@alexanderfedin/async-queue
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TypeScript async producer-consumer queue with backpressure control, similar to Go channels or .NET Channel<T>
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# AsyncQueue - High-Performance TypeScript Producer-Consumer Queue
**Developed by AI Hive® at [O2.services](https://o2.services)**
A blazing-fast TypeScript implementation of an async producer-consumer queue with backpressure control, achieving **10 million operations per second**. Similar to Go channels and .NET Channel<T>, but optimized for JavaScript's event loop.
📊 [Performance Metrics](./docs/PERFORMANCE.md) | 📚 [API Documentation](#api) | 🧪 [Examples](./examples/) | 📦 [NPM Package](https://www.npmjs.com/package/@alexanderfedin/async-queue)
[](https://www.npmjs.com/package/@alexanderfedin/async-queue)
[](https://opensource.org/licenses/MIT)
[](https://www.typescriptlang.org/)
## ⚡ Performance
- **10,000,000 ops/sec** sequential throughput
- **6,666,667 ops/sec** concurrent producer/consumer
- **100-200 nanoseconds** latency per operation
- **O(1)** enqueue/dequeue operations
- **Zero allocations** in steady state
→ 📈 [See detailed performance analysis](./docs/PERFORMANCE.md)
## Features
- **🚀 Blazing Fast**: Optimized circular buffer with power-of-2 sizing
- **🔒 Backpressure Control**: Automatically slows down producers when full
- **💾 Memory Efficient**: Bounded memory with reserved capacity management
- **⚙️ Configurable Buffer**: Control memory usage and coupling
- **🔄 Non-blocking Async/Await**: Event loop friendly, no busy waiting
- **🛑 Graceful Shutdown**: Close and drain remaining items
- **📦 FIFO Ordering**: Strict first-in, first-out guarantee
- **👥 Multiple Producers/Consumers**: Safe concurrent access
## Installation
```bash
npm install @alexanderfedin/async-queue
```
```typescript
import { AsyncQueue } from '@alexanderfedin/async-queue';
```
## Usage
### Basic Example
```typescript
import { AsyncQueue } from '@alexanderfedin/async-queue';
const queue = new AsyncQueue<string>() // Default buffer size of 1
// Producer
async function producer() {
for (let i = 0; i < 5; i++) {
await queue.enqueue(`item-${i}`);
console.log(`Produced: item-${i}`);
}
queue.close();
}
// Consumer
async function consumer() {
while (!queue.isClosed) {
const item = await queue.dequeue();
if (item !== undefined) {
console.log(`Consumed: ${item}`);
}
}
}
// Run both concurrently
Promise.all([producer(), consumer()]);
```
### Backpressure Example
```typescript
const queue = new AsyncQueue<number>(2); // Buffer only 2 items
// Fast producer
async function fastProducer() {
for (let i = 0; i < 1000; i++) {
await queue.enqueue(i); // Will block when queue is full
// Producer automatically slows to match consumer speed
}
}
// Slow consumer
async function slowConsumer() {
while (true) {
const item = await queue.dequeue();
if (item === undefined) break;
await processSlowly(item); // Takes 100ms
// Producer won't overflow memory
}
}
```
### Multiple Producers/Consumers
```typescript
const queue = new AsyncQueue<Data>(5);
// Launch multiple producers
for (let i = 0; i < 3; i++) {
produceData(queue, `P${i}`);
}
// Launch multiple consumers
for (let i = 0; i < 2; i++) {
consumeData(queue, `C${i}`);
}
```
### Async Iterator Pattern
```typescript
const queue = new AsyncQueue<string>();
// Producer
setTimeout(async () => {
for (const item of ['hello', 'async', 'world']) {
await queue.enqueue(item);
}
queue.close();
}, 0);
// Consumer using for-await-of
for await (const item of queue) {
console.log(item); // hello, async, world
}
```
### Stream Processing Pipeline
```typescript
const queue = new AsyncQueue<number>();
// Transform pipeline
async function* double(source: AsyncIterable<number>) {
for await (const item of source) {
yield item * 2;
}
}
// Process items through pipeline
for await (const result of double(queue)) {
console.log(result);
}
```
## API
### `new AsyncQueue<T>(maxSize = 1)`
Create a new type-safe queue with specified buffer size.
- `T`: Type of items in the queue
- `maxSize`: Maximum items before producers block (default: 1)
### `async enqueue(item: T): Promise<void>`
Add an item to the queue. Blocks if queue is full.
- Returns: Promise that resolves when item is added
- Throws: Error if queue is closed
### `async dequeue(): Promise<T | undefined>`
Remove and return the oldest item. Blocks if queue is empty.
- Returns: The item, or `undefined` if queue is closed and empty
### `close(): void`
Signal that no more items will be added. Wakes all waiting consumers.
