2016-10-26 00:13
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I am building a test crawler and wanted to know if Go (golang) caches DNS queries. I don't see anything about caching in the dnsclient. This seems like an important thing to add to any crawler to prevent lots of extra DNS queries.

Does Go (1.4+) cache DNS lookups?

If not, does debian/ubuntu/linux, windows, or darwin/OSX do any caching at the network level Go benefits from?

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我正在构建测试搜寻器,想知道Go(golang)是否缓存DNS查询。 我没有在 dnsclient 中看到有关缓存的任何信息。 添加到任何搜寻器以防止大量额外的DNS查询似乎很重要。


如果没有,debian / ubuntu / linux,windows是否可以使用? ,或darwin / OSX可以在网络级别进行任何缓存吗?Go可以从中受益吗?

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2条回答 默认 最新

  • dongqun5769 2016-10-26 01:52

    The answer to your question is no. There is no built-in dns caching in the std lib resolver. Would it be helpful? Maybe in some cases. Our org runs a local dns cache on each server and points resolv.conf there. So it wouldn't necessarily help us much to have caching in the language.

    There are some solutions that could help you. This package seems to have a pretty good solution. From the snippet in their readme you could even do:

    http.DefaultClient.Transport = &http.Transport {
      MaxIdleConnsPerHost: 64,
      Dial: func(network string, address string) (net.Conn, error) {
        separator := strings.LastIndex(address, ":")
        ip, _ := dnscache.FetchString(address[:separator])
        return net.Dial("tcp", ip + address[separator:])

    To enable it for all http requests from http.Get and friends.

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  • drcx71276 2016-11-16 00:24

    The Go resolver does not do any in-process caching. While it would be possible to roll your own, your best bet is probably to run a system-wide DNS cache on each machine. (My favourite being dnsmasq.)

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