-import type { JSONValue, MessageValue } from '../../utility-types'
+import type { JSONValue } from '../../utility-types'
+import { isKillBehavior, KillBehaviors } from '../../worker/worker-options'
import type { PoolOptions } from '../abstract-pool'
import type { ThreadWorkerWithMessageChannel } from './fixed'
import { FixedThreadPool } from './fixed'
/**
- * A thread pool with a min/max number of threads, is possible to execute tasks in sync or async mode as you prefer.
+ * A thread pool with a dynamic number of threads, but a guaranteed minimum number of threads.
*
- * This thread pool will create new workers when the other ones are busy, until the max number of threads,
- * when the max number of threads is reached, an event will be emitted, if you want to listen this event use the emitter method.
+ * This thread pool creates new threads when the others are busy, up to the maximum number of threads.
+ * When the maximum number of threads is reached, an event is emitted. If you want to listen to this event, use the pool's `emitter`.
+ *
+ * @template Data Type of data sent to the worker.
+ * @template Response Type of response of execution.
*
* @author [Alessandro Pio Ardizio](https://github.com/pioardi)
* @since 0.0.1
Response extends JSONValue = JSONValue
> extends FixedThreadPool<Data, Response> {
/**
- * @param min Min number of threads that will be always active
- * @param max Max number of threads that will be active
- * @param filename A file path with implementation of `ThreadWorker` class, relative path is fine.
- * @param opts An object with possible options for example `errorHandler`, `onlineHandler`. Default: `{ maxTasks: 1000 }`
+ * Constructs a new poolifier dynamic thread pool.
+ *
+ * @param min Minimum number of threads which are always active.
+ * @param max Maximum number of threads that can be created by this pool.
+ * @param filePath Path to an implementation of a `ThreadWorker` file, which can be relative or absolute.
+ * @param opts Options for this dynamic thread pool. Default: `{ maxTasks: 1000 }`
*/
public constructor (
min: number,
public readonly max: number,
- filename: string,
+ filePath: string,
opts: PoolOptions<ThreadWorkerWithMessageChannel> = { maxTasks: 1000 }
) {
- super(min, filename, opts)
+ super(min, filePath, opts)
}
+ /**
+ * Choose a thread for the next task.
+ *
+ * It will first check for and return an idle thread.
+ * If all threads are busy, then it will try to create a new one up to the `max` thread count.
+ * If the max thread 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 Thread worker.
+ */
protected chooseWorker (): ThreadWorkerWithMessageChannel {
- let worker: ThreadWorkerWithMessageChannel | undefined
- for (const entry of this.tasks) {
- if (entry[1] === 0) {
- worker = entry[0]
- break
+ 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.internalNewWorker()
- worker.port2?.on('message', (message: MessageValue<Data>) => {
- if (message.kill) {
- this.sendToWorker(worker, { kill: 1 })
- void this.destroyWorker(worker)
- this.removeWorker(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
}
}