perf: use optimized circular buffer implementation to store measurements history
[poolifier.git] / tests / pools / abstract-pool.test.mjs
index c0ba50b07b37b63ea7c28eb5b8df8bef829ae529..0c91349765f65c80884d4c50d8b45d93424e37fd 100644 (file)
@@ -1,10 +1,14 @@
+// eslint-disable-next-line n/no-unsupported-features/node-builtins
+import { createHook, executionAsyncId } from 'node:async_hooks'
 import { EventEmitterAsyncResource } from 'node:events'
-import { dirname, join } from 'node:path'
 import { readFileSync } from 'node:fs'
+import { dirname, join } from 'node:path'
 import { fileURLToPath } from 'node:url'
-import { createHook, executionAsyncId } from 'node:async_hooks'
+
 import { expect } from 'expect'
 import { restore, stub } from 'sinon'
+
+import { CircularBuffer } from '../../lib/circular-buffer.cjs'
 import {
   DynamicClusterPool,
   DynamicThreadPool,
@@ -14,12 +18,11 @@ import {
   PoolTypes,
   WorkerChoiceStrategies,
   WorkerTypes
-} from '../../lib/index.js'
-import { CircularArray } from '../../lib/circular-array.js'
-import { Deque } from '../../lib/deque.js'
-import { DEFAULT_TASK_NAME } from '../../lib/utils.js'
-import { waitPoolEvents } from '../test-utils.js'
-import { WorkerNode } from '../../lib/pools/worker-node.js'
+} from '../../lib/index.cjs'
+import { WorkerNode } from '../../lib/pools/worker-node.cjs'
+import { PriorityQueue } from '../../lib/priority-queue.cjs'
+import { DEFAULT_TASK_NAME } from '../../lib/utils.cjs'
+import { waitPoolEvents } from '../test-utils.cjs'
 
 describe('Abstract pool test suite', () => {
   const version = JSON.parse(
@@ -105,7 +108,7 @@ describe('Abstract pool test suite', () => {
   it('Verify that a negative number of workers is checked', () => {
     expect(
       () =>
-        new FixedClusterPool(-1, './tests/worker-files/cluster/testWorker.js')
+        new FixedClusterPool(-1, './tests/worker-files/cluster/testWorker.cjs')
     ).toThrow(
       new RangeError(
         'Cannot instantiate a pool with a negative number of workers'
@@ -146,7 +149,7 @@ describe('Abstract pool test suite', () => {
         new DynamicClusterPool(
           1,
           undefined,
-          './tests/worker-files/cluster/testWorker.js'
+          './tests/worker-files/cluster/testWorker.cjs'
         )
     ).toThrow(
       new TypeError(
@@ -170,7 +173,7 @@ describe('Abstract pool test suite', () => {
         new DynamicClusterPool(
           0,
           0.5,
-          './tests/worker-files/cluster/testWorker.js'
+          './tests/worker-files/cluster/testWorker.cjs'
         )
     ).toThrow(
       new TypeError(
@@ -206,7 +209,7 @@ describe('Abstract pool test suite', () => {
         new DynamicClusterPool(
           1,
           1,
-          './tests/worker-files/cluster/testWorker.js'
+          './tests/worker-files/cluster/testWorker.cjs'
         )
     ).toThrow(
       new RangeError(
@@ -221,6 +224,7 @@ describe('Abstract pool test suite', () => {
       './tests/worker-files/thread/testWorker.mjs'
     )
     expect(pool.emitter).toBeInstanceOf(EventEmitterAsyncResource)
+    expect(pool.emitter.eventNames()).toStrictEqual([])
     expect(pool.opts).toStrictEqual({
       startWorkers: true,
       enableEvents: true,
@@ -228,24 +232,9 @@ describe('Abstract pool test suite', () => {
       enableTasksQueue: false,
       workerChoiceStrategy: WorkerChoiceStrategies.ROUND_ROBIN
     })
-    expect(pool.workerChoiceStrategyContext.opts).toStrictEqual({
-      retries:
-        pool.info.maxSize +
-        Object.keys(pool.workerChoiceStrategyContext.opts.weights).length,
-      runTime: { median: false },
-      waitTime: { median: false },
-      elu: { median: false },
-      weights: expect.objectContaining({
-        0: expect.any(Number),
-        [pool.info.maxSize - 1]: expect.any(Number)
-      })
-    })
-    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategyContext
+    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategiesContext
       .workerChoiceStrategies) {
       expect(workerChoiceStrategy.opts).toStrictEqual({
-        retries:
-          pool.info.maxSize +
-          Object.keys(workerChoiceStrategy.opts.weights).length,
         runTime: { median: false },
         waitTime: { median: false },
         elu: { median: false },
@@ -286,7 +275,7 @@ describe('Abstract pool test suite', () => {
         concurrency: 2,
         size: Math.pow(numberOfWorkers, 2),
         taskStealing: true,
-        tasksStealingOnBackPressure: true,
+        tasksStealingOnBackPressure: false,
         tasksFinishedTimeout: 2000
       },
       workerChoiceStrategy: WorkerChoiceStrategies.LEAST_USED,
@@ -299,21 +288,9 @@ describe('Abstract pool test suite', () => {
       errorHandler: testHandler,
       exitHandler: testHandler
     })
-    expect(pool.workerChoiceStrategyContext.opts).toStrictEqual({
-      retries:
-        pool.info.maxSize +
-        Object.keys(pool.opts.workerChoiceStrategyOptions.weights).length,
-      runTime: { median: true },
-      waitTime: { median: false },
-      elu: { median: false },
-      weights: { 0: 300, 1: 200 }
-    })
-    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategyContext
+    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategiesContext
