build(deps-dev): apply updates
[poolifier.git] / src / pools / abstract-pool.ts
index 7b18d3556c72e6aee4629ae9831452325ea9d087..b7b30161ac7676511f0805d56a5a9284299c7f66 100644 (file)
@@ -1,17 +1,18 @@
+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
-} from '../utility-types'
+} from '../utility-types.js'
 import {
+  average,
   DEFAULT_TASK_NAME,
   EMPTY_FUNCTION,
-  average,
   exponentialDelay,
   isKillBehavior,
   isPlainObject,
@@ -20,9 +21,9 @@ import {
   min,
   round,
   sleep
-} from '../utils'
-import { KillBehaviors } from '../worker/worker-options'
-import type { TaskFunction } from '../worker/task-functions'
+} from '../utils.js'
+import type { TaskFunction } from '../worker/task-functions.js'
+import { KillBehaviors } from '../worker/worker-options.js'
 import {
   type IPool,
   PoolEvents,
@@ -31,25 +32,14 @@ import {
   type PoolType,
   PoolTypes,
   type TasksQueueOptions
-} from './pool'
-import type {
-  IWorker,
-  IWorkerNode,
-  TaskStatistics,
-  WorkerInfo,
-  WorkerNodeEventDetail,
-  WorkerType,
-  WorkerUsage
-} from './worker'
+} from './pool.js'
 import {
   Measurements,
   WorkerChoiceStrategies,
   type WorkerChoiceStrategy,
   type WorkerChoiceStrategyOptions
-} from './selection-strategies/selection-strategies-types'
-import { WorkerChoiceStrategyContext } from './selection-strategies/worker-choice-strategy-context'
-import { version } from './version'
-import { WorkerNode } from './worker-node'
+} from './selection-strategies/selection-strategies-types.js'
+import { WorkerChoiceStrategyContext } from './selection-strategies/worker-choice-strategy-context.js'
 import {
   checkFilePath,
   checkValidTasksQueueOptions,
@@ -60,7 +50,16 @@ import {
   updateTaskStatisticsWorkerUsage,
   updateWaitTimeWorkerUsage,
   waitWorkerNodeEvents
-} from './utils'
+} 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.
@@ -93,7 +92,7 @@ export abstract class AbstractPool<
   /**
    * Worker choice strategy context referencing a worker choice algorithm implementation.
    */
-  protected workerChoiceStrategyContext: WorkerChoiceStrategyContext<
+  protected workerChoiceStrategyContext?: WorkerChoiceStrategyContext<
   Worker,
   Data,
   Response
@@ -191,7 +190,9 @@ export abstract class AbstractPool<
     }
   }
 
-  private checkMinimumNumberOfWorkers (minimumNumberOfWorkers: number): void {
+  private checkMinimumNumberOfWorkers (
+    minimumNumberOfWorkers: number | undefined
+  ): void {
     if (minimumNumberOfWorkers == null) {
       throw new Error(
         'Cannot instantiate a pool without specifying the number of workers'
@@ -212,13 +213,11 @@ export abstract class AbstractPool<
   private checkPoolOptions (opts: PoolOptions<Worker>): void {
     if (isPlainObject(opts)) {
       this.opts.startWorkers = opts.startWorkers ?? true
-      checkValidWorkerChoiceStrategy(
-        opts.workerChoiceStrategy as WorkerChoiceStrategy
-      )
+      checkValidWorkerChoiceStrategy(opts.workerChoiceStrategy)
       this.opts.workerChoiceStrategy =
         opts.workerChoiceStrategy ?? WorkerChoiceStrategies.ROUND_ROBIN
       this.checkValidWorkerChoiceStrategyOptions(
-        opts.workerChoiceStrategyOptions as WorkerChoiceStrategyOptions
+        opts.workerChoiceStrategyOptions
       )
       if (opts.workerChoiceStrategyOptions != null) {
         this.opts.workerChoiceStrategyOptions = opts.workerChoiceStrategyOptions
@@ -227,9 +226,9 @@ export abstract class AbstractPool<
       this.opts.enableEvents = opts.enableEvents ?? true
       this.opts.enableTasksQueue = opts.enableTasksQueue ?? false
       if (this.opts.enableTasksQueue) {
-        checkValidTasksQueueOptions(opts.tasksQueueOptions as TasksQueueOptions)
+        checkValidTasksQueueOptions(opts.tasksQueueOptions)
         this.opts.tasksQueueOptions = this.buildTasksQueueOptions(
-          opts.tasksQueueOptions as TasksQueueOptions
+          opts.tasksQueueOptions
         )
       }
     } else {
@@ -238,7 +237,7 @@ export abstract class AbstractPool<
   }
 
