http://www.jackxiang.com/index.php zh-cn http://www.jackxiang.com/post// jack <xdy108@126.com> Fri, 21 Jun 2013 03:34:26 +0000 http://www.jackxiang.com/post//
strace了下发现：
getsockopt(3, SOL_SOCKET, SO_ERROR, [0], [4]) = 0 sendto(3, "GET /user/mobileUserLogin?uid=xd"..., 265, MSG_NOSIGNAL, NULL, 0) = 265 poll([{fd=3, events=POLLIN}], 1, 1000 )  = 0 (Timeout) poll([{fd=3, events=POLLIN}], 1, 0)     = 0 (Timeout) poll([{fd=3, events=POLLIN}], 1, 1000 )  = 0 (Timeout) poll([{fd=3, events=POLLIN}], 1, 0)     = 0 (Timeout) poll([{fd=3, events=POLLIN}], 1, 1000)  = 0 (Timeout) poll([{fd=3, events=POLLIN}], 1, 0)     = 0 (Timeout) poll([{fd=3, events=POLLIN}], 1, 1000)  = 0 (Timeout) poll([{fd=3, events=POLLIN}], 1, 0)     = 0 (Timeout)


我发现抽风的服务器可以通过--connect-timeout 来减少给接口调用方直接提示：name lookup timed out，
是用curl发现这个问题的：
curl的超时时间设置：
使用curl时，有两个超时时间：一个是连接超时时间，另一个是数据传输的最大允许时间。

连接超时时间用 --connect-timeout 参数来指定，数据传输的最大允许时间用 -m 参数来指定。
例如：
curl --connect-timeout 10 -m 20 "http://XXXXXXX"
连接超时的话，出错提示形如：
curl: (28) connect() timed out!
数据传输的最大允许时间超时的话，出错提示形如：
curl: (28) Operation timed out after 2000 milliseconds with 0 bytes received

--connect-timeout时间短，对本机的接口（接口再访问其它域名的机器）多次访问出现几率大：
curl --connect-timeout 1 "http://***"

According to cURL Error Codes, error code 6 stands for Couldn't resolve host. The given remote host was not resolved.
So I guess your DNS was not propagating properly at times ?


Under the hood, both curl_exec and file_get_contents perform nearly identical operations; they both use libresolv to:

    connect to a name server
    issue a dns request
    process the dns response

To further debug this, you can use curl_getinfo() to get detailed statistics about your requests; you can use this to get an idea of how long each part took using:

    CURLINFO_NAMELOOKUP_TIME
    CURLINFO_CONNECT_TIME
    CURLINFO_PRETRANSFER_TIME
    ...


The value of
the ptr variable is "name lookup timed out".

I am using the curl_easy interface. I am *not* setting
CURLOPT_NOSIGNAL, and I am also *not* setting any timeout options
(such as CURLOPT_TIMEOUT). My guess is that this crash is caused by a
signal that is emitted. I suspect that I need to set CURLOPT_NOSIGNAL
to 1L and then configure libcurl to use c-ares.


---------------------------------------------------------------------------------------
linux服务器因nameservers停止工作，导致name lookup timed out的解决方法。

刚服务器上的所有在线代理网站突然出现name lookup timed out问题，网上搜索了一下原来是服务器的nameservers问题，打开/etc/resolv.conf,看到

search box.net
nameserver 66.90.68.15
nameserver 66.90.68.169 v. m$ V- V% d, p% d, e
8 {; n5 t: M) Z% W
ping了下66.90.68.15果然不工作了! k4 v! @: x, ]3 \6 Y, ]0 ?0 n
* K, `5 n( m/ H7 X& B+ ]- n2 a
随便在google里输入“free nameservers”找到这家9 U/ J% b. ]* O* E# i, \' [
http://www.resolvingnameserver.com/freerns.html
Our current set of name servers that you can use are:+ F6 I# b3 s, L* |! F
205.234.170.215
205.234.170.217
打开resolv.conf，替换掉原来的IP，上传。- t) x0 \! j8 y
8 K" g8 e; x) T" k6 d: e
重启下服务器，问题解决。
( s8 r: {0 P$ D) r& j; I7 Q
其实还有一家比较有名的我以前介绍过
http://www.opendns.com/
208.67.222.222
208.67.220.220
我自己的windows计算机上用过，不过如果网站打开慢的话会出现他们的广告，不是很爽，希望使用的这家不要出现这样的情况。
) E, ]+ k8 _1 X
2009年3月25日更新：9 F8 ~. O3 c6 U6 f
205.234.170.215
205.234.170.217
有点慢，有时还是会出现“name lookup timed out”的情况，所以我还是选择了5 }& D5 k% s8 F7 V
208.67.222.222
208.67.220.220

来自：http://www.9125.info/redirect.php?fid=5&tid=286&goto=nextnewset ]]> http://www.jackxiang.com/post//#blogcomment <user@domain.com> Thu, 01 Jan 1970 00:00:00 +0000 http://www.jackxiang.com/post//#blogcomment