       .workerChoiceStrategies) {
       expect(workerChoiceStrategy.opts).toStrictEqual({
-        retries:
-          pool.info.maxSize +
-          Object.keys(pool.opts.workerChoiceStrategyOptions.weights).length,
         runTime: { median: true },
         waitTime: { median: false },
         elu: { median: false },
@@ -470,24 +447,9 @@ describe('Abstract pool test suite', () => {
       { workerChoiceStrategy: WorkerChoiceStrategies.FAIR_SHARE }
     )
     expect(pool.opts.workerChoiceStrategyOptions).toBeUndefined()
-    expect(pool.workerChoiceStrategyContext.opts).toStrictEqual({
-      retries:
-        pool.info.maxSize +
-        Object.keys(pool.workerChoiceStrategyContext.opts.weights).length,
-      runTime: { median: false },
-      waitTime: { median: false },
-      elu: { median: false },
-      weights: expect.objectContaining({
-        0: expect.any(Number),
-        [pool.info.maxSize - 1]: expect.any(Number)
-      })
-    })
-    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategyContext
+    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategiesContext
       .workerChoiceStrategies) {
       expect(workerChoiceStrategy.opts).toStrictEqual({
-        retries:
-          pool.info.maxSize +
-          Object.keys(workerChoiceStrategy.opts.weights).length,
         runTime: { median: false },
         waitTime: { median: false },
         elu: { median: false },
@@ -498,7 +460,7 @@ describe('Abstract pool test suite', () => {
       })
     }
     expect(
-      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+      pool.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
     ).toStrictEqual({
       runTime: {
         aggregate: true,
@@ -506,8 +468,8 @@ describe('Abstract pool test suite', () => {
         median: false
       },
       waitTime: {
-        aggregate: false,
-        average: false,
+        aggregate: true,
+        average: true,
         median: false
       },
       elu: {
@@ -524,24 +486,9 @@ describe('Abstract pool test suite', () => {
       runTime: { median: true },
       elu: { median: true }
     })
-    expect(pool.workerChoiceStrategyContext.opts).toStrictEqual({
-      retries:
-        pool.info.maxSize +
-        Object.keys(pool.workerChoiceStrategyContext.opts.weights).length,
-      runTime: { median: true },
-      waitTime: { median: false },
-      elu: { median: true },
-      weights: expect.objectContaining({
-        0: expect.any(Number),
-        [pool.info.maxSize - 1]: expect.any(Number)
-      })
-    })
-    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategyContext
+    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategiesContext
       .workerChoiceStrategies) {
       expect(workerChoiceStrategy.opts).toStrictEqual({
-        retries:
-          pool.info.maxSize +
-          Object.keys(workerChoiceStrategy.opts.weights).length,
         runTime: { median: true },
         waitTime: { median: false },
         elu: { median: true },
@@ -552,7 +499,7 @@ describe('Abstract pool test suite', () => {
       })
     }
     expect(
-      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+      pool.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
     ).toStrictEqual({
       runTime: {
         aggregate: true,
@@ -560,8 +507,8 @@ describe('Abstract pool test suite', () => {
         median: true
       },
       waitTime: {
-        aggregate: false,
-        average: false,
+        aggregate: true,
+        average: true,
         median: false
       },
       elu: {
@@ -578,24 +525,9 @@ describe('Abstract pool test suite', () => {
       runTime: { median: false },
       elu: { median: false }
     })
-    expect(pool.workerChoiceStrategyContext.opts).toStrictEqual({
-      retries:
-        pool.info.maxSize +
-        Object.keys(pool.workerChoiceStrategyContext.opts.weights).length,
-      runTime: { median: false },
-      waitTime: { median: false },
-      elu: { median: false },
-      weights: expect.objectContaining({
-        0: expect.any(Number),
-        [pool.info.maxSize - 1]: expect.any(Number)
-      })
-    })
-    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategyContext
+    for (const [, workerChoiceStrategy] of pool.workerChoiceStrategiesContext
       .workerChoiceStrategies) {
       expect(workerChoiceStrategy.opts).toStrictEqual({
-        retries:
-          pool.info.maxSize +
-          Object.keys(workerChoiceStrategy.opts.weights).length,
         runTime: { median: false },
         waitTime: { median: false },
         elu: { median: false },
@@ -606,7 +538,7 @@ describe('Abstract pool test suite', () => {
       })
     }
     expect(
-      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+      pool.workerChoiceStrategiesContext.getTaskStatisticsRequirements()
     ).toStrictEqual({
       runTime: {
         aggregate: true,
@@ -614,8 +546,8 @@ describe('Abstract pool test suite', () => {
         median: false
       },
       waitTime: {
-        aggregate: false,
-        average: false,
+        aggregate: true,
+        average: true,
         median: false
       },
       elu: {
@@ -659,7 +591,7 @@ describe('Abstract pool test suite', () => {
       concurrency: 1,
       size: Math.pow(numberOfWorkers, 2),
