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