Class DynamicClusterPool<Data, Response>

A cluster pool with a dynamic number of workers, but a guaranteed minimum number of workers.

This cluster pool creates new workers when the others are busy, up to the maximum number of workers. When the maximum number of workers is reached and workers are busy, an event is emitted. If you want to listen to this event, use the pool's emitter.

Author

Christopher Quadflieg

Since

2.0.0

Type Parameters

  • Data = unknown

    Type of data sent to the worker. This can only be structured-cloneable data.

  • Response = unknown

    Type of execution response. This can only be structured-cloneable data.

Hierarchy (view full)

Constructors

Properties

emitter?: EventEmitterAsyncResource

Event emitter integrated with async resource on which events can be listened to. The async tracking tooling identifier is poolifier:<PoolType>-<WorkerType>-pool.

Events that can currently be listened to:

  • 'ready': Emitted when the number of workers created in the pool has reached the minimum size expected and are ready. If the pool is dynamic with a minimum number of workers is set to zero, this event is emitted when at least one dynamic worker is ready.
  • 'busy': Emitted when the number of workers created in the pool has reached the maximum size expected and are executing concurrently their tasks quota.
  • 'full': Emitted when the pool is dynamic and the number of workers created has reached the maximum size expected.
  • 'empty': Emitted when the pool is dynamic with a minimum number of workers set to zero and the number of workers has reached the minimum size expected.
  • 'destroy': Emitted when the pool is destroyed.
  • 'error': Emitted when an uncaught error occurs.
  • 'taskError': Emitted when an error occurs while executing a task.
  • 'backPressure': Emitted when all worker nodes have back pressure (i.e. their tasks queue is full: queue size >= maximum queue size).
filePath: string

Path to the worker file.

maximumNumberOfWorkers?: number

Maximum number of workers that this pool manages.

minimumNumberOfWorkers: number

Minimum number of workers that this pool manages.

opts: PoolOptions<Worker>

Options for the pool.

promiseResponseMap: Map<string, PromiseResponseWrapper<Response>> = ...

The task execution response promise map:

  • key: The message id of each submitted task.
  • value: An object that contains the worker, the execution response promise resolve and reject callbacks.

When we receive a message from the worker, we get a map entry with the promise resolve/reject bound to the message id.

workerChoiceStrategyContext?: WorkerChoiceStrategyContext<Worker, Data, Response>

Worker choice strategy context referencing a worker choice algorithm implementation.

workerNodes: IWorkerNode<Worker, Data>[] = []

Pool worker nodes.

Accessors

  • get busy(): boolean
  • Whether the pool is busy or not.

    The pool busyness boolean status.

    Returns boolean

  • get full(): boolean
  • Whether the pool is full or not.

    The pool filling boolean status.

    Returns boolean

  • get type(): "fixed" | "dynamic"
  • The pool type.

    If it is 'dynamic', it provides the max property.

    Returns "fixed" | "dynamic"

  • get utilization(): number
  • The approximate pool utilization.

    Returns number

    The pool utilization.

  • get worker(): "thread" | "cluster"
  • The worker type.

    Returns "thread" | "cluster"

Methods

  • Executes the specified function in the worker constructor with the task data input parameter.

    Parameters

    • Optional data: Data

      The optional task input data for the specified task function. This can only be structured-cloneable data.

    • Optional name: string

      The optional name of the task function to execute. If not specified, the default task function will be executed.

    • Optional transferList: TransferListItem[]

      An optional array of transferable objects to transfer ownership of. Ownership of the transferred objects is given to the chosen pool's worker_threads worker and they should not be used in the main thread afterwards.

    Returns Promise<Response>

    Promise that will be fulfilled when the task is completed.

  • Sets the worker choice strategy in this pool.

    Parameters

    • workerChoiceStrategy: "ROUND_ROBIN" | "LEAST_USED" | "LEAST_BUSY" | "LEAST_ELU" | "FAIR_SHARE" | "WEIGHTED_ROUND_ROBIN" | "INTERLEAVED_WEIGHTED_ROUND_ROBIN"

      The worker choice strategy.

    • Optional workerChoiceStrategyOptions: WorkerChoiceStrategyOptions

      The worker choice strategy options.

    Returns void

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