CHANGELOG.md

   1 # Changelog
   2
   3 All notable changes to this project will be documented in this file.
   4
   5 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
   6 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   7
   8 ## [Unreleased]
   9
  10 ### Added
  11
  12 - HTTP server pool examples: express-cluster, express-hybrid.
  13
  14 ## [2.6.27] - 2023-08-15
  15
  16 ### Fixed
  17
  18 - Add `KillHandler` type definition to exported types.
  19
  20 ### Added
  21
  22 - Add `destroy` event to pool API.
  23
  24 ## [2.6.26] - 2023-08-15
  25
  26 ### Added
  27
  28 - Add kill handler to worker options allowing to execute custom code when worker is killed.
  29 - Add `listTaskFunctions()` method to pool API.
  30 - SMTP server pool example: nodemailer.
  31
  32 ## [2.6.25] - 2023-08-13
  33
  34 ### Added
  35
  36 - HTTP server pool examples: fastify-cluster, fastify-hybrid.
  37 - WebSocket server pool examples: ws-cluster, ws-hybrid.
  38
  39 ## [2.6.24] - 2023-08-12
  40
  41 ### Added
  42
  43 - Add array of transferable objects to the `execute()` method arguments.
  44 - WebSocket server pool examples: ws-worker_threads.
  45
  46 ## [2.6.23] - 2023-08-11
  47
  48 ### Fixed
  49
  50 - Fix pool busyness semantic when tasks queueing is enabled: the pool is busy when the number of executing tasks on each worker has reached the maximum tasks concurrency per worker.
  51
  52 ### Added
  53
  54 - HTTP client pool examples: fetch, node-fetch and axios with multiple task functions.
  55 - HTTP server pool examples: express-worker_threads, fastify-worker_threads.
  56
  57 ## [2.6.22] - 2023-08-10
  58
  59 ### Fixed
  60
  61 - Add missing `types` field to package.json `exports`.
  62
  63 ### Changed
  64
  65 - Structure markdown documentation (PR #811).
  66
  67 ## [2.6.21] - 2023-08-03
  68
  69 ### Changed
  70
  71 - Improve code documentation.
  72 - Code refactoring and cleanup for better maintainability and readability.
  73
  74 ## [2.6.20] - 2023-07-21
  75
  76 ### Fixed
  77
  78 - Fix queued tasks redistribution on error task execution starvation.
  79 - Ensure task queueing per worker condition is untangled from the pool busyness semantic.
  80
  81 ### Changed
  82
  83 - Drastically reduce lookups by worker in the worker nodes.
  84
  85 ## [2.6.19] - 2023-07-20
  86
  87 ### Added
  88
  89 - Dedicated internal communication channel for worker_threads pools.
  90
  91 ## [2.6.18] - 2023-07-19
  92
  93 ### Changed
  94
  95 - Code refactoring and cleanup for better maintainability and readability. Bundle size is a bit smaller.
  96
  97 ## [2.6.17] - 2023-07-16
  98
  99 ### Added
 100
 101 - Add `listTaskFunctions()` method to worker API.
 102
 103 ## [2.6.16] - 2023-07-12
 104
 105 ### Fixed
 106
 107 - Fix pool startup detection.
 108 - Fix worker task functions handling.
 109
 110 ## [2.6.15] - 2023-07-11
 111
 112 ### Added
 113
 114 - Take into account worker node readiness in worker choice strategies.
 115
 116 ## [2.6.14] - 2023-07-10
 117
 118 ### Fixed
 119
 120 - Fix task function statistics tracking.
 121
 122 ## [2.6.13] - 2023-07-10
 123
 124 ### Added
 125
 126 - Add per task function statistics tracking.
 127 - Add public methods to manipulate the worker task functions at runtime.
 128
 129 ## [2.6.12] - 2023-07-09
 130
 131 ### Fixed
 132
 133 - Workaround import issue with `node:os` module in node 16.x.x.
 134
 135 ## [2.6.11] - 2023-07-09
 136
 137 ### Fixed
 138
 139 - Fix pool readiness semantic.
 140
 141 ## [2.6.10] - 2023-07-08
 142
 143 ### Fixed
 144
 145 - Ensure workers are not recreated on error at pool startup.
 146
 147 ### Added
 148
 149 - Add `ready` and `strategy` fields to pool information.
