X-Git-Url: https://git.piment-noir.org/?a=blobdiff_plain;f=src%2Fpools%2Fabstract-pool.ts;h=81012fa0b4f736559fca73eb395bf7c622bce48a;hb=09a6305fb250c17cb2565f8cbe3d9afbb33f307c;hp=5ed353f602d4f0420e6fca66044122c749098074;hpb=e65c6cd9a3d6ed2e5b8af95120a5aa070101e945;p=poolifier.git

diff --git a/src/pools/abstract-pool.ts b/src/pools/abstract-pool.ts
index 5ed353f6..81012fa0 100644
--- a/src/pools/abstract-pool.ts
+++ b/src/pools/abstract-pool.ts
@@ -1,18 +1,27 @@
 import crypto from 'node:crypto'
-import type {
-  MessageValue,
-  PromiseWorkerResponseWrapper
-} from '../utility-types'
-import { EMPTY_FUNCTION } from '../utils'
+import type { MessageValue, PromiseResponseWrapper } from '../utility-types'
+import {
+  DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS,
+  EMPTY_FUNCTION,
+  isPlainObject,
+  median
+} from '../utils'
 import { KillBehaviors, isKillBehavior } from '../worker/worker-options'
-import type { PoolOptions } from './pool'
-import { PoolEmitter } from './pool'
-import type { IPoolInternal, TasksUsage, WorkerType } from './pool-internal'
-import { PoolType } from './pool-internal'
-import type { IPoolWorker } from './pool-worker'
+import { CircularArray } from '../circular-array'
+import { Queue } from '../queue'
+import {
+  type IPool,
+  PoolEmitter,
+  PoolEvents,
+  type PoolOptions,
+  PoolType,
+  type TasksQueueOptions
+} from './pool'
+import type { IWorker, Task, TasksUsage, WorkerNode } from './worker'
 import {
   WorkerChoiceStrategies,
-  type WorkerChoiceStrategy
+  type WorkerChoiceStrategy,
+  type WorkerChoiceStrategyOptions
 } from './selection-strategies/selection-strategies-types'
 import { WorkerChoiceStrategyContext } from './selection-strategies/worker-choice-strategy-context'
 
@@ -21,36 +30,36 @@ import { WorkerChoiceStrategyContext } from './selection-strategies/worker-choic
  *
  * @typeParam Worker - Type of worker which manages this pool.
  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
- * @typeParam Response - Type of response of execution. This can only be serializable data.
+ * @typeParam Response - Type of execution response. This can only be serializable data.
  */
 export abstract class AbstractPool<
-  Worker extends IPoolWorker,
+  Worker extends IWorker,
   Data = unknown,
   Response = unknown
-> implements IPoolInternal<Worker, Data, Response> {
-  /** {@inheritDoc} */
-  public readonly workers: Array<WorkerType<Worker>> = []
+> implements IPool<Worker, Data, Response> {
+  /** @inheritDoc */
+  public readonly workerNodes: Array<WorkerNode<Worker, Data>> = []
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public readonly emitter?: PoolEmitter
 
   /**
-   * The promise map.
+   * The execution response promise map.
    *
-   * - `key`: This is the message id of each submitted task.
-   * - `value`: An object that contains the worker, the resolve function and the reject function.
+   * - `key`: The message id of each submitted task.
+   * - `value`: An object that contains the worker, the execution response promise resolve and reject callbacks.
    *
-   * When we receive a message from the worker we get a map entry and resolve/reject the promise based on the message.
+   * When we receive a message from the worker, we get a map entry with the promise resolve/reject bound to the message id.
    */
-  protected promiseMap: Map<
+  protected promiseResponseMap: Map<
   string,
-  PromiseWorkerResponseWrapper<Worker, Response>
-  > = new Map<string, PromiseWorkerResponseWrapper<Worker, Response>>()
+  PromiseResponseWrapper<Worker, Response>
+  > = new Map<string, PromiseResponseWrapper<Worker, Response>>()
 
