如何有效地将渠道链接在一起？

Question

I'm trying to create message hub in golang. Messages are getting through different channels that persist in map[uint32]chan []float64. I do an endless loop over map and check if a channel has a message. If it has, I write it to the common client's write channel together with an incoming channel's id. It works fine, but uses all CPU, and other processes are throttled.

UPD: Items in map adding and removing dynamically by another function.

I thinking to limit CPU for this app through Docker, but maybe there is more elegant path?

My code :

    func (c *Client) accumHandler() {

    for !c.stop {
        c.channels.Range(func(key, value interface{}) bool {

            select {
            case message := <-value.(chan []float64):
                mess := map[uint32]interface{}{key.(uint32): message}

                select {
                case c.send <- mess:

                }

            default:

            }
            return !c.stop
        })
    }
}

Answer 1

If I'm reading the cards correctly, it seems like you are trying to pass along an array of floats to a common channel along with a channel identifier. I assume that you are doing this to pass multiple channels out to different publishers, but so that you only have to track a single channel for your consumer.

It turns out that you don't need to loop over channels to see when it's outputting a value. You can chain channels together inside of goroutines. For this reason, no busy wait is necessary. Something like this will suit your purposes (again, if I'm reading the cards correctly). Look for the all caps comment for the way around your busy loop. Link to playground.

var num_publishes = 3

func main() {
  num_publishers := 10
  single_consumer := make(chan []float64)

  for i:=0;i<num_publishers;i+=1 {
    c := make(chan []float64)

    // connect channel to your single consumer channel
    go func() { for { single_consumer <- <-c } }() // THIS IS PROBABLY WHAT YOU DIDN'T KNOW ABOUT

    // send the channel to the publisher
    go publisher(c, i*100)
  }

  // dumb consumer example
  for i:=0;i<num_publishers*num_publishes;i+=1 {
    fmt.Println(<-single_consumer)
  }
}

func publisher(c chan []float64, publisher_id int) {
  dummy := []float64{
    float64(publisher_id+1),
    float64(publisher_id+2),
    float64(publisher_id+3),
  }
  for i:=0;i<num_publishes;i+=1 {
    time.Sleep(time.Duration(rand.Intn(10000)) * time.Millisecond)
    c <- dummy
  }
}