 150 - Add pool event `ready` to notify when the number of workers created in the pool has reached the maximum size expected and are ready.
 151 - Add dynamic pool sizing checks.
 152
 153 ## [2.6.9] - 2023-07-07
 154
 155 ### Fixed
 156
 157 - Recreate the right worker type on uncaught exception.
 158
 159 ### Added
 160
 161 - Add minimum and maximum to internal measurement statistics.
 162 - Add `runTime` and `waitTime` to pool information.
 163 - Check worker inactive time only on dynamic worker.
 164
 165 ## [2.6.8] - 2023-07-03
 166
 167 ### Fixed
 168
 169 - Brown paper bag release to fix version handling in pool information.
 170
 171 ## [2.6.7] - 2023-07-03
 172
 173 ### Fixed
 174
 175 - Ensure worker queued tasks at error are reassigned to other pool workers.
 176
 177 ### Added
 178
 179 - Add pool `utilization` ratio to pool information.
 180 - Add `version` to pool information.
 181 - Add worker information to worker nodes.
 182
 183 ## [2.6.6] - 2023-07-01
 184
 185 ### Added
 186
 187 - Add safe helper `availableParallelism` to help sizing the pool.
 188
 189 ### Fixed
 190
 191 - Ensure message handler is only registered in worker.
 192
 193 ## [2.6.5] - 2023-06-27
 194
 195 ### Known issues
 196
 197 - Cluster pools tasks execution are not working by using ESM files extension: https://github.com/poolifier/poolifier/issues/782
 198
 199 ### Fixed
 200
 201 - Artificial version bump to 2.6.5 to workaround publication issue.
 202 - Ensure cluster pool destroy() gracefully shutdowns worker's server.
 203 - Ensure pool event is emitted before task error promise rejection.
 204 - Fix queued tasks count computation.
 205
 206 ### Removed
 207
 208 - Remove unneeded worker_threads worker `MessageChannel` internal usage for IPC.
 209
 210 ## [2.6.4] - 2023-06-27
 211
 212 ### Known issues
 213
 214 - Cluster pools tasks execution are not working by using ESM files extension: https://github.com/poolifier/poolifier/issues/782
 215
 216 ### Fixed
 217
 218 - Ensure cluster pool destroy() gracefully shutdowns worker's server.
 219 - Ensure pool event is emitted before task error promise rejection.
 220 - Fix queued tasks count computation.
 221
 222 ### Removed
 223
 224 - Remove unneeded worker_threads worker `MessageChannel` internal usage for IPC.
 225
 226 ## [2.6.3] - 2023-06-19
 227
 228 ### Fixed
 229
 230 - Ensure no tasks are queued when trying to soft kill a dynamic worker.
 231 - Update strategies internals after statistics computation.
 232
 233 ### Changed
 234
 235 - Optimize O(1) queue implementation.
 236
 237 ## [2.6.2] - 2023-06-12
 238
 239 ### Fixed
 240
 241 - Fix new worker use after creation in dynamic pool given the current worker choice strategy.
 242
 243 ## [2.6.1] - 2023-06-10
 244
 245 ### Added
 246
 247 - Add worker choice strategy documentation: [README.md](./docs/worker-choice-strategies.md).
 248
 249 ### Fixed
 250
 251 - Fix average statistics computation: ensure failed tasks are not accounted.
 252
 253 ## [2.6.0] - 2023-06-09
 254
 255 ### Added
 256
 257 - Add `LEAST_ELU` worker choice strategy (experimental).
 258 - Add tasks ELU instead of runtime support to `FAIR_SHARE` worker choice strategy.
 259
 260 ### Changed
 261
 262 - Refactor pool worker node usage internals.
 263 - Breaking change: refactor worker choice strategy statistics requirements: the syntax of the worker choice strategy options has changed.
 264 - Breaking change: pool information `info` property object fields have been renamed.
 265
 266 ### Fixed
 267
 268 - Fix wait time accounting.
 269 - Ensure worker choice strategy `LEAST_BUSY` accounts also tasks wait time.
 270 - Ensure worker choice strategy `LEAST_USED` accounts also queued tasks.
 271
 272 ## [2.5.4] - 2023-06-07
 273
 274 ### Added
 275
 276 - Add Event Loop Utilization (ELU) statistics to worker tasks usage.
