go 问题请教，想问下下面的代码为啥会导致死锁，导致的死锁如何解决

package main

import ("math/rand"; "time")

const R = 100 // number of readers const W = 10 // number of writers

var done chan bool

func db(reads chan chan int, writes chan int) { state := <- writes for { select { case reply := <-reads: reply <- state case state = <-writes: } } } func main() { reads, writes, done := make(chan chan int), make(chan int), make(chan bool) go db(reads, writes) for r := 0; r < R; r++ { // create R readers go func() { reply := make(chan int) for i := 0; i < 20; i++ { reads <- reply // stops in one out of 10 cases if rand.Intn(10) == 0 {select{}} else {<- reply} time.Sleep(time.Millisecond) } }() } for w := 0; w < W; w++ { // create W writers go func() { for i := 0; i < 20; i++ { writes <- rand.Int() % 100 time.Sleep(time.Millisecond) } done <- true }() } for k := 0; k < W; k++ {<- done} // wait for writers to terminate }