Add example for wasm_threads usage

[9SMTM6]

Would be an example for #680.

[ctron]

Thanks for the PR. That's awesome. I think we already have something for the headers on main. I'll try to document that. So we could add this too.

[ctron]

Using trunk from main or the most recent -alpha release, you can add:

[serve]
headers = { "X-Foo" = "bar" }

[9SMTM6]

@ctron If you've got something else let me know. I think this is about as well documented as it can be, I hope to avoid issues being created about this (if you look at wasm_thread issues then sadly many people did not read the documentation properly).

And thank you for the hint about the .cargo/config.toml file working for this at all, and being respected by trunk. IDK if I had found this otherwise.

[ctron]

Cool, thanks. One think that's missing, sorry for overlooking that before, is to add it to the list of CI example tests:

trunk/.github/workflows/ci.yaml

Lines 164 to 180 in f65cc10

	example:
	- cargo-manifest
	- cdylib
	- hooks
	- initializer
	- leptos
	- no-rust
	- proxy
	- seed
	- target-path
	- vanilla
	- webworker
	- webworker-gloo
	- webworker-module
	- yew
	- yew-tailwindcss
	- yew-tls

[9SMTM6]

right. that would've been to easy. The pipeline doesnt have nightly. My pipeline uses dtolnay/rust-toolchain@stable to get the toolchain, and that respects toolchain overrides. But here the CI is more complicated, doesn't look like that'd work. I'm uncertain if my example fits in there at all, with how you use trunk --config.

I won't be able to get to this until tomorrow evening at the soonest.

[ctron]

No worries, take your time. I think it's close!

[9SMTM6]

Hmm the failure wasnt because no nightly was present, but because it just used stable. In other words, it ignored the toolchain file. The --config flag is probably the reason. @ctron, I see 3 paths forward.

1. trunk --config is intended to act just as if trunk was invoked in said directory, which means that this would need fixing, since currently theres a difference whether I change to the example/wasm_threads directory and invoke trunk or call it with --config from root. In the first case it respects the tool override, in the other it does not.
2. if that is as intended, or will be fixed later, we could either make a specific job to test --config with intended situations or drop it, and then switch to the example directory in the CI and run trunk build in there directly.
3. I could make a separate CI for this example (or drop running it in CI, but considering its using nightly and all that it'd probably be a good idea to keep it).

In any case where we run this in the CI, we will probably have to further adjust the CI to download the correct toolchain (nightly with some additional components for this example, perhaps other modifications like additional modules for future examples). So far dtolnay/rust-toolchain has worked well for me, as I said, it automatically respected my toolchain override and downloaded the nightly together with the also specified rust-src component changed the toolchain file.

[ctron]

So having a rust-toolchain.toml should be sufficient. At least, that would be my expectation. cargo would automatically download the correct rust version.

So I think the problem is with 1.) … that it's not respecting the base directory of the config file.

[ctron]

Looks like that's more a cargo issue rust-lang/cargo#11036 (comment) … however, I think we need to fix it.

[9SMTM6]

At least, that would be my expectation. cargo would automatically download the correct rust version.

Yeah, you seem to be right, looking closer at the logs this seems to be what's happening.

Looks like that's more a cargo issue rust-lang/cargo#11036 (comment)

Okay, that would make sense if trunk invokes it like that.

So about that fix. Still, 3 ways.

1. Fix the issue upstream. Not a real solution. Assuming we do manage to solve this, it'd take a while to propagate here, and anyone with an outdated version of cargo still has the issue.
2. Always change the directory in the pipeline as a fix for this, while staying uncomplicated
3. Apply a specific fix for this example, with a link to the reason. I think the best way would be to make the example list in the ci file into a list of dicts with optional field 'cd' or similar, and depending on that we either use trunk - - config or cd path && trunk.

How often do you expect that --config is used? The example readme already has a bunch of qualifiers, so if it's not used often I'd leave a notice about this issus out of there. People should be able to figure out a fix (I explicitly mention nightly as required, and the compiler complains that we do something only allowed on nightly). Otherwise I can also add it I guess.

[ctron]

I think I've a PR for this: #844

[ctron]

I merged this PR. So maybe you can just rebase and we see if this does the trick.

[9SMTM6]

Nice, so we were able to solve this ourselves. It worked locally, so I think this should be it ;-P.

[ctron]

Thanks for finishing this up. That's a great example!

[Shapur1234]

Thanks for working on this!

I've just tried the new example and it works... mostly.
Most thread finish as the should, but a too much recursion error also appears. (Happens on both Librewolf and Chromium, using trunk 0.20.3

(The same too much recursion error also appear with my more complex app, but it could be a me issue)

Console:

INFO src/main.rs:15 
Available parallelism: Ok(2) [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:29 
hi number 1 from the main thread ThreadId(1)! [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:29 
hi number 2 from the main thread ThreadId(1)! [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:22 
hi number 1 from the spawned thread ThreadId(3)! [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:35 
Start scope test on thread ThreadId(2) [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:22 
hi number 1 from the spawned thread ThreadId(4)! [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
InternalError: too much recursion
2 [wasm_threads-d4756fe60b235b5f_bg.wasm:338386:1](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f_bg.wasm)
INFO src/main.rs:42 
hello from the first scoped thread ThreadId(5) [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:44 
a = [1, 2, 3] [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:50 
a[0..2] = [1, 2] [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:59 
Hello from scope "main" thread ThreadId(2) inside scope. [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:53 
hello from the second scoped thread ThreadId(6) [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)
INFO src/main.rs:68 
Scope done x = 4, a.len() = 4 [wasm_threads-d4756fe60b235b5f.js:408:17](http://127.0.0.1:8080/wasm_threads-d4756fe60b235b5f.js)

Any ideas what's going on?

[9SMTM6]

I've seen this too at times. It went away reliably in release mode though. And since I've used this in my App which always compiles dependencies with optimizations and it works fine.

I'm not entirely sure how it comes to be, but I don't think that's got anything to do with trunk.

[Shapur1234]

Yes, compiling in release mode fixes it, weird.
I don't remember seeing this this error when compiling wasm_thread using wasm-bindgen directly (But it has been some time).

[9SMTM6]

It going away with optimizations is probably coming from something like tail recursion optimization.

I'm mostly surprised where that amount of recursion is coming from. But I can't really see this being caused by trunk. It going away with optimizations on rust code means its gotta be in rust code - unless IÄm missing something -, and AFAIK trunk doesn't add a lot, or nothing, of that to the runtime of the website, and that optimization setting doesn't affect trunk either.

I'm also not entirely sure whats the result of that error either.

So if you add this to the Cargo.toml it also goes away:

[profile.dev.package."*"]
opt-level = 2

This will make clean rebuilds slower tho.

I did not test wasm_thread on its own, to be clear. I did never clone their repo.

[Shapur1234]

Yes, optimizing dependencies fixed it for me.
I might be worth noting this in the README.md of the example.

[9SMTM6]

I'll add it and improve grammar in a pr. I'll be terse, as I'm still not certain of whats really going on.