 277
 278 ### Changed
 279
 280 - Compute statistics at the worker level only if needed.
 281 - Add `worker_threads` options to thread pool options.
 282
 283 ### Fixed
 284
 285 - Make the `LEAST_BUSY` strategy only relies on task runtime.
 286
 287 ## [2.5.3] - 2023-06-04
 288
 289 ### Changed
 290
 291 - Refine pool information content.
 292 - Limit pool internals public exposure.
 293
 294 ## [2.5.2] - 2023-06-02
 295
 296 ### Added
 297
 298 - Add `taskError` pool event for task execution error.
 299 - Add pool information `info` property to pool.
 300 - Emit pool information on `busy` and `full` pool events.
 301
 302 ## [2.5.1] - 2023-06-01
 303
 304 ### Added
 305
 306 - Add pool option `restartWorkerOnError` to restart worker on uncaught error. Default to `true`.
 307 - Add `error` pool event for uncaught worker error.
 308
 309 ## [2.5.0] - 2023-05-31
 310
 311 ### Added
 312
 313 - Switch pool event emitter to `EventEmitterAsyncResource`.
 314 - Add tasks wait time accounting in per worker tasks usage.
 315 - Add interleaved weighted round robin `INTERLEAVED_WEIGHTED_ROUND_ROBIN` worker choice strategy (experimental).
 316
 317 ### Changed
 318
 319 - Renamed worker choice strategy `LESS_BUSY` to `LEAST_BUSY` and `LESS_USED` to `LEAST_USED`.
 320
 321 ## [2.4.14] - 2023-05-09
 322
 323 ### Fixed
 324
 325 - Ensure no undefined task runtime can land in the tasks history.
 326 - Fix median computation implementation once again.
 327
 328 ### Added
 329
 330 - Unit tests for median and queue implementations.
 331
 332 ## [2.4.13] - 2023-05-08
 333
 334 ### Fixed
 335
 336 - Fix worker choice strategy options validation.
 337 - Fix fair share worker choice strategy internals update: ensure virtual task end timestamp is computed at task submission.
 338
 339 ## [2.4.12] - 2023-05-06
 340
 341 ### Added
 342
 343 - Support multiple task functions per worker.
 344 - Add custom worker weights support to worker choice strategies options.
 345
 346 ### Changed
 347
 348 - Use O(1) queue implementation for tasks queueing.
 349
 350 ### Fixed
 351
 352 - Fix median computation implementation.
 353 - Fix fair share worker choice strategy internals update.
 354
 355 ## [2.4.11] - 2023-04-23
 356
 357 ### Changed
 358
 359 - Optimize free worker finding in worker choice strategies.
 360
 361 ## [2.4.10] - 2023-04-15
 362
 363 ### Fixed
 364
 365 - Fix typescript type definition for task function: ensure the input data is optional.
 366 - Fix typescript type definition for pool execute(): ensure the input data is optional.
 367
 368 ## [2.4.9] - 2023-04-15
 369
 370 ### Added
 371
 372 - Add tasks queue enablement runtime setter to pool.
 373 - Add tasks queue options runtime setter to pool.
 374 - Add worker choice strategy options runtime setter to pool.
 375
 376 ### Changed
 377
 378 - Remove the tasks queuing experimental status.
 379
 380 ### Fixed
 381
 382 - Fix task function type definition and validation.
 383 - Fix worker choice strategy options handling.
 384
 385 ## [2.4.8] - 2023-04-12
 386
 387 ### Fixed
 388
 389 - Fix message between main worker and worker type definition for tasks.
 390 - Fix code documentation.
 391
 392 ## [2.4.7] - 2023-04-11
 393
 394 ### Added
 395
 396 - Add worker tasks queue options to pool options.
 397
 398 ### Fixed
 399
 400 - Fix missing documentation.
 401
 402 ## [2.4.6] - 2023-04-10
 403
 404 ### Fixed
 405
 406 - Ensure one task at a time is executed per worker with tasks queueing enabled.
 407 - Properly count worker executing tasks with tasks queueing enabled.
 408
 409 ## [2.4.5] - 2023-04-09
 410
 411 ### Added
 412
 413 - Use monotonic high resolution timer for worker tasks runtime.
