How to avoid extra calls to main when creating web worker from binary?

[kettle11]

Summary

For context: I've been experimenting with creating a library that spawns web workers that share memory with each other and the main thread.

I've been basing my experiments off of the Raytrace Parallel example: https://github.com/rustwasm/wasm-bindgen/tree/master/examples/raytrace-parallel

An issue I've run into is that __wbindgen_start is called whenever init is called. So the binary's main is invoked extra times whenever the library tries to spawn a worker and call init for it.

Is there some way to disable the automatic call to __wbindgen_start so that it can be invoked only for the main thread? Or should a special init be introduced for web workers?

Additional Details

Work arounds:

• Require the binary using the library to insert some sort of check into main to detect that they're on a worker thread.
• Compile the binary as a lib and manually invoke start

[alexcrichton]

Currently this can't be done, you'll need to orchestrate something without the start function. The way multithreading works is to create an instance on each thread, which inherently runs the start function.

[daxpedda]

@alexcrichton would it be acceptable to add a function like initWithoutStart? Basically a copy of init but without the call to __wbindgen_start() at the end. Or is there some other reason/limitation why this isn't possible?