Deadlock -> kondisi dimana go routine saling tunggu -> alhasil tidak ada go routine yang berjalan.
Contoh Kasus #1
Jika channel in (pengirim) di inisisasi terlebih dahulu dan channel out (penerima) di inisiasi setelah channel in -> deadlock -> karena belum ada penerimanya.
Channel in dan channel out harus berjalan bersama -> caranya salah satu di inisiasi terlebih dahulu dan yang pertama di inisiasi dimasukkan ke dalam go routine.
Program #1
package main
import "fmt"
func main() {
ch := make(chan int)
// channel in (pengirim)
ch <- 1
// channel out (penerima)
go func() {
result := <- ch
fmt.Println(result)
}()
}
fatal error: all goroutines are asleep - deadlock!
goroutine 1 [chan send]:
main.main()
/tmp/uv1yQwKDgN.go:7 +0x37
exit status 2
package main
import "fmt"
func main() {
ch := make(chan int)
// channel out (penerima)
go func() {
result := <- ch
fmt.Println(result)
}()
// channel in (pengirim)
ch <- 1
}
1
package main
import "fmt"
func main() {
ch := make(chan int)
// channel in (pengirim)
go func() {
ch <- 1
}()
// channel out (penerima)
result := <- ch
fmt.Println(result)
}
1
Program #2
package main
import "fmt"
func f(value chan int) {
result := 100 + <- value
fmt.Printf("%d ", result)
}
func main() {
fmt.Println("Start")
value := make(chan int)
for i := 0; i < 10; i++ {
// channel in (pengirim)
value <- i
// channel out (penerima)
go f(value)
}
fmt.Println("\nEnd")
close(value)
}
Start
fatal error: all goroutines are asleep - deadlock!
goroutine 1 [chan send]:
main.main()
D:/go-server/main.go:15 +0x9e
exit status 2
package main
import "fmt"
func f(value chan int) {
result := 100 + <- value
fmt.Printf("%d ", result)
}
func main() {
fmt.Println("Start")
value := make(chan int)
for i := 0; i < 10; i++ {
//channel out (penerima)
go f(value)
// channel in (pengirim)
value <- i
}
fmt.Println("\nEnd")
close(value)
}
Start
100 101 102 103 104 105 106 107 108 109
End
package main
import "fmt"
func f(value chan int) {
result := 100 + <- value
fmt.Printf("%d ", result)
}
func main() {
fmt.Println("Start")
value := make(chan int)
for i := 0; i < 10; i++ {
// channel in (pengirim)
go func() {
value <- i
}()
//channel out (penerima)
f(value)
}
fmt.Println("\nEnd")
close(value)
}
Start
100 101 102 103 104 105 106 107 108 109
End
Program #3 deadlock jika channel tidak di close
package main
import (
"fmt"
)
func main() {
ch := make(chan int)
go func() {
for i := 0; i < 5; i++ {
// channel in
ch <- i
}
// channel must be close
// if not will be deadlock
close(ch)
}()
// channel out
for v := range ch {
fmt.Println(v)
}
}