   /**
-   * Worker choice strategy instance implementing the worker choice algorithm.
+   * Worker choice strategy context referencing a worker choice algorithm implementation.
    *
-   * Default to a strategy implementing a round robin algorithm.
+   * Default to a round robin algorithm.
    */
   protected workerChoiceStrategyContext: WorkerChoiceStrategyContext<
   Worker,
@@ -62,7 +71,7 @@ export abstract class AbstractPool<
    * Constructs a new poolifier pool.
    *
    * @param numberOfWorkers - Number of workers that this pool should manage.
-   * @param filePath - Path to the worker-file.
+   * @param filePath - Path to the worker file.
    * @param opts - Options for the pool.
    */
   public constructor (
@@ -76,6 +85,12 @@ export abstract class AbstractPool<
     this.checkNumberOfWorkers(this.numberOfWorkers)
     this.checkFilePath(this.filePath)
     this.checkPoolOptions(this.opts)
+
+    this.chooseWorkerNode = this.chooseWorkerNode.bind(this)
+    this.executeTask = this.executeTask.bind(this)
+    this.enqueueTask = this.enqueueTask.bind(this)
+    this.checkAndEmitEvents = this.checkAndEmitEvents.bind(this)
+
     this.setupHook()
 
     for (let i = 1; i <= this.numberOfWorkers; i++) {
@@ -85,22 +100,14 @@ export abstract class AbstractPool<
     if (this.opts.enableEvents === true) {
       this.emitter = new PoolEmitter()
     }
-    this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext(
+    this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext<
+    Worker,
+    Data,
+    Response
+    >(
       this,
-      () => {
-        const workerCreated = this.createAndSetupWorker()
-        this.registerWorkerMessageListener(workerCreated, message => {
-          if (
-            isKillBehavior(KillBehaviors.HARD, message.kill) ||
-            this.getWorkerTasksUsage(workerCreated)?.running === 0
-          ) {
-            // Kill received from the worker, means that no new tasks are submitted to that worker for a while ( > maxInactiveTime)
-            void this.destroyWorker(workerCreated)
-          }
-        })
-        return workerCreated
-      },
-      this.opts.workerChoiceStrategy
+      this.opts.workerChoiceStrategy,
+      this.opts.workerChoiceStrategyOptions
     )
   }
 
@@ -120,7 +127,7 @@ export abstract class AbstractPool<
       )
     } else if (!Number.isSafeInteger(numberOfWorkers)) {
       throw new TypeError(
-        'Cannot instantiate a pool with a non integer number of workers'
+        'Cannot instantiate a pool with a non safe integer number of workers'
       )
     } else if (numberOfWorkers < 0) {
       throw new RangeError(
@@ -132,105 +139,269 @@ export abstract class AbstractPool<
   }
 
   private checkPoolOptions (opts: PoolOptions<Worker>): void {
-    this.opts.workerChoiceStrategy =
-      opts.workerChoiceStrategy ?? WorkerChoiceStrategies.ROUND_ROBIN
-    this.opts.enableEvents = opts.enableEvents ?? true
+    if (isPlainObject(opts)) {
+      this.opts.workerChoiceStrategy =
+        opts.workerChoiceStrategy ?? WorkerChoiceStrategies.ROUND_ROBIN
+      this.checkValidWorkerChoiceStrategy(this.opts.workerChoiceStrategy)
+      this.opts.workerChoiceStrategyOptions =
+        opts.workerChoiceStrategyOptions ??
+        DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
+      this.checkValidWorkerChoiceStrategyOptions(
+        this.opts.workerChoiceStrategyOptions
+      )
+      this.opts.enableEvents = opts.enableEvents ?? true
+      this.opts.enableTasksQueue = opts.enableTasksQueue ?? false
+      if (this.opts.enableTasksQueue) {
+        this.checkValidTasksQueueOptions(
+          opts.tasksQueueOptions as TasksQueueOptions
+        )
+        this.opts.tasksQueueOptions = this.buildTasksQueueOptions(
+          opts.tasksQueueOptions as TasksQueueOptions
+        )
+      }
+    } else {
+      throw new TypeError('Invalid pool options: must be a plain object')
+    }
+  }
+
+  private checkValidWorkerChoiceStrategy (
+    workerChoiceStrategy: WorkerChoiceStrategy
+  ): void {
+    if (!Object.values(WorkerChoiceStrategies).includes(workerChoiceStrategy)) {
+      throw new Error(
+        `Invalid worker choice strategy '${workerChoiceStrategy}'`
+      )
+    }
   }
 
