Error when creating whl with std::thread code

[paulgheorghecristian]

Helo,

When I try creating threads in CPP, creating a wheel and importing in pyodide 0.21.0, I get this:

index.js:1 CppException std::__2::system_error: thread constructor failed: Resource temporarily unavailable

This is the program:

void run_threads() {
	std::thread t([&](){
		for (int i = 0; i < 10; i++) {
			std::cout << "i:" << i << std::endl;
		}
	});
	std::thread t2([&](){
		for (int j = 10; j < 20; j++) {
			std::cout << "j:" << j << std::endl;
		}		
	});

	t.join();
	t2.join();
}

PYBIND11_MODULE(example, m){
  m.def("run_threads", &run_threads, "Run threads");
}

I know there are some issues with running multithreaded code, is there any way I can make this work?

Thanks!

[ymd-h]

Hi, @paulgheorghecristian

In exodide, -pthread option is explicitly disabled.
As far as I remember, the option produced compile error (at least at that time).

https://github.com/ymd-h/exodide/blob/master/design.md#build-details

exodide/exodide/build.py

Lines 127 to 141 in b523224

	def exodide_unsupported_links() -> List[str]:
	"""
	Get exodide unsupported link args
	Returns
	-------
	list of str
	Unsupported link arguments for exodide
	"""
	return ["-shared", "-pthread",
	"-Wl,-Bsymbolic-functions",
	"-Wl,--strip-all",
	"-Wl,-strip-all",
	"-Wl,--sort-common",
	"-Wl,--as-needed"]

With my quick search, Pyodide hasn't supported thread yet, and I have no idea whether we could support thread separately.
pyodide/pyodide#237