module Throttle:sig..end
start_job
before beginning work and must call finish_job once, and only once, when a job is
completed.typet = privateLimiter.limiter
val create_exn : now:Time.t -> max_concurrent_jobs:int -> t
val try_start_job : t -> now:Time.t -> [ `Max_concurrent_jobs_running | `Start ]
val finish_job : t -> now:Time.t -> unit