       taskStealing: true,
-      tasksStealingOnBackPressure: true,
+      tasksStealingOnBackPressure: false,
       tasksFinishedTimeout: 2000
     })
     pool.enableTasksQueue(true, { concurrency: 2 })
@@ -668,7 +600,7 @@ describe('Abstract pool test suite', () => {
       concurrency: 2,
       size: Math.pow(numberOfWorkers, 2),
       taskStealing: true,
-      tasksStealingOnBackPressure: true,
+      tasksStealingOnBackPressure: false,
       tasksFinishedTimeout: 2000
     })
     pool.enableTasksQueue(false)
@@ -687,7 +619,7 @@ describe('Abstract pool test suite', () => {
       concurrency: 1,
       size: Math.pow(numberOfWorkers, 2),
       taskStealing: true,
-      tasksStealingOnBackPressure: true,
+      tasksStealingOnBackPressure: false,
       tasksFinishedTimeout: 2000
     })
     for (const workerNode of pool.workerNodes) {
@@ -774,7 +706,8 @@ describe('Abstract pool test suite', () => {
       worker: WorkerTypes.thread,
       started: true,
       ready: true,
-      strategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      defaultStrategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      strategyRetries: 0,
       minSize: numberOfWorkers,
       maxSize: numberOfWorkers,
       workerNodes: numberOfWorkers,
@@ -788,7 +721,7 @@ describe('Abstract pool test suite', () => {
     pool = new DynamicClusterPool(
       Math.floor(numberOfWorkers / 2),
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     expect(pool.info).toStrictEqual({
       version,
@@ -796,7 +729,8 @@ describe('Abstract pool test suite', () => {
       worker: WorkerTypes.cluster,
       started: true,
       ready: true,
-      strategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      defaultStrategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      strategyRetries: 0,
       minSize: Math.floor(numberOfWorkers / 2),
       maxSize: numberOfWorkers,
       workerNodes: Math.floor(numberOfWorkers / 2),
@@ -812,7 +746,7 @@ describe('Abstract pool test suite', () => {
   it('Verify that pool worker tasks usage are initialized', async () => {
     const pool = new FixedClusterPool(
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     for (const workerNode of pool.workerNodes) {
       expect(workerNode).toBeInstanceOf(WorkerNode)
@@ -827,17 +761,17 @@ describe('Abstract pool test suite', () => {
           failed: 0
         },
         runTime: {
-          history: new CircularArray()
+          history: expect.any(CircularBuffer)
         },
         waitTime: {
-          history: new CircularArray()
+          history: expect.any(CircularBuffer)
         },
         elu: {
           idle: {
-            history: new CircularArray()
+            history: expect.any(CircularBuffer)
           },
           active: {
-            history: new CircularArray()
+            history: expect.any(CircularBuffer)
           }
         }
       })
@@ -848,13 +782,14 @@ describe('Abstract pool test suite', () => {
   it('Verify that pool worker tasks queue are initialized', async () => {
     let pool = new FixedClusterPool(
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     for (const workerNode of pool.workerNodes) {
       expect(workerNode).toBeInstanceOf(WorkerNode)
-      expect(workerNode.tasksQueue).toBeInstanceOf(Deque)
+      expect(workerNode.tasksQueue).toBeInstanceOf(PriorityQueue)
       expect(workerNode.tasksQueue.size).toBe(0)
       expect(workerNode.tasksQueue.maxSize).toBe(0)
+      expect(workerNode.tasksQueue.bucketSize).toBe(numberOfWorkers * 2)
     }
     await pool.destroy()
     pool = new DynamicThreadPool(
@@ -864,9 +799,10 @@ describe('Abstract pool test suite', () => {
     )
     for (const workerNode of pool.workerNodes) {
       expect(workerNode).toBeInstanceOf(WorkerNode)
-      expect(workerNode.tasksQueue).toBeInstanceOf(Deque)
+      expect(workerNode.tasksQueue).toBeInstanceOf(PriorityQueue)
       expect(workerNode.tasksQueue.size).toBe(0)
       expect(workerNode.tasksQueue.maxSize).toBe(0)
+      expect(workerNode.tasksQueue.bucketSize).toBe(numberOfWorkers * 2)
     }
     await pool.destroy()
   })
@@ -874,7 +810,7 @@ describe('Abstract pool test suite', () => {
   it('Verify that pool worker info are initialized', async () => {
     let pool = new FixedClusterPool(
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     for (const workerNode of pool.workerNodes) {
       expect(workerNode).toBeInstanceOf(WorkerNode)
@@ -882,7 +818,9 @@ describe('Abstract pool test suite', () => {
         id: expect.any(Number),
         type: WorkerTypes.cluster,
         dynamic: false,
-        ready: true
+        ready: true,
+        stealing: false,
+        backPressure: false
       })
     }
     await pool.destroy()
@@ -897,7 +835,9 @@ describe('Abstract pool test suite', () => {
         id: expect.any(Number),
         type: WorkerTypes.thread,
         dynamic: false,
-        ready: true
+        ready: true,
+        stealing: false,
+        backPressure: false
       })
     }
     await pool.destroy()
@@ -924,15 +864,15 @@ describe('Abstract pool test suite', () => {
   it('Verify that pool can be started after initialization', async () => {
     const pool = new FixedClusterPool(
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js',
