# s3fifo 1.0: Zero-Allocation S3-FIFO Cache for Node.js is Ready for Production

> Source: <https://dev.to/jeongseop_byeon_9d8f61627/s3fifo-10-zero-allocation-s3-fifo-cache-for-nodejs-is-ready-for-production-27oc>
> Published: 2026-07-23 16:24:28+00:00

*Disclaimer: As a non-native English speaker, I used AI to help structure and polish this article.*

A few dayss ago, I shared [Implementing a Zero-Allocation S3-FIFO Cache in Node.js](https://dev.to/jeongseop_byeon_9d8f61627/implementing-a-zero-allocation-s3-fifo-cache-in-nodejs-520d)—an exploratory v0.1 release demonstrating how the **S3-FIFO (Simple and Scalable Scan-Resistant FIFO)** caching algorithm can be implemented using pre-allocated `TypedArray`

s to eliminate Garbage Collection (GC) pressure in Node.js.

Today, after extensive stress testing, architectural hardening, and 100% unit test coverage, I'm excited to announce the release of ** s3fifo v1.0.0**! 🚀

Traditional **LRU (Least Recently Used)** caches suffer from two major production drawbacks:

`set()`

, triggering frequent GC pauses under high-throughput workloads.
`s3fifo`

achieves `get`

/`set`

cycles by backing these queues with contiguous TypedArrays (`Uint32Array`

, `Float64Array`

) and reusable index pools.
---
## What's New in v1.0.0? (Production Readiness)
While v0.1 focused on core algorithm speed, `dump`

& `load`

)
Prevent `s3fifo`

1.0 supports serializing active resident entries alongside their original creation timestamps and remaining TTL:

``` python
import fs from "node:fs";
import { S3Fifo } from "s3fifo";
const cache = new S3Fifo<string>({ max: 10000 });
// 1. Export active cache items (optionally filter out temporary keys)
const dumpData = cache.dump((key, value) => !key.startsWith("temp:"));
fs.writeFileSync("cache-snapshot.json", JSON.stringify(dumpData));
// 2. On server startup / pre-warming: restore cache state instantly
const snapshot = JSON.parse(fs.readFileSync("cache-snapshot.json", "utf-8"));
cache.load(snapshot);
```

`dispose`

Callback)
When cache items are evicted, overwritten, or cleared, you often need to release external resources (e.g., closing file descriptors, destroying DB handles, or tracking eviction metrics).

``` js
const cache = new S3Fifo<Buffer>({
  max: 500,
  dispose: (key, buffer, reason) => {
    console.log(`Key ${key} removed due to: ${reason}`); // 'evict' | 'set' | 'delete' | 'clear'
    // Safely free native memory or resources
  },
});
```

🛡️

Re-Entrancy Protection:`dispose`

callbacks are safely deferred until the cache operation completes, preventing internal state corruption if a callback invokes`cache.set()`

or`cache.delete()`

recursively.## 3. 🔍 Side-Effect-Free Inspection (

`peek`

)Need to check a cached value for logging, health checks, or monitoring without bumping frequency counters or altering eviction status?

`peek()`

allows pure, side-effect-free reading:

``` js
// Does not modify S3-FIFO frequency bit fields or TTL timestamps
const val = cache.peek("user:1001");
```

`s3fifo`

1.0 integrates seamlessly with JavaScript's native iteration protocols:

```
// Standard JS Map style iterators
for (const [key, value] of cache) {
  console.log(key, value);
}
const keys = Array.from(cache.keys());
const values = Array.from(cache.values());
const entries = Array.from(cache.entries());
cache.forEach((val, key) => {
  /* ... */
});
```

`close`

)
In serverless, hot-reloading (HMR), or test environments, background timers can prevent process termination. The `close()`

method clears active background TTL tickers, releases memory buffers, and prevents memory leaks:

```
// Clean teardown on shutdown
cache.close();
console.log(cache.isClosed); // true
```

Tested on a Zipfian distribution (skew `0.99`

, working set of `100,000`

keys) comparing `s3fifo`

v1.0 to Node's popular `lru-cache`

:

| Cache Size (% of Pool) | lru-cache | s3fifo |
|---|---|---|
| 1% | 48.90% | 58.30% |
| 5% | 65.00% | 71.10% |
| 10% | 72.30% | 76.40% |
| 25% | 82.10% | 82.70% |
| 50% | 89.00% |
86.30% |

| Cache Size (% of Pool) | lru-cache | s3fifo |
|---|---|---|
| 1% | 10.8M | 15.5M |
| 5% | 10.8M | 14.4M |
| 10% | 10.2M | 14.3M |
| 25% | 10.3M | 13.5M |
| 50% | 10.3M | 14.7M |

`get`

/`set`

operations.
Install via npm:

```
npm install s3fifo
```

Basic usage:

``` js
import { S3Fifo } from "s3fifo";
const cache = new S3Fifo<string>({
  max: 1000,
  ttl: 60000, // 60s global TTL
});
cache.set("session:abc", "user_data");
console.log(cache.get("session:abc")); // 'user_data'
console.log(cache.size); // 1
```

`s3fifo`

a try! Bug reports, feedback, and GitHub stars are greatly appreciated! 🙏