Alive key does not expire

[Qwasser]

Hello!
I have built a doRedis cluster and currently running long term computations. After 1-2 days of computation cluster stucks. Stopping all workers does not help.
Last time it happened i checked redis keys and sow thet there was one "alive" key not expiring. I have manualy expired it and the job contined. I think there are several possibilities why this happens:

1. Some R worker thread somehow stucked in a loop (I am pretty shure that I stopped all threads but next time I will check more acuratelly)
2. setOK thread can not determine that R thread stoped (Is it possible?)
3. Expiration time was not set by setOK thread while alive key was created.