+      './tests/worker-files/cluster/testWorker.cjs',
       {
         startWorkers: false
       }
     )
     expect(pool.info.started).toBe(false)
     expect(pool.info.ready).toBe(false)
-    expect(pool.readyEventEmitted).toBe(false)
     expect(pool.workerNodes).toStrictEqual([])
+    expect(pool.readyEventEmitted).toBe(false)
     await expect(pool.execute()).rejects.toThrow(
       new Error('Cannot execute a task on not started pool')
     )
@@ -951,7 +891,7 @@ describe('Abstract pool test suite', () => {
   it('Verify that pool execute() arguments are checked', async () => {
     const pool = new FixedClusterPool(
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     await expect(pool.execute(undefined, 0)).rejects.toThrow(
       new TypeError('name argument must be a string')
@@ -974,7 +914,7 @@ describe('Abstract pool test suite', () => {
   it('Verify that pool worker tasks usage are computed', async () => {
     const pool = new FixedClusterPool(
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     const promises = new Set()
     const maxMultiplier = 2
@@ -993,17 +933,17 @@ describe('Abstract pool test suite', () => {
           failed: 0
         },
         runTime: {
-          history: expect.any(CircularArray)
+          history: expect.any(CircularBuffer)
         },
         waitTime: {
-          history: expect.any(CircularArray)
+          history: expect.any(CircularBuffer)
         },
         elu: {
           idle: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           },
           active: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           }
         }
       })
@@ -1021,17 +961,17 @@ describe('Abstract pool test suite', () => {
           failed: 0
         },
         runTime: {
-          history: expect.any(CircularArray)
+          history: expect.any(CircularBuffer)
         },
         waitTime: {
-          history: expect.any(CircularArray)
+          history: expect.any(CircularBuffer)
         },
         elu: {
           idle: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           },
           active: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           }
         }
       })
@@ -1039,7 +979,7 @@ describe('Abstract pool test suite', () => {
     await pool.destroy()
   })
 
-  it('Verify that pool worker tasks usage are reset at worker choice strategy change', async () => {
+  it("Verify that pool worker tasks usage aren't reset at worker choice strategy change", async () => {
     const pool = new DynamicThreadPool(
       Math.floor(numberOfWorkers / 2),
       numberOfWorkers,
@@ -1063,17 +1003,17 @@ describe('Abstract pool test suite', () => {
           failed: 0
         },
         runTime: {
-          history: expect.any(CircularArray)
+          history: expect.any(CircularBuffer)
         },
         waitTime: {
-          history: expect.any(CircularArray)
+          history: expect.any(CircularBuffer)
         },
         elu: {
           idle: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           },
           active: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           }
         }
       })
@@ -1081,16 +1021,12 @@ describe('Abstract pool test suite', () => {
       expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
         numberOfWorkers * maxMultiplier
       )
-      expect(workerNode.usage.runTime.history.length).toBe(0)
-      expect(workerNode.usage.waitTime.history.length).toBe(0)
-      expect(workerNode.usage.elu.idle.history.length).toBe(0)
-      expect(workerNode.usage.elu.active.history.length).toBe(0)
     }
     pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.FAIR_SHARE)
     for (const workerNode of pool.workerNodes) {
       expect(workerNode.usage).toStrictEqual({
         tasks: {
-          executed: 0,
+          executed: expect.any(Number),
           executing: 0,
           queued: 0,
           maxQueued: 0,
@@ -1099,24 +1035,24 @@ describe('Abstract pool test suite', () => {
           failed: 0
         },
         runTime: {
-          history: expect.any(CircularArray)
+          history: expect.any(CircularBuffer)
         },
         waitTime: {
-          history: expect.any(CircularArray)
+          history: expect.any(CircularBuffer)
         },
         elu: {
           idle: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           },
           active: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           }
         }
       })
-      expect(workerNode.usage.runTime.history.length).toBe(0)
-      expect(workerNode.usage.waitTime.history.length).toBe(0)
-      expect(workerNode.usage.elu.idle.history.length).toBe(0)
-      expect(workerNode.usage.elu.active.history.length).toBe(0)
+      expect(workerNode.usage.tasks.executed).toBeGreaterThan(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        numberOfWorkers * maxMultiplier
+      )
     }
     await pool.destroy()
   })
@@ -1125,7 +1061,7 @@ describe('Abstract pool test suite', () => {
     const pool = new DynamicClusterPool(
       Math.floor(numberOfWorkers / 2),
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     expect(pool.emitter.eventNames()).toStrictEqual([])
     let poolInfo
@@ -1143,7 +1079,8 @@ describe('Abstract pool test suite', () => {
