use tokio and actix-web together

[luxl]

I have a project which needs to have both a http server and a tcp server. So I choose actix-web and tokio(version 0.3.1).
But when I do the following in main.rs (start both tcp server and http server):

    tokio::spawn(async move {
        PetServer::new()
            .bind("0.0.0.0:8898").unwrap()
            .run().await.unwrap();
    });

    HttpServer::new(move || {
        App::new()
            .configure(pet_routes)
    }).bind("0.0.0.0:41310")?.run().await

It compiles, but it panic at runtime:

thread 'main' panicked at 'must be called from the context of Tokio runtime configured with either `basic_scheduler` or `threaded_scheduler`',

If I use the same tokio version as what actix-web depends(which is 0.2.x), it's ok.
So is this beacuse imcompatible between 0.2 and 0.3? Is there any other solutions if I want to use version 0.3 tokio while using actix-web(which is based on tokio 0.2.x)?

[Darksonn]

Tokio 0.2 and 0.3 are not directly compatible, but there is a compatibility layer available, which is described in the Compatibility between 0.2 and 0.3 section of the 0.3 announcement.

Assuming HttpServer requires Tokio 0.2, you can use it like this:

use tokio_compat_02::FutureExt;

start_server().compat().await;

async fn start_server() {
    HttpServer::new(move || {
        App::new()
            .configure(pet_routes)
    }).bind("0.0.0.0:41310")?.run().await
}

[sylvain101010]

Hi @Darksonn, Do you know if using the compatibility layer induces a performance cost, or if I should rather stay on tokio = "0.2"?

[davidbarsky]

If there is a cost, it's minimal at best. It's not something I'd worry about.

[Darksonn]

The compatibility has the cost of starting an 0.2 runtime alongside your 0.3 runtime. It's probably simpler to just use Tokio 0.2.