I had a worker called amazon_wish_list_importing_worker.
Attempting to use this worker gave the error:
failed to find slave socket </tmp/backgroundrb.21378/amazon_wish_list_importing_worker_14a6109786d0d0142bfc1d9e180655b9_0_0.17425047650004> - (RuntimeError?)
The actual socket file that got created was:
amazon_wish_list_importing_worker_14a6109786d0d0142bfc1d9e180655b9_0_0.174250
This appears to be missing the last eight characters. This would indicate that the maximum worker filename size is 25 characters.
The simplest resolution is probably to throw an error on starting the server, when the worker classes are first loaded, indicating which class name is two long.