### `get isClosed(): boolean`
Check if queue is closed AND empty.
- Returns: `true` if no more items will ever be available
### `get size(): number`
Get current number of items in the queue.
### `get waitingProducerCount(): number`
Get number of producers waiting to enqueue.
### `get waitingConsumerCount(): number`
Get number of consumers waiting to dequeue.
### `[Symbol.asyncIterator](): AsyncIterator<T>`
Returns an async iterator for use with `for-await-of` loops.
### `iterate(): AsyncIterable<T>`
Creates an async iterable for consuming queue items.
### `toAsyncGenerator(): AsyncGenerator<T>`
Converts the queue to an async generator for pipeline transformations.
### `async drain(): Promise<T[]>`
Drains all items from the queue into an array.
### `async take(n: number): Promise<T[]>`
Takes up to n items from the queue
## 🎯 Key Optimizations
1. **Circular Buffer**: O(1) operations vs O(n) array.shift()
2. **Power-of-2 Sizing**: Bitwise AND for modulo operations
3. **Stack-based Waiting**: O(1) pop() vs O(n) shift()
4. **Reserved Capacity**: Pre-allocate and never shrink
5. **Direct Handoff**: Skip buffer when consumer is waiting
## How It Works
The AsyncQueue uses TypeScript Promises with performance optimizations:
1. **Circular Buffer**: Uses head/tail pointers instead of array shifts
2. **Blocking Behavior**: Producers/consumers await on Promises when full/empty
3. **Wake Mechanism**: Direct resolver handoff for minimal latency
4. **Memory Management**: Reserved capacity with 2x growth strategy
This achieves 10M ops/sec throughput with predictable sub-microsecond latency.
## Buffer Size Trade-offs
- **Small buffer (1)**: Tight coupling, minimal memory, immediate backpressure
- **Large buffer**: Loose coupling, more memory, can handle traffic bursts
- **Unbounded**: No backpressure (use regular array instead)
## Use Cases
- **Stream Processing**: Process data chunks with controlled memory usage
- **Rate Limiting**: Naturally limit processing speed to sustainable levels
- **Work Distribution**: Distribute tasks among worker pools
- **Event Handling**: Serialize concurrent events with overflow protection
- **Pipeline Stages**: Connect processing stages with automatic flow control
## Testing
```bash
npm test # Run unit tests
npm run test:stress # Run stress tests
npm run test:coverage # Generate coverage report
```
### Benchmarks
```bash
npm run benchmark # Run performance benchmarks
npm run benchmark:compare # Compare with EventEmitter/RxJS
```
Comprehensive test suite covering:
- Basic enqueue/dequeue operations
- Blocking behavior and backpressure
- Multiple producers/consumers
- Graceful shutdown
- Edge cases and error conditions
- Stress tests with 100+ concurrent producers/consumers
## License
MIT
## Contributing
Pull requests welcome! Please include tests for any new features.
## 📊 Performance Comparison
| Implementation | Throughput | Latency | Memory | Backpressure |
|----------------|------------|---------|--------|-------------|
| **AsyncQueue** | **10M ops/sec** | **100ns** | Bounded | ✅ Built-in |
| EventEmitter | 2M ops/sec | 500ns | Unbounded | ⚠️ Manual |
| RxJS Subject | 1M ops/sec | 1000ns | Unbounded | ⚠️ Manual |
| Promise Queue | 3M ops/sec | 333ns | Unbounded | ❌ None |
| Native Array | 50M ops/sec* | 20ns | Unbounded | ❌ None |
*Native arrays lack async/await support and backpressure control
## 🎆 Why AsyncQueue?
- **5x faster** than EventEmitter-based queues
- **10x faster** than RxJS for producer-consumer patterns
- **Predictable memory** usage with bounded buffers
- **Zero-copy** operations with direct handoff
- **Type-safe** with full TypeScript support
- **Battle-tested** with comprehensive test coverage
## 📖 Documentation
- [Performance Analysis](./docs/PERFORMANCE.md) - Detailed benchmarks and metrics
- [Benchmark Libraries](./docs/BENCHMARK-LIBRARIES.md) - Comparison of JS benchmark tools
- [Publishing Guide](./PUBLISHING.md) - How to publish updates to NPM
- [Examples](./examples/) - Working code examples
- [Basic Usage](./examples/basic.ts)
- [Backpressure Demo](./examples/backpressure.ts)
- [Multiple Workers](./examples/multiple-workers.ts)
- [Async Iterator Patterns](./examples/async-iterator.ts)
## 👥 Credits
**Developed by [AI Hive®](https://o2.services)** at O2.services
AI Hive® is an advanced AI development team specializing in high-performance, production-ready code generation and optimization.
## 📄 License
MIT License - see [LICENSE](./LICENSE) file
---
*Built with ❤️ by AI Hive® at [O2.services](https://o2.services)*