-  /** {@inheritDoc} */
+  private checkValidWorkerChoiceStrategyOptions (
+    workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
+  ): void {
+    if (!isPlainObject(workerChoiceStrategyOptions)) {
+      throw new TypeError(
+        'Invalid worker choice strategy options: must be a plain object'
+      )
+    }
+    if (
+      workerChoiceStrategyOptions.weights != null &&
+      Object.keys(workerChoiceStrategyOptions.weights).length !== this.size
+    ) {
+      throw new Error(
+        'Invalid worker choice strategy options: must have a weight for each worker node'
+      )
+    }
+  }
+
+  private checkValidTasksQueueOptions (
+    tasksQueueOptions: TasksQueueOptions
+  ): void {
+    if (tasksQueueOptions != null && !isPlainObject(tasksQueueOptions)) {
+      throw new TypeError('Invalid tasks queue options: must be a plain object')
+    }
+    if ((tasksQueueOptions?.concurrency as number) <= 0) {
+      throw new Error(
+        `Invalid worker tasks concurrency '${
+          tasksQueueOptions.concurrency as number
+        }'`
+      )
+    }
+  }
+
+  /** @inheritDoc */
   public abstract get type (): PoolType
 
-  /** {@inheritDoc} */
-  public get numberOfRunningTasks (): number {
-    return this.promiseMap.size
+  /** @inheritDoc */
+  public abstract get size (): number
+
+  /**
+   * Number of tasks running in the pool.
+   */
+  private get numberOfRunningTasks (): number {
+    return this.workerNodes.reduce(
+      (accumulator, workerNode) => accumulator + workerNode.tasksUsage.running,
+      0
+    )
+  }
+
+  /**
+   * Number of tasks queued in the pool.
+   */
+  private get numberOfQueuedTasks (): number {
+    if (this.opts.enableTasksQueue === false) {
+      return 0
+    }
+    return this.workerNodes.reduce(
+      (accumulator, workerNode) => accumulator + workerNode.tasksQueue.size,
+      0
+    )
   }
 
   /**
-   * Gets the given worker key.
+   * Gets the given worker its worker node key.
    *
    * @param worker - The worker.
-   * @returns The worker key.
+   * @returns The worker node key if the worker is found in the pool worker nodes, `-1` otherwise.
    */
-  private getWorkerKey (worker: Worker): number {
-    return this.workers.findIndex(workerItem => workerItem.worker === worker)
+  private getWorkerNodeKey (worker: Worker): number {
+    return this.workerNodes.findIndex(
+      workerNode => workerNode.worker === worker
+    )
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public setWorkerChoiceStrategy (
-    workerChoiceStrategy: WorkerChoiceStrategy
+    workerChoiceStrategy: WorkerChoiceStrategy,
+    workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
   ): void {
+    this.checkValidWorkerChoiceStrategy(workerChoiceStrategy)
     this.opts.workerChoiceStrategy = workerChoiceStrategy
-    for (const workerItem of this.workers) {
-      this.setWorker(workerItem.worker, {
+    for (const workerNode of this.workerNodes) {
+      this.setWorkerNodeTasksUsage(workerNode, {
         run: 0,
         running: 0,
         runTime: 0,
-        avgRunTime: 0
+        runTimeHistory: new CircularArray(),
+        avgRunTime: 0,
+        medRunTime: 0,
+        waitTime: 0,
+        waitTimeHistory: new CircularArray(),
+        avgWaitTime: 0,
+        medWaitTime: 0,
+        error: 0
       })
     }
     this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
-      workerChoiceStrategy
+      this.opts.workerChoiceStrategy
     )
+    if (workerChoiceStrategyOptions != null) {
+      this.setWorkerChoiceStrategyOptions(workerChoiceStrategyOptions)
+    }
   }
 
-  /** {@inheritDoc} */
-  public abstract get busy (): boolean
-
-  protected internalGetBusyStatus (): boolean {
-    return (
-      this.numberOfRunningTasks >= this.numberOfWorkers &&
-      this.findFreeWorker() === false
+  /** @inheritDoc */
+  public setWorkerChoiceStrategyOptions (
+    workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
+  ): void {
+    this.checkValidWorkerChoiceStrategyOptions(workerChoiceStrategyOptions)
+    this.opts.workerChoiceStrategyOptions = workerChoiceStrategyOptions
+    this.workerChoiceStrategyContext.setOptions(
+      this.opts.workerChoiceStrategyOptions
     )
   }
 
