dns lookup very slow

[wencan]

go version:

go version go1.10.3 linux/amd64

go env:

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/user/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/user/Projects/Go"
GORACE=""
GOROOT="/opt/Go/current"
GOTMPDIR=""
GOTOOLDIR="/opt/Go/current/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build634905456=/tmp/go-build -gno-record-gcc-switches"

httpstat http://baidu.com
output:

Connected to 220.181.57.216:80

HTTP/1.1 200 OK
Server: Apache
Accept-Ranges: bytes
Cache-Control: max-age=86400
Content-Length: 81
Content-Type: text/html
Date: Mon, 13 Aug 2018 11:07:25 GMT
Etag: "51-47cf7e6ee8400"
Expires: Tue, 14 Aug 2018 11:07:25 GMT
Last-Modified: Tue, 12 Jan 2010 13:48:00 GMT
Connection: Keep-Alive

Body discarded

   DNS Lookup   TCP Connection   Server Processing   Content Transfer
[    8194ms  |          26ms  |             28ms  |             0ms  ]
             |                |                   |                  |
    namelookup:8194ms         |                   |                  |
                        connect:8220ms            |                  |
                                      starttransfer:8248ms           |
                                                                 total:8248ms   

[agnivade]

Looks like a dup of #21906.

Also, kindly provide the output of curl -w "status- %{http_code}, dnslookup- %{time_namelookup}" http://baidu.com -s -o /dev/null

[wencan]

my dns server is a internal server.
i changed it to 8.8.8.8, go ns lookup is fast.

curl and ping always normal.
go dns lookup slow only on some internal machines.

[agnivade]

I am going to mark it as duplicate of #21906. Please try with 1.11rc1 and comment on that issue. Thank you.

[wencan]

@agnivade

10.50.0.1 is my internal dns server

test1:

wencan@stretch:~$ docker run -it --dns 8.8.8.8 golang:1.11-rc-stretch /bin/bash
root@4523b2fc6b78:/go# go get -u -v  github.com/davecheney/httpstat
root@4523b2fc6b78:/go# httpstat http://baidu.com

Connected to 123.125.115.110:80

HTTP/1.1 200 OK
Server: Apache
Accept-Ranges: bytes
Cache-Control: max-age=86400
Content-Length: 81
Content-Type: text/html
Date: Thu, 23 Aug 2018 03:30:20 GMT
Etag: "51-47cf7e6ee8400"
Expires: Fri, 24 Aug 2018 03:30:20 GMT
Last-Modified: Tue, 12 Jan 2010 13:48:00 GMT
Connection: Keep-Alive

Body discarded

   DNS Lookup   TCP Connection   Server Processing   Content Transfer
[      97ms  |          23ms  |             24ms  |             0ms  ]
             |                |                   |                  |
    namelookup:97ms           |                   |                  |
                        connect:121ms             |                  |
                                      starttransfer:145ms            |
                                                                 total:145ms  

test2:

wencan@stretch:~$ docker run -it --rm --dns  10.50.0.1 golang:1.11-rc-stretch /bin/bash
root@ef8fc343110e:/go# go get -u -v  github.com/davecheney/httpstat
root@ef8fc343110e:/go#  httpstat http://baidu.com

Connected to 220.181.57.216:80

HTTP/1.1 200 OK
Server: Apache
Accept-Ranges: bytes
Cache-Control: max-age=86400
Content-Length: 81
Content-Type: text/html
Date: Thu, 23 Aug 2018 03:55:15 GMT
Etag: "51-47cf7e6ee8400"
Expires: Fri, 24 Aug 2018 03:55:15 GMT
Last-Modified: Tue, 12 Jan 2010 13:48:00 GMT
Connection: Keep-Alive

Body discarded

   DNS Lookup   TCP Connection   Server Processing   Content Transfer
[    8239ms  |          27ms  |             29ms  |             0ms  ]
             |                |                   |                  |
    namelookup:8239ms         |                   |                  |
                        connect:8267ms            |                  |
                                      starttransfer:8296ms           |
                                                                 total:8297ms   

test3:

wencan@stretch:~$ docker run -it --rm --dns 8.8.8.8 golang:1.10.3-stretch /bin/bash
root@33f3758a7160:/go# go get -u -v  github.com/davecheney/httpstat
root@33f3758a7160:/go#  httpstat http://baidu.com

Connected to 123.125.115.110:80

HTTP/1.1 200 OK
Server: Apache
Accept-Ranges: bytes
Cache-Control: max-age=86400
Content-Length: 81
Content-Type: text/html
Date: Thu, 23 Aug 2018 03:55:38 GMT
Etag: "51-47cf7e6ee8400"
Expires: Fri, 24 Aug 2018 03:55:38 GMT
Last-Modified: Tue, 12 Jan 2010 13:48:00 GMT
Connection: Keep-Alive

Body discarded

   DNS Lookup   TCP Connection   Server Processing   Content Transfer
[      55ms  |          24ms  |             24ms  |             0ms  ]
             |                |                   |                  |
    namelookup:55ms           |                   |                  |
                        connect:79ms              |                  |
                                      starttransfer:104ms            |
                                                                 total:104ms    

test4:

wencan@stretch:~$  docker run --rm -it --dns 10.50.0.1 golang:1.10.3-stretch /bin/bash
root@740ecbb8125c:/go# go get -u -v  github.com/davecheney/httpstat
root@740ecbb8125c:/go#  httpstat http://baidu.com

Connected to 220.181.57.216:80

HTTP/1.1 200 OK
Server: Apache
Accept-Ranges: bytes
Cache-Control: max-age=86400
Content-Length: 81
Content-Type: text/html
Date: Thu, 23 Aug 2018 03:55:50 GMT
Etag: "51-47cf7e6ee8400"
Expires: Fri, 24 Aug 2018 03:55:50 GMT
Last-Modified: Tue, 12 Jan 2010 13:48:00 GMT
Connection: Keep-Alive

Body discarded

   DNS Lookup   TCP Connection   Server Processing   Content Transfer
[    8289ms  |          26ms  |             28ms  |             0ms  ]
             |                |                   |                  |
    namelookup:8289ms         |                   |                  |
                        connect:8315ms            |                  |
                                      starttransfer:8344ms           |
                                                                 total:8344ms   

[agnivade]

Please comment on #21906 with your findings.