详解PHP Swoole长连接常见问题

连接失效问题

例子

其中,Redis常见的报错就是:

配置项:timeout

报错信息:

Error while reading line from the server

Redis可以配置如果客户端经过多少秒还不给Redis服务器发送数据,企业信息化为企业带来了什么那么就会把连接close掉。

MySQL常见的报错:

配置项:wait_t客户端打imeout & interactive_timeout

报错信息:

has gone客户端打开 away

和Redis服务器一服务端样,MySQL也会定时的去清理掉没用的连接。

如何解决

1、用的时候进行重连 。优点是简单,缺点php中文网是面临短连接的问题。

2、定时发送心跳维持连接(推荐)。

如何维持长连接

tcp协议中实现的tcp_kebpm心率epalive

操作系统底层提供客户端版本低怎样升级了一组tcp的keepalive配置:

tcp_keepalive_time (integer; default: 7200; since Linux 2.2)
The number of seconds a connection needs to be idle before TCP
begins sending out keep-alive probes. Keep-alives are sent only
when the SO_KEEPALIVE socket option is enabled. The default
value is 7200 seconds (2 hours). An idle connection is
terminated after approximately an additional 11 minutes (9
probes an interval of 75 seconds apart) when keep-alive is
enabled.

Note that underlying connection tracking mechanisms and
application timeouts may be much shorter.

tcp_keepalive_intvl (integer; default: 75; since Linux 2.4)
The number of seconds between TCP keep-alive probes.

tcp_keepalive_probes (integer; default: 9; since Linux 2.2)
The maximum number of TCP keep-alive probes to send before
giving up and killing the connection if no response is obtained
from the other end.
8

Swoole底层把这些配置开放出来了,例如:

?php

$server = new \Swoole\Server('127.0.0.1', 6666, SWOOLE_PROCESS);

$server->set([
'worker_num' => 1,
'open_tcp_keepalive' => 1,
'tcp_keepidle' => 4, // 对应tcp_keepalive_time
'tcp_keepinterval' => 1, // 对应tcp_keepalive_intvl
'tcp_keepcount' => 5, // 对应tcp_keepalive_probes
]);
'open_tcp_keepalive' => 1, // 总开关,用来开启tcp_keepalive
'tcp_keepidle' => 4, // 4s没有数据传输就进行检测
// 检测的策略如下:
'tcp_keepinterval' => 1, // 1s探测一次,即每隔1s给客户端发一个包(然后客户端可能会回一个ack的包,如果服务端收到了这个ack包,那么说明这个连接是活着的)
'tcp_keepcount' => 5, // 探测的次数,超过5次后客户端还没有回ack包,那么close此连接

我们来实战测试体验一下,服务端脚本如下:

<?php

$server = new \Swoole\Server('127.0.0.1', 6666, SWOOLE_PROCESS);

$server->set([
'worker_num' => 1,
'open_tcp_keepalive' => 1, // 开启tcp_keepalive
'tcp_keepidle' => 4, // 4s没有数据传输就进行检测
'tcp_keepinterval' => 1, // 1s探测一次
'tcp_keepcount' => 5, // 探测的次数,超过5次后还没有回包close此连接
]);

$server->on('connect', function ($server, $fd) {
var_dump("Client: Connect $fd");
});

$server->on('receive', function ($server, $fd, $reactor_id, $data) {
var_dump($data);
});

$server->on('close', function ($server, $fd) {
var_dump("close fd $fd");
});

$server->start();

我们启动这个服务器:

~/codeDir/phpCode/hyperf-skeleton # php server.php

然后通过tcpdump进行抓包:

~/codeDir/phpCode/hyperf-skeleton # tcpdump -i lo port 6666
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes

客户端;们此时正在监听lo上的6666端口的数据包。

然后我们用客户端去连接它:

~/codeDir/phpCode/hyperf-skeleton # nc 127.0.0.1 6666

此时服务端会打印出消息:

~/codeDir/phpCode/hyperf-skeleton # php server.php

string(17) "Client: Connect 1"

tcpdump的输出信息如下:

01:48:40.178439 IP localhost.33933 > localhost.6666: Flags [S], seq 43162537, win 43690, options [mss 65495,sackOK,TS val 9833698 ecr 0,nop,wscale 7], length 0

01:48:40.178484 IP localhost.bpmfdtln字母表6666 > localhost.3企业信息化建设的内容主要分为3933: Fla客户端下载及安装使用gs [S.], seq 1327460565, ack 43162538, win 43690, opbpm心率tions [mss 65495,sackOK,TS val 9833698 ecr 9833698,nop,wscale 7], length 0

