refactor: add ELU utilization to pool info
[poolifier.git] / src / pools / abstract-pool.ts
index 99744517ed6dc8261695ccfefaff71bee1cfc9a8..649d5f0d0d5e268b26f3285f3dd27aaae52a1c2d 100644 (file)
@@ -1,17 +1,20 @@
+import { AsyncResource } from 'node:async_hooks'
 import { randomUUID } from 'node:crypto'
+import { EventEmitterAsyncResource } from 'node:events'
 import { performance } from 'node:perf_hooks'
 import type { TransferListItem } from 'node:worker_threads'
-import { EventEmitterAsyncResource } from 'node:events'
-import { AsyncResource } from 'node:async_hooks'
+
 import type {
   MessageValue,
   PromiseResponseWrapper,
-  Task
+  Task,
+  TaskFunctionProperties
 } from '../utility-types.js'
 import {
+  average,
+  buildTaskFunctionProperties,
   DEFAULT_TASK_NAME,
   EMPTY_FUNCTION,
-  average,
   exponentialDelay,
   isKillBehavior,
   isPlainObject,
@@ -21,8 +24,11 @@ import {
   round,
   sleep
 } from '../utils.js'
+import type {
+  TaskFunction,
+  TaskFunctionObject
+} from '../worker/task-functions.js'
 import { KillBehaviors } from '../worker/worker-options.js'
-import type { TaskFunction } from '../worker/task-functions.js'
 import {
   type IPool,
   PoolEvents,
@@ -32,24 +38,16 @@ import {
   PoolTypes,
   type TasksQueueOptions
 } from './pool.js'
-import type {
-  IWorker,
-  IWorkerNode,
-  WorkerInfo,
-  WorkerNodeEventDetail,
-  WorkerType
-} from './worker.js'
 import {
   Measurements,
   WorkerChoiceStrategies,
   type WorkerChoiceStrategy,
   type WorkerChoiceStrategyOptions
 } from './selection-strategies/selection-strategies-types.js'
-import { WorkerChoiceStrategyContext } from './selection-strategies/worker-choice-strategy-context.js'
-import { version } from './version.js'
-import { WorkerNode } from './worker-node.js'
+import { WorkerChoiceStrategiesContext } from './selection-strategies/worker-choice-strategies-context.js'
 import {
   checkFilePath,
+  checkValidPriority,
   checkValidTasksQueueOptions,
   checkValidWorkerChoiceStrategy,
   getDefaultTasksQueueOptions,
@@ -59,6 +57,15 @@ import {
   updateWaitTimeWorkerUsage,
   waitWorkerNodeEvents
 } from './utils.js'
+import { version } from './version.js'
+import type {
+  IWorker,
+  IWorkerNode,
+  WorkerInfo,
+  WorkerNodeEventDetail,
+  WorkerType
+} from './worker.js'
+import { WorkerNode } from './worker-node.js'
 
 /**
  * Base class that implements some shared logic for all poolifier pools.
@@ -81,17 +88,22 @@ export abstract class AbstractPool<
   /**
    * The task execution response promise map:
    * - `key`: The message id of each submitted task.
-   * - `value`: An object that contains the worker, the execution response promise resolve and reject callbacks.
+   * - `value`: An object that contains task's worker node key, execution response promise resolve and reject callbacks, async resource.
    *
    * When we receive a message from the worker, we get a map entry with the promise resolve/reject bound to the message id.
    */
-  protected promiseResponseMap: Map<string, PromiseResponseWrapper<Response>> =
-    new Map<string, PromiseResponseWrapper<Response>>()
+  protected promiseResponseMap: Map<
+    `${string}-${string}-${string}-${string}-${string}`,
+  PromiseResponseWrapper<Response>
+  > = new Map<
+    `${string}-${string}-${string}-${string}-${string}`,
+    PromiseResponseWrapper<Response>
+    >()
 
   /**
-   * Worker choice strategy context referencing a worker choice algorithm implementation.
+   * Worker choice strategies context referencing worker choice algorithms implementation.
    */
-  protected workerChoiceStrategyContext?: WorkerChoiceStrategyContext<
+  protected workerChoiceStrategiesContext?: WorkerChoiceStrategiesContext<
   Worker,
   Data,
   Response
@@ -100,9 +112,12 @@ export abstract class AbstractPool<
   /**
    * The task functions added at runtime map:
    * - `key`: The task function name.
-   * - `value`: The task function itself.
+   * - `value`: The task function object.
    */
-  private readonly taskFunctions: Map<string, TaskFunction<Data, Response>>
+  private readonly taskFunctions: Map<
+  string,
+  TaskFunctionObject<Data, Response>
+  >
 
   /**
    * Whether the pool is started or not.
@@ -116,6 +131,10 @@ export abstract class AbstractPool<
    * Whether the pool is destroying or not.
    */
   private destroying: boolean
+  /**
+   * Whether the minimum number of workers is starting or not.
+   */
+  private startingMinimumNumberOfWorkers: boolean
   /**
    * Whether the pool ready event has been emitted or not.
    */
@@ -123,7 +142,7 @@ export abstract class AbstractPool<
   /**
    * The start timestamp of the pool.
    */
-  private readonly startTimestamp
+  private startTimestamp?: number
 
   /**
    * Constructs a new poolifier pool.
@@ -154,31 +173,31 @@ export abstract class AbstractPool<
     this.enqueueTask = this.enqueueTask.bind(this)
 
     if (this.opts.enableEvents === true) {
-      this.initializeEventEmitter()
+      this.initEventEmitter()
     }
-    this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext<
+    this.workerChoiceStrategiesContext = new WorkerChoiceStrategiesContext<
     Worker,
     Data,
     Response
     >(
       this,
-      this.opts.workerChoiceStrategy,
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      [this.opts.workerChoiceStrategy!],
       this.opts.workerChoiceStrategyOptions
     )
 
     this.setupHook()
 
-    this.taskFunctions = new Map<string, TaskFunction<Data, Response>>()
+    this.taskFunctions = new Map<string, TaskFunctionObject<Data, Response>>()
 
     this.started = false
     this.starting = false
     this.destroying = false
     this.readyEventEmitted = false
+    this.startingMinimumNumberOfWorkers = false
     if (this.opts.startWorkers === true) {
       this.start()
     }
-
-    this.startTimestamp = performance.now()
   }
 
   private checkPoolType (): void {
@@ -267,7 +286,7 @@ export abstract class AbstractPool<
     }
   }
 
