthread;            /* Thread descriptor */
-    pthread_attr_t attr;          /* Thread attributes */
+    char **save_argv;
+    uint worker_thread_count= 0, table_count= 0, i= 0;
+    pthread_t *worker_threads;       /* Thread descriptor */
+    pthread_attr_t attr;             /* Thread attributes */
     pthread_attr_init(&attr);
     pthread_attr_setdetachstate(&attr,
-                                PTHREAD_CREATE_DETACHED);
+                                PTHREAD_CREATE_JOINABLE);
 
     pthread_mutex_init(&counter_mutex, NULL);
     pthread_cond_init(&count_threshhold, NULL);
 
+    /* Count the number of tables. This number denotes the total number
+       of threads spawn.
+    */
+    save_argv= argv;
+    for (table_count= 0; *argv != NULL; argv++)
+      table_count++;
+    argv= save_argv;
+
+    if (!(worker_threads= (pthread_t*) my_malloc(table_count *
+                                                 sizeof(*worker_threads),
+                                                 MYF(0))))
+      return -2;
+
     for (counter= 0; *argv != NULL; argv++) /* Loop through tables */
     {
       pthread_mutex_lock(&counter_mutex);
@@ -638,15 +653,16 @@ int main(int argc, char **argv)
       counter++;
       pthread_mutex_unlock(&counter_mutex);
       /* now create the thread */
-      if (pthread_create(&mainthread, &attr, worker_thread, 
-                         (void *)*argv) != 0)
+      if (pthread_create(&worker_threads[worker_thread_count], &attr,
+                         worker_thread, (void *)*argv) != 0)
       {
         pthread_mutex_lock(&counter_mutex);
         counter--;
         pthread_mutex_unlock(&counter_mutex);
-        fprintf(stderr,"%s: Could not create thread\n",
-                my_progname);
+        fprintf(stderr,"%s: Could not create thread\n", my_progname);
+        continue;
       }
+      worker_thread_count++;
     }
 
     /*
@@ -664,6 +680,14 @@ int main(int argc, char **argv)
     pthread_mutex_destroy(&counter_mutex);
     pthread_cond_destroy(&count_threshhold);
     pthread_attr_destroy(&attr);
+
+    for(i= 0; i < worker_thread_count; i++)
+    {
+      if (pthread_join(worker_threads[i], NULL))
+        fprintf(stderr,"%s: Could not join worker thread.\n", my_progname);
+    }
+
+    my_free(worker_threads);
   }
   else
   {