Cleaned up output from thr_print_locks

mysys/thr_lock.c

@@ -1684,12 +1684,15 @@ void thr_print_locks(void)
   uint count=0;
 
   mysql_mutex_lock(&THR_LOCK_lock);
-  puts("Current locks:");
+  puts("Current active THR (table level locks):");
   for (list= thr_lock_thread_list; list && count++ < MAX_THREADS;
        list= list_rest(list))
   {
     THR_LOCK *lock=(THR_LOCK*) list->data;
     mysql_mutex_lock(&lock->mutex);
+    if ((lock->write.data || lock->read.data ||
+         lock->write_wait.data || lock->read_wait.data))
+    {
       printf("lock: 0x%lx:",(ulong) lock);
       if ((lock->write_wait.data || lock->read_wait.data) &&
           (! lock->read.data && ! lock->write.data))
@@ -1707,9 +1710,10 @@ void thr_print_locks(void)
       thr_print_lock("write_wait",&lock->write_wait);
       thr_print_lock("read",&lock->read);
       thr_print_lock("read_wait",&lock->read_wait);
-    mysql_mutex_unlock(&lock->mutex);
       puts("");
     }
+    mysql_mutex_unlock(&lock->mutex);
+  }
   fflush(stdout);
   mysql_mutex_unlock(&THR_LOCK_lock);
 }