-  private initializeEventEmitter (): void {
+  private initEventEmitter (): void {
     this.emitter = new EventEmitterAsyncResource({
       name: `poolifier:${this.type}-${this.worker}-pool`
     })
@@ -282,12 +301,13 @@ export abstract class AbstractPool<
       started: this.started,
       ready: this.ready,
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-      strategy: this.opts.workerChoiceStrategy!,
+      defaultStrategy: this.opts.workerChoiceStrategy!,
+      strategyRetries: this.workerChoiceStrategiesContext?.retriesCount ?? 0,
       minSize: this.minimumNumberOfWorkers,
       maxSize: this.maximumNumberOfWorkers ?? this.minimumNumberOfWorkers,
-      ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
-        ?.runTime.aggregate === true &&
-        this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+      ...(this.workerChoiceStrategiesContext?.getTaskStatisticsRequirements()
+        .runTime.aggregate === true &&
+        this.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
           .waitTime.aggregate && {
         utilization: round(this.utilization)
       }),
@@ -307,7 +327,7 @@ export abstract class AbstractPool<
         )
       }),
       busyWorkerNodes: this.workerNodes.reduce(
-        (accumulator, _workerNode, workerNodeKey) =>
+        (accumulator, _, workerNodeKey) =>
           this.isWorkerNodeBusy(workerNodeKey) ? accumulator + 1 : accumulator,
         0
       ),
@@ -350,8 +370,8 @@ export abstract class AbstractPool<
           accumulator + workerNode.usage.tasks.failed,
         0
       ),
-      ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
-        ?.runTime.aggregate === true && {
+      ...(this.workerChoiceStrategiesContext?.getTaskStatisticsRequirements()
+        .runTime.aggregate === true && {
         runTime: {
           minimum: round(
             min(
@@ -367,7 +387,7 @@ export abstract class AbstractPool<
               )
             )
           ),
-          ...(this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+          ...(this.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
             .runTime.average && {
             average: round(
               average(
@@ -379,7 +399,7 @@ export abstract class AbstractPool<
               )
             )
           }),
-          ...(this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+          ...(this.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
             .runTime.median && {
             median: round(
               median(
@@ -393,8 +413,8 @@ export abstract class AbstractPool<
           })
         }
       }),
-      ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
-        ?.waitTime.aggregate === true && {
+      ...(this.workerChoiceStrategiesContext?.getTaskStatisticsRequirements()
+        .waitTime.aggregate === true && {
         waitTime: {
           minimum: round(
             min(
@@ -410,7 +430,7 @@ export abstract class AbstractPool<
               )
             )
           ),
-          ...(this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+          ...(this.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
             .waitTime.average && {
             average: round(
               average(
@@ -422,7 +442,7 @@ export abstract class AbstractPool<
               )
             )
           }),
-          ...(this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+          ...(this.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
             .waitTime.median && {
             median: round(
               median(
@@ -435,6 +455,107 @@ export abstract class AbstractPool<
             )
           })
         }
+      }),
+      ...(this.workerChoiceStrategiesContext?.getTaskStatisticsRequirements()
+        .elu.aggregate === true && {
+        elu: {
+          idle: {
+            minimum: round(
+              min(
+                ...this.workerNodes.map(
+                  workerNode => workerNode.usage.elu.idle.minimum ?? Infinity
+                )
+              )
+            ),
+            maximum: round(
+              max(
+                ...this.workerNodes.map(
+                  workerNode => workerNode.usage.elu.idle.maximum ?? -Infinity
+                )
+              )
+            ),
+            ...(this.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
+              .elu.average && {
+              average: round(
+                average(
+                  this.workerNodes.reduce<number[]>(
+                    (accumulator, workerNode) =>
+                      accumulator.concat(workerNode.usage.elu.idle.history),
+                    []
+                  )
+                )
+              )
+            }),
+            ...(this.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
+              .elu.median && {
+              median: round(
+                median(
+                  this.workerNodes.reduce<number[]>(
+                    (accumulator, workerNode) =>
+                      accumulator.concat(workerNode.usage.elu.idle.history),
+                    []
+                  )
+                )
+              )
+            })
+          },
+          active: {
+            minimum: round(
+              min(
+                ...this.workerNodes.map(
+                  workerNode => workerNode.usage.elu.active.minimum ?? Infinity
+                )
+              )
+            ),
+            maximum: round(
+              max(
+                ...this.workerNodes.map(
+                  workerNode => workerNode.usage.elu.active.maximum ?? -Infinity
+                )
+              )
+            ),
+            ...(this.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
+              .elu.average && {
+              average: round(
+                average(
+                  this.workerNodes.reduce<number[]>(
+                    (accumulator, workerNode) =>
+                      accumulator.concat(workerNode.usage.elu.active.history),
+                    []
+                  )
+                )
+              )
+            }),
+            ...(this.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
+              .elu.median && {
+              median: round(
+                median(
+                  this.workerNodes.reduce<number[]>(
+                    (accumulator, workerNode) =>
+                      accumulator.concat(workerNode.usage.elu.active.history),
+                    []
+                  )
+                )
+              )
+            })
+          },
+          utilization: {
+            average: round(
+              average(
+                this.workerNodes.map(
+                  workerNode => workerNode.usage.elu.utilization ?? 0
+                )
+              )
+            ),
+            median: round(
+              median(
+                this.workerNodes.map(
+                  workerNode => workerNode.usage.elu.utilization ?? 0
+                )
+              )
+            )
+          }
+        }
       })
     }
   }
@@ -443,6 +564,9 @@ export abstract class AbstractPool<
    * The pool readiness boolean status.
    */
   private get ready (): boolean {
+    if (this.empty) {
+      return false
+    }
     return (
       this.workerNodes.reduce(
         (accumulator, workerNode) =>
@@ -454,12 +578,22 @@ export abstract class AbstractPool<
     )
   }
 
+  /**
+   * The pool emptiness boolean status.
+   */
+  protected get empty (): boolean {
+    return this.minimumNumberOfWorkers === 0 && this.workerNodes.length === 0
+  }
+
   /**
    * The approximate pool utilization.
    *
    * @returns The pool utilization.
    */
   private get utilization (): number {
+    if (this.startTimestamp == null) {
+      return 0
+    }
     const poolTimeCapacity =
       (performance.now() - this.startTimestamp) *
       (this.maximumNumberOfWorkers ?? this.minimumNumberOfWorkers)
@@ -521,31 +655,52 @@ export abstract class AbstractPool<
     workerChoiceStrategy: WorkerChoiceStrategy,
     workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
   ): void {
+    let requireSync = false
     checkValidWorkerChoiceStrategy(workerChoiceStrategy)
-    this.opts.workerChoiceStrategy = workerChoiceStrategy
-    this.workerChoiceStrategyContext?.setWorkerChoiceStrategy(
-      this.opts.workerChoiceStrategy
-    )
     if (workerChoiceStrategyOptions != null) {
-      this.setWorkerChoiceStrategyOptions(workerChoiceStrategyOptions)
+      requireSync = !this.setWorkerChoiceStrategyOptions(
+        workerChoiceStrategyOptions
+      )
     }
-    for (const [workerNodeKey, workerNode] of this.workerNodes.entries()) {
-      workerNode.resetUsage()
-      this.sendStatisticsMessageToWorker(workerNodeKey)
+    if (workerChoiceStrategy !== this.opts.workerChoiceStrategy) {
+      this.opts.workerChoiceStrategy = workerChoiceStrategy
+      this.workerChoiceStrategiesContext?.setDefaultWorkerChoiceStrategy(
+        this.opts.workerChoiceStrategy,
+        this.opts.workerChoiceStrategyOptions
+      )
+      requireSync = true
+    }
+    if (requireSync) {
+      this.workerChoiceStrategiesContext?.syncWorkerChoiceStrategies(
+        this.getWorkerChoiceStrategies(),
+        this.opts.workerChoiceStrategyOptions
+      )
+      for (const workerNodeKey of this.workerNodes.keys()) {
+        this.sendStatisticsMessageToWorker(workerNodeKey)
+      }
     }
   }
 
