module Ord: sig .. end
type Mapred_tasks.task
val compare : Mapred_tasks.task -> Mapred_tasks.task -> int
Compare here the tasks in an execution-friendly order, i.e. so that
Mapred_sched.executable_tasks returns a reasonably ordered list.
Sorting:
- `Map < `Sort < `Shuffle
- within map and sort, just sort by ID
- Shuffle: sort first by round (look at map_id delta, and at span
of partitions), then by IDs
