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       const workerExitPromise = new Promise<void>((resolve) => {
  76         workerSetElement.worker.on('exit', () => {
  77           resolve();
  78         });
  79       });
  80       await workerSetElement.worker.terminate();
  81       await workerExitPromise;
  82     }
  83     this.workerSet.clear();
  84   }
  85
  86   /** @inheritDoc */
  87   public async addElement(elementData: WorkerData): Promise<void> {
  88     if (!this.workerSet) {
  89       throw new Error("Cannot add a WorkerSet element: workers' set does not exist");
  90     }
  91     const workerSetElement = await this.getWorkerSetElement();
  92     workerSetElement.worker.postMessage({
  93       id: WorkerMessageEvents.startWorkerElement,
  94       data: elementData,
  95     });
  96     ++workerSetElement.numberOfWorkerElements;
  97     // Add element sequentially to optimize memory at startup
  98     if (this.workerOptions.elementStartDelay > 0) {
  99       await sleep(this.workerOptions.elementStartDelay);
 100     }
 101   }
 102
 103   /**
 104    * Adds a new `WorkerSetElement`.
 105    */
 106   private addWorkerSetElement(): WorkerSetElement {
 107     const worker = new Worker(this.workerScript, {
 108       env: SHARE_ENV,
 109       ...this.workerOptions.poolOptions.workerOptions,
 110     });
 111     worker.on(
 112       'message',
 113       this.workerOptions?.poolOptions?.messageHandler ?? WorkerConstants.EMPTY_FUNCTION
 114     );
 115     worker.on(
 116       'error',
 117       this.workerOptions?.poolOptions?.errorHandler ?? WorkerConstants.EMPTY_FUNCTION
 118     );
 119     worker.on('error', (error) => {
 120       if (this.emitter !== undefined) {
 121         this.emitter.emit(WorkerSetEvents.error, error);
 122       }
 123       if (this.workerOptions?.poolOptions?.restartWorkerOnError) {
 124         this.addWorkerSetElement();
 125       }
 126     });
 127     worker.on(
 128       'online',
 129       this.workerOptions?.poolOptions?.onlineHandler ?? WorkerConstants.EMPTY_FUNCTION
 130     );
 131     worker.on(
 132       'exit',
 133       this.workerOptions?.poolOptions?.exitHandler ?? WorkerConstants.EMPTY_FUNCTION
 134     );
 135     worker.once('exit', () =>
 136       this.removeWorkerSetElement(this.getWorkerSetElementByWorker(worker))
 137     );
 138     const workerSetElement: WorkerSetElement = { worker, numberOfWorkerElements: 0 };
 139     this.workerSet.add(workerSetElement);
 140     return workerSetElement;
 141   }
 142
 143   private removeWorkerSetElement(workerSetElement: WorkerSetElement): void {
 144     this.workerSet.delete(workerSetElement);
 145   }
 146
 147   private async getWorkerSetElement(): Promise<WorkerSetElement> {
 148     let chosenWorkerSetElement: WorkerSetElement;
 149     for (const workerSetElement of this.workerSet) {
 150       if (workerSetElement.numberOfWorkerElements < this.workerOptions.elementsPerWorker) {
 151         chosenWorkerSetElement = workerSetElement;
 152         break;
 153       }
 154     }
 155     if (!chosenWorkerSetElement) {
 156       chosenWorkerSetElement = this.addWorkerSetElement();
 157       // Add worker set element sequentially to optimize memory at startup
 158       this.workerOptions.workerStartDelay > 0 && (await sleep(this.workerOptions.workerStartDelay));
 159     }
 160     return chosenWorkerSetElement;
 161   }
 162
 163   private getWorkerSetElementByWorker(worker: Worker): WorkerSetElement | undefined {
 164     let workerSetElt: WorkerSetElement;
 165     for (const workerSetElement of this.workerSet) {
 166       if (workerSetElement.worker.threadId === worker.threadId) {
 167         workerSetElt = workerSetElement;
 168         break;
 169       }
 170     }
 171     return workerSetElt;
 172   }
 173 }