Session: Error while trying to free lock for ci_session

After digging into the metrics I don't think my case is a memory issue. According to CloudWatch the production Redis server has never come close to capacity, and I've been able to trigger it on staging (same RAM as production and <2 users) and in dev (local single user).

When you built the library, what issues caused you to put that message in? Do you have any thoughts on what we can look for?

It's unexpected behavior and as such it has to be logged - that's all the reasoning there needs to be.

This looks fishy though:

Code:

{
      "file":"\/var\/app\/current\/codeigniter\/application\/libraries\/Session\/MY_Session.php",
      "line":9,
      "function":"session_write_close",
      "args":[

      ]
   },