   /** @inheritDoc */
   public setWorkerChoiceStrategyOptions (
     workerChoiceStrategyOptions: WorkerChoiceStrategyOptions | undefined
-  ): void {
+  ): boolean {
     this.checkValidWorkerChoiceStrategyOptions(workerChoiceStrategyOptions)
     if (workerChoiceStrategyOptions != null) {
       this.opts.workerChoiceStrategyOptions = workerChoiceStrategyOptions
+      this.workerChoiceStrategiesContext?.setOptions(
+        this.opts.workerChoiceStrategyOptions
+      )
+      this.workerChoiceStrategiesContext?.syncWorkerChoiceStrategies(
+        this.getWorkerChoiceStrategies(),
+        this.opts.workerChoiceStrategyOptions
+      )
+      for (const workerNodeKey of this.workerNodes.keys()) {
+        this.sendStatisticsMessageToWorker(workerNodeKey)
+      }
+      return true
     }
-    this.workerChoiceStrategyContext?.setOptions(
-      this.opts.workerChoiceStrategyOptions
-    )
+    return false
   }
 
   /** @inheritDoc */
@@ -607,13 +762,13 @@ export abstract class AbstractPool<
   }
 
   private setTaskStealing (): void {
-    for (const [workerNodeKey] of this.workerNodes.entries()) {
+    for (const workerNodeKey of this.workerNodes.keys()) {
       this.workerNodes[workerNodeKey].on('idle', this.handleWorkerNodeIdleEvent)
     }
   }
 
   private unsetTaskStealing (): void {
-    for (const [workerNodeKey] of this.workerNodes.entries()) {
+    for (const workerNodeKey of this.workerNodes.keys()) {
       this.workerNodes[workerNodeKey].off(
         'idle',
         this.handleWorkerNodeIdleEvent
@@ -622,7 +777,7 @@ export abstract class AbstractPool<
   }
 
   private setTasksStealingOnBackPressure (): void {
-    for (const [workerNodeKey] of this.workerNodes.entries()) {
+    for (const workerNodeKey of this.workerNodes.keys()) {
       this.workerNodes[workerNodeKey].on(
         'backPressure',
         this.handleWorkerNodeBackPressureEvent
@@ -631,7 +786,7 @@ export abstract class AbstractPool<
   }
 
   private unsetTasksStealingOnBackPressure (): void {
-    for (const [workerNodeKey] of this.workerNodes.entries()) {
+    for (const workerNodeKey of this.workerNodes.keys()) {
       this.workerNodes[workerNodeKey].off(
         'backPressure',
         this.handleWorkerNodeBackPressureEvent
@@ -703,7 +858,7 @@ export abstract class AbstractPool<
         message: MessageValue<Response>
       ): void => {
         this.checkMessageWorkerId(message)
-        const workerId = this.getWorkerInfo(workerNodeKey).id
+        const workerId = this.getWorkerInfo(workerNodeKey)?.id
         if (
           message.taskFunctionOperationStatus != null &&
           message.workerId === workerId
@@ -774,7 +929,7 @@ export abstract class AbstractPool<
           }
         }
       }
-      for (const [workerNodeKey] of this.workerNodes.entries()) {
+      for (const workerNodeKey of this.workerNodes.keys()) {
         this.registerWorkerMessageListener(
           workerNodeKey,
           taskFunctionOperationsListener
@@ -786,21 +941,15 @@ export abstract class AbstractPool<
 
   /** @inheritDoc */
   public hasTaskFunction (name: string): boolean {
-    for (const workerNode of this.workerNodes) {
-      if (
-        Array.isArray(workerNode.info.taskFunctionNames) &&
-        workerNode.info.taskFunctionNames.includes(name)
-      ) {
-        return true
-      }
-    }
-    return false
+    return this.listTaskFunctionsProperties().some(
+      taskFunctionProperties => taskFunctionProperties.name === name
+    )
   }
 
   /** @inheritDoc */
   public async addTaskFunction (
     name: string,
-    fn: TaskFunction<Data, Response>
+    fn: TaskFunction<Data, Response> | TaskFunctionObject<Data, Response>
   ): Promise<boolean> {
     if (typeof name !== 'string') {
       throw new TypeError('name argument must be a string')
@@ -808,15 +957,26 @@ export abstract class AbstractPool<
     if (typeof name === 'string' && name.trim().length === 0) {
       throw new TypeError('name argument must not be an empty string')
     }
-    if (typeof fn !== 'function') {
-      throw new TypeError('fn argument must be a function')
+    if (typeof fn === 'function') {
+      fn = { taskFunction: fn } satisfies TaskFunctionObject<Data, Response>
+    }
+    if (typeof fn.taskFunction !== 'function') {
+      throw new TypeError('taskFunction property must be a function')
     }
+    checkValidPriority(fn.priority)
+    checkValidWorkerChoiceStrategy(fn.strategy)
     const opResult = await this.sendTaskFunctionOperationToWorkers({
       taskFunctionOperation: 'add',
-      taskFunctionName: name,
-      taskFunction: fn.toString()
+      taskFunctionProperties: buildTaskFunctionProperties(name, fn),
+      taskFunction: fn.taskFunction.toString()
     })
     this.taskFunctions.set(name, fn)
+    this.workerChoiceStrategiesContext?.syncWorkerChoiceStrategies(
+      this.getWorkerChoiceStrategies()
+    )
+    for (const workerNodeKey of this.workerNodes.keys()) {
+      this.sendStatisticsMessageToWorker(workerNodeKey)
+    }
     return opResult
   }
 
@@ -829,40 +989,139 @@ export abstract class AbstractPool<
     }
     const opResult = await this.sendTaskFunctionOperationToWorkers({
       taskFunctionOperation: 'remove',
-      taskFunctionName: name
+      taskFunctionProperties: buildTaskFunctionProperties(
+        name,
+        this.taskFunctions.get(name)
+      )
     })
-    this.deleteTaskFunctionWorkerUsages(name)
+    for (const workerNode of this.workerNodes) {
+      workerNode.deleteTaskFunctionWorkerUsage(name)
+    }
     this.taskFunctions.delete(name)
+    this.workerChoiceStrategiesContext?.syncWorkerChoiceStrategies(
+      this.getWorkerChoiceStrategies()
+    )
+    for (const workerNodeKey of this.workerNodes.keys()) {
+      this.sendStatisticsMessageToWorker(workerNodeKey)
+    }
     return opResult
   }
 
