fix: test for worker file existence
[poolifier.git] / tests / pools / selection-strategies / selection-strategies.test.js
index d9a01684e9b5b54c85675d3eb9f7573df0b1ea0d..6671b57781b1f51c15bdf0717f3c96cafcf0ca76 100644 (file)
@@ -1,9 +1,11 @@
 const { expect } = require('expect')
 const {
-  WorkerChoiceStrategies,
   DynamicThreadPool,
-  FixedThreadPool
-} = require('../../../lib/index')
+  FixedClusterPool,
+  FixedThreadPool,
+  WorkerChoiceStrategies
+} = require('../../../lib')
+const { CircularArray } = require('../../../lib/circular-array')
 
 describe('Selection strategies test suite', () => {
   const min = 0
@@ -11,11 +13,16 @@ describe('Selection strategies test suite', () => {
 
   it('Verify that WorkerChoiceStrategies enumeration provides string values', () => {
     expect(WorkerChoiceStrategies.ROUND_ROBIN).toBe('ROUND_ROBIN')
-    expect(WorkerChoiceStrategies.LESS_RECENTLY_USED).toBe('LESS_RECENTLY_USED')
+    expect(WorkerChoiceStrategies.LEAST_USED).toBe('LEAST_USED')
+    expect(WorkerChoiceStrategies.LEAST_BUSY).toBe('LEAST_BUSY')
+    expect(WorkerChoiceStrategies.LEAST_ELU).toBe('LEAST_ELU')
     expect(WorkerChoiceStrategies.FAIR_SHARE).toBe('FAIR_SHARE')
     expect(WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN).toBe(
       'WEIGHTED_ROUND_ROBIN'
     )
+    expect(WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN).toBe(
+      'INTERLEAVED_WEIGHTED_ROUND_ROBIN'
+    )
   })
 
   it('Verify ROUND_ROBIN strategy is the default at pool creation', async () => {
@@ -31,57 +38,159 @@ describe('Selection strategies test suite', () => {
     await pool.destroy()
   })
 
-  it('Verify ROUND_ROBIN strategy is taken at pool creation', async () => {
+  it('Verify available strategies are taken at pool creation', async () => {
+    for (const workerChoiceStrategy of Object.values(WorkerChoiceStrategies)) {
+      const pool = new FixedThreadPool(
+        max,
+        './tests/worker-files/thread/testWorker.js',
+        { workerChoiceStrategy }
+      )
+      expect(pool.opts.workerChoiceStrategy).toBe(workerChoiceStrategy)
+      expect(pool.workerChoiceStrategyContext.workerChoiceStrategy).toBe(
+        workerChoiceStrategy
+      )
+      await pool.destroy()
+    }
+  })
+
+  it('Verify available strategies can be set after pool creation', async () => {
+    for (const workerChoiceStrategy of Object.values(WorkerChoiceStrategies)) {
+      const pool = new DynamicThreadPool(
+        min,
+        max,
+        './tests/worker-files/thread/testWorker.js'
+      )
+      pool.setWorkerChoiceStrategy(workerChoiceStrategy)
+      expect(pool.opts.workerChoiceStrategy).toBe(workerChoiceStrategy)
+      expect(pool.workerChoiceStrategyContext.workerChoiceStrategy).toBe(
+        workerChoiceStrategy
+      )
+      await pool.destroy()
+    }
+  })
+
+  it('Verify available strategies default internals at pool creation', async () => {
     const pool = new FixedThreadPool(
       max,
-      './tests/worker-files/thread/testWorker.js',
-      { workerChoiceStrategy: WorkerChoiceStrategies.ROUND_ROBIN }
-    )
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.ROUND_ROBIN
+      './tests/worker-files/thread/testWorker.js'
     )
-    expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy().nextWorkerIndex
-    ).toBe(0)
-    // We need to clean up the resources after our test
+    for (const workerChoiceStrategy of Object.values(WorkerChoiceStrategies)) {
+      if (workerChoiceStrategy === WorkerChoiceStrategies.ROUND_ROBIN) {
+        expect(
+          pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+            workerChoiceStrategy
+          ).nextWorkerNodeKey
+        ).toBe(0)
+      } else if (workerChoiceStrategy === WorkerChoiceStrategies.FAIR_SHARE) {
+        expect(
+          pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+            workerChoiceStrategy
+          ).workersVirtualTaskEndTimestamp
+        ).toBeInstanceOf(Array)
+        expect(
+          pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+            workerChoiceStrategy
+          ).workersVirtualTaskEndTimestamp.length
+        ).toBe(0)
+      } else if (
+        workerChoiceStrategy === WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN
+      ) {
+        expect(
+          pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+            workerChoiceStrategy
+          ).nextWorkerNodeKey
+        ).toBe(0)
+        expect(
+          pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+            workerChoiceStrategy
+          ).defaultWorkerWeight
+        ).toBeGreaterThan(0)
+        expect(
+          pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+            workerChoiceStrategy
+          ).workerVirtualTaskRunTime
+        ).toBe(0)
+      }
+    }
     await pool.destroy()
   })
 
-  it('Verify ROUND_ROBIN strategy can be set after pool creation', async () => {
-    const pool = new DynamicThreadPool(
-      min,
+  it('Verify ROUND_ROBIN strategy default policy', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN
+    let pool = new FixedThreadPool(
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.ROUND_ROBIN)
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.ROUND_ROBIN
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: true
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: true
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify ROUND_ROBIN strategy default tasks usage statistics requirements', async () => {
+  it('Verify ROUND_ROBIN strategy default tasks statistics requirements', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN
     let pool = new FixedThreadPool(
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.ROUND_ROBIN)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ).toBe(false)