       worker: WorkerTypes.cluster,
       started: true,
       ready: true,
-      strategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      defaultStrategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      strategyRetries: expect.any(Number),
       minSize: expect.any(Number),
       maxSize: expect.any(Number),
       workerNodes: expect.any(Number),
@@ -1183,7 +1120,8 @@ describe('Abstract pool test suite', () => {
       worker: WorkerTypes.thread,
       started: true,
       ready: true,
-      strategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      defaultStrategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      strategyRetries: expect.any(Number),
       minSize: expect.any(Number),
       maxSize: expect.any(Number),
       workerNodes: expect.any(Number),
@@ -1222,7 +1160,8 @@ describe('Abstract pool test suite', () => {
       worker: WorkerTypes.thread,
       started: true,
       ready: true,
-      strategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      defaultStrategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      strategyRetries: expect.any(Number),
       minSize: expect.any(Number),
       maxSize: expect.any(Number),
       workerNodes: expect.any(Number),
@@ -1264,11 +1203,13 @@ describe('Abstract pool test suite', () => {
       worker: WorkerTypes.thread,
       started: true,
       ready: true,
-      strategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      defaultStrategy: WorkerChoiceStrategies.ROUND_ROBIN,
+      strategyRetries: expect.any(Number),
       minSize: expect.any(Number),
       maxSize: expect.any(Number),
       workerNodes: expect.any(Number),
       idleWorkerNodes: expect.any(Number),
+      stealingWorkerNodes: expect.any(Number),
       busyWorkerNodes: expect.any(Number),
       executedTasks: expect.any(Number),
       executingTasks: expect.any(Number),
@@ -1278,7 +1219,7 @@ describe('Abstract pool test suite', () => {
       stolenTasks: expect.any(Number),
       failedTasks: expect.any(Number)
     })
-    expect(pool.hasBackPressure.callCount).toBe(5)
+    expect(pool.hasBackPressure.callCount).toBeGreaterThanOrEqual(7)
     await pool.destroy()
   })
 
@@ -1308,7 +1249,7 @@ describe('Abstract pool test suite', () => {
     const elapsedTime = performance.now() - startTime
     expect(tasksFinished).toBeLessThanOrEqual(numberOfWorkers * maxMultiplier)
     expect(elapsedTime).toBeGreaterThanOrEqual(2000)
-    expect(elapsedTime).toBeLessThanOrEqual(tasksFinishedTimeout + 200)
+    expect(elapsedTime).toBeLessThanOrEqual(tasksFinishedTimeout + 800)
   })
 
   it('Verify that destroy() waits until the tasks finished timeout is reached', async () => {
@@ -1393,7 +1334,7 @@ describe('Abstract pool test suite', () => {
     await dynamicThreadPool.destroy()
     const fixedClusterPool = new FixedClusterPool(
       numberOfWorkers,
-      './tests/worker-files/cluster/testMultipleTaskFunctionsWorker.js'
+      './tests/worker-files/cluster/testMultipleTaskFunctionsWorker.cjs'
     )
     await waitPoolEvents(fixedClusterPool, PoolEvents.ready, 1)
     expect(fixedClusterPool.hasTaskFunction(DEFAULT_TASK_NAME)).toBe(true)
@@ -1422,29 +1363,72 @@ describe('Abstract pool test suite', () => {
       new TypeError('name argument must not be an empty string')
     )
     await expect(dynamicThreadPool.addTaskFunction('test', 0)).rejects.toThrow(
-      new TypeError('fn argument must be a function')
+      new TypeError('taskFunction property must be a function')
     )
     await expect(dynamicThreadPool.addTaskFunction('test', '')).rejects.toThrow(
-      new TypeError('fn argument must be a function')
+      new TypeError('taskFunction property must be a function')
     )
-    expect(dynamicThreadPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'test'
+    await expect(
+      dynamicThreadPool.addTaskFunction('test', { taskFunction: 0 })
+    ).rejects.toThrow(new TypeError('taskFunction property must be a function'))
+    await expect(
+      dynamicThreadPool.addTaskFunction('test', { taskFunction: '' })
+    ).rejects.toThrow(new TypeError('taskFunction property must be a function'))
+    await expect(
+      dynamicThreadPool.addTaskFunction('test', {
+        taskFunction: () => {},
+        priority: -21
+      })
+    ).rejects.toThrow(
+      new RangeError("Property 'priority' must be between -20 and 19")
+    )
+    await expect(
+      dynamicThreadPool.addTaskFunction('test', {
+        taskFunction: () => {},
+        priority: 20
+      })
+    ).rejects.toThrow(
+      new RangeError("Property 'priority' must be between -20 and 19")
+    )
+    await expect(
+      dynamicThreadPool.addTaskFunction('test', {
+        taskFunction: () => {},
+        strategy: 'invalidStrategy'
+      })
+    ).rejects.toThrow(
+      new Error("Invalid worker choice strategy 'invalidStrategy'")
+    )
+    expect(dynamicThreadPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'test' }
     ])
+    expect([
+      ...dynamicThreadPool.workerChoiceStrategiesContext.workerChoiceStrategies.keys()
+    ]).toStrictEqual([WorkerChoiceStrategies.ROUND_ROBIN])
     const echoTaskFunction = data => {
       return data
     }
     await expect(