   /** @inheritDoc */
-  public listTaskFunctionNames (): string[] {
+  public listTaskFunctionsProperties (): TaskFunctionProperties[] {
     for (const workerNode of this.workerNodes) {
       if (
-        Array.isArray(workerNode.info.taskFunctionNames) &&
-        workerNode.info.taskFunctionNames.length > 0
+        Array.isArray(workerNode.info.taskFunctionsProperties) &&
+        workerNode.info.taskFunctionsProperties.length > 0
       ) {
-        return workerNode.info.taskFunctionNames
+        return workerNode.info.taskFunctionsProperties
       }
     }
     return []
   }
 
+  /**
+   * Gets task function worker choice strategy, if any.
+   *
+   * @param name - The task function name.
+   * @returns The task function worker choice strategy if the task function worker choice strategy is defined, `undefined` otherwise.
+   */
+  private readonly getTaskFunctionWorkerChoiceStrategy = (
+    name?: string
+  ): WorkerChoiceStrategy | undefined => {
+    name = name ?? DEFAULT_TASK_NAME
+    const taskFunctionsProperties = this.listTaskFunctionsProperties()
+    if (name === DEFAULT_TASK_NAME) {
+      name = taskFunctionsProperties[1]?.name
+    }
+    return taskFunctionsProperties.find(
+      (taskFunctionProperties: TaskFunctionProperties) =>
+        taskFunctionProperties.name === name
+    )?.strategy
+  }
+
+  /**
+   * Gets worker node task function worker choice strategy, if any.
+   *
+   * @param workerNodeKey - The worker node key.
+   * @param name - The task function name.
+   * @returns The worker node task function worker choice strategy if the worker node task function worker choice strategy is defined, `undefined` otherwise.
+   */
+  private readonly getWorkerNodeTaskFunctionWorkerChoiceStrategy = (
+    workerNodeKey: number,
+    name?: string
+  ): WorkerChoiceStrategy | undefined => {
+    const workerInfo = this.getWorkerInfo(workerNodeKey)
+    if (workerInfo == null) {
+      return
+    }
+    name = name ?? DEFAULT_TASK_NAME
+    if (name === DEFAULT_TASK_NAME) {
+      name = workerInfo.taskFunctionsProperties?.[1]?.name
+    }
+    return workerInfo.taskFunctionsProperties?.find(
+      (taskFunctionProperties: TaskFunctionProperties) =>
+        taskFunctionProperties.name === name
+    )?.strategy
+  }
+
+  /**
+   * Gets worker node task function priority, if any.
+   *
+   * @param workerNodeKey - The worker node key.
+   * @param name - The task function name.
+   * @returns The worker node task function priority if the worker node task function priority is defined, `undefined` otherwise.
+   */
+  private readonly getWorkerNodeTaskFunctionPriority = (
+    workerNodeKey: number,
+    name?: string
+  ): number | undefined => {
+    const workerInfo = this.getWorkerInfo(workerNodeKey)
+    if (workerInfo == null) {
+      return
+    }
+    name = name ?? DEFAULT_TASK_NAME
+    if (name === DEFAULT_TASK_NAME) {
+      name = workerInfo.taskFunctionsProperties?.[1]?.name
+    }
+    return workerInfo.taskFunctionsProperties?.find(
+      (taskFunctionProperties: TaskFunctionProperties) =>
+        taskFunctionProperties.name === name
+    )?.priority
+  }
+
+  /**
+   * Gets the worker choice strategies registered in this pool.
+   *
+   * @returns The worker choice strategies.
+   */
+  private readonly getWorkerChoiceStrategies =
+    (): Set<WorkerChoiceStrategy> => {
+      return new Set([
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        this.opts.workerChoiceStrategy!,
+        ...(this.listTaskFunctionsProperties()
+          .map(
+            (taskFunctionProperties: TaskFunctionProperties) =>
+              taskFunctionProperties.strategy
+          )
+          .filter(
+            (strategy: WorkerChoiceStrategy | undefined) => strategy != null
+          ) as WorkerChoiceStrategy[])
+      ])
+    }
+
   /** @inheritDoc */
   public async setDefaultTaskFunction (name: string): Promise<boolean> {
     return await this.sendTaskFunctionOperationToWorkers({
       taskFunctionOperation: 'default',
-      taskFunctionName: name
+      taskFunctionProperties: buildTaskFunctionProperties(
+        name,
+        this.taskFunctions.get(name)
+      )
     })
   }
 
-  private deleteTaskFunctionWorkerUsages (name: string): void {
-    for (const workerNode of this.workerNodes) {
-      workerNode.deleteTaskFunctionWorkerUsage(name)
-    }
-  }
-
   private shallExecuteTask (workerNodeKey: number): boolean {
     return (
       this.tasksQueueSize(workerNodeKey) === 0 &&
@@ -876,7 +1135,7 @@ export abstract class AbstractPool<
   public async execute (
     data?: Data,
     name?: string,
-    transferList?: TransferListItem[]
+    transferList?: readonly TransferListItem[]
   ): Promise<Response> {
     return await new Promise<Response>((resolve, reject) => {
       if (!this.started) {
@@ -904,11 +1163,16 @@ export abstract class AbstractPool<
         return
       }
       const timestamp = performance.now()
-      const workerNodeKey = this.chooseWorkerNode()
+      const workerNodeKey = this.chooseWorkerNode(name)
       const task: Task<Data> = {
         name: name ?? DEFAULT_TASK_NAME,
         // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
         data: data ?? ({} as Data),
+        priority: this.getWorkerNodeTaskFunctionPriority(workerNodeKey, name),
+        strategy: this.getWorkerNodeTaskFunctionWorkerChoiceStrategy(
+          workerNodeKey,
+          name
+        ),
         transferList,
         timestamp,
         taskId: randomUUID()
@@ -937,6 +1201,25 @@ export abstract class AbstractPool<
     })
   }
 
