Serialisation cost of Python functions

[Andarius]

Hi !

I'm trying to find some side-project to use both python and rust. Sorry in advance if the question does not fit here.
Maybe it's a bit advanced but I would like to have your opinion on this: would it add too much overhead to call Python code using PyO3 within a Rust function matching for instance an actix endpoint ?

I found this thread regarding the performance overhead (compared to CPython) #1607 but I'm not sure if this would really be a big issue here.

use actix_web::{web, App, HttpRequest, HttpServer, Responder};

async fn greet(req: HttpRequest) -> impl Responder {
   // Call python function with GET arguments...
   // for instance fetch data from Postgresql and return it
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    HttpServer::new(|| {
        App::new()
            .route("/", web::get().to(greet))
            .route("/{name}", web::get().to(greet))
    })
    .bind(("127.0.0.1", 8080))?
    .run()
    .await
}

My idea would be to write the higher level code in a FastAPI fashion that would then create the app with the routes. But I'm not sure about the performance of executing the Python logic for the endpoint.

Thanks !

[davidhewitt]

Hey! Welcome, and pleased to hear you're interested in trying out PyO3 for a new project.

Maybe it's a bit advanced but I would like to have your opinion on this: would it add too much overhead to call Python code using PyO3 within a Rust function matching for instance an actix endpoint ?

To be honest, I think doing this is a really interesting concept that I'd wondered about playing with myself in the past (never found the time). How about looking at it the other way around: pure-Python webservers (maybe with a sprinkle of C at the core) are very common in industry and have sufficient performance for many applications. Writing the framework in Rust and then letting users write the endpoints in Python seems like a very interesting concept.

You might also be interested in https://github.com/litmus-web/litmus and https://github.com/litmus-web/Pyre-Writeup

[Andarius]

Hi! Thank you for your answer! Glad to know that the idea is not too far fetched :). I'll have a look at the links!