Go channel Learning

I spent several hours to figure out some conceptions about channel tonight

 

1. buffered channel and non-buffered Channel

Buffered Channel

bufferedchan := make(chan int, 1)

When adding element into bufferedchan, it will not blocked if it is not full.

For example:

package mainimport "fmt"func main() {    messages := make(chan string, 1)    messages <- "buffered"    fmt.Println("quit!")}

The program won't block and the answer is:

Quit!

 

2. Channel is thread safe,

package mainimport "fmt"func main() {    jobs := make(chan int, 5)    done := make(chan bool)    go func() {                           ------------------------------- (Part I)        fmt.Println("enter go routinue")        for {            j, more := <-jobs            if more {                fmt.Println("received job", j)            } else {                fmt.Println("received all jobs")                done <- true                return            }        }    }()    jobs <- 1                             ------------------------------- (part II)    jobs <- 2    jobs <- 3    close(jobs)    fmt.Println("sent all jobs and closed")
    <-done                                ------------------------------- (Part III)}

The result is:

Sent all jobs and closed
Enter go routinue
Received job 1
Received job 2
Received job 3
Received all jobs

 

Firstly, it executes (Part II) and stop at <-done.

And then a child routinue executes (part I) and done <-true.

Now the channel done is actived and continue to execute.

 

* If the channel jobs is not closed in main, the statement "J, more: = <-jobs" in (Part I) will block. The deadlock will happen.

* If we don't set "<-done" in main, main will not wait the child routinue to finish.

 

Go channel Learning