+  /**
+   * Starts the minimum number of workers.
+   */
+  private startMinimumNumberOfWorkers (initWorkerNodeUsage = false): void {
+    this.startingMinimumNumberOfWorkers = true
+    while (
+      this.workerNodes.reduce(
+        (accumulator, workerNode) =>
+          !workerNode.info.dynamic ? accumulator + 1 : accumulator,
+        0
+      ) < this.minimumNumberOfWorkers
+    ) {
+      const workerNodeKey = this.createAndSetupWorkerNode()
+      initWorkerNodeUsage &&
+        this.initWorkerNodeUsage(this.workerNodes[workerNodeKey])
+    }
+    this.startingMinimumNumberOfWorkers = false
+  }
+
   /** @inheritdoc */
   public start (): void {
     if (this.started) {
@@ -949,15 +1232,8 @@ export abstract class AbstractPool<
       throw new Error('Cannot start a destroying pool')
     }
     this.starting = true
-    while (
-      this.workerNodes.reduce(
-        (accumulator, workerNode) =>
-          !workerNode.info.dynamic ? accumulator + 1 : accumulator,
-        0
-      ) < this.minimumNumberOfWorkers
-    ) {
-      this.createAndSetupWorkerNode()
-    }
+    this.startMinimumNumberOfWorkers()
+    this.startTimestamp = performance.now()
     this.starting = false
     this.started = true
   }
@@ -975,14 +1251,14 @@ export abstract class AbstractPool<
     }
     this.destroying = true
     await Promise.all(
-      this.workerNodes.map(async (_workerNode, workerNodeKey) => {
+      this.workerNodes.map(async (_, workerNodeKey) => {
         await this.destroyWorkerNode(workerNodeKey)
       })
     )
     this.emitter?.emit(PoolEvents.destroy, this.info)
     this.emitter?.emitDestroy()
-    this.emitter?.removeAllListeners()
     this.readyEventEmitted = false
+    delete this.startTimestamp
     this.destroying = false
     this.started = false
   }
@@ -1045,7 +1321,9 @@ export abstract class AbstractPool<
   }
 
   /**
-   * Should return whether the worker is the main worker or not.
+   * Returns whether the worker is the main worker or not.
+   *
+   * @returns `true` if the worker is the main worker, `false` otherwise.
    */
   protected abstract isMain (): boolean
 
@@ -1065,7 +1343,7 @@ export abstract class AbstractPool<
       const workerUsage = this.workerNodes[workerNodeKey].usage
       ++workerUsage.tasks.executing
       updateWaitTimeWorkerUsage(
-        this.workerChoiceStrategyContext,
+        this.workerChoiceStrategiesContext,
         workerUsage,
         task
       )
@@ -1083,7 +1361,7 @@ export abstract class AbstractPool<
       ].getTaskFunctionWorkerUsage(task.name!)!
       ++taskFunctionWorkerUsage.tasks.executing
       updateWaitTimeWorkerUsage(
-        this.workerChoiceStrategyContext,
+        this.workerChoiceStrategiesContext,
         taskFunctionWorkerUsage,
         task
       )
@@ -1101,22 +1379,22 @@ export abstract class AbstractPool<
     workerNodeKey: number,
     message: MessageValue<Response>
   ): void {
-    let needWorkerChoiceStrategyUpdate = false
+    let needWorkerChoiceStrategiesUpdate = false
     // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
     if (this.workerNodes[workerNodeKey]?.usage != null) {
       const workerUsage = this.workerNodes[workerNodeKey].usage
       updateTaskStatisticsWorkerUsage(workerUsage, message)
       updateRunTimeWorkerUsage(
-        this.workerChoiceStrategyContext,
+        this.workerChoiceStrategiesContext,
         workerUsage,
         message
       )
       updateEluWorkerUsage(
-        this.workerChoiceStrategyContext,
+        this.workerChoiceStrategiesContext,
         workerUsage,
         message
       )
-      needWorkerChoiceStrategyUpdate = true
+      needWorkerChoiceStrategiesUpdate = true
     }
     if (
       this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
@@ -1132,19 +1410,19 @@ export abstract class AbstractPool<
       ].getTaskFunctionWorkerUsage(message.taskPerformance!.name)!
       updateTaskStatisticsWorkerUsage(taskFunctionWorkerUsage, message)
       updateRunTimeWorkerUsage(
-        this.workerChoiceStrategyContext,
+        this.workerChoiceStrategiesContext,
         taskFunctionWorkerUsage,
         message
       )
       updateEluWorkerUsage(
-        this.workerChoiceStrategyContext,
+        this.workerChoiceStrategiesContext,
         taskFunctionWorkerUsage,
         message
       )
-      needWorkerChoiceStrategyUpdate = true
+      needWorkerChoiceStrategiesUpdate = true
     }
-    if (needWorkerChoiceStrategyUpdate) {
-      this.workerChoiceStrategyContext?.update(workerNodeKey)
+    if (needWorkerChoiceStrategiesUpdate) {
+      this.workerChoiceStrategiesContext?.update(workerNodeKey)
     }
   }
 
@@ -1157,30 +1435,32 @@ export abstract class AbstractPool<
   private shallUpdateTaskFunctionWorkerUsage (workerNodeKey: number): boolean {
     const workerInfo = this.getWorkerInfo(workerNodeKey)
     return (
-      Array.isArray(workerInfo.taskFunctionNames) &&
-      workerInfo.taskFunctionNames.length > 2
+      workerInfo != null &&
+      Array.isArray(workerInfo.taskFunctionsProperties) &&
+      workerInfo.taskFunctionsProperties.length > 2
     )
   }
 
   /**
    * Chooses a worker node for the next task.
    *
-   * The default worker choice strategy uses a round robin algorithm to distribute the tasks.
-   *
+   * @param name - The task function name.
    * @returns The chosen worker node key
    */
-  private chooseWorkerNode (): number {
+  private chooseWorkerNode (name?: string): number {
     if (this.shallCreateDynamicWorker()) {
       const workerNodeKey = this.createAndSetupDynamicWorkerNode()
       if (
-        this.workerChoiceStrategyContext?.getStrategyPolicy()
-          .dynamicWorkerUsage === true
+        this.workerChoiceStrategiesContext?.getPolicy().dynamicWorkerUsage ===
+        true
       ) {
         return workerNodeKey
       }
     }
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-    return this.workerChoiceStrategyContext!.execute()!
+    return this.workerChoiceStrategiesContext!.execute(
+      this.getTaskFunctionWorkerChoiceStrategy(name)
+    )
   }
 
   /**
@@ -1200,9 +1480,47 @@ export abstract class AbstractPool<
   protected abstract sendToWorker (
     workerNodeKey: number,
     message: MessageValue<Data>,
-    transferList?: TransferListItem[]
+    transferList?: readonly TransferListItem[]
   ): void
 
