Concurrency · Example 34
Channel Buffering
fmtBy default channels are unbuffered, meaning that they will only accept sends if there is a corresponding receive ready to receive the sent value. Buffered channels accept a limited number of values without a corresponding receiver.
package main
import "fmt"
func main() {Here we make a channel of strings buffering up to 2 values.
messages := make(chan string, 2)Because this channel is buffered, we can send these values into the channel without a corresponding concurrent receive.
messages <- "buffered"
messages <- "channel"len and cap report how many values are waiting and how many fit.
fmt.Println("len", len(messages), "cap", cap(messages))Later we can receive these two values as usual.
fmt.Println(<-messages)
fmt.Println(<-messages)A third send without a receiver would block forever. With no other goroutine running, the runtime detects that and stops the program with "fatal error: all goroutines are asleep - deadlock!".
}$ go run ./34_channel_buffering len 2 cap 2 buffered channel