chore: Add docstring to clarify that inmemory service are not suitable for production

environment

Resolves https://github.com/google/adk-python/issues/1569

PiperOrigin-RevId: 780013850

src/google/adk/artifacts/in_memory_artifact_service.py

@@ -11,8 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-"""An in-memory implementation of the artifact service."""
+from __future__ import annotations
 
 import logging
 from typing import Optional
@@ -28,7 +27,11 @@ logger = logging.getLogger("google_adk." + __name__)
 
 
 class InMemoryArtifactService(BaseArtifactService, BaseModel):
-  """An in-memory implementation of the artifact service."""
+  """An in-memory implementation of the artifact service.
+
+  It is not suitable for multi-threaded production environments. Use it for
+  testing and development only.
+  """
 
   artifacts: dict[str, list[types.Part]] = Field(default_factory=dict)
 

src/google/adk/memory/in_memory_memory_service.py

@@ -11,8 +11,6 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-
 from __future__ import annotations
 
 import re
@@ -43,6 +41,9 @@ class InMemoryMemoryService(BaseMemoryService):
   """An in-memory memory service for prototyping purpose only.
 
   Uses keyword matching instead of semantic search.
+
+  It is not suitable for multi-threaded production environments. Use it for
+  testing and development only.
   """
 
   def __init__(self):

src/google/adk/sessions/in_memory_session_service.py

@@ -33,7 +33,11 @@ logger = logging.getLogger('google_adk.' + __name__)
 
 
 class InMemorySessionService(BaseSessionService):
-  """An in-memory implementation of the session service."""
+  """An in-memory implementation of the session service.
+
+  It is not suitable for multi-threaded production environments. Use it for
+  testing and development only.
+  """
 
   def __init__(self):
     # A map from app name to a map from user ID to a map from session ID to