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
     await pool.destroy()
     pool = new DynamicThreadPool(
       min,
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.ROUND_ROBIN)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ).toBe(false)
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
@@ -92,15 +201,43 @@ describe('Selection strategies test suite', () => {
       './tests/worker-files/thread/testWorker.js',
       { workerChoiceStrategy: WorkerChoiceStrategies.ROUND_ROBIN }
     )
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.ROUND_ROBIN
-    )
     // TODO: Create a better test to cover `RoundRobinWorkerChoiceStrategy#choose`
-    const promises = []
-    for (let i = 0; i < max * 2; i++) {
-      promises.push(pool.execute())
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
     }
     await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toStrictEqual({
+        tasks: {
+          executed: maxMultiplier,
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        WorkerChoiceStrategies.ROUND_ROBIN
+      ).nextWorkerNodeKey
+    ).toBe(0)
     // We need to clean up the resources after our test
     await pool.destroy()
   })
@@ -112,28 +249,90 @@ describe('Selection strategies test suite', () => {
       './tests/worker-files/thread/testWorker.js',
       { workerChoiceStrategy: WorkerChoiceStrategies.ROUND_ROBIN }
     )
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.ROUND_ROBIN
-    )
     // TODO: Create a better test to cover `RoundRobinWorkerChoiceStrategy#choose`
-    const promises = []
-    for (let i = 0; i < max * 2; i++) {
-      promises.push(pool.execute())
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
     }
     await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toStrictEqual({
+        tasks: {
+          executed: maxMultiplier,
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        WorkerChoiceStrategies.ROUND_ROBIN
+      ).nextWorkerNodeKey
+    ).toBe(0)
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
+  it('Verify ROUND_ROBIN strategy runtime behavior', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN
+    let pool = new FixedClusterPool(
+      max,
+      './tests/worker-files/cluster/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    let results = new Set()
+    for (let i = 0; i < max; i++) {
+      results.add(pool.workerNodes[pool.chooseWorkerNode()].worker.id)
+    }
+    expect(results.size).toBe(max)
+    await pool.destroy()
+    pool = new FixedThreadPool(
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    results = new Set()
+    for (let i = 0; i < max; i++) {
+      results.add(pool.workerNodes[pool.chooseWorkerNode()].worker.threadId)
+    }
+    expect(results.size).toBe(max)
+    await pool.destroy()
+  })
+
   it('Verify ROUND_ROBIN strategy internals are resets after setting it', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN
     let pool = new FixedThreadPool(
       max,
       './tests/worker-files/thread/testWorker.js',
       { workerChoiceStrategy: WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.ROUND_ROBIN)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy().nextWorkerIndex
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).nextWorkerNodeKey
+    ).toBeDefined()
+    pool.setWorkerChoiceStrategy(workerChoiceStrategy)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).nextWorkerNodeKey
     ).toBe(0)
     await pool.destroy()
     pool = new DynamicThreadPool(
@@ -142,160 +341,648 @@ describe('Selection strategies test suite', () => {
       './tests/worker-files/thread/testWorker.js',
       { workerChoiceStrategy: WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.ROUND_ROBIN)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .workerChoiceStrategy.nextWorkerIndex
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).nextWorkerNodeKey
+    ).toBeDefined()
+    pool.setWorkerChoiceStrategy(workerChoiceStrategy)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).nextWorkerNodeKey
     ).toBe(0)
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify LESS_RECENTLY_USED strategy is taken at pool creation', async () => {
-    const pool = new FixedThreadPool(
+  it('Verify LEAST_USED strategy default policy', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.LEAST_USED
+    let pool = new FixedThreadPool(
       max,
       './tests/worker-files/thread/testWorker.js',
-      { workerChoiceStrategy: WorkerChoiceStrategies.LESS_RECENTLY_USED }
+      { workerChoiceStrategy }
     )
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.LESS_RECENTLY_USED
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: false
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: false
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify LESS_RECENTLY_USED strategy can be set after pool creation', async () => {
+  it('Verify LEAST_USED strategy default tasks statistics requirements', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.LEAST_USED
+    let pool = new FixedThreadPool(
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify LEAST_USED strategy can be run in a fixed pool', async () => {
     const pool = new FixedThreadPool(
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy: WorkerChoiceStrategies.LEAST_USED }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.LESS_RECENTLY_USED)
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.LESS_RECENTLY_USED
+    // TODO: Create a better test to cover `LeastUsedWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
+    }
+    await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toStrictEqual({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+    }
