我是Go的新手，正在尝试实现一个网络爬虫。它应该异步解析网页并将其内容保存到文件中，每个新页面保存为一个文件。但是在我添加了以下代码后，它卡住了：
    u, _ := url.Parse(uri)
    fileName := u.Host + u.RawQuery + ".html"
    body, err := ioutil.ReadAll(resp.Body)
    writes <- writer{fileName: fileName, body: body}
有人可以帮我解决这个问题吗？基本上，我想从响应体中获取数据，将其推送到通道中，然后从通道中获取数据并将其放入文件中。
看起来`writes`通道没有被初始化，向一个空通道发送数据会导致永远阻塞。
package main
import (
	"crypto/tls"
	"flag"
	"fmt"
	"io/ioutil"
	"net/http"
	"net/url"
	"os"
	"runtime"
	"./linksCollector"
)
type writer struct {
	fileName string
	body     []byte
}
var writes = make(chan writer)
func usage() {
	fmt.Fprintf(os.Stderr, "usage: crawl http://example.com/")
	flag.PrintDefaults()
	os.Exit(2)
}
func check(e error) {
	if e != nil {
		panic(e)
	}
}
func main() {
	runtime.GOMAXPROCS(8)
	flag.Usage = usage
	flag.Parse()
	args := flag.Args()
	fmt.Println(args)
	if len(args) < 1 {
		usage()
		fmt.Println("Please specify start page")
		os.Exit(1)
	}
	queue := make(chan string)
	filteredQueue := make(chan string)
	go func() { queue <- args[0] }()
	go filterQueue(queue, filteredQueue)
	for uri := range filteredQueue {
		go enqueue(uri, queue)
	}
	for {
		select {
		case data := <-writes:
			f, err := os.Create(data.fileName)
			check(err)
			defer f.Close()
			_, err = f.Write(data.body)
			check(err)
		}
	}
}
func filterQueue(in chan string, out chan string) {
	var seen = make(map[string]bool)
	for val := range in {
		if !seen[val] {
			seen[val] = true
			out <- val
		}
	}
}
func enqueue(uri string, queue chan string) {
	fmt.Println("fetching", uri)
	transport := &http.Transport{
		TLSClientConfig: &tls.Config{
			InsecureSkipVerify: true,
		},
	}
	client := http.Client{Transport: transport}
	resp, err := client.Get(uri)
	check(err)
	defer resp.Body.Close()
	u, _ := url.Parse(uri)
	fileName := u.Host + u.RawQuery + ".html";
	body, err := ioutil.ReadAll(resp.Body)
	writes <- writer{fileName: fileName, body: body}
	links := collectlinks.All(resp.Body)
	for _, link := range links {
		absolute := fixURL(link, uri)
		if uri != "" {
			go func() { queue <- absolute }()
		}
	}
}
func fixURL(href, base string) string {
	uri, err := url.Parse(href)
	if err != nil {
		return ""
	}
	baseURL, err := url.Parse(base)
	if err != nil {
		return ""
	}
	uri = baseURL.ResolveReference(uri)
	return uri.String()
}

for uri := range filteredQueue {
go enqueue(uri, queue)
}

go func() {
for uri := range filteredQueue {
go enqueue(uri, queue)
}
}()