-  /** {@inheritDoc} */
-  public findFreeWorker (): Worker | false {
-    for (const workerItem of this.workers) {
-      if (workerItem.tasksUsage.running === 0) {
-        // A worker is free, return the matching worker
-        return workerItem.worker
-      }
+  /** @inheritDoc */
+  public enableTasksQueue (
+    enable: boolean,
+    tasksQueueOptions?: TasksQueueOptions
+  ): void {
+    if (this.opts.enableTasksQueue === true && !enable) {
+      this.flushTasksQueues()
     }
-    return false
+    this.opts.enableTasksQueue = enable
+    this.setTasksQueueOptions(tasksQueueOptions as TasksQueueOptions)
   }
 
-  /** {@inheritDoc} */
-  public async execute (data: Data): Promise<Response> {
-    const worker = this.chooseWorker()
-    const messageId = crypto.randomUUID()
-    const res = this.internalExecute(worker, messageId)
-    this.checkAndEmitBusy()
-    this.sendToWorker(worker, {
+  /** @inheritDoc */
+  public setTasksQueueOptions (tasksQueueOptions: TasksQueueOptions): void {
+    if (this.opts.enableTasksQueue === true) {
+      this.checkValidTasksQueueOptions(tasksQueueOptions)
+      this.opts.tasksQueueOptions =
+        this.buildTasksQueueOptions(tasksQueueOptions)
+    } else {
+      delete this.opts.tasksQueueOptions
+    }
+  }
+
+  private buildTasksQueueOptions (
+    tasksQueueOptions: TasksQueueOptions
+  ): TasksQueueOptions {
+    return {
+      concurrency: tasksQueueOptions?.concurrency ?? 1
+    }
+  }
+
+  /**
+   * Whether the pool is full or not.
+   *
+   * The pool filling boolean status.
+   */
+  protected abstract get full (): boolean
+
+  /**
+   * Whether the pool is busy or not.
+   *
+   * The pool busyness boolean status.
+   */
+  protected abstract get busy (): boolean
+
+  protected internalBusy (): boolean {
+    return (
+      this.workerNodes.findIndex(workerNode => {
+        return workerNode.tasksUsage.running === 0
+      }) === -1
+    )
+  }
+
+  /** @inheritDoc */
+  public async execute (data?: Data, name?: string): Promise<Response> {
+    const submissionTimestamp = performance.now()
+    const workerNodeKey = this.chooseWorkerNode()
+    const submittedTask: Task<Data> = {
+      name,
       // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
       data: data ?? ({} as Data),
-      id: messageId
+      submissionTimestamp,
+      id: crypto.randomUUID()
+    }
+    const res = new Promise<Response>((resolve, reject) => {
+      this.promiseResponseMap.set(submittedTask.id as string, {
+        resolve,
+        reject,
+        worker: this.workerNodes[workerNodeKey].worker
+      })
     })
+    if (
+      this.opts.enableTasksQueue === true &&
+      (this.busy ||
+        this.workerNodes[workerNodeKey].tasksUsage.running >=
+          ((this.opts.tasksQueueOptions as TasksQueueOptions)
+            .concurrency as number))
+    ) {
+      this.enqueueTask(workerNodeKey, submittedTask)
+    } else {
+      this.executeTask(workerNodeKey, submittedTask)
+    }
+    this.workerChoiceStrategyContext.update(workerNodeKey)
+    this.checkAndEmitEvents()
     // eslint-disable-next-line @typescript-eslint/return-await
     return res
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public async destroy (): Promise<void> {
     await Promise.all(
-      this.workers.map(async workerItem => {
-        await this.destroyWorker(workerItem.worker)
+      this.workerNodes.map(async (workerNode, workerNodeKey) => {
+        this.flushTasksQueue(workerNodeKey)
+        await this.destroyWorker(workerNode.worker)
       })
     )
   }
 
   /**
-   * Shutdowns given worker.
+   * Shutdowns the given worker.
    *
-   * @param worker - A worker within `workers`.
+   * @param worker - A worker within `workerNodes`.
    */
   protected abstract destroyWorker (worker: Worker): void | Promise<void>
 
   /**
-   * Setup hook that can be overridden by a Poolifier pool implementation
-   * to run code before workers are created in the abstract constructor.
+   * Setup hook to execute code before worker node are created in the abstract constructor.
+   * Can be overridden
+   *
+   * @virtual
    */
   protected setupHook (): void {
-    // Can be overridden
+    // Intentionally empty
   }
 
