Memory leak on rclpy subscriber

During the work, we noticed that memory consumption of our docker container(with ROS2 Foxy) has been increased with time. We did research and found that this memory is allocated for the node, written in python.

We tried to reproduce the issue with a simple application and we reproduced it on clean foxy docker with a demo application.

Bug report

Required Info:

• Operating System:
  • Ubuntu 18.04(doesn’t matter in this case, as in docker other OS is used)
• Installation type:
  • binaries
• Version or commit hash:
  • Foxy
• DDS implementation:
  • default
• Client library (if applicable):
  • rclpy

Steps to reproduce issue

1. Download docker file from the repository dockerfile
2. Go to the folder where you’ve saved dockerfile in the previous step Build docker with a command like docker build -t ros2-foxy .
3. Run docker with the listener from demo py package docker run -it --rm ros2-foxy ros2 run demo_nodes_py listener
4. Run rqt tool on your environment or in the other docker
5. Check if /chatter topic is available. It should be created by the listener node
6. In rqt, configure message publisher to send messages to the chatter with high frequency, e.g. 5000Hz. The frequency doesn’t matter, but with such frequency, we will see issue sooner
7. Check docker(where the listener is run) memory consumption. In my case it was ~60Mb
8. Wait for some time, in my case about 30 min

Expected behavior

Memory consumption is on the same level

Actual behavior

Memory consumption is increased to 330mB

Additional information

Memory consumption is not decreased when we stop message publishing.

[iuhilnehc-ynos]

@fujitatomoya

with _WaitSet() to call __enter__ and __exit__, it seems there is no memory leak. https://github.com/ros2/rclpy/blob/d7b4688743a99063e444f216f30c462fb03369b3/rclpy/rclpy/executors.py#L63-L71

Maybe it’s related to

diff --git a/rclpy/src/rclpy/_rclpy.c b/rclpy/src/rclpy/_rclpy.c
index a09b91a..b1bcefa 100644
--- a/rclpy/src/rclpy/_rclpy.c
+++ b/rclpy/src/rclpy/_rclpy.c
@@ -3446,10 +3446,12 @@ rclpy_message_info_to_dict(rmw_message_info_t * message_info)
   PyObject * source_timestamp = PyLong_FromLongLong(message_info->source_timestamp);
   if (source_timestamp != NULL) {
     PyDict_SetItemString(dict, "source_timestamp", source_timestamp);
+    Py_DecRef(source_timestamp);
   }
-  PyObject * received_timestamp = PyLong_FromLongLong(message_info->source_timestamp);
+  PyObject * received_timestamp = PyLong_FromLongLong(message_info->received_timestamp);
   if (received_timestamp != NULL) {
-    PyDict_SetItemString(dict, "received_timestamp", source_timestamp);
+    PyDict_SetItemString(dict, "received_timestamp", received_timestamp);
+    Py_DecRef(received_timestamp);
   }
 
   // check for errors

[yfedi]

Yes, as the issue has been addressed we can close it