I would, on the whole, usually rather have a deadlock than a race since they tend to crash rather than silently corrupt state ... and the ones that cause retrie

I would, on the whole, usually rather have a deadlock than a race since they tend to crash rather than silently corrupt state ... and the ones that cause retries rather than crashes tend to show up in the profiler. But that's an "err on the side of" rule of thumb rather than a defence of blindly locking things.