   /**
@@ -239,61 +410,100 @@ export abstract class AbstractPool<
   protected abstract isMain (): boolean
 
   /**
-   * Hook executed before the worker task promise resolution.
+   * Hook executed before the worker task execution.
    * Can be overridden.
    *
-   * @param worker - The worker.
+   * @param workerNodeKey - The worker node key.
    */
-  protected beforePromiseWorkerResponseHook (worker: Worker): void {
-    ++(this.getWorkerTasksUsage(worker) as TasksUsage).running
+  protected beforeTaskExecutionHook (
+    workerNodeKey: number,
+    task: Task<Data>
+  ): void {
+    ++this.workerNodes[workerNodeKey].tasksUsage.running
   }
 
   /**
-   * Hook executed after the worker task promise resolution.
+   * Hook executed after the worker task execution.
    * Can be overridden.
    *
+   * @param worker - The worker.
    * @param message - The received message.
-   * @param promise - The Promise response.
    */
-  protected afterPromiseWorkerResponseHook (
-    message: MessageValue<Response>,
-    promise: PromiseWorkerResponseWrapper<Worker, Response>
+  protected afterTaskExecutionHook (
+    worker: Worker,
+    message: MessageValue<Response>
   ): void {
-    const workerTasksUsage = this.getWorkerTasksUsage(
-      promise.worker
-    ) as TasksUsage
+    const workerNodeKey = this.getWorkerNodeKey(worker)
+    const workerTasksUsage = this.workerNodes[workerNodeKey].tasksUsage
     --workerTasksUsage.running
     ++workerTasksUsage.run
-    if (
-      this.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ) {
-      workerTasksUsage.runTime += message.taskRunTime ?? 0
-      if (workerTasksUsage.run !== 0) {
+    if (message.error != null) {
+      ++workerTasksUsage.error
+    }
+    if (this.workerChoiceStrategyContext.getRequiredStatistics().runTime) {
+      workerTasksUsage.runTime += message.runTime ?? 0
+      if (
+        this.workerChoiceStrategyContext.getRequiredStatistics().avgRunTime &&
+        workerTasksUsage.run !== 0
+      ) {
         workerTasksUsage.avgRunTime =
           workerTasksUsage.runTime / workerTasksUsage.run
       }
+      if (
+        this.workerChoiceStrategyContext.getRequiredStatistics().medRunTime &&
+        message.runTime != null
+      ) {
+        workerTasksUsage.runTimeHistory.push(message.runTime)
+        workerTasksUsage.medRunTime = median(workerTasksUsage.runTimeHistory)
+      }
+    }
+    if (this.workerChoiceStrategyContext.getRequiredStatistics().waitTime) {
+      workerTasksUsage.waitTime += message.waitTime ?? 0
+      if (
+        this.workerChoiceStrategyContext.getRequiredStatistics().avgWaitTime &&
+        workerTasksUsage.run !== 0
+      ) {
+        workerTasksUsage.avgWaitTime =
+          workerTasksUsage.waitTime / workerTasksUsage.run
+      }
+      if (
+        this.workerChoiceStrategyContext.getRequiredStatistics().medWaitTime &&
+        message.waitTime != null
+      ) {
+        workerTasksUsage.waitTimeHistory.push(message.waitTime)
+        workerTasksUsage.medWaitTime = median(workerTasksUsage.waitTimeHistory)
+      }
     }
   }
 
   /**
-   * Removes the given worker from the pool.
-   *
-   * @param worker - The worker that will be removed.
-   */
-  protected removeWorker (worker: Worker): void {
-    this.workers.splice(this.getWorkerKey(worker), 1)
-  }
-
-  /**
-   * Chooses a worker for the next task.
+   * Chooses a worker node for the next task.
    *
-   * The default implementation uses a round robin algorithm to distribute the load.
+   * The default worker choice strategy uses a round robin algorithm to distribute the load.
    *
-   * @returns Worker.
+   * @returns The worker node key
    */
-  protected chooseWorker (): Worker {
-    return this.workerChoiceStrategyContext.execute()
+  protected chooseWorkerNode (): number {
+    let workerNodeKey: number
+    if (this.type === PoolType.DYNAMIC && !this.full && this.internalBusy()) {
+      const workerCreated = this.createAndSetupWorker()
+      this.registerWorkerMessageListener(workerCreated, message => {
+        const currentWorkerNodeKey = this.getWorkerNodeKey(workerCreated)
+        if (
+          isKillBehavior(KillBehaviors.HARD, message.kill) ||
+          (message.kill != null &&
+            this.workerNodes[currentWorkerNodeKey].tasksUsage.running === 0)
+        ) {
+          // Kill message received from the worker: no new tasks are submitted to that worker for a while ( > maxInactiveTime)
+          this.flushTasksQueue(currentWorkerNodeKey)
+          void (this.destroyWorker(workerCreated) as Promise<void>)
+        }
+      })
+      workerNodeKey = this.getWorkerNodeKey(workerCreated)
+    } else {
+      workerNodeKey = this.workerChoiceStrategyContext.execute()
+    }
+    return workerNodeKey
   }
 
