Go by Example: Select
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Go’s select lets you wait on multiple channel operations. Combining goroutines and channels with select is a powerful feature of Go. |
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package main
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import "time"
import "fmt"
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func main() {
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For our example we’ll select across two channels. |
c1 := make(chan string)
c2 := make(chan string)
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Each channel will receive a value after some amount of time, to simulate e.g. blocking RPC operations executing in concurrent goroutines. |
go func() {
time.Sleep(time.Second * 1)
c1 <- "one"
}()
go func() {
time.Sleep(time.Second * 2)
c2 <- "two"
}()
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We’ll use |
for i := 0; i < 2; i++ {
select {
case msg1 := <-c1:
fmt.Println("received", msg1)
case msg2 := <-c2:
fmt.Println("received", msg2)
}
}
}
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We receive the values |
$ time go run select.go
received one
received two
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Note that the total execution time is only ~2 seconds
since both the 1 and 2 second |
real 0m2.245s
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Previous example: Channel Directions.
Next example: Timeouts.