Somehow the server always spawn at least 2 threads.

[elichai]

If I don't mention the amount of threads or if I put .threads(1) I still see that there are 2 different threads operating.
Example code:

use jsonrpc_http_server::jsonrpc_core::*;
use jsonrpc_http_server::*;
use std::thread::{self, current, JoinHandle};

use jsonrpc_client_http::HttpTransport;
use jsonrpc_client_core::{jsonrpc_client, expand_params};


fn main() {
    let server = launch_server();
    thread::sleep(std::time::Duration::from_secs(5));

    let handles = send_requests(10);
    let results: Vec<_> = handles.into_iter().map(|h|h.join().unwrap()).collect();
    println!("{:?}", results);


}

fn launch_server() -> Server {
    let mut io = IoHandler::new();
    io.add_method("say_hello", |_: Params| {
        println!("I'm in thread ID: {:?}, name: {:?}", current().id(), current().name());
        Ok(Value::String("hello".to_string()))
    });

    let server = ServerBuilder::new(io)
        .threads(1)
        .start_http(&"127.0.0.1:3030".parse().unwrap())
        .unwrap();
    server
}



jsonrpc_client!(pub struct KeyManagementClient {
    pub fn say_hello(&mut self) -> RpcRequest<Value>;
});

fn send_requests(n: usize) -> Vec<JoinHandle<Value>> {
    let mut handles = Vec::with_capacity(n);
    for _ in 0..n {
        let handle = thread::spawn( || {
            let transport = HttpTransport::new().standalone().unwrap();
            let transport_handle = transport.handle("http://127.0.0.1:3030").unwrap();
            let mut client = KeyManagementClient::new(transport_handle);
            client.say_hello().call().unwrap()
        });
        handles.push(handle);
    }
    handles
}

Output:

I'm in thread ID: ThreadId(2), name: Some("jsonrpc-eventloop-0")
I'm in thread ID: ThreadId(3), name: Some("jsonrpc-eventloop-1")
I'm in thread ID: ThreadId(2), name: Some("jsonrpc-eventloop-0")
I'm in thread ID: ThreadId(3), name: Some("jsonrpc-eventloop-1")
I'm in thread ID: ThreadId(3), name: Some("jsonrpc-eventloop-1")
I'm in thread ID: ThreadId(2), name: Some("jsonrpc-eventloop-0")
I'm in thread ID: ThreadId(3), name: Some("jsonrpc-eventloop-1")
I'm in thread ID: ThreadId(2), name: Some("jsonrpc-eventloop-0")
I'm in thread ID: ThreadId(3), name: Some("jsonrpc-eventloop-1")
I'm in thread ID: ThreadId(2), name: Some("jsonrpc-eventloop-0")
[String("hello"), String("hello"), String("hello"), String("hello"), String("hello"), String("hello"), String("hello"), String("hello"), String("hello"), String("hello")]

As You can see there's threadID 2 and 3, (jsonrpc-eventloop-0 and jsonrpc-eventloop-1) both operate within the code of the server.

cc #423 @tomusdrw

[elichai]

@tomusdrw ?

[tomusdrw]

Indeed, seems that during switch to tokio configuring .threads is basically useless or at least doesnt' work correctly.

• serve function that in the original design was supposed to be running an event loop and block the thread is currently just spawning a task to executor.
• Executor is configured to run in number of threads that depend on number of cores and for your system it seems to be 2.
• And we also start a completely useless thread that just waits for the tokio::runtime to finish when we spawn the Reactor.
  

  jsonrpc/server-utils/src/reactor.rs

  Line 127 in 584327b

  runtime.shutdown_on_idle().wait().unwrap();

I'll try to look into it and clean it up a bit.