+  /**
+   * Initializes the worker node usage with sensible default values gathered during runtime.
+   *
+   * @param workerNode - The worker node.
+   */
+  private initWorkerNodeUsage (workerNode: IWorkerNode<Worker, Data>): void {
+    if (
+      this.workerChoiceStrategiesContext?.getTaskStatisticsRequirements()
+        .runTime.aggregate === true
+    ) {
+      workerNode.usage.runTime.aggregate = min(
+        ...this.workerNodes.map(
+          workerNode => workerNode.usage.runTime.aggregate ?? Infinity
+        )
+      )
+    }
+    if (
+      this.workerChoiceStrategiesContext?.getTaskStatisticsRequirements()
+        .waitTime.aggregate === true
+    ) {
+      workerNode.usage.waitTime.aggregate = min(
+        ...this.workerNodes.map(
+          workerNode => workerNode.usage.waitTime.aggregate ?? Infinity
+        )
+      )
+    }
+    if (
+      this.workerChoiceStrategiesContext?.getTaskStatisticsRequirements().elu
+        .aggregate === true
+    ) {
+      workerNode.usage.elu.active.aggregate = min(
+        ...this.workerNodes.map(
+          workerNode => workerNode.usage.elu.active.aggregate ?? Infinity
+        )
+      )
+    }
+  }
+
   /**
    * Creates a new, completely set up worker node.
    *
@@ -1222,7 +1540,7 @@ export abstract class AbstractPool<
       'error',
       this.opts.errorHandler ?? EMPTY_FUNCTION
     )
-    workerNode.registerWorkerEventHandler('error', (error: Error) => {
+    workerNode.registerOnceWorkerEventHandler('error', (error: Error) => {
       workerNode.info.ready = false
       this.emitter?.emit(PoolEvents.error, error)
       if (
@@ -1232,8 +1550,8 @@ export abstract class AbstractPool<
       ) {
         if (workerNode.info.dynamic) {
           this.createAndSetupDynamicWorkerNode()
-        } else {
-          this.createAndSetupWorkerNode()
+        } else if (!this.startingMinimumNumberOfWorkers) {
+          this.startMinimumNumberOfWorkers(true)
         }
       }
       if (
@@ -1243,7 +1561,8 @@ export abstract class AbstractPool<
       ) {
         this.redistributeQueuedTasks(this.workerNodes.indexOf(workerNode))
       }
-      workerNode.terminate().catch(error => {
+      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+      workerNode?.terminate().catch((error: unknown) => {
         this.emitter?.emit(PoolEvents.error, error)
       })
     })
@@ -1253,6 +1572,13 @@ export abstract class AbstractPool<
     )
     workerNode.registerOnceWorkerEventHandler('exit', () => {
       this.removeWorkerNode(workerNode)
+      if (
+        this.started &&
+        !this.startingMinimumNumberOfWorkers &&
+        !this.destroying
+      ) {
+        this.startMinimumNumberOfWorkers(true)
+      }
     })
     const workerNodeKey = this.addWorkerNode(workerNode)
     this.afterWorkerNodeSetup(workerNodeKey)
@@ -1271,7 +1597,7 @@ export abstract class AbstractPool<
       const localWorkerNodeKey = this.getWorkerNodeKeyByWorkerId(
         message.workerId
       )
-      const workerUsage = this.workerNodes[localWorkerNodeKey].usage
+      const workerUsage = this.workerNodes[localWorkerNodeKey]?.usage
       // Kill message received from worker
       if (
         isKillBehavior(KillBehaviors.HARD, message.kill) ||
@@ -1284,7 +1610,7 @@ export abstract class AbstractPool<
       ) {
         // Flag the worker node as not ready immediately
         this.flagWorkerNodeAsNotReady(localWorkerNodeKey)
-        this.destroyWorkerNode(localWorkerNodeKey).catch(error => {
+        this.destroyWorkerNode(localWorkerNodeKey).catch((error: unknown) => {
           this.emitter?.emit(PoolEvents.error, error)
         })
       }
@@ -1293,12 +1619,15 @@ export abstract class AbstractPool<
       checkActive: true
     })
     if (this.taskFunctions.size > 0) {
-      for (const [taskFunctionName, taskFunction] of this.taskFunctions) {
+      for (const [taskFunctionName, taskFunctionObject] of this.taskFunctions) {
         this.sendTaskFunctionOperationToWorker(workerNodeKey, {
           taskFunctionOperation: 'add',
-          taskFunctionName,
-          taskFunction: taskFunction.toString()
-        }).catch(error => {
+          taskFunctionProperties: buildTaskFunctionProperties(
+            taskFunctionName,
+            taskFunctionObject
+          ),
+          taskFunction: taskFunctionObject.taskFunction.toString()
+        }).catch((error: unknown) => {
           this.emitter?.emit(PoolEvents.error, error)
         })
       }
@@ -1306,13 +1635,14 @@ export abstract class AbstractPool<
     const workerNode = this.workerNodes[workerNodeKey]
     workerNode.info.dynamic = true
     if (
-      this.workerChoiceStrategyContext?.getStrategyPolicy()
-        .dynamicWorkerReady === true ||
-      this.workerChoiceStrategyContext?.getStrategyPolicy()
-        .dynamicWorkerUsage === true
+      this.workerChoiceStrategiesContext?.getPolicy().dynamicWorkerReady ===
+        true ||
+      this.workerChoiceStrategiesContext?.getPolicy().dynamicWorkerUsage ===
+        true
     ) {
       workerNode.info.ready = true
     }
+    this.initWorkerNodeUsage(workerNode)
     this.checkAndEmitDynamicWorkerCreationEvents()
     return workerNodeKey
   }
@@ -1404,11 +1734,11 @@ export abstract class AbstractPool<
     this.sendToWorker(workerNodeKey, {
       statistics: {
         runTime:
-          this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
-            ?.runTime.aggregate ?? false,
+          this.workerChoiceStrategiesContext?.getTaskStatisticsRequirements()
+            .runTime.aggregate ?? false,
         elu:
-          this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()?.elu
-            .aggregate ?? false
+          this.workerChoiceStrategiesContext?.getTaskStatisticsRequirements()
+            .elu.aggregate ?? false
       }
     })
   }
@@ -1425,14 +1755,15 @@ export abstract class AbstractPool<
     }
   }
 
-  private redistributeQueuedTasks (workerNodeKey: number): void {
-    if (workerNodeKey === -1 || this.cannotStealTask()) {
+  private redistributeQueuedTasks (sourceWorkerNodeKey: number): void {
+    if (sourceWorkerNodeKey === -1 || this.cannotStealTask()) {
       return
     }
-    while (this.tasksQueueSize(workerNodeKey) > 0) {
+    while (this.tasksQueueSize(sourceWorkerNodeKey) > 0) {
       const destinationWorkerNodeKey = this.workerNodes.reduce(
         (minWorkerNodeKey, workerNode, workerNodeKey, workerNodes) => {
-          return workerNode.info.ready &&
+          return sourceWorkerNodeKey !== workerNodeKey &&
+            workerNode.info.ready &&
             workerNode.usage.tasks.queued <
               workerNodes[minWorkerNodeKey].usage.tasks.queued
             ? workerNodeKey
@@ -1443,7 +1774,7 @@ export abstract class AbstractPool<
       this.handleTask(
         destinationWorkerNodeKey,
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-        this.dequeueTask(workerNodeKey)!
+        this.dequeueTask(sourceWorkerNodeKey)!
       )
     }
   }
@@ -1461,28 +1792,21 @@ export abstract class AbstractPool<
       this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
       workerNode.getTaskFunctionWorkerUsage(taskName) != null
     ) {
-      const taskFunctionWorkerUsage =
-        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-        workerNode.getTaskFunctionWorkerUsage(taskName)!
-      ++taskFunctionWorkerUsage.tasks.stolen
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      ++workerNode.getTaskFunctionWorkerUsage(taskName)!.tasks.stolen
     }
   }
 
