Unable to find a reason as to why this code deadlocks. The aim here is make the worker go routines do some work only after they are signaled.
If the signalStream channel is removed from the code, it works fine. But when this is introduced, it deadlocks. Not sure the reason for this. Also if there are any tools to explain the occurrence of deadlock, it would help.
package main
import (
"log"
"sync"
)
const jobs = 10
const workers = 5
var wg sync.WaitGroup
func main() {
// create channel
dataStream := make(chan interface{})
signalStream := make(chan interface{})
// Generate workers
for i := 1; i <= workers; i++ {
wg.Add(1)
go worker(dataStream, signalStream, i*100)
}
// Generate jobs
for i := 1; i <= jobs; i++ {
dataStream <- i
}
close(dataStream)
// start consuming data
close(signalStream)
wg.Wait()
}
func worker(c <-chan interface{}, s <-chan interface{}, id int) {
defer wg.Done()
<-s
for i := range c {
log.Printf("routine - %d - %d \n", id, i)
}
}
Generate the jobs in a separate gorouine, i.e. put the whole jobs loop into a goroutine. If you don't then dataStream <- i will block and your program will never "start consuming data"
// Generate jobs
go func() {
for i := 1; i <= jobs; i++ {
dataStream <- i
}
close(dataStream)
}()