   private checkValidWorkerChoiceStrategyOptions (
-    workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
+    workerChoiceStrategyOptions: WorkerChoiceStrategyOptions | undefined
   ): void {
     if (
       workerChoiceStrategyOptions != null &&
@@ -283,13 +282,17 @@ export abstract class AbstractPool<
       worker: this.worker,
       started: this.started,
       ready: this.ready,
-      strategy: this.opts.workerChoiceStrategy as WorkerChoiceStrategy,
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      strategy: this.opts.workerChoiceStrategy!,
+      strategyRetries: this.workerChoiceStrategyContext?.retriesCount ?? 0,
       minSize: this.minimumNumberOfWorkers,
       maxSize: this.maximumNumberOfWorkers ?? this.minimumNumberOfWorkers,
       ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
-        .runTime.aggregate &&
-        this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
-          .waitTime.aggregate && { utilization: round(this.utilization) }),
+        .runTime.aggregate === true &&
+        this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+          .waitTime.aggregate && {
+        utilization: round(this.utilization)
+      }),
       workerNodes: this.workerNodes.length,
       idleWorkerNodes: this.workerNodes.reduce(
         (accumulator, workerNode) =>
@@ -330,7 +333,7 @@ export abstract class AbstractPool<
       ...(this.opts.enableTasksQueue === true && {
         maxQueuedTasks: this.workerNodes.reduce(
           (accumulator, workerNode) =>
-            accumulator + (workerNode.usage.tasks?.maxQueued ?? 0),
+            accumulator + (workerNode.usage.tasks.maxQueued ?? 0),
           0
         )
       }),
@@ -350,23 +353,23 @@ export abstract class AbstractPool<
         0
       ),
       ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
-        .runTime.aggregate && {
+        .runTime.aggregate === true && {
         runTime: {
           minimum: round(
             min(
               ...this.workerNodes.map(
-                workerNode => workerNode.usage.runTime?.minimum ?? Infinity
+                workerNode => workerNode.usage.runTime.minimum ?? Infinity
               )
             )
           ),
           maximum: round(
             max(
               ...this.workerNodes.map(
-                workerNode => workerNode.usage.runTime?.maximum ?? -Infinity
+                workerNode => workerNode.usage.runTime.maximum ?? -Infinity
               )
             )
           ),
-          ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
+          ...(this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
             .runTime.average && {
             average: round(
               average(
@@ -378,7 +381,7 @@ export abstract class AbstractPool<
               )
             )
           }),
-          ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
+          ...(this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
             .runTime.median && {
             median: round(
               median(
@@ -393,23 +396,23 @@ export abstract class AbstractPool<
         }
       }),
       ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
-        .waitTime.aggregate && {
+        .waitTime.aggregate === true && {
         waitTime: {
           minimum: round(
             min(
               ...this.workerNodes.map(
-                workerNode => workerNode.usage.waitTime?.minimum ?? Infinity
+                workerNode => workerNode.usage.waitTime.minimum ?? Infinity
               )
             )
           ),
           maximum: round(
             max(
               ...this.workerNodes.map(
-                workerNode => workerNode.usage.waitTime?.maximum ?? -Infinity
+                workerNode => workerNode.usage.waitTime.maximum ?? -Infinity
               )
             )
           ),
-          ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
+          ...(this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
             .waitTime.average && {
             average: round(
               average(
@@ -421,7 +424,7 @@ export abstract class AbstractPool<
               )
             )
           }),
-          ...(this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
+          ...(this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
             .waitTime.median && {
             median: round(
               median(
@@ -442,6 +445,9 @@ export abstract class AbstractPool<
    * The pool readiness boolean status.
    */
   private get ready (): boolean {
+    if (this.empty) {
+      return false
+    }
     return (
       this.workerNodes.reduce(
         (accumulator, workerNode) =>
@@ -453,6 +459,13 @@ 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.
    *
@@ -464,12 +477,12 @@ export abstract class AbstractPool<
       (this.maximumNumberOfWorkers ?? this.minimumNumberOfWorkers)
     const totalTasksRunTime = this.workerNodes.reduce(
       (accumulator, workerNode) =>
-        accumulator + (workerNode.usage.runTime?.aggregate ?? 0),
+        accumulator + (workerNode.usage.runTime.aggregate ?? 0),
       0
     )
     const totalTasksWaitTime = this.workerNodes.reduce(
       (accumulator, workerNode) =>
-        accumulator + (workerNode.usage.waitTime?.aggregate ?? 0),
+        accumulator + (workerNode.usage.waitTime.aggregate ?? 0),
       0
     )
     return (totalTasksRunTime + totalTasksWaitTime) / poolTimeCapacity
@@ -522,7 +535,7 @@ export abstract class AbstractPool<
   ): void {
     checkValidWorkerChoiceStrategy(workerChoiceStrategy)
     this.opts.workerChoiceStrategy = workerChoiceStrategy
-    this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
+    this.workerChoiceStrategyContext?.setWorkerChoiceStrategy(
       this.opts.workerChoiceStrategy
     )
     if (workerChoiceStrategyOptions != null) {
@@ -536,14 +549,13 @@ export abstract class AbstractPool<
 
