stop holding a reference to a Promise when it is resolved

[ceymard]

I'm coming back on this closed PR : https://astegmaier.github.io/cached-promise-memory-leak/index.html

I still observe memory leaks in my application due to the includeFile Map. It would seem there is some regression around Promises in Chrome at least.

Wouldn't it still be somewhat better to guard against this possibility by not holding the promise objects in the Map to be sure ?

This approach is a lot simpler (I forgot that Promise.resolve() actually unboxes Promises), maybe you would consider it mergeable ?

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Name	Status	Preview	Updated (UTC)
shoelace	✅ Ready (Inspect)	Visit Preview	Apr 3, 2023 0:22am

[claviska]

This looks much simpler! Thanks for updating it. Do you think it's worth adding a comment to explain why we're doing it this way? Feel free to paste a link back to this PR for context.

[ceymard]

Yes I was actually thinking about explaining it but since there were no comments I restrained myself. I'll comment it.

[ceymard]

For reference, this PR addresses unresolved points we had in #1249 relative to the handling of Promises in the includeFiles Map used to cache network results, especially for icons.

In some browser implementations, the Promise objects seem to cause a leak by retaining all the code that used then() on them. It's weird, it shouldn't happen (one would assume that when it is resolved, all the pending then() calls are completely flushed), but it definitely does.

The "fix" is to remove the Promise objects from the Map once they've resolved to make sure they don't retain anyone.

[ceymard]

Force pushed with the comments.

[claviska]

Thanks for this!