Why do errors appear after the “death” of a worker?

Question

go

Googling, I realized that in go all my problems will be solved by the worker. That's what I'm on shitcode

package main

import "fmt"
import "sync"

import "time"

var wg sync.WaitGroup

func worker(id int, jobs <-chan int, results chan<- int) {
  defer func() { wg.Done() }()
  for j := range jobs {
    fmt.Println("worker", id, "processing job", j)
    time.Sleep(time.Second)
    results <- j
  }
}

func main() {
  jobs := make(chan int, 100)
  results := make(chan int, 100)

  for w := 1; w <= 10; w++ {
    wg.Add(1)
    go worker(w, jobs, results)
  }

  for j := 1; j <= 90; j++ {
    jobs <- j
  }

  for msg := range results {
    fmt.Println("worker", msg)
  }

  wg.Wait()
  close(jobs)
  close(results)
  fmt.Println("main finished")

}

Errors after code completes

fatal error: all goroutines are asleep - deadlock!

goroutine 1 [chan receive]:
main.main()
        C:/Documents and Settings/lucifer/Рабочий ст
 +0x12d

goroutine 5 [chan receive]:
main.worker(0x1, 0x10744000, 0x107441e0)
        C:/Documents and Settings/lucifer/Рабочий ст
 +0x66
created by main.main
        C:/Documents and Settings/lucifer/Рабочий ст
 +0xc3

Answer 1

After for j do close(jobs), then for range cancel will end after removing the last element from the channel

Answer 2

Working example at play.golang.org

package main

import (
  "fmt"
  "sync"
  "time"
)

var wg sync.WaitGroup

func worker(id int, jobs <-chan int, results chan<- int) {
  defer wg.Done()
  
  for j := range jobs {
    fmt.Println("worker", id, "processing job", j)
    time.Sleep(time.Second)
    results <- j
  }
}

func main() {
  jobs := make(chan int, 100)
  results := make(chan int, 100)

  for w := 1; w <= 5; w++ {
    wg.Add(1)
    go worker(w, jobs, results)
  }

  for j := 1; j <= 10; j++ {
    jobs <- j
  }

  close(jobs)
  wg.Wait()
  close(results)

  for msg := range results {
    fmt.Println("worker", msg)
  }

  fmt.Println("main finished")
}