---
title: Improved memory efficiency for WebAssembly Workers
description: With the introduction of FinalizationRegistry in Workers Runtime, toolchains like Emscripten and wasm-bindgen can automatically reclaim unused WebAssembly heap and reduce memory leaks.
image: https://edgetunnel-b2h.pages.dev/changelog-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://edgetunnel-b2h.pages.dev/changelog/llms.txt  
> Use this file to discover all available pages before exploring further. 

[Skip to content](#%5Ftop) 

# Changelog

New updates and improvements at Cloudflare.

[ Subscribe to RSS ](https://edgetunnel-b2h.pages.dev/changelog/rss/index.xml) [ View RSS feeds ](https://edgetunnel-b2h.pages.dev/fundamentals/new-features/available-rss-feeds/) 

![hero image](https://edgetunnel-b2h.pages.dev/_astro/hero.CVYJHPAd_26AMqX.svg) 

[ ← Back to all posts ](https://edgetunnel-b2h.pages.dev/changelog/) 

## Improved memory efficiency for WebAssembly Workers

May 08, 2025 

[ Workers ](https://edgetunnel-b2h.pages.dev/workers/) 

[FinalizationRegistry ↗](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global%5FObjects/FinalizationRegistry) is now available in Workers. You can opt-in using the [enable\_weak\_ref](https://edgetunnel-b2h.pages.dev/workers/configuration/compatibility-flags/#enable-finalizationregistry-and-weakref) compatibility flag.

This can reduce memory leaks when using WebAssembly-based Workers, which includes [Python Workers](https://edgetunnel-b2h.pages.dev/workers/languages/python/) and [Rust Workers](https://edgetunnel-b2h.pages.dev/workers/languages/rust/). The FinalizationRegistry works by enabling toolchains such as [Emscripten ↗](https://emscripten.org/) and [wasm-bindgen ↗](https://wasm-bindgen.github.io/wasm-bindgen/) to automatically free WebAssembly heap allocations. If you are using WASM and seeing Exceeded Memory errors and cannot determine a cause using [memory profiling](https://edgetunnel-b2h.pages.dev/workers/observability/dev-tools/memory-usage/), you may want to enable the FinalizationRegistry.

For more information refer to the [enable\_weak\_ref](https://edgetunnel-b2h.pages.dev/workers/configuration/compatibility-flags/#enable-finalizationregistry-and-weakref) compatibility flag documentation.

```json
{"@context":"https://schema.org","@type":"BlogPosting","@id":"https://edgetunnel-b2h.pages.dev/changelog/post/2025-05-08-finalization-registry/#page","headline":"Improved memory efficiency for WebAssembly Workers · Changelog","description":"With the introduction of FinalizationRegistry in Workers Runtime, toolchains like Emscripten and wasm-bindgen can automatically reclaim unused WebAssembly heap and reduce memory leaks.","url":"https://edgetunnel-b2h.pages.dev/changelog/post/2025-05-08-finalization-registry/","inLanguage":"en","image":"https://edgetunnel-b2h.pages.dev/changelog-preview.png","dateModified":"2025-05-08","datePublished":"2025-05-08","publisher":{"@type":"Organization","name":"Cloudflare","url":"https://www.cloudflare.com/"},"isPartOf":{"@type":"WebSite","@id":"https://edgetunnel-b2h.pages.dev/#website","name":"Cloudflare Docs","url":"https://edgetunnel-b2h.pages.dev/"}}
```