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify LEAST_USED strategy can be run in a dynamic pool', async () => {
+    const pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy: WorkerChoiceStrategies.LEAST_USED }
     )
+    // TODO: Create a better test to cover `LeastUsedWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
+    }
+    await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toStrictEqual({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+    }
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify LESS_RECENTLY_USED strategy default tasks usage statistics requirements', async () => {
+  it('Verify LEAST_BUSY strategy default policy', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.LEAST_BUSY
     let pool = new FixedThreadPool(
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: false
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: false
+    })
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify LEAST_BUSY strategy default tasks statistics requirements', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.LEAST_BUSY
+    let pool = new FixedThreadPool(
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.LESS_RECENTLY_USED)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ).toBe(false)
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: true,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: true,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
     await pool.destroy()
     pool = new DynamicThreadPool(
       min,
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.LESS_RECENTLY_USED)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ).toBe(false)
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: true,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: true,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify LESS_RECENTLY_USED strategy can be run in a fixed pool', async () => {
+  it('Verify LEAST_BUSY strategy can be run in a fixed pool', async () => {
     const pool = new FixedThreadPool(
       max,
       './tests/worker-files/thread/testWorker.js',
-      { workerChoiceStrategy: WorkerChoiceStrategies.LESS_RECENTLY_USED }
+      { workerChoiceStrategy: WorkerChoiceStrategies.LEAST_BUSY }
     )
-    // TODO: Create a better test to cover `LessRecentlyUsedWorkerChoiceStrategy#choose`
-    const promises = []
-    for (let i = 0; i < max * 2; i++) {
-      promises.push(pool.execute())
+    // TODO: Create a better test to cover `LeastBusyWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
     }
     await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toMatchObject({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      if (workerNode.usage.runTime.aggregate == null) {
+        expect(workerNode.usage.runTime.aggregate).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.aggregate).toBeGreaterThan(0)
+      }
+      if (workerNode.usage.waitTime.aggregate == null) {
+        expect(workerNode.usage.waitTime.aggregate).toBeUndefined()
+      } else {
+        expect(workerNode.usage.waitTime.aggregate).toBeGreaterThan(0)
+      }
+    }
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify LESS_RECENTLY_USED strategy can be run in a dynamic pool', async () => {
+  it('Verify LEAST_BUSY strategy can be run in a dynamic pool', async () => {
     const pool = new DynamicThreadPool(
       min,
       max,
       './tests/worker-files/thread/testWorker.js',
-      { workerChoiceStrategy: WorkerChoiceStrategies.LESS_RECENTLY_USED }
+      { workerChoiceStrategy: WorkerChoiceStrategies.LEAST_BUSY }
     )
-    // TODO: Create a better test to cover `LessRecentlyUsedWorkerChoiceStrategy#choose`
-    const promises = []
-    for (let i = 0; i < max * 2; i++) {
-      promises.push(pool.execute())
+    // TODO: Create a better test to cover `LeastBusyWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
     }
     await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toMatchObject({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      if (workerNode.usage.runTime.aggregate == null) {
+        expect(workerNode.usage.runTime.aggregate).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.aggregate).toBeGreaterThan(0)
+      }
+      if (workerNode.usage.waitTime.aggregate == null) {
+        expect(workerNode.usage.waitTime.aggregate).toBeUndefined()
+      } else {
+        expect(workerNode.usage.waitTime.aggregate).toBeGreaterThan(0)
+      }
+    }
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify LEAST_ELU strategy default policy', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.LEAST_ELU
+    let pool = new FixedThreadPool(
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: false
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: false
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify FAIR_SHARE strategy is taken at pool creation', async () => {
+  it('Verify LEAST_ELU strategy default tasks statistics requirements', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.LEAST_ELU
+    let pool = new FixedThreadPool(
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: true,
+        average: false,
+        median: false
+      }
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: true,
+        average: false,
+        median: false
+      }
+    })
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify LEAST_ELU strategy can be run in a fixed pool', async () => {
     const pool = new FixedThreadPool(
       max,
       './tests/worker-files/thread/testWorker.js',
-      { workerChoiceStrategy: WorkerChoiceStrategies.FAIR_SHARE }
+      { workerChoiceStrategy: WorkerChoiceStrategies.LEAST_ELU }
     )
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.FAIR_SHARE
+    // TODO: Create a better test to cover `LeastEluWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