-      dynamicThreadPool.addTaskFunction('echo', echoTaskFunction)
+      dynamicThreadPool.addTaskFunction('echo', {
+        taskFunction: echoTaskFunction,
+        strategy: WorkerChoiceStrategies.LEAST_ELU
+      })
     ).resolves.toBe(true)
     expect(dynamicThreadPool.taskFunctions.size).toBe(1)
-    expect(dynamicThreadPool.taskFunctions.get('echo')).toStrictEqual(
-      echoTaskFunction
-    )
-    expect(dynamicThreadPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'test',
-      'echo'
+    expect(dynamicThreadPool.taskFunctions.get('echo')).toStrictEqual({
+      taskFunction: echoTaskFunction,
+      strategy: WorkerChoiceStrategies.LEAST_ELU
+    })
+    expect([
+      ...dynamicThreadPool.workerChoiceStrategiesContext.workerChoiceStrategies.keys()
+    ]).toStrictEqual([
+      WorkerChoiceStrategies.ROUND_ROBIN,
+      WorkerChoiceStrategies.LEAST_ELU
+    ])
+    expect(dynamicThreadPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'test' },
+      { name: 'echo', strategy: WorkerChoiceStrategies.LEAST_ELU }
     ])
     const taskFunctionData = { test: 'test' }
     const echoResult = await dynamicThreadPool.execute(taskFunctionData, 'echo')
@@ -1460,20 +1444,60 @@ describe('Abstract pool test suite', () => {
           failed: 0
         },
         runTime: {
-          history: new CircularArray()
+          history: expect.any(CircularBuffer)
         },
         waitTime: {
-          history: new CircularArray()
+          history: expect.any(CircularBuffer)
         },
-        elu: {
-          idle: {
-            history: new CircularArray()
-          },
-          active: {
-            history: new CircularArray()
-          }
-        }
+        elu: expect.objectContaining({
+          idle: expect.objectContaining({
+            history: expect.any(CircularBuffer)
+          }),
+          active: expect.objectContaining({
+            history: expect.any(CircularBuffer)
+          })
+        })
       })
+      expect(
+        workerNode.getTaskFunctionWorkerUsage('echo').tasks.executed
+      ).toBeGreaterThan(0)
+      if (
+        workerNode.getTaskFunctionWorkerUsage('echo').elu.active.aggregate ==
+        null
+      ) {
+        expect(
+          workerNode.getTaskFunctionWorkerUsage('echo').elu.active.aggregate
+        ).toBeUndefined()
+      } else {
+        expect(
+          workerNode.getTaskFunctionWorkerUsage('echo').elu.active.aggregate
+        ).toBeGreaterThan(0)
+      }
+      if (
+        workerNode.getTaskFunctionWorkerUsage('echo').elu.idle.aggregate == null
+      ) {
+        expect(
+          workerNode.getTaskFunctionWorkerUsage('echo').elu.idle.aggregate
+        ).toBeUndefined()
+      } else {
+        expect(
+          workerNode.getTaskFunctionWorkerUsage('echo').elu.idle.aggregate
+        ).toBeGreaterThanOrEqual(0)
+      }
+      if (
+        workerNode.getTaskFunctionWorkerUsage('echo').elu.utilization == null
+      ) {
+        expect(
+          workerNode.getTaskFunctionWorkerUsage('echo').elu.utilization
+        ).toBeUndefined()
+      } else {
+        expect(
+          workerNode.getTaskFunctionWorkerUsage('echo').elu.utilization
+        ).toBeGreaterThanOrEqual(0)
+        expect(
+          workerNode.getTaskFunctionWorkerUsage('echo').elu.utilization
+        ).toBeLessThanOrEqual(1)
+      }
     }
     await dynamicThreadPool.destroy()
   })
@@ -1485,9 +1509,9 @@ describe('Abstract pool test suite', () => {
       './tests/worker-files/thread/testWorker.mjs'
     )
     await waitPoolEvents(dynamicThreadPool, PoolEvents.ready, 1)
-    expect(dynamicThreadPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'test'
+    expect(dynamicThreadPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'test' }
     ])
     await expect(dynamicThreadPool.removeTaskFunction('test')).rejects.toThrow(
       new Error('Cannot remove a task function not handled on the pool side')
@@ -1495,52 +1519,65 @@ describe('Abstract pool test suite', () => {
     const echoTaskFunction = data => {
       return data
     }
-    await dynamicThreadPool.addTaskFunction('echo', echoTaskFunction)
+    await dynamicThreadPool.addTaskFunction('echo', {
+      taskFunction: echoTaskFunction,
+      strategy: WorkerChoiceStrategies.LEAST_ELU
+    })
     expect(dynamicThreadPool.taskFunctions.size).toBe(1)
-    expect(dynamicThreadPool.taskFunctions.get('echo')).toStrictEqual(
-      echoTaskFunction
-    )
-    expect(dynamicThreadPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'test',
-      'echo'
+    expect(dynamicThreadPool.taskFunctions.get('echo')).toStrictEqual({
+      taskFunction: echoTaskFunction,
+      strategy: WorkerChoiceStrategies.LEAST_ELU
+    })
+    expect([
+      ...dynamicThreadPool.workerChoiceStrategiesContext.workerChoiceStrategies.keys()
+    ]).toStrictEqual([
+      WorkerChoiceStrategies.ROUND_ROBIN,
+      WorkerChoiceStrategies.LEAST_ELU
+    ])
+    expect(dynamicThreadPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'test' },
+      { name: 'echo', strategy: WorkerChoiceStrategies.LEAST_ELU }
     ])
     await expect(dynamicThreadPool.removeTaskFunction('echo')).resolves.toBe(
       true
     )
     expect(dynamicThreadPool.taskFunctions.size).toBe(0)
     expect(dynamicThreadPool.taskFunctions.get('echo')).toBeUndefined()
