> > My question is - if the slaves to execute the tasks are decided by the > scheduler, how does the DRF get used by the master in balancing the slaves? > Does it not get used for choosing the right slaves for the tasks? Relevant > pointers to the code are also welcome. >
I think the DRF allocator (hierarchical.cpp) is mainly used to balance the fair share of roles/frameworks rather than slaves, and it does not get used for choosing the right slaves for tasks (since it has no idea about tasks) which is the responsibility of framework scheduler, instead it is responsible for sending slaves to framework scheduler as resource offer and such process can be affected by framework scheduler as well, e.g., framework scheduler sets filter to refuse a specific slave for a specific duration, https://github.com/apache/mesos/blob/0.26.0/src/master/allocator/mesos/hierarchical.cpp#L761:L806
