import { EventEmitter } from 'node:events'
+import { type TransferListItem } from 'node:worker_threads'
import type {
ErrorHandler,
ExitHandler,
* Enumeration of pool events.
*/
export const PoolEvents = Object.freeze({
- full: 'full',
ready: 'ready',
busy: 'busy',
+ full: 'full',
+ destroy: 'destroy',
error: 'error',
- taskError: 'taskError'
+ taskError: 'taskError',
+ backPressure: 'backPressure'
} as const)
/**
readonly strategy: WorkerChoiceStrategy
readonly minSize: number
readonly maxSize: number
- /** Pool utilization ratio. */
+ /** Pool utilization. */
readonly utilization?: number
- /** Pool total worker nodes */
+ /** Pool total worker nodes. */
readonly workerNodes: number
- /** Pool idle worker nodes */
+ /** Pool idle worker nodes. */
readonly idleWorkerNodes: number
- /** Pool busy worker nodes */
+ /** Pool busy worker nodes. */
readonly busyWorkerNodes: number
readonly executedTasks: number
readonly executingTasks: number
- readonly queuedTasks: number
- readonly maxQueuedTasks: number
+ readonly queuedTasks?: number
+ readonly maxQueuedTasks?: number
+ readonly backPressure?: boolean
readonly failedTasks: number
readonly runTime?: {
readonly minimum: number
* @typeParam Worker - Type of worker.
*/
export interface PoolOptions<Worker extends IWorker> {
+ /**
+ * A function that will listen for online event on each worker.
+ */
+ onlineHandler?: OnlineHandler<Worker>
/**
* A function that will listen for message event on each worker.
*/
* A function that will listen for error event on each worker.
*/
errorHandler?: ErrorHandler<Worker>
- /**
- * A function that will listen for online event on each worker.
- */
- onlineHandler?: OnlineHandler<Worker>
/**
* A function that will listen for exit event on each worker.
*/
readonly info: PoolInfo
/**
* Pool worker nodes.
+ *
+ * @internal
*/
readonly workerNodes: Array<IWorkerNode<Worker, Data>>
+ /**
+ * Whether the worker node has back pressure (i.e. its tasks queue is full).
+ *
+ * @param workerNodeKey - The worker node key.
+ * @returns `true` if the worker node has back pressure, `false` otherwise.
+ * @internal
+ */
+ readonly hasWorkerNodeBackPressure: (workerNodeKey: number) => boolean
/**
* Emitter on which events can be listened to.
*
* Events that can currently be listened to:
*
- * - `'full'`: Emitted when the pool is dynamic and the number of workers created has reached the maximum size expected.
- * - `'ready'`: Emitted when the number of workers created in the pool has reached the maximum size expected and are ready.
+ * - `'ready'`: Emitted when the number of workers created in the pool has reached the minimum size expected and are ready.
* - `'busy'`: Emitted when the number of workers created in the pool has reached the maximum size expected and are executing at least one task.
+ * - `'full'`: Emitted when the pool is dynamic and the number of workers created has reached the maximum 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 \>= pool maximum size^2).
*/
readonly emitter?: PoolEmitter
/**
* Executes the specified function in the worker constructor with the task data input parameter.
*
- * @param data - The task input data for the specified worker function. This can only be structured-cloneable data.
- * @param name - The name of the worker function to execute. If not specified, the default worker function will be executed.
+ * @param data - The optional task input data for the specified task function. This can only be structured-cloneable data.
+ * @param name - The optional name of the task function to execute. If not specified, the default task function will be executed.
+ * @param transferList - An optional array of transferable objects to transfer ownership of. Ownership of the transferred objects is given to the pool's worker_threads worker and they should not be used in the main thread afterwards.
* @returns Promise that will be fulfilled when the task is completed.
*/
- readonly execute: (data?: Data, name?: string) => Promise<Response>
+ readonly execute: (
+ data?: Data,
+ name?: string,
+ transferList?: TransferListItem[]
+ ) => Promise<Response>
/**
- * Terminates every current worker in this pool.
+ * Terminates all workers in this pool.
*/
readonly destroy: () => Promise<void>
+ /**
+ * Lists the names of task function available in this pool.
+ *
+ * @returns The names of task function available in this pool.
+ */
+ readonly listTaskFunctions: () => string[]
/**
* Sets the worker choice strategy in this pool.
*