   /** @inheritDoc */
   public setWorkerChoiceStrategyOptions (
-    workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
+    workerChoiceStrategyOptions: WorkerChoiceStrategyOptions | undefined
   ): void {
     this.checkValidWorkerChoiceStrategyOptions(workerChoiceStrategyOptions)
     if (workerChoiceStrategyOptions != null) {
       this.opts.workerChoiceStrategyOptions = workerChoiceStrategyOptions
     }
-    this.workerChoiceStrategyContext.setOptions(
-      this,
+    this.workerChoiceStrategyContext?.setOptions(
       this.opts.workerChoiceStrategyOptions
     )
   }
@@ -559,16 +571,19 @@ export abstract class AbstractPool<
       this.flushTasksQueues()
     }
     this.opts.enableTasksQueue = enable
-    this.setTasksQueueOptions(tasksQueueOptions as TasksQueueOptions)
+    this.setTasksQueueOptions(tasksQueueOptions)
   }
 
   /** @inheritDoc */
-  public setTasksQueueOptions (tasksQueueOptions: TasksQueueOptions): void {
+  public setTasksQueueOptions (
+    tasksQueueOptions: TasksQueueOptions | undefined
+  ): void {
     if (this.opts.enableTasksQueue === true) {
       checkValidTasksQueueOptions(tasksQueueOptions)
       this.opts.tasksQueueOptions =
         this.buildTasksQueueOptions(tasksQueueOptions)
-      this.setTasksQueueSize(this.opts.tasksQueueOptions.size as number)
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      this.setTasksQueueSize(this.opts.tasksQueueOptions.size!)
       if (this.opts.tasksQueueOptions.taskStealing === true) {
         this.unsetTaskStealing()
         this.setTaskStealing()
@@ -587,7 +602,7 @@ export abstract class AbstractPool<
   }
 
   private buildTasksQueueOptions (
-    tasksQueueOptions: TasksQueueOptions
+    tasksQueueOptions: TasksQueueOptions | undefined
   ): TasksQueueOptions {
     return {
       ...getDefaultTasksQueueOptions(
@@ -605,18 +620,15 @@ export abstract class AbstractPool<
 
   private setTaskStealing (): void {
     for (const [workerNodeKey] of this.workerNodes.entries()) {
-      this.workerNodes[workerNodeKey].on(
-        'idleWorkerNode',
-        this.handleIdleWorkerNodeEvent
-      )
+      this.workerNodes[workerNodeKey].on('idle', this.handleWorkerNodeIdleEvent)
     }
   }
 
