Do not modify tags dict on start_run()

mlflow/tracking/_tracking_service/client.py

@@ -94,18 +94,18 @@ def create_run(self, experiment_id, start_time=None, tags=None):
         :return: :py:class:`mlflow.entities.Run` that was created.
         """
 
-        tags = tags if tags else {}
+        run_tags = tags if tags else {}
 
         # Extract user from tags
         # This logic is temporary; the user_id attribute of runs is deprecated and will be removed
         # in a later release.
-        user_id = tags.get(MLFLOW_USER, "unknown")
+        user_id = run_tags.get(MLFLOW_USER, "unknown")
 
         return self.store.create_run(
             experiment_id=experiment_id,
             user_id=user_id,
             start_time=start_time or int(time.time() * 1000),
-            tags=[RunTag(key, value) for (key, value) in tags.items()],
+            tags=[RunTag(key, value) for (key, value) in run_tags.items()],
         )
 
     def list_run_infos(

mlflow/tracking/fluent.py

@@ -8,6 +8,7 @@
 import time
 import logging
 import inspect
+from copy import deepcopy
 from packaging.version import Version
 from typing import Any, Dict, List, Optional, Union, TYPE_CHECKING
 
@@ -278,15 +279,15 @@ def start_run(
 
         exp_id_for_run = experiment_id if experiment_id is not None else _get_experiment_id()
 
-        user_specified_tags = tags or {}
+        user_specified_tags = deepcopy(tags) or {}
         if parent_run_id is not None:
             user_specified_tags[MLFLOW_PARENT_RUN_ID] = parent_run_id
         if run_name is not None:
             user_specified_tags[MLFLOW_RUN_NAME] = run_name
 
-        tags = context_registry.resolve_tags(user_specified_tags)
+        resolved_tags = context_registry.resolve_tags(user_specified_tags)
 
-        active_run_obj = client.create_run(experiment_id=exp_id_for_run, tags=tags)
+        active_run_obj = client.create_run(experiment_id=exp_id_for_run, tags=resolved_tags)
 
     _active_run_stack.append(ActiveRun(active_run_obj))
     return _active_run_stack[-1]