dovhpmnm31216 2017-12-08 12:18
浏览 2595
已采纳

为什么用CGO_ENABLED = 0编译慢?

When writing programs which utilize network, you can see quite noticeable slowdown of compilation with CGO_ENABLED=0.

For example, the simplest HTTP server:

package main

import (
    "flag"
    "fmt"
    "log"
    "net/http"
)

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hi! glad you requested %s.
", r.URL.Path[1:])
}

func main() {
    port := flag.Int("port", 9000, "")
    flag.Parse()

    http.HandleFunc("/", handler)
    err := http.ListenAndServe(fmt.Sprintf(":%d", *port), nil)
    if err != nil {
        log.Fatal(err)
    }
}

the timings are:

% time go build
go build  0.46s user 0.06s system 131% cpu 0.396 total
% time CGO_ENABLED=0 go build
CGO_ENABLED=0 go build  3.93s user 0.15s system 143% cpu 2.849 total

So far I'm not using bindings to C so CGo handling or not seems irrelevant, what I'd like to do is to compile 100% static binary, but not if there's such slowdown.

What is the cause of such behavior?

  • 写回答

2条回答 默认 最新

  • dongzhang8680 2017-12-08 14:06
    关注

    The problem is that the standard library packages are built without flags. CGO_ENABLED changes build flags and therefore it can't use the pre-built packages so most of the standard library needs to be rebuilt.

    As the other answer mentioned, go build -i will install the packages built with the new flags, but that won't really solve much because if you install packages built with CGO_ENABLED=0, it will speed up all future builds with CGO_ENABLED=0, but it will slow down all the builds without it.

    Unfortunately the way pre-built packages are installed by default today is pretty inefficient because everything goes into the same directory under the same names regardless of how it's built. If you want to be able to have fast builds of go programs with different flags, besides doing go build -i you also need to use the the -installsuffix and/or the -pkgdir flags. In the system I work in, we have a handful of different compilation modes, each mode has different flags (because of a lot of old C code we interface with) and each mode also has its own -pkgdir.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论
查看更多回答(1条)

报告相同问题?

悬赏问题

  • ¥15 在误装Windows server2019 后如何利用Windows.old恢复?
  • ¥20 代码实现状态连接包过滤防火墙的设计与实现
  • ¥15 vscode的红色箭头爆红和has no default export报错
  • ¥15 关于#sql#的问题:#情况描述 在用vs对项目进行调试时,出现找不到网络路径,然后查看SQL配置工具,发现SQL服务显示远程调用过程失败(相关搜索:防火墙)
  • ¥15 eNSP中基于默认路由及浮动路由的公司与分部互联和校园网综合项目
  • ¥15 主要进行描述泥浆在管路不同区段泥浆的密度不相同,泥浆的密度有高有低,此时管路的摩阻分布需要怎么计算,(标签-matlab)
  • ¥40 通过编制程序计算圆管内层流充分发展对流换热,参数如图5-4,以及公式5-16所示,要求用表5-6对程序计算准确性进行验证
  • ¥20 该学习哪个编程语言? AI会取代程序员吗?
  • ¥15 ensp如何拼通IP地址
  • ¥15 saber软件导入Ibis模型报错