--- a
+++ b/mmaction/utils/misc.py
@@ -0,0 +1,27 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import ctypes
+import random
+import string
+
+
+def get_random_string(length=15):
+    """Get random string with letters and digits.
+
+    Args:
+        length (int): Length of random string. Default: 15.
+    """
+    return ''.join(
+        random.choice(string.ascii_letters + string.digits)
+        for _ in range(length))
+
+
+def get_thread_id():
+    """Get current thread id."""
+    # use ctype to find thread id
+    thread_id = ctypes.CDLL('libc.so.6').syscall(186)
+    return thread_id
+
+
+def get_shm_dir():
+    """Get shm dir for temporary usage."""
+    return '/dev/shm'