   private updateTaskSequentiallyStolenStatisticsWorkerUsage (
-    workerNodeKey: number
+    workerNodeKey: number,
+    taskName: string,
+    previousTaskName?: string
   ): void {
     const workerNode = this.workerNodes[workerNodeKey]
     // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
     if (workerNode?.usage != null) {
       ++workerNode.usage.tasks.sequentiallyStolen
     }
-  }
-
-  private updateTaskSequentiallyStolenStatisticsTaskFunctionWorkerUsage (
-    workerNodeKey: number,
-    taskName: string
-  ): void {
-    const workerNode = this.workerNodes[workerNodeKey]
     if (
       this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
       workerNode.getTaskFunctionWorkerUsage(taskName) != null
@@ -1490,33 +1814,36 @@ export abstract class AbstractPool<
       const taskFunctionWorkerUsage =
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
         workerNode.getTaskFunctionWorkerUsage(taskName)!
-      ++taskFunctionWorkerUsage.tasks.sequentiallyStolen
+      if (
+        taskFunctionWorkerUsage.tasks.sequentiallyStolen === 0 ||
+        (previousTaskName != null &&
+          previousTaskName === taskName &&
+          taskFunctionWorkerUsage.tasks.sequentiallyStolen > 0)
+      ) {
+        ++taskFunctionWorkerUsage.tasks.sequentiallyStolen
+      } else if (taskFunctionWorkerUsage.tasks.sequentiallyStolen > 0) {
+        taskFunctionWorkerUsage.tasks.sequentiallyStolen = 0
+      }
     }
   }
 
   private resetTaskSequentiallyStolenStatisticsWorkerUsage (
-    workerNodeKey: number
+    workerNodeKey: number,
+    taskName: string
   ): void {
     const workerNode = this.workerNodes[workerNodeKey]
     // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
     if (workerNode?.usage != null) {
       workerNode.usage.tasks.sequentiallyStolen = 0
     }
-  }
-
-  private resetTaskSequentiallyStolenStatisticsTaskFunctionWorkerUsage (
-    workerNodeKey: number,
-    taskName: string
-  ): void {
-    const workerNode = this.workerNodes[workerNodeKey]
     if (
       this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
       workerNode.getTaskFunctionWorkerUsage(taskName) != null
     ) {
-      const taskFunctionWorkerUsage =
-        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-        workerNode.getTaskFunctionWorkerUsage(taskName)!
-      taskFunctionWorkerUsage.tasks.sequentiallyStolen = 0
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      workerNode.getTaskFunctionWorkerUsage(
+        taskName
+      )!.tasks.sequentiallyStolen = 0
     }
   }
 
@@ -1531,6 +1858,11 @@ export abstract class AbstractPool<
       )
     }
     const workerInfo = this.getWorkerInfo(workerNodeKey)
+    if (workerInfo == null) {
+      throw new Error(
+        `Worker node with key '${workerNodeKey}' not found in pool`
+      )
+    }
     if (
       this.cannotStealTask() ||
       (this.info.stealingWorkerNodes ?? 0) >
@@ -1538,64 +1870,46 @@ export abstract class AbstractPool<
     ) {
       if (previousStolenTask != null) {
         workerInfo.stealing = false
+        this.resetTaskSequentiallyStolenStatisticsWorkerUsage(
+          workerNodeKey,
+          // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+          previousStolenTask.name!
+        )
       }
       return
     }
     const workerNodeTasksUsage = this.workerNodes[workerNodeKey].usage.tasks
     if (
       previousStolenTask != null &&
-      workerNodeTasksUsage.sequentiallyStolen > 0 &&
       (workerNodeTasksUsage.executing > 0 ||
         this.tasksQueueSize(workerNodeKey) > 0)
     ) {
       workerInfo.stealing = false
-      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-      for (const taskName of this.workerNodes[workerNodeKey].info
-        .taskFunctionNames!) {
-        this.resetTaskSequentiallyStolenStatisticsTaskFunctionWorkerUsage(
-          workerNodeKey,
-          taskName
-        )
-      }
-      this.resetTaskSequentiallyStolenStatisticsWorkerUsage(workerNodeKey)
+      this.resetTaskSequentiallyStolenStatisticsWorkerUsage(
+        workerNodeKey,
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        previousStolenTask.name!
+      )
       return
     }
     workerInfo.stealing = true
     const stolenTask = this.workerNodeStealTask(workerNodeKey)
-    if (
-      this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
-      stolenTask != null
-    ) {
-      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-      const taskFunctionTasksWorkerUsage = this.workerNodes[
-        workerNodeKey
+    if (stolenTask != null) {
+      this.updateTaskSequentiallyStolenStatisticsWorkerUsage(
+        workerNodeKey,
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-      ].getTaskFunctionWorkerUsage(stolenTask.name!)!.tasks
-      if (
-        taskFunctionTasksWorkerUsage.sequentiallyStolen === 0 ||
-        (previousStolenTask != null &&
-          previousStolenTask.name === stolenTask.name &&
-          taskFunctionTasksWorkerUsage.sequentiallyStolen > 0)
-      ) {
-        this.updateTaskSequentiallyStolenStatisticsTaskFunctionWorkerUsage(
-          workerNodeKey,
-          // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-          stolenTask.name!
-        )
-      } else {
-        this.resetTaskSequentiallyStolenStatisticsTaskFunctionWorkerUsage(
-          workerNodeKey,
-          // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-          stolenTask.name!
-        )
-      }
+        stolenTask.name!,
+        previousStolenTask?.name
+      )
     }
     sleep(exponentialDelay(workerNodeTasksUsage.sequentiallyStolen))
       .then(() => {
         this.handleWorkerNodeIdleEvent(eventDetail, stolenTask)
         return undefined
       })
-      .catch(EMPTY_FUNCTION)
+      .catch((error: unknown) => {
+        this.emitter?.emit(PoolEvents.error, error)
+      })
   }
 