-    expect(dynamicThreadPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'test'
+    expect([
+      ...dynamicThreadPool.workerChoiceStrategiesContext.workerChoiceStrategies.keys()
+    ]).toStrictEqual([WorkerChoiceStrategies.ROUND_ROBIN])
+    expect(dynamicThreadPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'test' }
     ])
     await dynamicThreadPool.destroy()
   })
 
-  it('Verify that listTaskFunctionNames() is working', async () => {
+  it('Verify that listTaskFunctionsProperties() is working', async () => {
     const dynamicThreadPool = new DynamicThreadPool(
       Math.floor(numberOfWorkers / 2),
       numberOfWorkers,
       './tests/worker-files/thread/testMultipleTaskFunctionsWorker.mjs'
     )
     await waitPoolEvents(dynamicThreadPool, PoolEvents.ready, 1)
-    expect(dynamicThreadPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'jsonIntegerSerialization',
-      'factorial',
-      'fibonacci'
+    expect(dynamicThreadPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'jsonIntegerSerialization' },
+      { name: 'factorial' },
+      { name: 'fibonacci' }
     ])
     await dynamicThreadPool.destroy()
     const fixedClusterPool = new FixedClusterPool(
       numberOfWorkers,
-      './tests/worker-files/cluster/testMultipleTaskFunctionsWorker.js'
+      './tests/worker-files/cluster/testMultipleTaskFunctionsWorker.cjs'
     )
     await waitPoolEvents(fixedClusterPool, PoolEvents.ready, 1)
-    expect(fixedClusterPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'jsonIntegerSerialization',
-      'factorial',
-      'fibonacci'
+    expect(fixedClusterPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'jsonIntegerSerialization' },
+      { name: 'factorial' },
+      { name: 'fibonacci' }
     ])
     await fixedClusterPool.destroy()
   })
@@ -1572,29 +1609,29 @@ describe('Abstract pool test suite', () => {
         `Task function operation 'default' failed on worker ${workerId} with error: 'Error: Cannot set the default task function to a non-existing task function'`
       )
     )
-    expect(dynamicThreadPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'jsonIntegerSerialization',
-      'factorial',
-      'fibonacci'
+    expect(dynamicThreadPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'jsonIntegerSerialization' },
+      { name: 'factorial' },
+      { name: 'fibonacci' }
     ])
     await expect(
       dynamicThreadPool.setDefaultTaskFunction('factorial')
     ).resolves.toBe(true)
-    expect(dynamicThreadPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'factorial',
-      'jsonIntegerSerialization',
-      'fibonacci'
+    expect(dynamicThreadPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'factorial' },
+      { name: 'jsonIntegerSerialization' },
+      { name: 'fibonacci' }
     ])
     await expect(
       dynamicThreadPool.setDefaultTaskFunction('fibonacci')
     ).resolves.toBe(true)
-    expect(dynamicThreadPool.listTaskFunctionNames()).toStrictEqual([
-      DEFAULT_TASK_NAME,
-      'fibonacci',
-      'jsonIntegerSerialization',
-      'factorial'
+    expect(dynamicThreadPool.listTaskFunctionsProperties()).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'fibonacci' },
+      { name: 'jsonIntegerSerialization' },
+      { name: 'factorial' }
     ])
     await dynamicThreadPool.destroy()
   })
@@ -1603,7 +1640,76 @@ describe('Abstract pool test suite', () => {
     const pool = new DynamicClusterPool(
       Math.floor(numberOfWorkers / 2),
       numberOfWorkers,
-      './tests/worker-files/cluster/testMultipleTaskFunctionsWorker.js'
+      './tests/worker-files/cluster/testMultipleTaskFunctionsWorker.cjs'
+    )
+    const data = { n: 10 }
+    const result0 = await pool.execute(data)
+    expect(result0).toStrictEqual({ ok: 1 })
+    const result1 = await pool.execute(data, 'jsonIntegerSerialization')
+    expect(result1).toStrictEqual({ ok: 1 })
+    const result2 = await pool.execute(data, 'factorial')
+    expect(result2).toBe(3628800)
+    const result3 = await pool.execute(data, 'fibonacci')
+    expect(result3).toBe(55)
+    expect(pool.info.executingTasks).toBe(0)
+    expect(pool.info.executedTasks).toBe(4)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.info.taskFunctionsProperties).toStrictEqual([
+        { name: DEFAULT_TASK_NAME },
+        { name: 'jsonIntegerSerialization' },
+        { name: 'factorial' },
+        { name: 'fibonacci' }
+      ])
+      expect(workerNode.taskFunctionsUsage.size).toBe(3)
+      expect(workerNode.usage.tasks.executed).toBeGreaterThan(0)
+      for (const taskFunctionProperties of pool.listTaskFunctionsProperties()) {
+        expect(
+          workerNode.getTaskFunctionWorkerUsage(taskFunctionProperties.name)
+        ).toStrictEqual({
+          tasks: {
+            executed: expect.any(Number),
+            executing: 0,
+            failed: 0,
+            queued: 0,
+            sequentiallyStolen: 0,
+            stolen: 0
+          },
+          runTime: {
+            history: expect.any(CircularBuffer)
+          },
+          waitTime: {
+            history: expect.any(CircularBuffer)
+          },
+          elu: {
+            idle: {
+              history: expect.any(CircularBuffer)
