Component causes panic in 0.14.0 but not in 0.13.0

[kevboh]

Hello. I'm evaluating wasmex for a corporate project that involves running javascript compiled into wasm via Javy. I found that a very similar test component (one taken from the Javy documentation) causes a panic in 0.14.0 but runs fine in 0.13.0. The panic is:

thread 'wasmex-async' (108257044) panicked at /Users/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wasmtime-wasi-39.0.1/src/runtime.rs:108:15:
                   Cannot start a runtime from within a runtime. This happens because a function (like `block_on`) attempted to block the current thread while the thread is being used to drive asynchronous tasks.

I can't attach the .wasm file, but here are steps to repro, with code:

1. Save index.js as

export function foo() {
  console.log("Hello from foo!");
}

console.log("Hello world!");

and index.wit as

package local:main;

world index-world {
  export foo: func();
}

2. javy build index.js -C wit=index.wit -C wit-world=index-world -o index.wasm
3. wasm-tools component embed index.wit index.wasm --world index-world -o index.embedded.wasm
4. wasm-tools component new index.embedded.wasm --adapt wasi_snapshot_preview1.reactor.wasm -o index.component.wasm with the version-appropriate reactor.wasm from wasmtime

Then run the following:

Mix.install([{:wasmex, "0.14.0"}])
bytes = File.read!("index.component.wasm")
{:ok, pid} = Wasmex.Components.start_link(%{bytes: bytes, wasi: %Wasmex.Wasi.WasiP2Options{}})
{:ok, result} = Wasmex.Components.call_function(pid, "foo", [])

In 0.13.0 this will correctly log and return. In 0.14.0 it panics.

[tessi]

hey @kevboh , thanks for the bug report! this is interesting indeed. I'll have a look 💜

[tessi]

Hey, I got the core of the issue figured out (we're handling some asynchronous edge cases bad in 0.14.0 and need to fully use wasmtime's async API even for non-async cases). I got your specific case working now, but need to do the same refactor to the non-component API as well. It will take me some more days :)

[kevboh]

@tessi thanks for tracking it down! No rush.

[thomas9911]

also encountered this issue. For now pinning the version to 0.13.0