Tracks the current state of workers, data, and computations.
Handles transitions between different task states. Notifies the Scheduler of changes by messaging passing through Queues, which the Scheduler listens to responds accordingly.
All events are handled quickly, in linear time with respect to their input (which is often of constant size) and generally within a millisecond. Additionally when Cythonized, this can be faster still. To accomplish this the scheduler tracks a lot of state. Every operation maintains the consistency of this state.
Users typically do not interact with Transitions
directly. Instead users interact with the Client
, which in turn engages the Scheduler
affecting different transitions here under-the-hood. In the background Worker``s also engage with the ``Scheduler
affecting these state transitions as well.
State
The Transitions
object contains the following state variables. Each variable is listed along with what it stores and a brief description.
tasks: {task key: TaskState}
Tasks currently known to the scheduler
unrunnable: {TaskState}
Tasks in the "no-worker" state
workers: {worker key: WorkerState}
Workers currently connected to the scheduler
idle: {WorkerState}
:
Set of workers that are not fully utilized
saturated: {WorkerState}
:
Set of workers that are not over-utilized
running: {WorkerState}
:
Set of workers that are currently in running state
clients: {client key: ClientState}
Clients currently connected to the scheduler
task_duration: {key-prefix: time}
Time we expect certain functions to take, e.g. {'sum': 0.25}
Underlying task state of dynamic scheduler
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