 414 - Add worker tasks median runtime to statistics.
 415 - Add worker tasks queue (experimental).
 416
 417 ## [2.4.4] - 2023-04-07
 418
 419 ### Added
 420
 421 - Add `PoolEvents` enumeration and `PoolEvent` type.
 422
 423 ### Fixed
 424
 425 - Destroy worker only on alive check.
 426
 427 ## [2.4.3] - 2023-04-07
 428
 429 ### Fixed
 430
 431 - Fix typedoc generation with inheritance.
 432
 433 ## [2.4.2] - 2023-04-06
 434
 435 ### Added
 436
 437 - Add `full` event to dynamic pool.
 438 - Keep worker choice strategy in memory for conditional reuse.
 439
 440 ### Fixed
 441
 442 - Fix possible negative worker key at worker removal in worker choice strategies.
 443
 444 ## [2.4.1] - 2023-04-05
 445
 446 ### Changed
 447
 448 - Optimize worker choice strategy for dynamic pool.
 449
 450 ### Fixed
 451
 452 - Ensure dynamic pool does not alter worker choice strategy expected behavior.
 453
 454 ## [2.4.0] - 2023-04-04
 455
 456 ### Added
 457
 458 - Add `LESS_BUSY` worker choice strategy.
 459
 460 ### Changed
 461
 462 - Optimize worker storage in pool.
 463 - Optimize worker alive status check.
 464 - BREAKING CHANGE: Rename worker choice strategy `LESS_RECENTLY_USED` to `LESS_USED`.
 465 - Optimize `LESS_USED` worker choice strategy.
 466 - Update benchmarks versus external threads pools.
 467 - Optimize tasks usage statistics requirements for worker choice strategy.
 468
 469 ### Fixed
 470
 471 - Ensure trimmable characters are checked at pool initialization.
 472 - Fix message id integer overflow.
 473 - Fix pool worker removal in worker choice strategy internals.
 474 - Fix package publication with pnpm.
 475
 476 ## [2.4.0-3] - 2023-04-04
 477
 478 ### Added
 479
 480 - Add `LESS_BUSY` worker choice strategy.
 481
 482 ### Changed
 483
 484 - Optimize worker storage in pool.
 485 - Optimize worker alive status check.
 486 - BREAKING CHANGE: Rename worker choice strategy `LESS_RECENTLY_USED` to `LESS_USED`.
 487 - Optimize `LESS_USED` worker choice strategy.
 488 - Update benchmarks versus external threads pools.
 489
 490 ### Fixed
 491
 492 - Ensure trimmable characters are checked at pool initialization.
 493 - Fix message id integer overflow.
 494 - Fix pool worker removal in worker choice strategy internals.
 495 - Fix package publication with pnpm.
 496
 497 ## [2.4.0-2] - 2023-04-03
 498
 499 ### Added
 500
 501 - Add `LESS_BUSY` worker choice strategy.
 502
 503 ### Changed
 504
 505 - Optimize worker storage in pool.
 506 - Optimize worker alive status check.
 507 - BREAKING CHANGE: Rename worker choice strategy `LESS_RECENTLY_USED` to `LESS_USED`.
 508 - Optimize `LESS_USED` worker choice strategy.
 509
 510 ### Fixed
 511
 512 - Ensure trimmable characters are checked at pool initialization.
 513 - Fix message id integer overflow.
 514 - Fix pool worker removal in worker choice strategy internals.
 515 - Fix package publication with pnpm.
 516
 517 ## [2.4.0-1] - 2023-04-03
 518
 519 ### Added
 520
 521 - Add `LESS_BUSY` worker choice strategy.
 522
 523 ### Changed
 524
 525 - Optimize worker storage in pool.
 526 - Optimize worker alive status check.
 527 - BREAKING CHANGE: Rename worker choice strategy `LESS_RECENTLY_USED` to `LESS_USED`.
 528 - Optimize `LESS_USED` worker choice strategy.
 529
 530 ### Fixed
 531
 532 - Ensure trimmable characters are checked at pool initialization.
 533 - Fix message id integer overflow.
 534 - Fix pool worker removal in worker choice strategy internals.
 535
 536 ## [2.4.0-0] - 2023-04-03
 537
 538 ### Added
 539
 540 - Add `LESS_BUSY` worker choice strategy.
 541
 542 ### Changed
 543
 544 - Optimize worker storage in pool.
 545 - Optimize worker alive status check.
 546 - BREAKING CHANGE: Rename worker choice strategy `LESS_RECENTLY_USED` to `LESS_USED`.
 547 - Optimize `LESS_USED` worker choice strategy.
 548
 549 ### Fixed
 550
 551 - Ensure trimmable characters are checked at pool initialization.
 552 - Fix message id integer overflow.
 553 - Fix pool worker removal in worker choice strategy internals.
 554
 555 ## [2.3.10] - 2023-03-18
 556
 557 ### Fixed
 558
 559 - Fix package.json `exports` syntax for ESM and CommonJS.
 560
 561 ### Changed
 562
 563 - Permit SemVer pre-release publication.
 564
 565 ## [2.3.10-2] - 2023-03-18
 566
 567 ### Fixed
 568
 569 - Fix package.json `exports` syntax for ESM and CommonJS.
 570
 571 ## [2.3.10-1] - 2023-03-18
 572
 573 ### Changed
 574
 575 - Permit SemVer pre-release publication.
 576
 577 ## [2.3.10-0] - 2023-03-18
 578
 579 ### Fixed
 580
 581 - Fix package.json `exports` syntax for ESM and CommonJS.
 582
 583 ## [2.3.9] - 2023-03-18
 584
 585 ### Changed
 586
 587 - Introduce ESM module support along with CommonJS one.
 588
 589 ### Fixed
 590
 591 - Fix brown paper bag bug referencing the same object literal.
 592
 593 ## [2.3.8] - 2023-03-18
 594
 595 ### Changed
 596
 597 - Switch internal benchmarking code to benny.
 598 - Switch to TypeScript 5.x.x.
 599 - Switch rollup bundler plugins to core ones.
 600 - Switch to TSDoc syntax.
 601 - Enforce conventional commits.
 602
 603 ### Fixed
 604
 605 - Fix random integer generator.
 606 - Fix worker choice strategy pool type identification at initialization.
 607
 608 ## [2.3.7] - 2022-10-23
 609
 610 ### Changed
 611
 612 - Switch to open collective FOSS project funding platform.
 613 - Switch to ts-standard linter configuration on TypeScript code.
 614
 615 ### Fixed
 616
 617 - Fixed missing async on pool execute method.
 618 - Fixed typing in TypeScript example.
 619 - Fixed types in unit tests.
 620
 621 ## [2.3.6] - 2022-10-22
 622
 623 ### Changed
 624
 625 - Cleanup pool attributes and methods.
 626 - Refine error types thrown.
 627
 628 ### Fixed
 629
 630 - Fix continuous integration build on windows.
 631 - Fix code coverage reporting by using c8 instead of nyc.
 632
 633 ## [2.3.5] - 2022-10-21
 634
 635 ### Changed
 636
 637 - Improve benchmarks: add IO intensive task workload, add task size option, integrate code into linter.
 638 - Optimize tasks usage lookup implementation.
 639
 640 ### Fixed
 641
 642 - Fix missed pool event emitter type export.
 643 - Fix typedoc documentation generation.
 644
 645 ## [2.3.4] - 2022-10-17
 646
 647 ### Added
 648
 649 - Fully automate release process with release-it.
 650
 651 ### Changed
 652
 653 - Optimize fair share task scheduling algorithm implementation.
 654 - Update benchmarks versus external pools results with latest version.
 655
 656 ## [2.3.3] - 2022-10-15
 657
 658 ### Added
 659
 660 - Add support for [cluster settings](https://nodejs.org/api/cluster.html#cluster_cluster_settings) in cluster pool options.
 661
 662 ## [2.3.2] - 2022-10-14
 663
 664 ### Changed
 665
 666 - Optimize fair share worker selection strategy implementation.
 667
 668 ### Fixed
 669
 670 - Fix WRR worker selection strategy: ensure the condition triggering the round robin can be fulfilled.
 671
 672 ## [2.3.1] - 2022-10-13
 673
 674 ### Added
 675
 676 - Pool worker choice strategies:
 677   - `WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN` strategy based on weighted round robin scheduling algorithm using tasks execution time for now.
 678   - `WorkerChoiceStrategies.FAIR_SHARE` strategy based on fair share scheduling algorithm using tasks execution time for now.
 679
 680 ## [2.2.2] - 2022-10-09
 681
 682 ### Fixed
 683
 684 - Fixed `README.md` file.
 685
 686 ## [2.2.1] - 2022-10-08
 687
 688 ### Added
 689
 690 - Dynamic worker choice strategy change at runtime.
 691
 692 ## [2.2.0] - 2022-01-05
 693
 694 ### Breaking Changes
 695
 696 - Support only Node.js version 16.x.x for cluster pool: upstream cluster API have changed on that version.
 697
 698 ## [2.1.0] - 2021-08-29
 699
 700 ### Added
 701
 702 - Add an optional pool option `messageHandler` to `PoolOptions<Worker>` for registering a message handler callback on each worker.
 703
 704 ### Breaking Changes
 705
 706 - `AbstractWorker` class `maxInactiveTime`, `killBehavior` and `async` attributes have been removed in favour of the same ones in the worker options `opts` public attribute.
 707 - `AbstractWorker` class `lastTask` attribute have been renamed to `lastTaskTimestamp`.
 708 - `AbstractWorker` class `interval` attribute have been renamed to `aliveInterval`.
 709 - `AbstractWorker` class cannot be instantiated without specifying the `mainWorker` argument referencing the main worker.
 710
 711 ## [2.0.2] - 2021-05-12
 712
 713 ### Bug fixes
 714
 715 - Fix `busy` event emission on fixed pool type
 716
 717 ## [2.0.1] - 2021-03-16
 718
 719 ### Bug fixes
 720
 721 - Check if pool options are properly set.
 722 - `busy` event is emitted on all pool types.
 723
 724 ## [2.0.0] - 2021-03-01
 725
 726 ### Bug fixes
 727
 728 - Now a thread/process by default is not deleted when the task submitted take more time than maxInactiveTime configured (issue #70).
 729
 730 ### Breaking Changes
 731
 732 - `FullPool` event is now renamed to `busy`.
 733 - `maxInactiveTime` on `ThreadWorker` default behavior is now changed, if you want to keep the old behavior set `killBehavior` to `KillBehaviors.HARD`.
 734   _Find more details on our JSDoc._
 735
 736 - `maxTasks` option on `FixedThreadPool` and `DynamicThreadPool` is now removed since is no more needed.
 737
 738 - We changed some internal structures, but you shouldn't be too affected by them as these are internal changes.
 739
 740 ### Pool options types declaration merge
 741
 742 `FixedThreadPoolOptions` and `DynamicThreadPoolOptions` type declarations have been merged to `PoolOptions<Worker>`.
 743
 744 #### New `export` strategy
 745
 746 ```js
 747 // Before
 748 const DynamicThreadPool = require('poolifier/lib/dynamic')
 749 // After
 750 const { DynamicThreadPool } = require('poolifier/lib/dynamic')
 751 ```
 752
 753 But you should always prefer just using
 754
 755 ```js
 756 const { DynamicThreadPool } = require('poolifier')
 757 ```
 758
 759 #### New type definitions for input data and response
 760
 761 For cluster worker and worker-thread pools, you can now only send and receive structured-cloneable data.
 762 _This is not a limitation by poolifier but Node.js._
 763
 764 #### Public property replacements
 765
 766 `numWorkers` property is now `numberOfWorkers`
 767
 768 #### Internal (protected) properties and methods renaming
 769
 770 These properties are not intended for end users
 771
 772 - `id` => `nextMessageId`
 773
 774 These methods are not intended for end users
 775
 776 - `_chooseWorker` => `chooseWorker`
 777 - `_newWorker` => `createWorker`
 778 - `_execute` => `internalExecute`
 779 - `_chooseWorker` => `chooseWorker`
 780 - `_checkAlive` => `checkAlive`
 781 - `_run` => `run`
 782 - `_runAsync` => `runAsync`
 783
 784 ## [1.1.0] - 2020-05-21
 785
 786 ### Added
 787
 788 - ThreadWorker support async functions as option
 789 - Various external library patches
 790
 791 ## [1.0.0] - 2020-01-24
 792
 793 ### Added
 794
 795 - FixedThreadPool implementation
 796 - DynamicThreadPool implementation
 797 - WorkerThread implementation to improve developer experience