Calling into a component that includes the println macro hangs

[DamianReeves]

Calling into the component built here, results in a hang as long as a println! is included.

As seen here:
https://github.com/DamianReeves/wasm-components-ftw/blob/5a85c47fdc62288cb46952484f760231073c5152/crates/morphir-platform/src/lib.rs#L11-L15

If I remove the println things work fine.

Not sure if its relevant, but if I transpile with tracing, I notice when I insert a println! call, my code seems to hang on the following wasi call is traces:

[module="wasi:cli/[email protected]", function="get-stdin"] call

[guybedford]

Thanks for posting. Unfortunately I was unable to build this test case on arm64. Can you just share the direct component binary that is causing the issue?

[DamianReeves]

Sure thing: Here you go!

dist.zip

[guybedford]

It seems you've built the full preview2-shim library into a single file on Node.js. Unfortunately I think this might be breaking some invariants of the syncification that spawns a worker here:

var _rawDebug = nodeProcess._rawDebug || console.error.bind(console);
var workerPath = fileURLToPath(new URL("./worker-thread.js", import.meta.url));
var httpIncomingHandlers = new Map;
var instanceId = Math.round(Math.random() * 1000).toString();
var DEBUG_DEFAULT = false;
var DEBUG = env.PREVIEW2_SHIM_DEBUG === "0" ? false : env.PREVIEW2_SHIM_DEBUG === "1" ? true : DEBUG_DEFAULT;
var ioCall = createSyncFn(workerPath, DEBUG, (type, id, payload) => {

[DamianReeves]

It seems you've built the full preview2-shim library into a single file on Node.js. Unfortunately I think this might be breaking some invariants of the syncification that spawns a worker here:

So does this mean I need to change my bundling code not to bundle the preview-shim?

[guybedford]

Yes exactly, or at least not bundle in the worker invocation as that must be a separate file.