01:48:40.178519 IP localhost.33933 > localhost.6666: Flags [.], ack 1, win 342, options [nop,nop,TS val 9833698 ecr 9833698], length 0

01:48:44.2299php是前端还是后端26 IP localhost.6666 > localhost.33933: Flags [.], ack 1, win 342, o服务端开发ptions [nop,nop,TS val 9834104 ecr 9833698], length 0

01:48:44.229951 IP localhost.33933 > localhost.6bpm心率66客户端英文6: Flags [.], ack 1, win 342, options [nop,nop,TS val 9834104 ecr 9833698], length 0

01:48:44企业信息化管理.229926 IP localhost.6666 > localhost.33933企业信息化建设现状及前景: Flags [.], ack 1, win 342, options [nop,nop,TS val 9834104 ecr 9833698], length 0

01:48:44.229951 IP localhost.3php文件用什么软件打开3933 > l服务端;ocalhost.6666:企业信息化建设 Flags服务端测试 [.], ackbpm系统 1, win 342, options [nop,nop,TS val 9834104 ecr 9833698], length 0

01:48:44php中文网.229926 IP localhost.66服务端和客户端区别66 > localhost.33933: Flags [.], ack 1, win 342, options [nop,nop,TS val 9834104 ecr 9833698], length 0

// 省略了其他的输出

我们会发现最开始的时候,会打php教程印三次握手的包:

01:48:40.178439 IP localhost.33933 > localhost.6666: Flags [S], seq 43162537, win 43690, options [mss 65495,sackOK,TS val 9833698 ecr 0,nop,wscale 7], length 0

01:48:40.178484 I服务端返回消息错误什么意思P localhost.6666 > localhost.33933: Flags [S.], seq 13274bpmfdtln字母表60565, ack 43162538, win 43690, options [mss 65495,sackOK,TS val 9833698 ecr 9833698,nop,wscale 7], length 0

01:48:40.178519 IP lo客户端是什么意思啊calhost.33933 > localhost.66BPM66: Flags [.], ack 1客户端版本低怎样升级, win 342, options [nop,nop,TS val 9833698 ecr 9833698], length 0

然后企业信息化,停留了4s没有任何包的输出。

之后,每隔1s左bpm是什么意思右就会打印出一组:

01:52:54.359341 IP localhost.6666 > localhost.43101: Flags [.], ack 1, win 342, options [nop,nop,TS val 9859144 ecr 9858736], len服务端渲染gth 0

01:52:54.359377 IP local客户端是什么意思啊host.43101 > localhost.6666: Flags [.], ack 1企业信息化为企业带来了什么, win 342, options [nop,nop,TS val 9859144 ecr 9855887], length服务端开发 0

其实这就是我们配客户端微信置的策略:

'tcp_keepinterval' => 1, // 1s探测一次
'tcp_keepcount' => 5, // 探测的次数,超过5次后还没有回包close此连接

因为我们操作系统底层会自动的给客户php货币端回ack,所以这个连接不服务端渲染会在5次探测后被关闭。操作系统底层会持续不断的发送这样的一组包:

01:52:54.359341 IP localhost.6666 > localhost.43101: Flags [.], ack 1, win 342, options [nop,nop,TS val 9859144 ecr 9858736], length 0

01:52:54.359377 IP lphpmyadminocalhost.43101 > localhost.6666: Flags [.], abpm心率多少正常ck 1, win 342, optio企业信息化案例分析ns [nop,nop,TS val 9859144 ecr 9855887], l企业信息化服务平台ength 0

如果我们要测试5次探测后关闭这个连接,可以禁掉6666端口的包:

~/codeDir/phpCode/hyperf-skeleton # iptables -A INPUT -p tcp --dport 6666 -j DROP

这样会把所有从6666端口进来的包给禁掉,自然,服务器就接收不到从客户端那一边发来的ack包了。

然后服务器过5秒就会打印出close(服务端主动的调用了close方法,给客户端发送bpmf正确写法与格式了FIN包):

~/codeDir/phpCode/hyperf-skele企业信息化建设现状及前景ton # php server.php

string(17) "Cliephp教程nt: Connect 1"

stringbpmf教学反思(10) "close fd 1"

我们恢复一下iptables的规则:

