src/worker/WorkerSet.ts

   1 // Partial Copyright Jerome Benoit. 2021-2023. All Rights Reserved.
   2
   3 import EventEmitterAsyncResource from 'node:events';
   4 import { SHARE_ENV, Worker } from 'node:worker_threads';
   5
   6 import { WorkerAbstract } from './WorkerAbstract';
   7 import { WorkerConstants } from './WorkerConstants';
   8 import {
   9   type SetInfo,
  10   type WorkerData,
  11   WorkerMessageEvents,
  12   type WorkerOptions,
  13   type WorkerSetElement,
  14   WorkerSetEvents,
  15 } from './WorkerTypes';
  16 import { sleep } from './WorkerUtils';
  17
  18 export class WorkerSet extends WorkerAbstract<WorkerData> {
  19   public readonly emitter: EventEmitterAsyncResource;
  20   private readonly workerSet: Set<WorkerSetElement>;
  21
  22   /**
  23    * Create a new `WorkerSet`.
  24    *
  25    * @param workerScript -
  26    * @param workerOptions -
  27    */
  28   constructor(workerScript: string, workerOptions?: WorkerOptions) {
  29     super(workerScript, workerOptions);
  30     this.workerSet = new Set<WorkerSetElement>();
  31     this.emitter = new EventEmitterAsyncResource();
  32   }
  33
  34   get info(): SetInfo {
  35     return {
  36       size: this.size,
  37       runningElements: [...this.workerSet].reduce(
  38         (accumulator, workerSetElement) => accumulator + workerSetElement.numberOfWorkerElements,
  39         0
  40       ),
  41       elementsPerWorker: this.maxElementsPerWorker,
  42     };
  43   }
  44
  45   get size(): number {
  46     return this.workerSet.size;
  47   }
  48
  49   get maxElementsPerWorker(): number | undefined {
  50     return this.workerOptions.elementsPerWorker;
  51   }
  52
  53   /** @inheritDoc */
  54   public async start(): Promise<void> {
  55     this.addWorkerSetElement();
  56     // Add worker set element sequentially to optimize memory at startup
  57     this.workerOptions.workerStartDelay > 0 && (await sleep(this.workerOptions.workerStartDelay));
  58   }
  59
  60   /** @inheritDoc */
  61   public async stop(): Promise<void> {
  62     for (const workerSetElement of this.workerSet) {
  63       await workerSetElement.worker.terminate();
  64     }
  65     this.workerSet.clear();
  66   }
  67
  68   /** @inheritDoc */
  69   public async addElement(elementData: WorkerData): Promise<void> {
  70     if (!this.workerSet) {
  71       throw new Error("Cannot add a WorkerSet element: workers' set does not exist");
  72     }
  73     const workerSetElement = await this.getWorkerSetElement();
  74     workerSetElement.worker.postMessage({
  75       id: WorkerMessageEvents.startWorkerElement,
  76       data: elementData,
  77     });
  78     ++workerSetElement.numberOfWorkerElements;
  79     // Add element sequentially to optimize memory at startup
  80     if (this.workerOptions.elementStartDelay > 0) {
  81       await sleep(this.workerOptions.elementStartDelay);
  82     }
  83   }
  84
  85   /**
  86    * Add a new `WorkerSetElement`.
  87    */
  88   private addWorkerSetElement(): WorkerSetElement {
  89     const worker = new Worker(this.workerScript, {
  90       env: SHARE_ENV,
  91       ...this.workerOptions.poolOptions.workerOptions,
  92     });
  93     worker.on(
  94       'message',
  95       this.workerOptions?.poolOptions?.messageHandler ?? WorkerConstants.EMPTY_FUNCTION
  96     );
  97     worker.on(
  98       'error',
  99       this.workerOptions?.poolOptions?.errorHandler ?? WorkerConstants.EMPTY_FUNCTION
 100     );
 101     worker.on('error', (error) => {
 102       this.emitter.emit(WorkerSetEvents.error, error);
 103       this.addWorkerSetElement();
 104     });
 105     worker.on(
 106       'online',
 107       this.workerOptions?.poolOptions?.onlineHandler ?? WorkerConstants.EMPTY_FUNCTION
 108     );
 109     worker.on(
 110       'exit',
 111       this.workerOptions?.poolOptions?.exitHandler ?? WorkerConstants.EMPTY_FUNCTION
 112     );
 113     worker.on('exit', () => this.workerSet.delete(this.getWorkerSetElementByWorker(worker)));
 114     const workerSetElement: WorkerSetElement = { worker, numberOfWorkerElements: 0 };
 115     this.workerSet.add(workerSetElement);
 116     return workerSetElement;
 117   }
 118
 119   private async getWorkerSetElement(): Promise<WorkerSetElement> {
 120     let chosenWorkerSetElement: WorkerSetElement;
 121     for (const workerSetElement of this.workerSet) {
 122       if (workerSetElement.numberOfWorkerElements < this.workerOptions.elementsPerWorker) {
 123         chosenWorkerSetElement = workerSetElement;
 124         break;
 125       }
 126     }
 127     if (!chosenWorkerSetElement) {
 128       chosenWorkerSetElement = this.addWorkerSetElement();
 129       // Add worker set element sequentially to optimize memory at startup
 130       this.workerOptions.workerStartDelay > 0 && (await sleep(this.workerOptions.workerStartDelay));
 131     }
 132     return chosenWorkerSetElement;
 133   }
 134
 135   private getWorkerSetElementByWorker(worker: Worker): WorkerSetElement | undefined {
 136     let workerSetElt: WorkerSetElement;
 137     for (const workerSetElement of this.workerSet) {
 138       if (workerSetElement.worker.threadId === worker.threadId) {
 139         workerSetElt = workerSetElement;
 140         break;
 141       }
 142     }
 143     return workerSetElt;
 144   }
 145 }