Simple queue model example

Question

Is there a simple program which demonstrates how queues work in Go. I just need something like add number 1 to 10 in queue and pull those from the queue in parallel using another thread.

Answer 1

A queue that is safe for concurrent use is basically a language construct: channel.

A channel–by design–is safe for concurrent send and receive. This is detaild here: If I am using channels properly should I need to use mutexes? Values sent on it are received in the order they were sent.

You can read more about channels here: What are golang channels used for?

A very simple example:

c := make(chan int, 10) // buffer for 10 elements

// Producer: send elements in a new goroutine
go func() {
    for i := 0; i < 10; i++ {
        c <- i
    }
    close(c)
}()

// Consumer: receive all elements sent on it before it was closed:
for v := range c {
    fmt.Println("Received:", v)
}

Output (try it on the Go Playground):

Received: 0
Received: 1
Received: 2
Received: 3
Received: 4
Received: 5
Received: 6
Received: 7
Received: 8
Received: 9

Note that the channel buffer (10 in this example) has nothing to do with the number of elements you want to send "through" it. The buffer tells how many elements the channel may "store", or in other words, how many elements you may send on it without blocking when there are nobody is receiving from it. When the channel's buffer is full, further sends will block until someone starts receiving values from it.