gitaly-ruby doesn't restart whilst consuming 20gb of memory

From my understand of the documentation, gitaly-ruby should restart when it starts leaking more than 200mb of memory. On our application I observe that after restarting gitaly-ruby, memory usage spikes quickly to 10gb and then slowly increases until it has to be manually killed when it uses all available memory.

What steps can I take to debug the cause of this? Is the failure to restart logged somewhere?