   private readonly workerNodeStealTask = (
@@ -1616,9 +1930,8 @@ export abstract class AbstractPool<
     )
     if (sourceWorkerNode != null) {
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-      const task = sourceWorkerNode.popTask()!
+      const task = sourceWorkerNode.dequeueLastPrioritizedTask()!
       this.handleTask(workerNodeKey, task)
-      this.updateTaskSequentiallyStolenStatisticsWorkerUsage(workerNodeKey)
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       this.updateTaskStolenStatisticsWorkerUsage(workerNodeKey, task.name!)
       return task
@@ -1630,17 +1943,18 @@ export abstract class AbstractPool<
   ): void => {
     if (
       this.cannotStealTask() ||
+      this.hasBackPressure() ||
       (this.info.stealingWorkerNodes ?? 0) >
         Math.floor(this.workerNodes.length / 2)
     ) {
       return
     }
-    const { workerId } = eventDetail
     const sizeOffset = 1
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     if (this.opts.tasksQueueOptions!.size! <= sizeOffset) {
       return
     }
+    const { workerId } = eventDetail
     const sourceWorkerNode =
       this.workerNodes[this.getWorkerNodeKeyByWorkerId(workerId)]
     const workerNodes = this.workerNodes
@@ -1660,9 +1974,14 @@ export abstract class AbstractPool<
           this.opts.tasksQueueOptions!.size! - sizeOffset
       ) {
         const workerInfo = this.getWorkerInfo(workerNodeKey)
+        if (workerInfo == null) {
+          throw new Error(
+            `Worker node with key '${workerNodeKey}' not found in pool`
+          )
+        }
         workerInfo.stealing = true
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-        const task = sourceWorkerNode.popTask()!
+        const task = sourceWorkerNode.dequeueLastPrioritizedTask()!
         this.handleTask(workerNodeKey, task)
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
         this.updateTaskStolenStatisticsWorkerUsage(workerNodeKey, task.name!)
@@ -1678,34 +1997,42 @@ export abstract class AbstractPool<
     message: MessageValue<Response>
   ): void => {
     this.checkMessageWorkerId(message)
-    const { workerId, ready, taskId, taskFunctionNames } = message
-    if (ready != null && taskFunctionNames != null) {
+    const { workerId, ready, taskId, taskFunctionsProperties } = message
+    if (ready != null && taskFunctionsProperties != null) {
       // Worker ready response received from worker
       this.handleWorkerReadyResponse(message)
+    } else if (taskFunctionsProperties != null) {
+      // Task function properties message received from worker
+      const workerNodeKey = this.getWorkerNodeKeyByWorkerId(workerId)
+      const workerInfo = this.getWorkerInfo(workerNodeKey)
+      if (workerInfo != null) {
+        workerInfo.taskFunctionsProperties = taskFunctionsProperties
+        this.sendStatisticsMessageToWorker(workerNodeKey)
+      }
     } else if (taskId != null) {
       // Task execution response received from worker
       this.handleTaskExecutionResponse(message)
-    } else if (taskFunctionNames != null) {
-      // Task function names message received from worker
-      this.getWorkerInfo(
-        this.getWorkerNodeKeyByWorkerId(workerId)
-      ).taskFunctionNames = taskFunctionNames
+    }
+  }
+
+  private checkAndEmitReadyEvent (): void {
+    if (!this.readyEventEmitted && this.ready) {
+      this.emitter?.emit(PoolEvents.ready, this.info)
+      this.readyEventEmitted = true
     }
   }
 
   private handleWorkerReadyResponse (message: MessageValue<Response>): void {
-    const { workerId, ready, taskFunctionNames } = message
+    const { workerId, ready, taskFunctionsProperties } = message
     if (ready == null || !ready) {
       throw new Error(`Worker ${workerId} failed to initialize`)
     }
-    const workerNode =
-      this.workerNodes[this.getWorkerNodeKeyByWorkerId(workerId)]
+    const workerNodeKey = this.getWorkerNodeKeyByWorkerId(workerId)
+    const workerNode = this.workerNodes[workerNodeKey]
     workerNode.info.ready = ready
-    workerNode.info.taskFunctionNames = taskFunctionNames
-    if (!this.readyEventEmitted && this.ready) {
-      this.emitter?.emit(PoolEvents.ready, this.info)
-      this.readyEventEmitted = true
-    }
+    workerNode.info.taskFunctionsProperties = taskFunctionsProperties
+    this.sendStatisticsMessageToWorker(workerNodeKey)
+    this.checkAndEmitReadyEvent()
   }
 
   private handleTaskExecutionResponse (message: MessageValue<Response>): void {
@@ -1733,8 +2060,14 @@ export abstract class AbstractPool<
       this.afterTaskExecutionHook(workerNodeKey, message)
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       this.promiseResponseMap.delete(taskId!)
-      workerNode.emit('taskFinished', taskId)
-      if (this.opts.enableTasksQueue === true && !this.destroying) {
+      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+      workerNode?.emit('taskFinished', taskId)
+      if (
+        this.opts.enableTasksQueue === true &&
+        !this.destroying &&
+        // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+        workerNode != null
+      ) {
         const workerNodeTasksUsage = workerNode.usage.tasks
         if (
           this.tasksQueueSize(workerNodeKey) > 0 &&
@@ -1751,8 +2084,7 @@ export abstract class AbstractPool<
           workerNodeTasksUsage.sequentiallyStolen === 0
         ) {
           workerNode.emit('idle', {
-            // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-            workerId: workerId!,
+            workerId,
             workerNodeKey
           })
         }
@@ -1783,13 +2115,8 @@ export abstract class AbstractPool<
    * @param workerNodeKey - The worker node key.
    * @returns The worker information.
    */
-  protected getWorkerInfo (workerNodeKey: number): WorkerInfo {
-    const workerInfo = this.workerNodes[workerNodeKey]?.info
-    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
-    if (workerInfo == null) {
-      throw new Error(`Worker node with key '${workerNodeKey}' not found`)
-    }
-    return workerInfo
+  protected getWorkerInfo (workerNodeKey: number): WorkerInfo | undefined {
+    return this.workerNodes[workerNodeKey]?.info
   }
 
   /**
@@ -1808,7 +2135,9 @@ export abstract class AbstractPool<
           this.opts.tasksQueueOptions?.size ??
           getDefaultTasksQueueOptions(
             this.maximumNumberOfWorkers ?? this.minimumNumberOfWorkers
-          ).size
+          ).size,
+        tasksQueueBucketSize:
+          (this.maximumNumberOfWorkers ?? this.minimumNumberOfWorkers) * 2
       }
     )
     // Flag the worker node as ready at pool startup.
@@ -1834,6 +2163,13 @@ export abstract class AbstractPool<
     return workerNodeKey
   }
 
+  private checkAndEmitEmptyEvent (): void {
+    if (this.empty) {
+      this.emitter?.emit(PoolEvents.empty, this.info)
+      this.readyEventEmitted = false
+    }
+  }
+
   /**
    * Removes the worker node from the pool worker nodes.
    *
@@ -1843,12 +2179,16 @@ export abstract class AbstractPool<
     const workerNodeKey = this.workerNodes.indexOf(workerNode)
     if (workerNodeKey !== -1) {
       this.workerNodes.splice(workerNodeKey, 1)
-      this.workerChoiceStrategyContext?.remove(workerNodeKey)
+      this.workerChoiceStrategiesContext?.remove(workerNodeKey)
     }
+    this.checkAndEmitEmptyEvent()
   }
 
   protected flagWorkerNodeAsNotReady (workerNodeKey: number): void {
-    this.getWorkerInfo(workerNodeKey).ready = false
+    const workerInfo = this.getWorkerInfo(workerNodeKey)
+    if (workerInfo != null) {
+      workerInfo.ready = false
+    }
   }
 
   private hasBackPressure (): boolean {
@@ -1898,7 +2238,7 @@ export abstract class AbstractPool<
   }
 
   private flushTasksQueues (): void {
-    for (const [workerNodeKey] of this.workerNodes.entries()) {
+    for (const workerNodeKey of this.workerNodes.keys()) {
       this.flushTasksQueue(workerNodeKey)
     }
   }