   private unsetTaskStealing (): void {
     for (const [workerNodeKey] of this.workerNodes.entries()) {
       this.workerNodes[workerNodeKey].off(
-        'idleWorkerNode',
-        this.handleIdleWorkerNodeEvent
+        'idle',
+        this.handleWorkerNodeIdleEvent
       )
     }
   }
@@ -625,7 +637,7 @@ export abstract class AbstractPool<
     for (const [workerNodeKey] of this.workerNodes.entries()) {
       this.workerNodes[workerNodeKey].on(
         'backPressure',
-        this.handleBackPressureEvent
+        this.handleWorkerNodeBackPressureEvent
       )
     }
   }
@@ -634,7 +646,7 @@ export abstract class AbstractPool<
     for (const [workerNodeKey] of this.workerNodes.entries()) {
       this.workerNodes[workerNodeKey].off(
         'backPressure',
-        this.handleBackPressureEvent
+        this.handleWorkerNodeBackPressureEvent
       )
     }
   }
@@ -670,7 +682,8 @@ export abstract class AbstractPool<
           workerNode =>
             workerNode.info.ready &&
             workerNode.usage.tasks.executing <
-              (this.opts.tasksQueueOptions?.concurrency as number)
+              // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+              this.opts.tasksQueueOptions!.concurrency!
         ) === -1
       )
     }
@@ -686,7 +699,8 @@ export abstract class AbstractPool<
     if (this.opts.enableTasksQueue === true) {
       return (
         this.workerNodes[workerNodeKey].usage.tasks.executing >=
-        (this.opts.tasksQueueOptions?.concurrency as number)
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        this.opts.tasksQueueOptions!.concurrency!
       )
     }
     return this.workerNodes[workerNodeKey].usage.tasks.executing > 0
@@ -701,21 +715,17 @@ export abstract class AbstractPool<
         message: MessageValue<Response>
       ): void => {
         this.checkMessageWorkerId(message)
-        const workerId = this.getWorkerInfo(workerNodeKey).id as number
+        const workerId = this.getWorkerInfo(workerNodeKey)?.id
         if (
           message.taskFunctionOperationStatus != null &&
           message.workerId === workerId
         ) {
           if (message.taskFunctionOperationStatus) {
             resolve(true)
-          } else if (!message.taskFunctionOperationStatus) {
+          } else {
             reject(
               new Error(
-                `Task function operation '${
-                  message.taskFunctionOperation as string
-                }' failed on worker ${message.workerId} with error: '${
-                  message.workerError?.message as string
-                }'`
+                `Task function operation '${message.taskFunctionOperation}' failed on worker ${message.workerId} with error: '${message.workerError?.message}'`
               )
             )
           }
@@ -763,10 +773,8 @@ export abstract class AbstractPool<
                 new Error(
                   `Task function operation '${
                     message.taskFunctionOperation as string
-                  }' failed on worker ${
-                    errorResponse?.workerId as number
-                  } with error: '${
-                    errorResponse?.workerError?.message as string
+                  }' failed on worker ${errorResponse?.workerId} with error: '${
+                    errorResponse?.workerError?.message
                   }'`
                 )
               )
@@ -871,7 +879,8 @@ export abstract class AbstractPool<
     return (
       this.tasksQueueSize(workerNodeKey) === 0 &&
       this.workerNodes[workerNodeKey].usage.tasks.executing <
-        (this.opts.tasksQueueOptions?.concurrency as number)
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        this.opts.tasksQueueOptions!.concurrency!
     )
   }
 
@@ -916,7 +925,8 @@ export abstract class AbstractPool<
         timestamp,
         taskId: randomUUID()
       }
-      this.promiseResponseMap.set(task.taskId as string, {
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      this.promiseResponseMap.set(task.taskId!, {
         resolve,
         reject,
         workerNodeKey,
@@ -983,7 +993,6 @@ export abstract class AbstractPool<
     )
     this.emitter?.emit(PoolEvents.destroy, this.info)
     this.emitter?.emitDestroy()
-    this.emitter?.removeAllListeners()
     this.readyEventEmitted = false
     this.destroying = false
     this.started = false
@@ -991,7 +1000,8 @@ export abstract class AbstractPool<
 
   private async sendKillMessageToWorker (workerNodeKey: number): Promise<void> {
     await new Promise<void>((resolve, reject) => {
-      if (this.workerNodes?.[workerNodeKey] == null) {
+      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+      if (this.workerNodes[workerNodeKey] == null) {
         resolve()
         return
       }
@@ -1002,9 +1012,7 @@ export abstract class AbstractPool<
         } else if (message.kill === 'failure') {
           reject(
             new Error(
-              `Kill message handling failed on worker ${
-                message.workerId as number
-              }`
+              `Kill message handling failed on worker ${message.workerId}`
             )
           )
         }
@@ -1063,6 +1071,7 @@ export abstract class AbstractPool<
     workerNodeKey: number,
     task: Task<Data>
   ): void {
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
     if (this.workerNodes[workerNodeKey]?.usage != null) {
       const workerUsage = this.workerNodes[workerNodeKey].usage
       ++workerUsage.tasks.executing
@@ -1074,13 +1083,15 @@ export abstract class AbstractPool<
     }
     if (
       this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
-      this.workerNodes[workerNodeKey].getTaskFunctionWorkerUsage(
-        task.name as string
-      ) != null
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      this.workerNodes[workerNodeKey].getTaskFunctionWorkerUsage(task.name!) !=
+        null
     ) {
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       const taskFunctionWorkerUsage = this.workerNodes[
         workerNodeKey
-      ].getTaskFunctionWorkerUsage(task.name as string) as WorkerUsage
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      ].getTaskFunctionWorkerUsage(task.name!)!
       ++taskFunctionWorkerUsage.tasks.executing
       updateWaitTimeWorkerUsage(
         this.workerChoiceStrategyContext,
@@ -1102,6 +1113,7 @@ export abstract class AbstractPool<
     message: MessageValue<Response>
   ): void {
     let needWorkerChoiceStrategyUpdate = 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)
@@ -1120,14 +1132,15 @@ export abstract class AbstractPool<
     if (
       this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
       this.workerNodes[workerNodeKey].getTaskFunctionWorkerUsage(
-        message.taskPerformance?.name as string
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        message.taskPerformance!.name
       ) != null
     ) {
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       const taskFunctionWorkerUsage = this.workerNodes[
         workerNodeKey
-      ].getTaskFunctionWorkerUsage(
-        message.taskPerformance?.name as string
-      ) as WorkerUsage
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      ].getTaskFunctionWorkerUsage(message.taskPerformance!.name)!
       updateTaskStatisticsWorkerUsage(taskFunctionWorkerUsage, message)
       updateRunTimeWorkerUsage(
         this.workerChoiceStrategyContext,
@@ -1142,7 +1155,7 @@ export abstract class AbstractPool<
       needWorkerChoiceStrategyUpdate = true
     }
     if (needWorkerChoiceStrategyUpdate) {
-      this.workerChoiceStrategyContext.update(workerNodeKey)
+      this.workerChoiceStrategyContext?.update(workerNodeKey)
     }
   }
 