+            },
+            active: {
+              history: expect.any(CircularBuffer)
+            }
+          }
+        })
+        expect(
+          workerNode.getTaskFunctionWorkerUsage(taskFunctionProperties.name)
+            .tasks.executed
+        ).toBeGreaterThan(0)
+      }
+      expect(
+        workerNode.getTaskFunctionWorkerUsage(DEFAULT_TASK_NAME)
+      ).toStrictEqual(
+        workerNode.getTaskFunctionWorkerUsage(
+          workerNode.info.taskFunctionsProperties[1].name
+        )
+      )
+    }
+    await pool.destroy()
+  })
+
+  it('Verify that task function objects worker is working', async () => {
+    const pool = new DynamicThreadPool(
+      Math.floor(numberOfWorkers / 2),
+      numberOfWorkers,
+      './tests/worker-files/thread/testTaskFunctionObjectsWorker.mjs'
     )
     const data = { n: 10 }
     const result0 = await pool.execute(data)
@@ -1617,15 +1723,18 @@ describe('Abstract pool test suite', () => {
     expect(pool.info.executingTasks).toBe(0)
     expect(pool.info.executedTasks).toBe(4)
     for (const workerNode of pool.workerNodes) {
-      expect(workerNode.info.taskFunctionNames).toStrictEqual([
-        DEFAULT_TASK_NAME,
-        'jsonIntegerSerialization',
-        'factorial',
-        'fibonacci'
+      expect(workerNode.info.taskFunctionsProperties).toStrictEqual([
+        { name: DEFAULT_TASK_NAME },
+        { name: 'jsonIntegerSerialization' },
+        { name: 'factorial' },
+        { name: 'fibonacci' }
       ])
       expect(workerNode.taskFunctionsUsage.size).toBe(3)
-      for (const name of pool.listTaskFunctionNames()) {
-        expect(workerNode.getTaskFunctionWorkerUsage(name)).toStrictEqual({
+      expect(workerNode.usage.tasks.executed).toBeGreaterThan(0)
+      for (const taskFunctionProperties of pool.listTaskFunctionsProperties()) {
+        expect(
+          workerNode.getTaskFunctionWorkerUsage(taskFunctionProperties.name)
+        ).toStrictEqual({
           tasks: {
             executed: expect.any(Number),
             executing: 0,
@@ -1635,29 +1744,30 @@ describe('Abstract pool test suite', () => {
             stolen: 0
           },
           runTime: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           },
           waitTime: {
-            history: expect.any(CircularArray)
+            history: expect.any(CircularBuffer)
           },
           elu: {
             idle: {
-              history: expect.any(CircularArray)
+              history: expect.any(CircularBuffer)
             },
             active: {
-              history: expect.any(CircularArray)
+              history: expect.any(CircularBuffer)
             }
           }
         })
         expect(
-          workerNode.getTaskFunctionWorkerUsage(name).tasks.executed
+          workerNode.getTaskFunctionWorkerUsage(taskFunctionProperties.name)
+            .tasks.executed
         ).toBeGreaterThan(0)
       }
       expect(
         workerNode.getTaskFunctionWorkerUsage(DEFAULT_TASK_NAME)
       ).toStrictEqual(
         workerNode.getTaskFunctionWorkerUsage(
-          workerNode.info.taskFunctionNames[1]
+          workerNode.info.taskFunctionsProperties[1].name
         )
       )
     }
@@ -1668,7 +1778,7 @@ describe('Abstract pool test suite', () => {
     const pool = new DynamicClusterPool(
       Math.floor(numberOfWorkers / 2),
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     const workerNodeKey = 0
     await expect(
@@ -1681,19 +1791,23 @@ describe('Abstract pool test suite', () => {
     const pool = new DynamicClusterPool(
       Math.floor(numberOfWorkers / 2),
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     const workerNodeKey = 0
     await expect(
       pool.sendTaskFunctionOperationToWorker(workerNodeKey, {
         taskFunctionOperation: 'add',
-        taskFunctionName: 'empty',
+        taskFunctionProperties: { name: 'empty' },
         taskFunction: (() => {}).toString()
       })
     ).resolves.toBe(true)
     expect(
-      pool.workerNodes[workerNodeKey].info.taskFunctionNames
-    ).toStrictEqual([DEFAULT_TASK_NAME, 'test', 'empty'])
+      pool.workerNodes[workerNodeKey].info.taskFunctionsProperties
+    ).toStrictEqual([
+      { name: DEFAULT_TASK_NAME },
+      { name: 'test' },
+      { name: 'empty' }
+    ])
     await pool.destroy()
   })
 
@@ -1701,20 +1815,20 @@ describe('Abstract pool test suite', () => {
     const pool = new DynamicClusterPool(
       Math.floor(numberOfWorkers / 2),
       numberOfWorkers,
-      './tests/worker-files/cluster/testWorker.js'
+      './tests/worker-files/cluster/testWorker.cjs'
     )
     await expect(
       pool.sendTaskFunctionOperationToWorkers({
         taskFunctionOperation: 'add',
-        taskFunctionName: 'empty',
+        taskFunctionProperties: { name: 'empty' },
         taskFunction: (() => {}).toString()
       })
     ).resolves.toBe(true)
     for (const workerNode of pool.workerNodes) {
-      expect(workerNode.info.taskFunctionNames).toStrictEqual([
-        DEFAULT_TASK_NAME,
-        'test',
-        'empty'
+      expect(workerNode.info.taskFunctionsProperties).toStrictEqual([
+        { name: DEFAULT_TASK_NAME },
+        { name: 'test' },
+        { name: 'empty' }
       ])
     }
     await pool.destroy()