Select statement

Context

The select statement lets a goroutine wait on multiple channel operations. It blocks until one of its cases can proceed. If multiple are ready, one is chosen at random.

Example

Wait on two channels and print whichever receives first.

Code example

package main

import (
    "fmt"
    "time"
)

func main() {
    ch1 := make(chan string)
    ch2 := make(chan string)

    go func() {
        time.Sleep(1 * time.Second)
        ch1 <- "one"
    }()
    go func() {
        time.Sleep(2 * time.Second)
        ch2 <- "two"
    }()

    for i := 0; i < 2; i++ {
        select {
        case msg1 := <-ch1:
            fmt.Println("Received", msg1)
        case msg2 := <-ch2:
            fmt.Println("Received", msg2)
        }
    }
}

Output

Received one
Received two

Useful links

• Go spec: Select statements
• Go by Example: Select