I'm sorry but I fail to find how this is relevant. TSR was an old simple trick in achieving a likeliness of non-preemptive multitasking on an operating system

I'm sorry but I fail to find how this is relevant. TSR was an old simple trick in achieving a likeliness of non-preemptive multitasking on an operating system that didn't have any multitasking, but only one single active process. Sidekiq (or Celery or nearly any task runner system) are designed for multitasking operating systems and they all keep the master process running, spawning/forking worker processes (or threads or whatever primitives they use for concurrency) as needed. They don't use CPU interrupts to stay active (IRQs aren't particularly accessible to user space), as most queue systems don't exactly allow it - typically they have a sleep-poll-repeat cycle. Though if the queue system allows it they may sleep waiting for I/O (which, in turn, indeed, could be triggered by an IRQ), but that's the closest resemblance I can find - and it's quite a stretch.