Offload functions to worker threads with shared memory primitives for Node.js.
feat: roundRobin() and leastBusy() balancer factories
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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src/balancers.ts
+35
src/balancers.ts
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import type { Balancer, WorkerHandle } from './runner.ts';
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/**
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* Creates a round-robin balancer that cycles through workers in order.
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* @returns A fresh Balancer instance.
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*/
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export function roundRobin(): Balancer {
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let next = 0;
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return {
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select(workers: readonly WorkerHandle[]): WorkerHandle {
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const worker = workers[next % workers.length];
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next++;
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return worker;
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},
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};
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}
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/**
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* Creates a least-busy balancer that picks the worker with the lowest activeCount.
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* Ties are broken by index (first wins).
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* @returns A fresh Balancer instance.
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*/
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export function leastBusy(): Balancer {
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return {
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select(workers: readonly WorkerHandle[]): WorkerHandle {
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let best = workers[0];
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for (let i = 1; i < workers.length; i++) {
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if (workers[i].activeCount < best.activeCount) {
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best = workers[i];
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}
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}
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return best;
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},
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};
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}
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-1
src/index.ts
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-1
src/index.ts
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export { workers } from './worker-pool.ts';
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export { transfer } from './transfer.ts';
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export { assign } from './assign.ts';
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export type { Runner, WorkerHandle, WorkerOptions } from './runner.ts';
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export { roundRobin, leastBusy } from './balancers.ts';
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export type { Balancer, Runner, WorkerHandle, WorkerOptions } from './runner.ts';
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export {
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shared,
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int8,
+36
test/balancers.test.ts
+36
test/balancers.test.ts
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import { describe, it } from 'node:test';
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import assert from 'node:assert/strict';
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import { roundRobin, leastBusy } from 'moroutine';
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import type { WorkerHandle } from 'moroutine';
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function mockHandle(activeCount: number): WorkerHandle {
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return { activeCount, thread: {} as any, exec: {} as any };
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}
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describe('roundRobin()', () => {
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it('cycles through workers in order', () => {
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const b = roundRobin();
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const handles = [mockHandle(0), mockHandle(0), mockHandle(0)];
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const task = { id: 'test', args: [], uid: 0 } as any;
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assert.equal(b.select(handles, task), handles[0]);
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assert.equal(b.select(handles, task), handles[1]);
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assert.equal(b.select(handles, task), handles[2]);
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assert.equal(b.select(handles, task), handles[0]);
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});
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});
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describe('leastBusy()', () => {
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it('picks worker with lowest activeCount', () => {
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const b = leastBusy();
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const handles = [mockHandle(3), mockHandle(1), mockHandle(2)];
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const task = { id: 'test', args: [], uid: 0 } as any;
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assert.equal(b.select(handles, task), handles[1]);
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});
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it('breaks ties by index', () => {
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const b = leastBusy();
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const handles = [mockHandle(1), mockHandle(1), mockHandle(1)];
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const task = { id: 'test', args: [], uid: 0 } as any;
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assert.equal(b.select(handles, task), handles[0]);
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});
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});