ETL should be reactive #2838
Description
Issue Description
Current design of the ETL's taskman is proactive rather than reactive. There should not be need to sleep/wait inside of taskman threads - everything should be more reactive and threads should not have to sleep arbitrary amount of time.
In #2802 we add a workaround which makes the ETL fast enough to rival the old implementation. However this is not a proper fix so let's do it right.