PromisePool

A generic, typed, event-driven promise pool for concurrent task execution with prioritization, timeouts, and retries — implemented in TypeScript.

Source code on GitHub

Features

• Limit the number of concurrent asynchronous tasks.
• Support for task timeouts and automatic abortion.
• Retry logic with configurable attempt limits.
• Priority-based task queuing (0 = highest, 5 = lowest).
• Optional success/failure callbacks.
• Graceful shutdown and pause/resume support.
• Emits drain event when the queue is empty and all tasks complete.

Installation

npm install promise-pool-async

Usage

import { PromisePool } from './PromisePool';

const pool = new PromisePool<string>({
  size: 3,
  timeout: 1000,
  retries: 2,
  onSuccess: (res) => console.log('✅ Success:', res),
  onFailure: (err, left) => console.warn('❌ Failed:', err, 'Retries left:', left)
});

pool.on('drain', () => console.log('All tasks complete.'));

pool.add((signal) => someAsyncFunction(signal), 1);
pool.add((signal) => anotherTask(signal), 3);

API

Constructor

new PromisePool<T>({
  size: number;
  timeout: number; // in milliseconds
  retries: number;
  onSuccess?: (result: T) => void;
  onFailure?: (error: unknown, retriesLeft: number) => void;
});

Methods

add(task, priority = 3, retries?)

Add a task to the pool with optional priority and retry count.

shutdown()

Gracefully stop processing and abort running tasks.

Events

• drain: Emitted when the queue is empty and no tasks are running.

Task Format

Tasks should return a Promise<T> and accept an AbortSignal:

const task = (signal: AbortSignal) => {
  return new Promise<string>((resolve, reject) => {
    if (signal.aborted) return reject(new Error('Aborted'));
    // Perform async work
  });
};

License

MIT