@@ -1172,12 +1185,14 @@ export abstract class AbstractPool<
     if (this.shallCreateDynamicWorker()) {
       const workerNodeKey = this.createAndSetupDynamicWorkerNode()
       if (
-        this.workerChoiceStrategyContext.getStrategyPolicy().dynamicWorkerUsage
+        this.workerChoiceStrategyContext?.getStrategyPolicy()
+          .dynamicWorkerUsage === true
       ) {
         return workerNodeKey
       }
     }
-    return this.workerChoiceStrategyContext.execute()
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    return this.workerChoiceStrategyContext!.execute()
   }
 
   /**
@@ -1240,7 +1255,8 @@ 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)
       })
     })
@@ -1268,7 +1284,7 @@ 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) ||
@@ -1281,12 +1297,11 @@ 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)
         })
       }
     })
-    const workerInfo = this.getWorkerInfo(workerNodeKey)
     this.sendToWorker(workerNodeKey, {
       checkActive: true
     })
@@ -1296,17 +1311,20 @@ export abstract class AbstractPool<
           taskFunctionOperation: 'add',
           taskFunctionName,
           taskFunction: taskFunction.toString()
-        }).catch(error => {
+        }).catch((error: unknown) => {
           this.emitter?.emit(PoolEvents.error, error)
         })
       }
     }
-    workerInfo.dynamic = true
+    const workerNode = this.workerNodes[workerNodeKey]
+    workerNode.info.dynamic = true
     if (
-      this.workerChoiceStrategyContext.getStrategyPolicy().dynamicWorkerReady ||
-      this.workerChoiceStrategyContext.getStrategyPolicy().dynamicWorkerUsage
+      this.workerChoiceStrategyContext?.getStrategyPolicy()
+        .dynamicWorkerReady === true ||
+      this.workerChoiceStrategyContext?.getStrategyPolicy()
+        .dynamicWorkerUsage === true
     ) {
-      workerInfo.ready = true
+      workerNode.info.ready = true
     }
     this.checkAndEmitDynamicWorkerCreationEvents()
     return workerNodeKey
@@ -1370,14 +1388,14 @@ export abstract class AbstractPool<
     if (this.opts.enableTasksQueue === true) {
       if (this.opts.tasksQueueOptions?.taskStealing === true) {
         this.workerNodes[workerNodeKey].on(
-          'idleWorkerNode',
-          this.handleIdleWorkerNodeEvent
+          'idle',
+          this.handleWorkerNodeIdleEvent
         )
       }
       if (this.opts.tasksQueueOptions?.tasksStealingOnBackPressure === true) {
         this.workerNodes[workerNodeKey].on(
           'backPressure',
-          this.handleBackPressureEvent
+          this.handleWorkerNodeBackPressureEvent
         )
       }
     }
@@ -1399,10 +1417,11 @@ export abstract class AbstractPool<
     this.sendToWorker(workerNodeKey, {
       statistics: {
         runTime:
-          this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
-            .runTime.aggregate,
-        elu: this.workerChoiceStrategyContext.getTaskStatisticsRequirements()
-          .elu.aggregate
+          this.workerChoiceStrategyContext?.getTaskStatisticsRequirements()
+            .runTime.aggregate ?? false,
+        elu:
+          this.workerChoiceStrategyContext?.getTaskStatisticsRequirements().elu
+            .aggregate ?? false
       }
     })
   }
@@ -1436,7 +1455,8 @@ export abstract class AbstractPool<
       )
       this.handleTask(
         destinationWorkerNodeKey,
-        this.dequeueTask(workerNodeKey) as Task<Data>
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        this.dequeueTask(workerNodeKey)!
       )
     }
   }
@@ -1446,6 +1466,7 @@ export abstract class AbstractPool<
     taskName: string
   ): void {
     const workerNode = this.workerNodes[workerNodeKey]
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
     if (workerNode?.usage != null) {
       ++workerNode.usage.tasks.stolen
     }
@@ -1453,9 +1474,9 @@ export abstract class AbstractPool<
       this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
       workerNode.getTaskFunctionWorkerUsage(taskName) != null
     ) {
-      const taskFunctionWorkerUsage = workerNode.getTaskFunctionWorkerUsage(
-        taskName
-      ) as WorkerUsage
+      const taskFunctionWorkerUsage =
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        workerNode.getTaskFunctionWorkerUsage(taskName)!
       ++taskFunctionWorkerUsage.tasks.stolen
     }
   }
@@ -1464,6 +1485,7 @@ export abstract class AbstractPool<
     workerNodeKey: number
   ): void {
     const workerNode = this.workerNodes[workerNodeKey]
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
     if (workerNode?.usage != null) {
       ++workerNode.usage.tasks.sequentiallyStolen
     }
@@ -1478,9 +1500,9 @@ export abstract class AbstractPool<
       this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
       workerNode.getTaskFunctionWorkerUsage(taskName) != null
     ) {
-      const taskFunctionWorkerUsage = workerNode.getTaskFunctionWorkerUsage(
-        taskName
-      ) as WorkerUsage
+      const taskFunctionWorkerUsage =
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        workerNode.getTaskFunctionWorkerUsage(taskName)!
       ++taskFunctionWorkerUsage.tasks.sequentiallyStolen
     }
   }
@@ -1489,6 +1511,7 @@ export abstract class AbstractPool<
     workerNodeKey: number
   ): void {
     const workerNode = this.workerNodes[workerNodeKey]
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
     if (workerNode?.usage != null) {
       workerNode.usage.tasks.sequentiallyStolen = 0
     }
@@ -1503,43 +1526,45 @@ export abstract class AbstractPool<
       this.shallUpdateTaskFunctionWorkerUsage(workerNodeKey) &&
       workerNode.getTaskFunctionWorkerUsage(taskName) != null
     ) {
-      const taskFunctionWorkerUsage = workerNode.getTaskFunctionWorkerUsage(
-        taskName
-      ) as WorkerUsage
+      const taskFunctionWorkerUsage =
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        workerNode.getTaskFunctionWorkerUsage(taskName)!
       taskFunctionWorkerUsage.tasks.sequentiallyStolen = 0
     }
   }
 