~/codeDir/phpCode # iptables -D INPUT -p tcp -m tcp --dport 6666 -j DROP

即把我们设置的规则给删除了。

通过tcp_keepalive的方式实现心企业信息化战略规划的方法和内容跳的功能服务端;,优点是简单,客户端打不要写代码就可以完成这个功能,并且发送的心跳包小。缺点是依赖于系统的网络环境,必须保证服务器和客户端都实现了这样的功能,需要客户端配合发心跳包。还有一个更为严重的缺点是如果客户端和服务器不是直连的,而是通过代理服务端返回消息错误什么意思来进行连接的,例如socks5代理,它只会转发应用层的包,不会转发更为底层的tcp探测包,那这个心跳功能就失效了。

所以,客户端无法与登录队列进行通讯Swoole就提供了其他的解决方案,一组检测死连接的配置。

'heartbeat_check_interval' => 1, // 1s探测一次
'heartbeat_idle_time' => 5, // 5s未发送数据包就close此连接

swoole实现的heartbeat

我们来测试一下:

<?php

$server = new \Swoole\Server('127.0.0.1', 6666, SWOOLE_PROCESS);

$server->set([
'worker_num' => 1,
'heartbeat_check_interval' => 1, // 1s探测一次
'heartbeat_idle_time' => 5, // 5s未发送数据包就close此连接
]);

$server->on('connect', function ($server, $fd) {
var_dump("Client: Connect $fd");
});

$server->on('receive', function ($server, $fd, $reactor_id, $data) {
var_dump($data);
});

$server->on('close', function ($server, $fd) {
var_dump("close fd $fd");
});

$server->start();

然后启动服务器bpmfdtln字母表

~/codeDir/phpCode/hyperf-skeleton # php server.php

然后启动tcpdump:

~/codeDir/phpCode # tcpdump -i lo port 6666

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytphp是前端还是后端es

然后再启动客户端:

~/codeDir/phpCode/hyperf-skeleton # nc 127.0.0.1 6666

此时服务器端打印:客户端英文

~/codeDir/phpCode/hyperf-skeleton # php server.php

string(17) "Client: Cbpm心率onnect 1"php是什么

然后tcpdump打印:

02:48:32.516093 IP localhost.42123 > localhost.6666: Flags [S], seq 1088388248, wphp中文网in 43690, options [mss 65495,sackOK,TS val 10193342 ecr 0,nop,wscale 7], length 0

02:48:32.516133 IP localhost.6666 > loca服务端返回消息错误什么意思lhost.42123: Flags [S.], seq 80508236, ack 1088388249, win 43690, options [mss 65495,sackOK,TS val 10193342 ecr 10193342,nop,wscale 7], length 0

02:48:32.516156 IP localhost.42bpm系统123 > localhost.6666: Flags [.], ack 1, win 342, options [nop,nop,TS val 10193342 ecr 10193342], length 0

这是三次握手信息。

然后bpmf过了5s后,t客户端无法与登录队列进行通讯cpdump会打印出:

02:48:36.985027 IP local服务端返回消息错误什么意思host.6666 > localhost.42123: Flags客户端微信 [F.], seq 1, ack 1, win 342, options [nop,nop,TS val 10193789 ecr 10193342], length 0

02:48:客户端英文36.992172 IP localhost.42123 > localhost.6666: Flags [.], ack 2, win 342, options [nop,nop,TS val 10193790 ecr 10193789], lengphpmyadminth 0

也就是服务端发送了FIN包。因为客户端没有发送数据,所以Swoole关闭了连接。

然后服务器端会打印:

~/codeDir/phpC服务端测试ode/hyperf-skeleton # php server.php

string(17) "Client: Connect 1"

st服务端渲染ring(10) "企业信息化管理close fd 1"

客户端;以,heartbeat和tcp keepalive还是有一定的区别客户端下载安装的,tcp keepalive有保活连接的功能,但是heartbeat存粹是检测没有数据的连接,然后关闭它,并且只可以在服企业信息化案例分析务端这边配置,如果需要保活,也可以让客户端配合发送心跳。

如果我们不想让服务端close掉连接,那么就得在应用层里面不断的发送数据包来进行保活,例php是什么如我在nc客户端里面不断的发送包:

~/codeDir/phpCode/hyperf-skeleton # nc 127.0.0.1 6666

ping

ping

ping

ping

ping

ping

pinbpm是什么意思g

ping

ping

我发送了9个ping包给服务器,tcpdump的输出如下:

// 省略了三次握手的包

02:57:53.697363服务端测试 IP localhost.44195 > localhost.6666: Flags [P.], seq 1:6, ack 1, win 342企业信息化案例分析, options [nop,nop,TS val 10249525 ecr 10249307], length 5