+    }
+    await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toMatchObject({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: expect.objectContaining({
+            history: expect.any(CircularArray)
+          }),
+          active: expect.objectContaining({
+            history: expect.any(CircularArray)
+          })
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      if (workerNode.usage.elu.utilization == null) {
+        expect(workerNode.usage.elu.utilization).toBeUndefined()
+      } else {
+        expect(workerNode.usage.elu.utilization).toBeGreaterThanOrEqual(0)
+        expect(workerNode.usage.elu.utilization).toBeLessThanOrEqual(1)
+      }
+    }
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify LEAST_ELU strategy can be run in a dynamic pool', async () => {
+    const pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy: WorkerChoiceStrategies.LEAST_ELU }
     )
-    for (const worker of pool.workerChoiceStrategyContext
-      .getWorkerChoiceStrategy()
-      .workerLastVirtualTaskTimestamp.keys()) {
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workerLastVirtualTaskTimestamp.get(worker).start
-      ).toBe(0)
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workerLastVirtualTaskTimestamp.get(worker).end
-      ).toBe(0)
+    // TODO: Create a better test to cover `LeastEluWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
+    }
+    await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toMatchObject({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: expect.objectContaining({
+            history: expect.any(CircularArray)
+          }),
+          active: expect.objectContaining({
+            history: expect.any(CircularArray)
+          })
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      if (workerNode.usage.elu.utilization == null) {
+        expect(workerNode.usage.elu.utilization).toBeUndefined()
+      } else {
+        expect(workerNode.usage.elu.utilization).toBeGreaterThanOrEqual(0)
+        expect(workerNode.usage.elu.utilization).toBeLessThanOrEqual(1)
+      }
     }
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify FAIR_SHARE strategy can be set after pool creation', async () => {
-    const pool = new FixedThreadPool(
+  it('Verify FAIR_SHARE strategy default policy', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.FAIR_SHARE
+    let pool = new FixedThreadPool(
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.FAIR_SHARE)
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.FAIR_SHARE
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: false
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: false
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify FAIR_SHARE strategy default tasks usage statistics requirements', async () => {
+  it('Verify FAIR_SHARE strategy default tasks statistics requirements', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.FAIR_SHARE
     let pool = new FixedThreadPool(
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.FAIR_SHARE)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ).toBe(true)
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: true,
+        average: true,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: true,
+        average: true,
+        median: false
+      }
+    })
     await pool.destroy()
     pool = new DynamicThreadPool(
       min,
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.FAIR_SHARE)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ).toBe(true)
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: true,
+        average: true,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: true,
+        average: true,
+        median: false
+      }
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
@@ -307,11 +994,62 @@ describe('Selection strategies test suite', () => {
       { workerChoiceStrategy: WorkerChoiceStrategies.FAIR_SHARE }
     )
     // TODO: Create a better test to cover `FairShareChoiceStrategy#choose`
-    const promises = []
-    for (let i = 0; i < max * 2; i++) {
-      promises.push(pool.execute())
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
     }
     await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toMatchObject({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: expect.objectContaining({
+          history: expect.any(CircularArray)
+        }),
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: expect.objectContaining({
+            history: expect.any(CircularArray)
+          }),
+          active: expect.objectContaining({
+            history: expect.any(CircularArray)
+          })
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      if (workerNode.usage.runTime.aggregate == null) {
+        expect(workerNode.usage.runTime.aggregate).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.aggregate).toBeGreaterThan(0)
+      }
+      if (workerNode.usage.runTime.average == null) {
+        expect(workerNode.usage.runTime.average).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.average).toBeGreaterThan(0)
+      }
+      if (workerNode.usage.elu.utilization == null) {
+        expect(workerNode.usage.elu.utilization).toBeUndefined()
+      } else {
+        expect(workerNode.usage.elu.utilization).toBeGreaterThanOrEqual(0)
+        expect(workerNode.usage.elu.utilization).toBeLessThanOrEqual(1)
+      }
+    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp.length
+    ).toBe(pool.workerNodes.length)
     // We need to clean up the resources after our test
     await pool.destroy()
   })
@@ -324,39 +1062,174 @@ describe('Selection strategies test suite', () => {
       { workerChoiceStrategy: WorkerChoiceStrategies.FAIR_SHARE }
     )
