WptAgent docker container is getting bigger

I have private instance of WPT in Docker containers. I have done everything exacly as described here.
Running tests is working fine, but container with agent is getting bigger with every test. At the beginning, its size was about 25MB, but after 25 tests it grown to 650MB. I am running tests from command line using node.js wpt wrapper.
Is that a normal situation, and if not, how can I prevent wptagent container from expanding?

EDIT: here are the parameters I call runTest method with:
{ pollResults: 5, timeout: 600, firstViewOnly: true, video: false, runs: 1 }

By default, Docker only launches a container with 64MB of shared memory. That might not be enough for headless Chrome on the agent to work based on the size of the page it’s checking.

Check to see if there are a bunch of core. files in the /wptagent folder in the docker container. If there are, you may want to try launching the container with --shm-size=1g to see if that helps keep chrome from dumping whenever it runs out of shared memory.

Thanks, I think this solved the issue