AtomicInteger = bus locking. Not a big deal but potentially stealing cycles from everybody.
Linear Ring buffer = false sharing extravaganza.
jobs are processed FIFO...meh.
small jobs = very inefficient, esp if they don't happen to be the same code/linear data and happen to go to the same worker.
large jobs = potentially long latency...job submission to completion.
I can't think of a game client reason to use this model. And like I said earlier I can't think of a reason to be anything other than SPSC. Strawman example: Take an audio processing thread. Of course it's completely reasonable to have multiple threads wanting to send commands to it, but there's no reason for it to be through a single communication channel.
I'm only thinking about consumer grade hardware. Otherwise we're talking about MMO server code...and anyone ready for that doesn't need this conversation. Consider:
1) Is there any major paradigm shift in CPU ISAs on the horizion? No.
2) How fast is the number of physical cores growing? It's complete stagnated.
3) How likely are we to see multi-socket consumer devices soon. Not very.
And even if I'm wrong on any of these points it doesn't really matter because it'll be years before penetration is large enough to be worth considering. So SPSC is completely viable for the foreseeable future.