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