     // TODO: Create a better test to cover `FairShareChoiceStrategy#choose`
-    const promises = []
-    for (let i = 0; i < max * 2; i++) {
-      promises.push(pool.execute())
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
     }
     await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toMatchObject({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: expect.objectContaining({
+          history: expect.any(CircularArray)
+        }),
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: expect.objectContaining({
+            history: expect.any(CircularArray)
+          }),
+          active: expect.objectContaining({
+            history: expect.any(CircularArray)
+          })
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      if (workerNode.usage.runTime.aggregate == null) {
+        expect(workerNode.usage.runTime.aggregate).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.aggregate).toBeGreaterThan(0)
+      }
+      if (workerNode.usage.runTime.average == null) {
+        expect(workerNode.usage.runTime.average).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.average).toBeGreaterThan(0)
+      }
+      if (workerNode.usage.elu.utilization == null) {
+        expect(workerNode.usage.elu.utilization).toBeUndefined()
+      } else {
+        expect(workerNode.usage.elu.utilization).toBeGreaterThanOrEqual(0)
+        expect(workerNode.usage.elu.utilization).toBeLessThanOrEqual(1)
+      }
+    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp.length
+    ).toBe(pool.workerNodes.length)
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify FAIR_SHARE strategy can be run in a dynamic pool with median runtime statistic', async () => {
+    const pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      {
+        workerChoiceStrategy: WorkerChoiceStrategies.FAIR_SHARE,
+        workerChoiceStrategyOptions: {
+          runTime: { median: true }
+        }
+      }
+    )
+    // TODO: Create a better test to cover `FairShareChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
+    }
+    await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toMatchObject({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: expect.objectContaining({
+          history: expect.any(CircularArray)
+        }),
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: expect.objectContaining({
+            history: expect.any(CircularArray)
+          }),
+          active: expect.objectContaining({
+            history: expect.any(CircularArray)
+          })
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      if (workerNode.usage.runTime.aggregate == null) {
+        expect(workerNode.usage.runTime.aggregate).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.aggregate).toBeGreaterThan(0)
+      }
+      if (workerNode.usage.runTime.median == null) {
+        expect(workerNode.usage.runTime.median).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.median).toBeGreaterThan(0)
+      }
+      if (workerNode.usage.elu.utilization == null) {
+        expect(workerNode.usage.elu.utilization).toBeUndefined()
+      } else {
+        expect(workerNode.usage.elu.utilization).toBeGreaterThanOrEqual(0)
+        expect(workerNode.usage.elu.utilization).toBeLessThanOrEqual(1)
+      }
+    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp.length
+    ).toBe(pool.workerNodes.length)
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
   it('Verify FAIR_SHARE strategy internals are resets after setting it', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.FAIR_SHARE
     let pool = new FixedThreadPool(
       max,
       './tests/worker-files/thread/testWorker.js'
     )
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .workerLastVirtualTaskTimestamp
-    ).toBeUndefined()
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.FAIR_SHARE)
-    for (const worker of pool.workerChoiceStrategyContext
-      .getWorkerChoiceStrategy()
-      .workerLastVirtualTaskTimestamp.keys()) {
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workerLastVirtualTaskTimestamp.get(worker).start
-      ).toBe(0)
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workerLastVirtualTaskTimestamp.get(worker).end
-      ).toBe(0)
-    }
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp
+    ).toBeInstanceOf(Array)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp.length
+    ).toBe(0)
+    pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+      workerChoiceStrategy
+    ).workersVirtualTaskEndTimestamp[0] = performance.now()
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp.length
+    ).toBe(1)
+    pool.setWorkerChoiceStrategy(workerChoiceStrategy)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp
+    ).toBeInstanceOf(Array)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp.length
+    ).toBe(0)
     await pool.destroy()
     pool = new DynamicThreadPool(
       min,
@@ -364,169 +1237,666 @@ describe('Selection strategies test suite', () => {
       './tests/worker-files/thread/testWorker.js'
     )
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .workerChoiceStrategy.workerLastVirtualTaskTimestamp
-    ).toBeUndefined()
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.FAIR_SHARE)
-    for (const worker of pool.workerChoiceStrategyContext
-      .getWorkerChoiceStrategy()
-      .workerChoiceStrategy.workerLastVirtualTaskTimestamp.keys()) {
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workerChoiceStrategy.workerLastVirtualTaskTimestamp.get(worker).start
-      ).toBe(0)
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workerChoiceStrategy.workerLastVirtualTaskTimestamp.get(worker).end
-      ).toBe(0)
-    }
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp
+    ).toBeInstanceOf(Array)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp.length
