求教网络多次connect的问题?-PHP Tutorial-php.cn

Table of Contents

回复内容：

Home

Backend Development

PHP Tutorial

求教网络多次connect的问题?

Jun 06, 2016 pm 08:06 PM

http ip php tcp

在查看有时候文件上传到cdn比较慢的情况。
使用strace查看到以下系统调用。
求教网络多次connect的问题?

我有一些疑问：

查询dns的时候，connect了一次之后，为何会有两次sendto。看样子两次都发送了同个域名过去。
连接cdn的时候出现了多次connect，我很不理解这个过程，可否帮我讲解下，发生了什么，为什么这样。

<code>futex(0x7fbfc9b9ff04, FUTEX_WAKE_PRIVATE, 2147483647) = 0
socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 6
connect(6, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("221.181.196.155")}, 16) = 0
getsockname(6, {sa_family=AF_INET, sin_port=htons(44696), sin_addr=inet_addr("10.250.1.110")}, [16]) = 0
connect(6, {sa_family=AF_UNSPEC, sa_data="\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16) = 0
connect(6, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("211.142.193.60")}, 16) = 0
getsockname(6, {sa_family=AF_INET, sin_port=htons(45965), sin_addr=inet_addr("10.250.1.110")}, [16]) = 0
connect(6, {sa_family=AF_UNSPEC, sa_data="\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16) = 0
connect(6, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("183.203.25.158")}, 16) = 0
getsockname(6, {sa_family=AF_INET, sin_port=htons(59516), sin_addr=inet_addr("10.250.1.110")}, [16]) = 0
close(6)                                = 0
gettimeofday({1464771775, 191396}, NULL) = 0
alarm(0)                                = 30
rt_sigaction(SIGALRM, {SIG_DFL, [], SA_RESTORER, 0x7fbfc98419a0}, NULL, 8) = 0
clock_gettime(CLOCK_MONOTONIC, {11494888, 559945294}) = 0
clock_gettime(CLOCK_MONOTONIC, {11494888, 560020269}) = 0
socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 6
fcntl(6, F_GETFL)                       = 0x2 (flags O_RDWR)
fcntl(6, F_SETFL, O_RDWR|O_NONBLOCK)    = 0
connect(6, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("221.181.196.155")}, 16) = -1 EINPROGRESS (Operation now in progress)</code>

Copy after login

回复内容：

在查看有时候文件上传到cdn比较慢的情况。
使用strace查看到以下系统调用。
求教网络多次connect的问题?

我有一些疑问：

查询dns的时候，connect了一次之后，为何会有两次sendto。看样子两次都发送了同个域名过去。
连接cdn的时候出现了多次connect，我很不理解这个过程，可否帮我讲解下，发生了什么，为什么这样。

<code>futex(0x7fbfc9b9ff04, FUTEX_WAKE_PRIVATE, 2147483647) = 0
socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 6
connect(6, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("221.181.196.155")}, 16) = 0
getsockname(6, {sa_family=AF_INET, sin_port=htons(44696), sin_addr=inet_addr("10.250.1.110")}, [16]) = 0
connect(6, {sa_family=AF_UNSPEC, sa_data="\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16) = 0
connect(6, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("211.142.193.60")}, 16) = 0
getsockname(6, {sa_family=AF_INET, sin_port=htons(45965), sin_addr=inet_addr("10.250.1.110")}, [16]) = 0
connect(6, {sa_family=AF_UNSPEC, sa_data="\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16) = 0
connect(6, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("183.203.25.158")}, 16) = 0
getsockname(6, {sa_family=AF_INET, sin_port=htons(59516), sin_addr=inet_addr("10.250.1.110")}, [16]) = 0
close(6)                                = 0
gettimeofday({1464771775, 191396}, NULL) = 0
alarm(0)                                = 30
rt_sigaction(SIGALRM, {SIG_DFL, [], SA_RESTORER, 0x7fbfc98419a0}, NULL, 8) = 0
clock_gettime(CLOCK_MONOTONIC, {11494888, 559945294}) = 0
clock_gettime(CLOCK_MONOTONIC, {11494888, 560020269}) = 0
socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 6
fcntl(6, F_GETFL)                       = 0x2 (flags O_RDWR)
fcntl(6, F_SETFL, O_RDWR|O_NONBLOCK)    = 0
connect(6, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("221.181.196.155")}, 16) = -1 EINPROGRESS (Operation now in progress)</code>

Copy after login

tcp 三次握手

cdn 会连接到多个节点

第一个问题我不知道。

第二个，解析DNS之后会有多个A记录，看样子先进行了测速之类的任务，然后选择最优服务器上传数据。

Statement of this Website

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn