| 1 | import { cpus } from 'os' |
| 2 | import type { AbstractPoolWorker } from '../abstract-pool-worker' |
| 3 | import type { IPoolInternal } from '../pool-internal' |
| 4 | import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy' |
| 5 | |
| 6 | /** |
| 7 | * Task run time. |
| 8 | */ |
| 9 | type TaskRunTime = { |
| 10 | weight: number |
| 11 | runTime: number |
| 12 | } |
| 13 | |
| 14 | /** |
| 15 | * Selects the next worker with a weighted round robin scheduling algorithm. |
| 16 | * Loosely modeled after the weighted round robin queueing algorithm: https://en.wikipedia.org/wiki/Weighted_round_robin. |
| 17 | * |
| 18 | * @template Worker Type of worker which manages the strategy. |
| 19 | * @template Data Type of data sent to the worker. This can only be serializable data. |
| 20 | * @template Response Type of response of execution. This can only be serializable data. |
| 21 | */ |
| 22 | export class WeightedRoundRobinWorkerChoiceStrategy< |
| 23 | Worker extends AbstractPoolWorker, |
| 24 | Data, |
| 25 | Response |
| 26 | > extends AbstractWorkerChoiceStrategy<Worker, Data, Response> { |
| 27 | /** |
| 28 | * Worker index where the previous task was submitted. |
| 29 | */ |
| 30 | private previousWorkerIndex: number = 0 |
| 31 | /** |
| 32 | * Worker index where the current task will be submitted. |
| 33 | */ |
| 34 | private currentWorkerIndex: number = 0 |
| 35 | /** |
| 36 | * Default worker weight. |
| 37 | */ |
| 38 | private defaultWorkerWeight: number |
| 39 | /** |
| 40 | * Per worker task runtime map. |
| 41 | */ |
| 42 | private workerTaskRunTime: Map<Worker, TaskRunTime> = new Map< |
| 43 | Worker, |
| 44 | TaskRunTime |
| 45 | >() |
| 46 | |
| 47 | /** |
| 48 | * Constructs a worker choice strategy that selects with a weighted round robin scheduling algorithm. |
| 49 | * |
| 50 | * @param pool The pool instance. |
| 51 | */ |
| 52 | public constructor (pool: IPoolInternal<Worker, Data, Response>) { |
| 53 | super(pool) |
| 54 | this.defaultWorkerWeight = this.computeWorkerWeight() |
| 55 | this.initWorkerTaskRunTime() |
| 56 | } |
| 57 | |
| 58 | /** @inheritDoc */ |
| 59 | public choose (): Worker { |
| 60 | const currentWorker = this.pool.workers[this.currentWorkerIndex] |
| 61 | if (this.isDynamicPool === true) { |
| 62 | this.workerTaskRunTime.has(currentWorker) === false && |
| 63 | this.workerTaskRunTime.set(currentWorker, { |
| 64 | weight: this.defaultWorkerWeight, |
| 65 | runTime: 0 |
| 66 | }) |
| 67 | } |
| 68 | const workerVirtualTaskRunTime = |
| 69 | this.getWorkerVirtualTaskRunTime(currentWorker) ?? 0 |
| 70 | const workerTaskWeight = |
| 71 | this.workerTaskRunTime.get(currentWorker)?.weight ?? |
| 72 | this.defaultWorkerWeight |
| 73 | if (this.currentWorkerIndex === this.previousWorkerIndex) { |
| 74 | const workerTaskRunTime = |
| 75 | (this.workerTaskRunTime.get(currentWorker)?.runTime ?? 0) + |
| 76 | workerVirtualTaskRunTime |
| 77 | this.workerTaskRunTime.set(currentWorker, { |
| 78 | weight: workerTaskWeight, |
| 79 | runTime: workerTaskRunTime |
| 80 | }) |
| 81 | } else { |
| 82 | this.workerTaskRunTime.set(currentWorker, { |
| 83 | weight: workerTaskWeight, |
| 84 | runTime: 0 |
| 85 | }) |
| 86 | } |
| 87 | if ( |
| 88 | workerVirtualTaskRunTime < |
| 89 | (this.workerTaskRunTime.get(currentWorker) ?? this.defaultWorkerWeight) |
| 90 | ) { |
| 91 | this.previousWorkerIndex = this.currentWorkerIndex |
| 92 | } else { |
| 93 | this.previousWorkerIndex = this.currentWorkerIndex |
| 94 | this.currentWorkerIndex = |
| 95 | this.pool.workers.length - 1 === this.currentWorkerIndex |
| 96 | ? 0 |
| 97 | : this.currentWorkerIndex + 1 |
| 98 | } |
| 99 | return this.pool.workers[this.currentWorkerIndex] |
| 100 | } |
| 101 | |
| 102 | private computeWorkerWeight () { |
| 103 | let cpusCycleTimeWeight = 0 |
| 104 | for (const cpu of cpus()) { |
| 105 | // CPU estimated cycle time |
| 106 | const numberOfDigit = cpu.speed.toString().length - 1 |
| 107 | const cpuCycleTime = 1 / (cpu.speed / Math.pow(10, numberOfDigit)) |
| 108 | cpusCycleTimeWeight += cpuCycleTime * Math.pow(10, numberOfDigit) |
| 109 | } |
| 110 | return cpusCycleTimeWeight / cpus().length |
| 111 | } |
| 112 | |
| 113 | private initWorkerTaskRunTime () { |
| 114 | for (const worker of this.pool.workers) { |
| 115 | this.workerTaskRunTime.set(worker, { |
| 116 | weight: this.defaultWorkerWeight, |
| 117 | runTime: 0 |
| 118 | }) |
| 119 | } |
| 120 | } |
| 121 | |
| 122 | private getWorkerVirtualTaskRunTime (worker: Worker): number | undefined { |
| 123 | return this.pool.getWorkerAverageTasksRunTime(worker) |
| 124 | } |
| 125 | } |