Sharing dependencies with workers

[Tsury]

I have 3 web workers + the main code, all importing comlink (for instance, it can be any other common dependency). When I build, all 4 entry points (main + workers) contain the comlink code. The main code has an import to a comlink file, and the 3 workers have it inline in their entrypoint file.

I want them all to share the code, instead of having 4 instances of it, to decrease bundle size and build time. I want them all to import the same file.
How can this be achieved?

[sadn1ck]

I'm not sure if this will work – but try using worker.rollupOptions.output.manualChunks to spit out a separate chunk for comlink? I'm not sure how to also share that same chunk with your non-worker entry

[Tsury]

Didn't work - but I did find a middleground - 1 copy for the main code and 1 copy for all of the workers... Good enough for now I guess.

[Mihara]

Any new insight on that since?

So I have a web worker I'm loading like this:

    const w = new Worker(new URL("./that.worker", import.meta.url), {
        credentials: "same-origin",
        type: "module"
    });

It works and runs and does what it is supposed to. The problem is that the worker absolutely requires a large (500kb) library that is also used throughout the rest of the project (a mess of separate entry points sharing code, designed for embedding inside a really brittle legacy PHP site.)

It is fairly important that it share at least this 500kb library (and preferably other code) with the rest of the project, which already chunks dependencies the way I like, but Vite seems insistent on duplicating chunks. If I just pass rollupOptions identical to build to worker in vite.config.ts, I end up with slightly different separate bundles, because of course it uses slightly different parts of the library.

I tried compiling it as a separate entrypoint, but then I can't actually load it as a worker, because either Vite produces some bogus URL in the output or makes a separate set of bundles anyway.

If I build my worker as a separate entry point, and then, directly in the bundled code, change new Worker(new URL.... to new Worker(new URL("where the entry point is", the resulting worker runs properly, and loads the same bundles the rest of the code does, while the worker-centric bundles Vite built remain inert. I.e. if I could potentially get Vite to stuff the URL of the entry point (together with the hash) into new Worker my problem would be solved, but I can't seem to figure out how to do that either.

I'm pretty sure this is supposed to be possible (https://bundlers.tooling.report/code-splitting/between-workers/) but it's entirely unclear to me how to get Vite to actually do that.