Bug 281662 – Transferring buffers to a closed MessageChannel causes memory leaks in Safari Networking

• Status: NEW
• Component: DOM

[Ivan Čurić]

const { port1, port2 } = new MessageChannel();
port2.close();

port1.postMessage(e.data, [e.data.imageData.data.buffer]);

This approach can be used to alleviate memory pressure in V8 as it forces GC.

When used in Safari, this memory never gets GC'd, and the leak happens in the "Safari Networking" process for some reason, and can't be reclaimed until you restart Safari.
You can't find this leak in the Web Inspector.

Repro:

Enable the option "Toss transferable to empty MessageChannel" and observe memory usage in Activity Monitor

https://imagedata-worker-leak.netlify.app/
https://github.com/ivancuric/memory-leak-repro

[Radar WebKit Bug Importer]

<rdar://problem/138550781>