Two Agents, One Local Model: Do They Run in Parallel, or Take Turns? I Measured It.
A reader asked what happens if I run two local coding agents against the same Qwen 3.8 model on one Mac at the same time. I thought I knew the answer. I was wrong. So I read the server source, wrote a barrier-synchronized load driver to remove the human-ordering bias, and measured it. Batching is real up to 32 wide, but it is not free, and three innocent-looking choices collapse it back to a single lane.
A reader on Reddit asked me a sharp question about my last post. I had trialed a second local coding agent, Hermes, pointed at the same local Qwen 3.8 model my other agent already uses. His question was simple. Did I ever run both agents at the same time, two separate harnesses hammering one model on one Mac at once. And what about Hermes spawning its own sub-agents against that same endpoint. Is any of that predictable.