-  private readonly handleIdleWorkerNodeEvent = (
+  private readonly handleWorkerNodeIdleEvent = (
     eventDetail: WorkerNodeEventDetail,
     previousStolenTask?: Task<Data>
   ): void => {
     const { workerNodeKey } = eventDetail
     if (workerNodeKey == null) {
       throw new Error(
-        'WorkerNode event detail workerNodeKey property must be defined'
+        "WorkerNode event detail 'workerNodeKey' property must be defined"
       )
     }
+    const workerInfo = this.getWorkerInfo(workerNodeKey)
     if (
       this.cannotStealTask() ||
-      (this.info.stealingWorkerNodes as number) >
+      (this.info.stealingWorkerNodes ?? 0) >
         Math.floor(this.workerNodes.length / 2)
     ) {
-      if (previousStolenTask != null) {
-        this.getWorkerInfo(workerNodeKey).stealing = false
+      if (workerInfo != null && previousStolenTask != null) {
+        workerInfo.stealing = false
       }
       return
     }
     const workerNodeTasksUsage = this.workerNodes[workerNodeKey].usage.tasks
     if (
+      workerInfo != null &&
       previousStolenTask != null &&
       workerNodeTasksUsage.sequentiallyStolen > 0 &&
       (workerNodeTasksUsage.executing > 0 ||
         this.tasksQueueSize(workerNodeKey) > 0)
     ) {
-      this.getWorkerInfo(workerNodeKey).stealing = false
-      for (const taskName of this.workerNodes[workerNodeKey].info
-        .taskFunctionNames as string[]) {
+      workerInfo.stealing = false
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      for (const taskName of workerInfo.taskFunctionNames!) {
         this.resetTaskSequentiallyStolenStatisticsTaskFunctionWorkerUsage(
           workerNodeKey,
           taskName
@@ -1548,16 +1573,22 @@ export abstract class AbstractPool<
       this.resetTaskSequentiallyStolenStatisticsWorkerUsage(workerNodeKey)
       return
     }
-    this.getWorkerInfo(workerNodeKey).stealing = true
+    if (workerInfo == null) {
+      throw new Error(
+        `Worker node with key '${workerNodeKey}' not found in pool`
+      )
+    }
+    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
-      ].getTaskFunctionWorkerUsage(stolenTask.name as string)
-        ?.tasks as TaskStatistics
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      ].getTaskFunctionWorkerUsage(stolenTask.name!)!.tasks
       if (
         taskFunctionTasksWorkerUsage.sequentiallyStolen === 0 ||
         (previousStolenTask != null &&
@@ -1566,21 +1597,25 @@ export abstract class AbstractPool<
       ) {
         this.updateTaskSequentiallyStolenStatisticsTaskFunctionWorkerUsage(
           workerNodeKey,
-          stolenTask.name as string
+          // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+          stolenTask.name!
         )
       } else {
         this.resetTaskSequentiallyStolenStatisticsTaskFunctionWorkerUsage(
           workerNodeKey,
-          stolenTask.name as string
+          // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+          stolenTask.name!
         )
       }
     }
     sleep(exponentialDelay(workerNodeTasksUsage.sequentiallyStolen))
       .then(() => {
-        this.handleIdleWorkerNodeEvent(eventDetail, stolenTask)
+        this.handleWorkerNodeIdleEvent(eventDetail, stolenTask)
         return undefined
       })
-      .catch(EMPTY_FUNCTION)
+      .catch((error: unknown) => {
+        this.emitter?.emit(PoolEvents.error, error)
+      })
   }
 
