Can JsValue memory leak?

[oblique]

I'm working a a project which moves a lot of data to JS. The data are initially Rust structs and then converted to JsValue by using serde-wasm-bindgen and send to JS, however I notice that memory usage grows a lot over time.

My questions:

1. If JsValue is sent to the JS. Will garbage collector deallocate it?
2. If JsValue is not sent to the JS, but dropped in Rust. Will it memory leak or deallocated by GC?
3. If JsValue is sent from JS to Rust and is dropped. Will garbage collector deallocate it?
4. If 2 or 3 memory leak, how can I free the memory?

[daxpedda]

Generally speaking, all the cases you mentioned, should be handled by the GC.
However there are some subtle issues that can't really be resolved because of the limitations surrounding JS, see #3917.

All-in-all, unless something is intentionally not cleaning up memory, everything should be handled correctly by the GC eventually.
If not, you have likely found a bug. Let us know if you do!

(I'm not familiar with serde-wasm-bindgen)

[daxpedda]

Forgot to mention #3854 as well, so if you encountered that it will be fixed in the next release.

[caiges]

Out of curiosity, how is the decision to release made?

[daxpedda]

There is no specific process in place, its done on request.

It has already been requested, including by myself, so I'm currently working on the last couple of things before the release.
I'm hoping today? But seems I've said that two days ago already, so wish me luck!

[oblique]

Just in the case that any other poor soul is looking for the memory leak but can not find it: The memory leak for me was because of tracing-web's performance layer. It was calling Performance.mark() and Performance.measure() which creates JS objects that live throughout the whole process. This is not a bug in tracing-web but it is how performance marks work.