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 { EMPTY_FUNCTION, workerSetVersion } from './WorkerConstants';
   8 import {
   9   type SetInfo,
  10   type WorkerData,
  11   type WorkerMessage,
  12   WorkerMessageEvents,
  13   type WorkerOptions,
  14   type WorkerSetElement,
  15   WorkerSetEvents,
  16 } from './WorkerTypes';
  17 import { randomizeDelay, sleep } from './WorkerUtils';
  18
  19 export class WorkerSet extends WorkerAbstract<WorkerData> {
  20   public readonly emitter: EventEmitterAsyncResource | undefined;
  21   private readonly workerSet: Set<WorkerSetElement>;
  22   private started: boolean;
  23   private workerStartup: boolean;
  24
  25   /**
  26    * Creates a new `WorkerSet`.
  27    *
  28    * @param workerScript -
  29    * @param workerOptions -
  30    */
  31   constructor(workerScript: string, workerOptions: WorkerOptions) {
  32     super(workerScript, workerOptions);
  33     if (
  34       this.workerOptions.elementsPerWorker === null ||
  35       this.workerOptions.elementsPerWorker === undefined
  36     ) {
  37       throw new TypeError('Elements per worker is not defined');
  38     }
  39     if (!Number.isSafeInteger(this.workerOptions.elementsPerWorker)) {
  40       throw new TypeError('Elements per worker must be an integer');
  41     }
  42     if (this.workerOptions.elementsPerWorker <= 0) {
  43       throw new RangeError('Elements per worker must be greater than zero');
  44     }
  45     this.workerSet = new Set<WorkerSetElement>();
  46     if (this.workerOptions.poolOptions?.enableEvents) {
  47       this.emitter = new EventEmitterAsyncResource({ name: 'workerset' });
  48     }
  49     this.started = false;
  50     this.workerStartup = false;
  51   }
  52
  53   get info(): SetInfo {
  54     return {
  55       version: workerSetVersion,
  56       type: 'set',
  57       worker: 'thread',
  58       size: this.size,
  59       elementsExecuting: [...this.workerSet].reduce(
  60         (accumulator, workerSetElement) => accumulator + workerSetElement.numberOfWorkerElements,
  61         0,
  62       ),
  63       elementsPerWorker: this.maxElementsPerWorker!,
  64     };
  65   }
  66
  67   get size(): number {
  68     return this.workerSet.size;
  69   }
  70
  71   get maxElementsPerWorker(): number | undefined {
  72     return this.workerOptions.elementsPerWorker;
  73   }
  74
  75   /** @inheritDoc */
  76   public async start(): Promise<void> {
  77     this.addWorkerSetElement();
  78     // Add worker set element sequentially to optimize memory at startup
  79     this.workerOptions.workerStartDelay! > 0 &&
  80       (await sleep(randomizeDelay(this.workerOptions.workerStartDelay!)));
  81     this.started = true;
  82   }
  83
  84   /** @inheritDoc */
  85   public async stop(): Promise<void> {
  86     for (const workerSetElement of this.workerSet) {
  87       const worker = workerSetElement.worker;
  88       const waitWorkerExit = new Promise<void>((resolve) => {
  89         worker.once('exit', () => {
  90           resolve();
  91         });
  92       });
  93       await worker.terminate();
  94       await waitWorkerExit;
  95       this.emitter?.emitDestroy();
  96       this.started = false;
  97     }
  98   }
  99
 100   /** @inheritDoc */
 101   public async addElement(elementData: WorkerData): Promise<void> {
 102     if (!this.started) {
 103       throw new Error('Cannot add a WorkerSet element: not started');
 104     }
 105     if (!this.workerSet) {
 106       throw new Error("Cannot add a WorkerSet element: 'workerSet' property does not exist");
 107     }
 108     const workerSetElement = await this.getWorkerSetElement();
 109     workerSetElement.worker.postMessage({
 110       event: WorkerMessageEvents.startWorkerElement,
 111       data: elementData,
 112     });
 113     ++workerSetElement.numberOfWorkerElements;
 114     // Add element sequentially to optimize memory at startup
 115     if (this.workerOptions.elementStartDelay! > 0) {
 116       await sleep(randomizeDelay(this.workerOptions.elementStartDelay!));
 117     }
 118   }
 119
 120   /**
 121    * Adds a new `WorkerSetElement`.
 122    */
 123   private addWorkerSetElement(): WorkerSetElement {
 124     this.workerStartup = true;
 125     const worker = new Worker(this.workerScript, {
 126       env: SHARE_ENV,
 127       ...this.workerOptions.poolOptions?.workerOptions,
 128     });
 129     worker.on('message', this.workerOptions.poolOptions?.messageHandler ?? EMPTY_FUNCTION);
 130     worker.on('message', (message: WorkerMessage<WorkerData>) => {
 131       if (message.event === WorkerMessageEvents.startedWorkerElement) {
 132         this.emitter?.emit(WorkerSetEvents.elementStarted, this.info);
 133       } else if (message.event === WorkerMessageEvents.startWorkerElementError) {
 134         this.emitter?.emit(WorkerSetEvents.elementError, message.data);
 135       }
 136     });
 137     worker.on('error', this.workerOptions.poolOptions?.errorHandler ?? EMPTY_FUNCTION);
 138     worker.on('error', (error) => {
 139       this.emitter?.emit(WorkerSetEvents.error, error);
 140       if (
 141         this.workerOptions.poolOptions?.restartWorkerOnError &&
 142         this.started &&
 143         !this.workerStartup
 144       ) {
 145         this.addWorkerSetElement();
 146       }
 147     });
 148     worker.on('online', this.workerOptions.poolOptions?.onlineHandler ?? EMPTY_FUNCTION);
 149     worker.on('exit', this.workerOptions.poolOptions?.exitHandler ?? EMPTY_FUNCTION);
 150     worker.once('exit', () =>
 151       this.removeWorkerSetElement(this.getWorkerSetElementByWorker(worker)!),
 152     );
 153     const workerSetElement: WorkerSetElement = { worker, numberOfWorkerElements: 0 };
 154     this.workerSet.add(workerSetElement);
 155     this.workerStartup = false;
 156     return workerSetElement;
 157   }
 158
 159   private removeWorkerSetElement(workerSetElement: WorkerSetElement): void {
 160     this.workerSet.delete(workerSetElement);
 161   }
 162
 163   private async getWorkerSetElement(): Promise<WorkerSetElement> {
 164     let chosenWorkerSetElement: WorkerSetElement | undefined;
 165     for (const workerSetElement of this.workerSet) {
 166       if (workerSetElement.numberOfWorkerElements < this.workerOptions.elementsPerWorker!) {
 167         chosenWorkerSetElement = workerSetElement;
 168         break;
 169       }
 170     }
 171     if (!chosenWorkerSetElement) {
 172       chosenWorkerSetElement = this.addWorkerSetElement();
 173       // Add worker set element sequentially to optimize memory at startup
 174       this.workerOptions.workerStartDelay! > 0 &&
 175         (await sleep(randomizeDelay(this.workerOptions.workerStartDelay!)));
 176     }
 177     return chosenWorkerSetElement;
 178   }
 179
 180   private getWorkerSetElementByWorker(worker: Worker): WorkerSetElement | undefined {
 181     let workerSetElt: WorkerSetElement | undefined;
 182     for (const workerSetElement of this.workerSet) {
 183       if (workerSetElement.worker.threadId === worker.threadId) {
 184         workerSetElt = workerSetElement;
 185         break;
 186       }
 187     }
 188     return workerSetElt;
 189   }
 190 }