   private readonly workerNodeStealTask = (
@@ -1600,30 +1635,30 @@ export abstract class AbstractPool<
         sourceWorkerNode.usage.tasks.queued > 0
     )
     if (sourceWorkerNode != null) {
-      const task = sourceWorkerNode.popTask() as Task<Data>
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      const task = sourceWorkerNode.popTask()!
       this.handleTask(workerNodeKey, task)
       this.updateTaskSequentiallyStolenStatisticsWorkerUsage(workerNodeKey)
-      this.updateTaskStolenStatisticsWorkerUsage(
-        workerNodeKey,
-        task.name as string
-      )
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      this.updateTaskStolenStatisticsWorkerUsage(workerNodeKey, task.name!)
       return task
     }
   }
 
-  private readonly handleBackPressureEvent = (
+  private readonly handleWorkerNodeBackPressureEvent = (
     eventDetail: WorkerNodeEventDetail
   ): void => {
     if (
       this.cannotStealTask() ||
-      (this.info.stealingWorkerNodes as number) >
+      (this.info.stealingWorkerNodes ?? 0) >
         Math.floor(this.workerNodes.length / 2)
     ) {
       return
     }
     const { workerId } = eventDetail
     const sizeOffset = 1
-    if ((this.opts.tasksQueueOptions?.size as number) <= sizeOffset) {
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    if (this.opts.tasksQueueOptions!.size! <= sizeOffset) {
       return
     }
     const sourceWorkerNode =
@@ -1641,16 +1676,22 @@ export abstract class AbstractPool<
         !workerNode.info.stealing &&
         workerNode.info.id !== workerId &&
         workerNode.usage.tasks.queued <
-          (this.opts.tasksQueueOptions?.size as number) - sizeOffset
+          // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+          this.opts.tasksQueueOptions!.size! - sizeOffset
       ) {
-        this.getWorkerInfo(workerNodeKey).stealing = true
-        const task = sourceWorkerNode.popTask() as Task<Data>
+        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()!
         this.handleTask(workerNodeKey, task)
-        this.updateTaskStolenStatisticsWorkerUsage(
-          workerNodeKey,
-          task.name as string
-        )
-        this.getWorkerInfo(workerNodeKey).stealing = false
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        this.updateTaskStolenStatisticsWorkerUsage(workerNodeKey, task.name!)
+        workerInfo.stealing = false
       }
     }
   }
@@ -1671,31 +1712,38 @@ export abstract class AbstractPool<
       this.handleTaskExecutionResponse(message)
     } else if (taskFunctionNames != null) {
       // Task function names message received from worker
-      this.getWorkerInfo(
+      const workerInfo = this.getWorkerInfo(
         this.getWorkerNodeKeyByWorkerId(workerId)
-      ).taskFunctionNames = taskFunctionNames
+      )
+      if (workerInfo != null) {
+        workerInfo.taskFunctionNames = taskFunctionNames
+      }
     }
   }
 
-  private handleWorkerReadyResponse (message: MessageValue<Response>): void {
-    const { workerId, ready, taskFunctionNames } = message
-    if (ready === false) {
-      throw new Error(`Worker ${workerId as number} failed to initialize`)
-    }
-    const workerInfo = this.getWorkerInfo(
-      this.getWorkerNodeKeyByWorkerId(workerId)
-    )
-    workerInfo.ready = ready as boolean
-    workerInfo.taskFunctionNames = taskFunctionNames
+  private checkAndEmitReadyEvent (): void {
     if (!this.readyEventEmitted && this.ready) {
-      this.readyEventEmitted = true
       this.emitter?.emit(PoolEvents.ready, this.info)
+      this.readyEventEmitted = true
     }
   }
 
