Here is my golang program which I am playing with just to get my concepts right.
When I run the program it is deadlocked I don’t understand why ?
Please anyone point out what is going wrong ?
package main
import (
"fmt"
"sync"
)
var wg sync.WaitGroup
func main() {
numOfGoRoutines := 10
wg.Add(numOfGoRoutines)
ch := make(chan int, numOfGoRoutines)
for i := 0; i < numOfGoRoutines; i++ {
a := i
go sqr(ch, a, wg)
}
wg.Wait()
fmt.Println("After WAIT")
close(ch)
var res int
for i := range ch {
res += i
}
ch = nil
fmt.Println("result = ", res)
}
func sqr(ch chan int, val int, wg sync.WaitGroup) {
fmt.Println("go - ", val)
s := val * val
ch <- s
wg.Done()
}
and the output is:
warning: GOPATH set to GOROOT (C:\\Go) has no effect
go - 9
go - 0
go - 1
go - 2
go - 3
go - 4
go - 5
go - 6
go - 7
go - 8
fatal error: all goroutines are asleep - deadlock!
goroutine 1 [semacquire]:
sync.runtime_Semacquire(0x5bcabc)
C:/Go/src/runtime/sema.go:47 +0x2d
sync.(*WaitGroup).Wait(0x5bcab0)
C:/Go/src/sync/waitgroup.go:127 +0xbb
main.main()
C:/demo/go-work/main.go:20 +0xdf
exit status 2