Race condition using WebSockets

[palkeo]

Hi,

I'm using ethers v0.2.1. When doing heavily parallel RPCs over a websocket connection, there seem to be multiple requests using the same JSONRPC request ID, which leads to messages like "Replacing a pending request with id xxx".

I originally tried to reproduce in a test, but I was never able to. However a program is able to reliably exhibit the problem:

use std::sync::Arc;
use std::error::Error;
use ethers::prelude::*;

async fn do_rpc(ws: Arc<Provider<Ws>>) {
    ws.get_chainid().await.unwrap();
}

#[tokio::main]
async fn main() {
    let p = Arc::new(Provider::<Ws>::connect("ws://NODE_URL_HERE").await.unwrap());

    for _ in 0..8192 {
        tokio::task::spawn(do_rpc(p.clone()));
    };
}

Beginning of the output when running it:

Replacing a pending request with id 43
Replacing a pending request with id 59
thread 'tokio-runtime-worker' panicked at 'called `Result::unwrap()` on an `Err` value: JsonRpcClientError(Canceled(Canceled))', main.rs:6:28
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread 'tokio-runtime-worker' panicked at 'called `Result::unwrap()` on an `Err` value: JsonRpcClientError(Canceled(Canceled))', main.rs:6:28
Replacing a pending request with id 152
Replacing a pending request with id 153
thread 'tokio-runtime-worker' panicked at 'called `Result::unwrap()` on an `Err` value: JsonRpcClientError(Canceled(Canceled))', main.rs:6:28
Replacing a pending request with id 369
Replacing a pending request with id 405
Replacing a pending request with id 538
Replacing a pending request with id 552