   /**
@@ -308,7 +518,7 @@ export abstract class AbstractPool<
   ): void
 
   /**
-   * Registers a listener callback on a given worker.
+   * Registers a listener callback on the given worker.
    *
    * @param worker - The worker which should register a listener.
    * @param listener - The message listener callback.
@@ -323,7 +533,7 @@ export abstract class AbstractPool<
   protected abstract createWorker (): Worker
 
   /**
-   * Function that can be hooked up when a worker has been newly created and moved to the workers registry.
+   * Function that can be hooked up when a worker has been newly created and moved to the pool worker nodes.
    *
    * Can be used to update the `maxListeners` or binding the `main-worker`\<-\>`worker` connection if not bind by default.
    *
@@ -332,7 +542,7 @@ export abstract class AbstractPool<
   protected abstract afterWorkerSetup (worker: Worker): void
 
   /**
-   * Creates a new worker for this pool and sets it up completely.
+   * Creates a new worker and sets it up completely in the pool worker nodes.
    *
    * @returns New, completely set up worker.
    */
@@ -344,15 +554,10 @@ export abstract class AbstractPool<
     worker.on('online', this.opts.onlineHandler ?? EMPTY_FUNCTION)
     worker.on('exit', this.opts.exitHandler ?? EMPTY_FUNCTION)
     worker.once('exit', () => {
-      this.removeWorker(worker)
+      this.removeWorkerNode(worker)
     })
 
-    this.setWorker(worker, {
-      run: 0,
-      running: 0,
-      runTime: 0,
-      avgRunTime: 0
-    })
+    this.pushWorkerNode(worker)
 
     this.afterWorkerSetup(worker)
 
@@ -360,62 +565,151 @@ export abstract class AbstractPool<
   }
 
   /**
-   * This function is the listener registered for each worker.
+   * This function is the listener registered for each worker message.
    *
    * @returns The listener function to execute when a message is received from a worker.
    */
   protected workerListener (): (message: MessageValue<Response>) => void {
     return message => {
-      if (message.id !== undefined) {
-        const promise = this.promiseMap.get(message.id)
-        if (promise !== undefined) {
+      if (message.id != null) {
+        // Task execution response received
+        const promiseResponse = this.promiseResponseMap.get(message.id)
+        if (promiseResponse != null) {
           if (message.error != null) {
-            promise.reject(message.error)
+            promiseResponse.reject(message.error)
           } else {
-            promise.resolve(message.data as Response)
+            promiseResponse.resolve(message.data as Response)
+          }
+          this.afterTaskExecutionHook(promiseResponse.worker, message)
+          this.promiseResponseMap.delete(message.id)
+          const workerNodeKey = this.getWorkerNodeKey(promiseResponse.worker)
+          if (
+            this.opts.enableTasksQueue === true &&
+            this.tasksQueueSize(workerNodeKey) > 0
+          ) {
+            this.executeTask(
+              workerNodeKey,
+              this.dequeueTask(workerNodeKey) as Task<Data>
+            )
           }
-          this.afterPromiseWorkerResponseHook(message, promise)
-          this.promiseMap.delete(message.id)
         }
       }
     }
   }
 
-  private async internalExecute (
-    worker: Worker,
-    messageId: string
-  ): Promise<Response> {
-    this.beforePromiseWorkerResponseHook(worker)
-    return await new Promise<Response>((resolve, reject) => {
-      this.promiseMap.set(messageId, { resolve, reject, worker })
-    })
+  private checkAndEmitEvents (): void {
+    if (this.opts.enableEvents === true) {
+      if (this.busy) {
+        this.emitter?.emit(PoolEvents.busy)
+      }
+      if (this.type === PoolType.DYNAMIC && this.full) {
+        this.emitter?.emit(PoolEvents.full)
+      }
+    }
   }
 
