Create session_latest symlink for Ray sessions (#5580)

python/ray/node.py

@@ -19,7 +19,7 @@ import ray
 import ray.ray_constants as ray_constants
 import ray.services
 from ray.resource_spec import ResourceSpec
-from ray.utils import try_to_create_directory
+from ray.utils import try_to_create_directory, try_to_symlink_directory
 
 # Logger for this module. It should be configured at the entry point
 # into the program using Ray. Ray configures it by default automatically
@@ -27,6 +27,7 @@ from ray.utils import try_to_create_directory
 logger = logging.getLogger(__name__)
 
 PY3 = sys.version_info.major >= 3
+SESSION_LATEST = "session_latest"
 
 
 class Node(object):
@@ -171,9 +172,11 @@ class Node(object):
         else:
             self._session_dir = ray.utils.decode(
                 redis_client.get("session_dir"))
+        session_symlink = os.path.join(self._temp_dir, SESSION_LATEST)
 
         # Send a warning message if the session exists.
         try_to_create_directory(self._session_dir)
+        try_to_symlink_directory(self._session_dir, session_symlink)
         # Create a directory to be used for socket files.
         self._sockets_dir = os.path.join(self._session_dir, "sockets")
         try_to_create_directory(self._sockets_dir, warn_if_exist=False)