-import { EventEmitter } from 'events'
-import type { FixedClusterPoolOptions, WorkerWithMessageChannel } from './fixed'
+import type { Worker } from 'cluster'
+import type { JSONValue } from '../../utility-types'
+import { isKillBehavior, KillBehaviors } from '../../worker/worker-options'
+import type { ClusterPoolOptions } from './fixed'
import { FixedClusterPool } from './fixed'
-class MyEmitter extends EventEmitter {}
-
-export type DynamicClusterPoolOptions = FixedClusterPoolOptions
-
/**
- * A cluster pool with a min/max number of workers, is possible to execute tasks in sync or async mode as you prefer.
+ * 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, an event is emitted. If you want to listen to this event, use the pool's `emitter`.
*
- * This cluster pool will create new workers when the other ones are busy, until the max number of workers,
- * when the max number of workers is reached, an event will be emitted, if you want to listen this event use the emitter method.
+ * @template Data Type of data sent to the worker.
+ * @template Response Type of response of execution.
*
* @author [Christopher Quadflieg](https://github.com/Shinigami92)
* @since 2.0.0
*/
export class DynamicClusterPool<
- // eslint-disable-next-line @typescript-eslint/no-explicit-any
- Data = any,
- // eslint-disable-next-line @typescript-eslint/no-explicit-any
- Response = any
+ Data extends JSONValue = JSONValue,
+ Response extends JSONValue = JSONValue
> extends FixedClusterPool<Data, Response> {
- public readonly emitter: MyEmitter
-
/**
- * @param min Min number of workers that will be always active
- * @param max Max number of workers that will be active
- * @param filename A file path with implementation of `ClusterWorker` class, relative path is fine.
- * @param opts An object with possible options for example `errorHandler`, `onlineHandler`. Default: `{ maxTasks: 1000 }`
+ * Constructs a new poolifier dynamic cluster pool.
+ *
+ * @param min Minimum number of workers which are always active.
+ * @param max Maximum number of workers that can be created by this pool.
+ * @param filePath Path to an implementation of a `ClusterWorker` file, which can be relative or absolute.
+ * @param opts Options for this dynamic cluster pool. Default: `{ maxTasks: 1000 }`
*/
public constructor (
- public readonly min: number,
+ min: number,
public readonly max: number,
- public readonly filename: string,
- public readonly opts: DynamicClusterPoolOptions = { maxTasks: 1000 }
+ filePath: string,
+ opts: ClusterPoolOptions = { maxTasks: 1000 }
) {
- super(min, filename, opts)
-
- this.emitter = new MyEmitter()
+ super(min, filePath, opts)
}
- protected chooseWorker (): WorkerWithMessageChannel {
- let worker: WorkerWithMessageChannel | undefined
- for (const entry of this.tasks) {
- if (entry[1] === 0) {
- worker = entry[0]
- break
+ /**
+ * Choose a worker for the next task.
+ *
+ * It will first check for and return an idle worker.
+ * If all workers are busy, then it will try to create a new one up to the `max` worker count.
+ * If the max worker count is reached, the emitter will emit a `FullPool` event and it will fall back to using a round robin algorithm to distribute the load.
+ *
+ * @returns Cluster worker.
+ */
+ protected chooseWorker (): Worker {
+ for (const [worker, numberOfTasks] of this.tasks) {
+ if (numberOfTasks === 0) {
+ // A worker is free, use it
+ return worker
}
}
- if (worker) {
- // a worker is free, use it
- return worker
- } else {
- if (this.workers.length === this.max) {
- this.emitter.emit('FullPool')
- return super.chooseWorker()
- }
- // all workers are busy create a new worker
- const worker = this.newWorker()
- worker.on('message', (message: { kill?: number }) => {
- if (message.kill) {
- worker.send({ kill: 1 })
- worker.kill()
- // clean workers from data structures
- const workerIndex = this.workers.indexOf(worker)
- this.workers.splice(workerIndex, 1)
- this.tasks.delete(worker)
- }
- })
- return worker
+ if (this.workers.length === this.max) {
+ this.emitter.emit('FullPool')
+ return super.chooseWorker()
}
+
+ // All workers are busy, create a new worker
+ const workerCreated = this.createAndSetupWorker()
+ this.registerWorkerMessageListener<Data>(workerCreated, message => {
+ const tasksInProgress = this.tasks.get(workerCreated)
+ if (
+ isKillBehavior(KillBehaviors.HARD, message.kill) ||
+ tasksInProgress === 0
+ ) {
+ // Kill received from the worker, means that no new tasks are submitted to that worker for a while ( > maxInactiveTime)
+ void this.destroyWorker(workerCreated)
+ }
+ })
+ return workerCreated
}
}