+    ).toBe(0)
+    pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+      workerChoiceStrategy
+    ).workersVirtualTaskEndTimestamp[0] = performance.now()
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp.length
+    ).toBe(1)
+    pool.setWorkerChoiceStrategy(workerChoiceStrategy)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp
+    ).toBeInstanceOf(Array)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workersVirtualTaskEndTimestamp.length
+    ).toBe(0)
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify WEIGHTED_ROUND_ROBIN strategy default policy', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN
+    let pool = new FixedThreadPool(
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: true
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: true
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify WEIGHTED_ROUND_ROBIN strategy is taken at pool creation', async () => {
+  it('Verify WEIGHTED_ROUND_ROBIN strategy default tasks statistics requirements', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN
+    let pool = new FixedThreadPool(
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: true,
+        average: true,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
+    )
+    expect(
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: true,
+        average: true,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify WEIGHTED_ROUND_ROBIN strategy can be run in a fixed pool', async () => {
     const pool = new FixedThreadPool(
       max,
       './tests/worker-files/thread/testWorker.js',
       { workerChoiceStrategy: WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN }
     )
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN
+    // TODO: Create a better test to cover `WeightedRoundRobinWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
+    }
+    await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toStrictEqual({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: expect.objectContaining({
+          history: expect.any(CircularArray)
+        }),
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      if (workerNode.usage.runTime.aggregate == null) {
+        expect(workerNode.usage.runTime.aggregate).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.aggregate).toBeGreaterThan(0)
+      }
+      if (workerNode.usage.runTime.average == null) {
+        expect(workerNode.usage.runTime.average).toBeUndefined()
+      } else {
+        expect(workerNode.usage.runTime.average).toBeGreaterThan(0)
+      }
+    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeGreaterThan(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).workerVirtualTaskRunTime
+    ).toBeGreaterThanOrEqual(0)
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify WEIGHTED_ROUND_ROBIN strategy can be run in a dynamic pool', async () => {
+    const pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy: WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN }
     )
+    // TODO: Create a better test to cover `WeightedRoundRobinWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
+    }
+    await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toStrictEqual({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          aggregate: expect.any(Number),
+          maximum: expect.any(Number),
+          minimum: expect.any(Number),
+          average: expect.any(Number),
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      expect(workerNode.usage.runTime.aggregate).toBeGreaterThan(0)
+      expect(workerNode.usage.runTime.average).toBeGreaterThan(0)
+    }
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .previousWorkerIndex
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeGreaterThan(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).workerVirtualTaskRunTime
+    ).toBeGreaterThanOrEqual(0)
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify WEIGHTED_ROUND_ROBIN strategy can be run in a dynamic pool with median runtime statistic', async () => {
+    const pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      {
+        workerChoiceStrategy: WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN,
+        workerChoiceStrategyOptions: {
+          runTime: { median: true }
+        }
+      }
+    )
+    // TODO: Create a better test to cover `WeightedRoundRobinWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
+    }
+    await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toStrictEqual({
+        tasks: {
+          executed: expect.any(Number),
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          aggregate: expect.any(Number),
+          maximum: expect.any(Number),
+          minimum: expect.any(Number),
+          median: expect.any(Number),
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+      expect(workerNode.usage.tasks.executed).toBeGreaterThanOrEqual(0)
+      expect(workerNode.usage.tasks.executed).toBeLessThanOrEqual(
+        max * maxMultiplier
+      )
+      expect(workerNode.usage.runTime.aggregate).toBeGreaterThan(0)
+      expect(workerNode.usage.runTime.median).toBeGreaterThan(0)
+    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeGreaterThan(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).workerVirtualTaskRunTime
+    ).toBeGreaterThanOrEqual(0)
+    // We need to clean up the resources after our test
+    await pool.destroy()
+  })
+
+  it('Verify WEIGHTED_ROUND_ROBIN strategy internals are resets after setting it', async () => {
+    const workerChoiceStrategy = WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN
+    let pool = new FixedThreadPool(
+      max,
+      './tests/worker-files/thread/testWorker.js'
+    )
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).nextWorkerNodeKey
