src/worker/WorkerSet.ts

   1 // Partial Copyright Jerome Benoit. 2021-2023. All Rights Reserved.
   2
   3 import { EventEmitter } 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: EventEmitter;
  20   private readonly workerSet: Set<WorkerSetElement>;
  21
  22   /**
  23    * Creates a new `WorkerSet`.
  24    *
  25    * @param workerScript -
  26    * @param workerOptions -
  27    */
  28   constructor(workerScript: string, workerOptions?: WorkerOptions) {
  29     super(workerScript, workerOptions);
  30     this.workerOptions.poolOptions = {
  31       ...{
  32         enableEvents: true,
  33         restartWorkerOnError: true,
  34       },
  35       ...this.workerOptions.poolOptions,
  36     };
  37     this.workerSet = new Set<WorkerSetElement>();
  38     if (this.workerOptions?.poolOptions?.enableEvents) {
  39       this.emitter = new EventEmitter();
  40     }
  41   }
  42
  43   get info(): SetInfo {
  44     return {
  45       version: WorkerConstants.version,
  46       type: 'set',
  47       worker: 'thread',
  48       size: this.size,
  49       elementsExecuting: [...this.workerSet].reduce(
  50         (accumulator, workerSetElement) => accumulator + workerSetElement.numberOfWorkerElements,
  51         0
  52       ),
  53       elementsPerWorker: this.maxElementsPerWorker,
  54     };
  55   }
  56
  57   get size(): number {
  58     return this.workerSet.size;
  59   }
  60
  61   get maxElementsPerWorker(): number | undefined {
  62     return this.workerOptions.elementsPerWorker;
  63   }
  64
  65   /** @inheritDoc */
  66   public async start(): Promise<void> {
  67     this.addWorkerSetElement();
  68     // Add worker set element sequentially to optimize memory at startup
  69     this.workerOptions.workerStartDelay > 0 && (await sleep(this.workerOptions.workerStartDelay));
  70   }
  71
  72   /** @inheritDoc */
  73   public async stop(): Promise<void> {
  74     for (const workerSetElement of this.workerSet) {
  75       await workerSetElement.worker.terminate();
  76     }
  77     this.workerSet.clear();
  78   }
  79
  80   /** @inheritDoc */
  81   public async addElement(elementData: WorkerData): Promise<void> {
  82     if (!this.workerSet) {
  83       throw new Error("Cannot add a WorkerSet element: workers' set does not exist");
  84     }
  85     const workerSetElement = await this.getWorkerSetElement();
  86     workerSetElement.worker.postMessage({
  87       id: WorkerMessageEvents.startWorkerElement,
  88       data: elementData,
  89     });
  90     ++workerSetElement.numberOfWorkerElements;
  91     // Add element sequentially to optimize memory at startup
  92     if (this.workerOptions.elementStartDelay > 0) {
  93       await sleep(this.workerOptions.elementStartDelay);
  94     }
  95   }
  96
  97   /**
  98    * Adds a new `WorkerSetElement`.
  99    */
 100   private addWorkerSetElement(): WorkerSetElement {
 101     const worker = new Worker(this.workerScript, {
 102       env: SHARE_ENV,
 103       ...this.workerOptions.poolOptions.workerOptions,
 104     });
 105     worker.on(
 106       'message',
 107       this.workerOptions?.poolOptions?.messageHandler ?? WorkerConstants.EMPTY_FUNCTION
 108     );
 109     worker.on(
 110       'error',
 111       this.workerOptions?.poolOptions?.errorHandler ?? WorkerConstants.EMPTY_FUNCTION
 112     );
 113     worker.on('error', (error) => {
 114       if (this.emitter !== undefined) {
 115         this.emitter.emit(WorkerSetEvents.error, error);
 116       }
 117       if (this.workerOptions?.poolOptions?.restartWorkerOnError) {
 118         this.addWorkerSetElement();
 119       }
 120     });
 121     worker.on(
 122       'online',
 123       this.workerOptions?.poolOptions?.onlineHandler ?? WorkerConstants.EMPTY_FUNCTION
 124     );
 125     worker.on(
 126       'exit',
 127       this.workerOptions?.poolOptions?.exitHandler ?? WorkerConstants.EMPTY_FUNCTION
 128     );
 129     worker.once('exit', () => this.workerSet.delete(this.getWorkerSetElementByWorker(worker)));
 130     const workerSetElement: WorkerSetElement = { worker, numberOfWorkerElements: 0 };
 131     this.workerSet.add(workerSetElement);
 132     return workerSetElement;
 133   }
 134
 135   private async getWorkerSetElement(): Promise<WorkerSetElement> {
 136     let chosenWorkerSetElement: WorkerSetElement;
 137     for (const workerSetElement of this.workerSet) {
 138       if (workerSetElement.numberOfWorkerElements < this.workerOptions.elementsPerWorker) {
 139         chosenWorkerSetElement = workerSetElement;
 140         break;
 141       }
 142     }
 143     if (!chosenWorkerSetElement) {
 144       chosenWorkerSetElement = this.addWorkerSetElement();
 145       // Add worker set element sequentially to optimize memory at startup
 146       this.workerOptions.workerStartDelay > 0 && (await sleep(this.workerOptions.workerStartDelay));
 147     }
 148     return chosenWorkerSetElement;
 149   }
 150
 151   private getWorkerSetElementByWorker(worker: Worker): WorkerSetElement | undefined {
 152     let workerSetElt: WorkerSetElement;
 153     for (const workerSetElement of this.workerSet) {
 154       if (workerSetElement.worker.threadId === worker.threadId) {
 155         workerSetElt = workerSetElement;
 156         break;
 157       }
 158     }
 159     return workerSetElt;
 160   }
 161 }