Web3 blocks with low count of tokio threads

[bkolad]

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Web3 runs fine with the following tokio settings: #[tokio::main] but it blocks indefinitely with #[tokio::main(max_threads = 4)] or #[tokio::main(core_threads = 40, max_threads = 40)]

[tomusdrw]

@bkolad any particular transport?

[bkolad]

@tomusdrw it is web3::transports::Http

[tomusdrw]

Would you mind testing with Ws as well? I checked the code but there is nothing fancy we do that would cause such behaviour and I feel tempted to blame hyper.

[bkolad]

I confirm it works with Ws, thx.

[Fedalto]

I'm getting this same error with both http and ws transports. The code blocks indefinitely when trying to get the current block number.

Here's a small code that reproduces this error:

use tokio;

// #[tokio::main] // works
#[tokio::main(max_threads=4)]  // fails
async fn main() {
    let transport = web3::transports::Http::new("http://localhost:8545").unwrap();
    // let transport = web3::transports::WebSocket::new("ws://localhost:8546")
    //     .await
    //     .unwrap();
    let chain = web3::Web3::new(transport);

    let block_number = chain.eth().block_number().await.unwrap();
    println!("{}", block_number);
}

Tested on web3 0.14 and 0.15 and tokio 0.2.25.