-  private checkAndEmitBusy (): void {
-    if (this.opts.enableEvents === true && this.busy) {
-      this.emitter?.emit('busy')
-    }
+  /**
+   * Sets the given worker node its tasks usage in the pool.
+   *
+   * @param workerNode - The worker node.
+   * @param tasksUsage - The worker node tasks usage.
+   */
+  private setWorkerNodeTasksUsage (
+    workerNode: WorkerNode<Worker, Data>,
+    tasksUsage: TasksUsage
+  ): void {
+    workerNode.tasksUsage = tasksUsage
   }
 
-  /** {@inheritDoc} */
-  public getWorkerTasksUsage (worker: Worker): TasksUsage | undefined {
-    const workerKey = this.getWorkerKey(worker)
-    if (workerKey !== -1) {
-      return this.workers[workerKey].tasksUsage
-    }
-    throw new Error('Worker could not be found in the pool')
+  /**
+   * Pushes the given worker in the pool worker nodes.
+   *
+   * @param worker - The worker.
+   * @returns The worker nodes length.
+   */
+  private pushWorkerNode (worker: Worker): number {
+    return this.workerNodes.push({
+      worker,
+      tasksUsage: {
+        run: 0,
+        running: 0,
+        runTime: 0,
+        runTimeHistory: new CircularArray(),
+        avgRunTime: 0,
+        medRunTime: 0,
+        waitTime: 0,
+        waitTimeHistory: new CircularArray(),
+        avgWaitTime: 0,
+        medWaitTime: 0,
+        error: 0
+      },
+      tasksQueue: new Queue<Task<Data>>()
+    })
   }
 
   /**
-   * Sets the given worker.
+   * Sets the given worker in the pool worker nodes.
    *
+   * @param workerNodeKey - The worker node key.
    * @param worker - The worker.
    * @param tasksUsage - The worker tasks usage.
+   * @param tasksQueue - The worker task queue.
    */
-  private setWorker (worker: Worker, tasksUsage: TasksUsage): void {
-    this.workers.push({
+  private setWorkerNode (
+    workerNodeKey: number,
+    worker: Worker,
+    tasksUsage: TasksUsage,
+    tasksQueue: Queue<Task<Data>>
+  ): void {
+    this.workerNodes[workerNodeKey] = {
       worker,
-      tasksUsage
-    })
+      tasksUsage,
+      tasksQueue
+    }
+  }
+
+  /**
+   * Removes the given worker from the pool worker nodes.
+   *
+   * @param worker - The worker.
+   */
+  private removeWorkerNode (worker: Worker): void {
+    const workerNodeKey = this.getWorkerNodeKey(worker)
+    this.workerNodes.splice(workerNodeKey, 1)
+    this.workerChoiceStrategyContext.remove(workerNodeKey)
+  }
+
+  private executeTask (workerNodeKey: number, task: Task<Data>): void {
+    this.beforeTaskExecutionHook(workerNodeKey, task)
+    this.sendToWorker(this.workerNodes[workerNodeKey].worker, task)
+  }
+
+  private enqueueTask (workerNodeKey: number, task: Task<Data>): number {
+    return this.workerNodes[workerNodeKey].tasksQueue.enqueue(task)
+  }
+
+  private dequeueTask (workerNodeKey: number): Task<Data> | undefined {
+    return this.workerNodes[workerNodeKey].tasksQueue.dequeue()
+  }
+
+  private tasksQueueSize (workerNodeKey: number): number {
+    return this.workerNodes[workerNodeKey].tasksQueue.size
+  }
+
+  private flushTasksQueue (workerNodeKey: number): void {
+    if (this.tasksQueueSize(workerNodeKey) > 0) {
+      for (let i = 0; i < this.tasksQueueSize(workerNodeKey); i++) {
+        this.executeTask(
+          workerNodeKey,
+          this.dequeueTask(workerNodeKey) as Task<Data>
+        )
+      }
+    }
+  }
+
+  private flushTasksQueues (): void {
+    for (const [workerNodeKey] of this.workerNodes.entries()) {
+      this.flushTasksQueue(workerNodeKey)
+    }
   }
 }