+  private handleWorkerReadyResponse (message: MessageValue<Response>): void {
+    const { workerId, ready, taskFunctionNames } = message
+    if (ready == null || !ready) {
+      throw new Error(`Worker ${workerId} failed to initialize`)
+    }
+    const workerNode =
+      this.workerNodes[this.getWorkerNodeKeyByWorkerId(workerId)]
+    workerNode.info.ready = ready
+    workerNode.info.taskFunctionNames = taskFunctionNames
+    this.checkAndEmitReadyEvent()
+  }
+
   private handleTaskExecutionResponse (message: MessageValue<Response>): void {
     const { workerId, taskId, workerError, data } = message
-    const promiseResponse = this.promiseResponseMap.get(taskId as string)
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    const promiseResponse = this.promiseResponseMap.get(taskId!)
     if (promiseResponse != null) {
       const { resolve, reject, workerNodeKey, asyncResource } = promiseResponse
       const workerNode = this.workerNodes[workerNodeKey]
@@ -1715,27 +1763,33 @@ export abstract class AbstractPool<
       }
       asyncResource?.emitDestroy()
       this.afterTaskExecutionHook(workerNodeKey, message)
-      this.promiseResponseMap.delete(taskId as string)
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      this.promiseResponseMap.delete(taskId!)
+      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
       workerNode?.emit('taskFinished', taskId)
-      if (this.opts.enableTasksQueue === true && !this.destroying) {
+      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 &&
           workerNodeTasksUsage.executing <
-            (this.opts.tasksQueueOptions?.concurrency as number)
+            // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+            this.opts.tasksQueueOptions!.concurrency!
         ) {
-          this.executeTask(
-            workerNodeKey,
-            this.dequeueTask(workerNodeKey) as Task<Data>
-          )
+          // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+          this.executeTask(workerNodeKey, this.dequeueTask(workerNodeKey)!)
         }
         if (
           workerNodeTasksUsage.executing === 0 &&
           this.tasksQueueSize(workerNodeKey) === 0 &&
           workerNodeTasksUsage.sequentiallyStolen === 0
         ) {
-          workerNode.emit('idleWorkerNode', {
-            workerId: workerId as number,
+          workerNode.emit('idle', {
+            workerId,
             workerNodeKey
           })
         }
@@ -1766,7 +1820,7 @@ export abstract class AbstractPool<
    * @param workerNodeKey - The worker node key.
    * @returns The worker information.
    */
-  protected getWorkerInfo (workerNodeKey: number): WorkerInfo {
+  protected getWorkerInfo (workerNodeKey: number): WorkerInfo | undefined {
     return this.workerNodes[workerNodeKey]?.info
   }
 
@@ -1812,6 +1866,13 @@ 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.
    *
@@ -1821,20 +1882,16 @@ export abstract class AbstractPool<
     const workerNodeKey = this.workerNodes.indexOf(workerNode)
     if (workerNodeKey !== -1) {
       this.workerNodes.splice(workerNodeKey, 1)
-      this.workerChoiceStrategyContext.remove(workerNodeKey)
+      this.workerChoiceStrategyContext?.remove(workerNodeKey)
     }
+    this.checkAndEmitEmptyEvent()
   }
 
   protected flagWorkerNodeAsNotReady (workerNodeKey: number): void {
-    this.getWorkerInfo(workerNodeKey).ready = false
-  }
-
-  /** @inheritDoc */
-  public hasWorkerNodeBackPressure (workerNodeKey: number): boolean {
-    return (
-      this.opts.enableTasksQueue === true &&
-      this.workerNodes[workerNodeKey].hasBackPressure()
-    )
+    const workerInfo = this.getWorkerInfo(workerNodeKey)
+    if (workerInfo != null) {
+      workerInfo.ready = false
+    }
   }
 
   private hasBackPressure (): boolean {
@@ -1875,10 +1932,8 @@ export abstract class AbstractPool<
   protected flushTasksQueue (workerNodeKey: number): number {
     let flushedTasks = 0
     while (this.tasksQueueSize(workerNodeKey) > 0) {
-      this.executeTask(
-        workerNodeKey,
-        this.dequeueTask(workerNodeKey) as Task<Data>
-      )
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      this.executeTask(workerNodeKey, this.dequeueTask(workerNodeKey)!)
       ++flushedTasks
     }
     this.workerNodes[workerNodeKey].clearTasksQueue()