Does Tokio have a limit on the number of tasks

[xiashaohua]

The code is:

    let topics = [TOPIC1,TOPIC2,TOPIC3];
    for &topic in topics.iter() {
        let message_sender_tmp = message_sender.clone();
        let  sessions_tmp = Arc::clone(&sessions);
        tokio::spawn(async move {
            sub_common_topic(sessions_tmp, message_sender_tmp, topic.to_string()).await;
        });
    }

    loop {
        tokio::select! {
            Some(res) = message_receiver.recv() => {
                let nc = nc.clone();
                println!("recv {:?}",res);
                tokio::spawn(async move{
                    println!("into task");
                    
                    let response = create_message_by_struct(res);
                    println!("step 1");
                    let topic = TOPIC_RESPONSE;
                    println!("step 2");
                    pub_to_topic_async(&nc, &topic, response.clone()).await;
                    info!("send message to topic: {},message is {:?}",topic.clone(),response);
                });
            }
            else => {
                continue
            }
        }
    }

when I add TOPIC4 to topics, the task in loop not run at all。If i add TOPIC4 and remove another topic. It will work fine, I dont know why is it or is there something wrong with my usage.

[Darksonn]

No, there is no maximum number of tasks. If some of your tasks are not running, you should investigate if some of the other tasks are blocking the thread, as this can prevent tasks from running.

One thing I notice is that the continue in your else branch would lead to an infinite loop. You only hit the else branch when the channel is closed, so you should break from the loop in that case.

[xiashaohua]

I used the resident task to consume the topic,and use th sync api。The process should be blocked for this reason.The task works fine when I change to the asyn API

[xiashaohua]

thanks for your help