+    ).toBeDefined()
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeDefined()
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workerVirtualTaskRunTime
+    ).toBeDefined()
+    pool.setWorkerChoiceStrategy(workerChoiceStrategy)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).nextWorkerNodeKey
+    ).toBe(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeGreaterThan(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workerVirtualTaskRunTime
     ).toBe(0)
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js'
+    )
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).nextWorkerNodeKey
+    ).toBeDefined()
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeDefined()
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .currentWorkerIndex
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workerVirtualTaskRunTime
+    ).toBeDefined()
+    pool.setWorkerChoiceStrategy(workerChoiceStrategy)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).nextWorkerNodeKey
     ).toBe(0)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .defaultWorkerWeight
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
     ).toBeGreaterThan(0)
-    for (const worker of pool.workerChoiceStrategyContext
-      .getWorkerChoiceStrategy()
-      .workersTaskRunTime.keys()) {
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workersTaskRunTime.get(worker).weight
-      ).toBeGreaterThan(0)
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workersTaskRunTime.get(worker).runTime
-      ).toBe(0)
-    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).workerVirtualTaskRunTime
+    ).toBe(0)
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify WEIGHTED_ROUND_ROBIN strategy can be set after pool creation', async () => {
-    const pool = new FixedThreadPool(
+  it('Verify INTERLEAVED_WEIGHTED_ROUND_ROBIN strategy default policy', async () => {
+    const workerChoiceStrategy =
+      WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN
+    let pool = new FixedThreadPool(
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN)
-    expect(pool.opts.workerChoiceStrategy).toBe(
-      WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: true
+    })
+    await pool.destroy()
+    pool = new DynamicThreadPool(
+      min,
+      max,
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
+    expect(pool.workerChoiceStrategyContext.getStrategyPolicy()).toStrictEqual({
+      useDynamicWorker: true
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify WEIGHTED_ROUND_ROBIN strategy default tasks usage statistics requirements', async () => {
+  it('Verify INTERLEAVED_WEIGHTED_ROUND_ROBIN strategy default tasks statistics requirements', async () => {
+    const workerChoiceStrategy =
+      WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN
     let pool = new FixedThreadPool(
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ).toBe(true)
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
     await pool.destroy()
     pool = new DynamicThreadPool(
       min,
       max,
-      './tests/worker-files/thread/testWorker.js'
+      './tests/worker-files/thread/testWorker.js',
+      { workerChoiceStrategy }
     )
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ).toBe(true)
+      pool.workerChoiceStrategyContext.getTaskStatisticsRequirements()
+    ).toStrictEqual({
+      runTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      waitTime: {
+        aggregate: false,
+        average: false,
+        median: false
+      },
+      elu: {
+        aggregate: false,
+        average: false,
+        median: false
+      }
+    })
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify WEIGHTED_ROUND_ROBIN strategy can be run in a fixed pool', async () => {
+  it('Verify INTERLEAVED_WEIGHTED_ROUND_ROBIN strategy can be run in a fixed pool', async () => {
     const pool = new FixedThreadPool(
       max,
       './tests/worker-files/thread/testWorker.js',
-      { workerChoiceStrategy: WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN }
+      {
+        workerChoiceStrategy:
+          WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN
+      }
     )
-    // TODO: Create a better test to cover `WeightedRoundRobinWorkerChoiceStrategy#choose`
-    const promises = []
-    for (let i = 0; i < max * 2; i++) {
-      promises.push(pool.execute())
+    // TODO: Create a better test to cover `InterleavedWeightedRoundRobinWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
     }
     await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toStrictEqual({
+        tasks: {
+          executed: maxMultiplier,
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeGreaterThan(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).roundId
+    ).toBe(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).nextWorkerNodeKey
+    ).toBe(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).roundWeights
+    ).toStrictEqual([
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ])
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify WEIGHTED_ROUND_ROBIN strategy can be run in a dynamic pool', async () => {
+  it('Verify INTERLEAVED_WEIGHTED_ROUND_ROBIN strategy can be run in a dynamic pool', async () => {
     const pool = new DynamicThreadPool(
       min,
       max,
       './tests/worker-files/thread/testWorker.js',
-      { workerChoiceStrategy: WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN }
+      {
+        workerChoiceStrategy:
+          WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN
+      }
     )
-    // TODO: Create a better test to cover `WeightedRoundRobinWorkerChoiceStrategy#choose`
-    const promises = []
-    for (let i = 0; i < max * 2; i++) {
-      promises.push(pool.execute())
+    // TODO: Create a better test to cover `InterleavedWeightedRoundRobinWorkerChoiceStrategy#choose`
+    const promises = new Set()
+    const maxMultiplier = 2
+    for (let i = 0; i < max * maxMultiplier; i++) {
+      promises.add(pool.execute())
     }
     await Promise.all(promises)
+    for (const workerNode of pool.workerNodes) {
+      expect(workerNode.usage).toStrictEqual({
+        tasks: {
+          executed: maxMultiplier,
+          executing: 0,
+          queued: 0,
+          maxQueued: 0,
+          failed: 0
+        },
+        runTime: {
+          history: expect.any(CircularArray)
+        },
+        waitTime: {
+          history: expect.any(CircularArray)
+        },
+        elu: {
+          idle: {
+            history: expect.any(CircularArray)
+          },
+          active: {
+            history: expect.any(CircularArray)
+          }
+        }
+      })
+    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeGreaterThan(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).roundId
+    ).toBe(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).nextWorkerNodeKey
+    ).toBe(0)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).roundWeights
+    ).toStrictEqual([
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ])
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify WEIGHTED_ROUND_ROBIN strategy internals are resets after setting it', async () => {
+  it('Verify INTERLEAVED_WEIGHTED_ROUND_ROBIN strategy internals are resets after setting it', async () => {
+    const workerChoiceStrategy =
+      WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN
     let pool = new FixedThreadPool(
       max,
       './tests/worker-files/thread/testWorker.js'
     )
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .workersTaskRunTime
-    ).toBeUndefined()
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN)
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).roundId
+    ).toBeDefined()
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .previousWorkerIndex
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).nextWorkerNodeKey
+    ).toBeDefined()
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeDefined()
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).roundWeights
+    ).toBeDefined()
+    pool.setWorkerChoiceStrategy(workerChoiceStrategy)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).roundId
     ).toBe(0)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .currentWorkerIndex
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).nextWorkerNodeKey
     ).toBe(0)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .defaultWorkerWeight
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
     ).toBeGreaterThan(0)
-    for (const worker of pool.workerChoiceStrategyContext
-      .getWorkerChoiceStrategy()
-      .workersTaskRunTime.keys()) {
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workersTaskRunTime.get(worker).runTime
-      ).toBe(0)
-    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).roundWeights
+    ).toStrictEqual([
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ])
     await pool.destroy()
     pool = new DynamicThreadPool(
       min,
@@ -534,36 +1904,50 @@ describe('Selection strategies test suite', () => {
       './tests/worker-files/thread/testWorker.js'
     )
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .workerChoiceStrategy.workersTaskRunTime
-    ).toBeUndefined()
-    pool.setWorkerChoiceStrategy(WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN)
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).roundId
+    ).toBeDefined()
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .workerChoiceStrategy.previousWorkerIndex
-    ).toBe(0)
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).nextWorkerNodeKey
+    ).toBeDefined()
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .workerChoiceStrategy.currentWorkerIndex
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).defaultWorkerWeight
+    ).toBeDefined()
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).roundWeights
+    ).toBeDefined()
+    pool.setWorkerChoiceStrategy(workerChoiceStrategy)
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).nextWorkerNodeKey
     ).toBe(0)
     expect(
-      pool.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .workerChoiceStrategy.defaultWorkerWeight
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
     ).toBeGreaterThan(0)
-    for (const worker of pool.workerChoiceStrategyContext
-      .getWorkerChoiceStrategy()
-      .workerChoiceStrategy.workersTaskRunTime.keys()) {
-      expect(
-        pool.workerChoiceStrategyContext
-          .getWorkerChoiceStrategy()
-          .workerChoiceStrategy.workersTaskRunTime.get(worker).runTime
-      ).toBe(0)
-    }
+    expect(
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        workerChoiceStrategy
+      ).roundWeights
+    ).toStrictEqual([
+      pool.workerChoiceStrategyContext.workerChoiceStrategies.get(
+        pool.workerChoiceStrategyContext.workerChoiceStrategy
+      ).defaultWorkerWeight
+    ])
     // We need to clean up the resources after our test
     await pool.destroy()
   })
 
-  it('Verify unknown strategies throw error', () => {
+  it('Verify unknown strategy throw error', () => {
     expect(
       () =>
         new DynamicThreadPool(
@@ -572,8 +1956,6 @@ describe('Selection strategies test suite', () => {
           './tests/worker-files/thread/testWorker.js',
           { workerChoiceStrategy: 'UNKNOWN_STRATEGY' }
         )
-    ).toThrowError(
-      new Error("Worker choice strategy 'UNKNOWN_STRATEGY' not found")
-    )
+    ).toThrowError("Invalid worker choice strategy 'UNKNOWN_STRATEGY'")
   })
 })