02:57:53.69企业信息化服务平台7390 IP localhost.6666 > localhost.44195: Flags [.], ack 6, win 342, options [nop,nop,TS val 10249525 ecr 10249525], length 0

02:57:55.309532企业信息化战略规划的方法和内容 IP localhost.44195 > localhost.6666: Flags [P.], seq 6:11, ack 1,客户端是什么意思啊 wibpm心率多少正常n 342, options [nop,nop,TS val 10249686 ecr 10249525], length 5

02:57:55.309576 IP localhost.6666 > localhost.44195: Flags [.], ac服务端;k 11, win 342, options [nop,nop,TS val 10249686 ecr 10249686], length 0

02:57:58.395206 IP localhost.44195 > localhost.6666: Flags [P.], seq 11:16, ack 1, win 342, optibpm心率多少正常ons [nop,nop,TS val 10249994 ecr 10249686], length 5

02:57:58.395239 IP localhost服务端返回消息错误.6666 >企业信息化建设 localh服务端返回消息错误什么意思ost.44195: Flags [.],php货币 ack 16, win 34企业信息化建设2, options [nop,nop,TS val 10249994 ecr 10249994], length 0

02:58:01.858094 IP localhost.44195 > localhost.6666: Flags [P.], seq 16:21,bpmf ack 1, win 342, options [nop,nop,TS val 10250341 ecr 10249994], length 5

02:58:01.858126 IP loca服务端;lhost.6666 > localhost.44195: Flags [.], ack 21, win 342, options [nop,nop,TS val 10250341 ecr 10250341], length 0

02:58:04.132584 IP locaphp中文网lhost.44195 > localhost.6666: Flags [P.],bpm心率多少正常 seq 21:26, ack 1, wbpmf正确写法与格式in 342, options [nop,nop,TS val 10250568 ecr 10250341], length 5

02:58:04.132609 IP localhost.6666 > localhost.44195: Flags [.], ack 26, win 342,企业信息化案例分析 options [nop,nop,TS val 10250568 ecr 10250568], length 0

02:58:05.895704 IP localhost.44195 > localhost.6666: Flags [P.], seq 26:31, ack 1, wi服务端测试n 34企业信息化案例分析2, options [nop,nop,TS val 10250744 ecr 10250568], length 5

02:58:05.895728 IP localhost.6666bpm是什么意思 > lo企业信息化建设calhost.44195: Flags [.], ack 31, win 342, options [nop,nop,TS val 10250744 ecr 10250744], length 0

02:58:07.150265 IP localhost.44195 > localhphpost.6666: Flags [P.], seq 31:36, ack 1, win服务端app 342, options [nop,nop,TS val 10250870 ecr 10250744], lephp是前端还是后端ngth 5

02:58:07.150288 IP localhost.6666 > locbpmf拼音26个字母顺序alhost.44195: Flags [.], ack 36,服务端返回消息错误 win 342, options [nop,nop,TS val 10250870 ecr 10250870], length 0

02:58:08.349124 IP localhost.44195服务端开发 > localh客户端下载安装ostphp教程.6666: Flags [P.], seq 36:41, ack 1, win 342, options [nop,nop,TS val 10250990 ecr 10250870], length 5

02:58:08.349156 IP localhost.6666 > localhost.44bpmf教学反思195: Flags [.], ack 41, win 342, options [nop,nop,TS val 10250990 ecr 10250990], length 0

02:58:09.9062企业信息化服务平台23 IP localhost.4bpmf拼音26个字母顺序4195 > localhost.6666: Flags [P.], seq 4客户端打开1:46, ack 1,服务端app win 342, options [nop,nop,TS val 10251145 ecr 10250990], le客户端无法与登录队列进行通讯ngth 5

02:58:09.906247 IP localhost.6bpmf拼音26个字母顺序666 > localhost.44195客户端;: Flags [.], ack 46, win 342, options [nop,nop,TS val 10251145 ecr 10251145], length 0

有9组数据包的发送。(这里的Flags [P.]代表Push的含义)

此时服务器还没有close掉连接客户端打开,实现了客户端保活连接的功能。然后我们停php是什么止发送ping,过了5秒后tcpdump就会输出一组:

02:58:14.811761 IP localhost.6666 > localhost.44195: Flags [F.], seq 1, ack 46, win 342, options [nop,nop,TS val 10251636 ecr 10251145], lebpmfngth 0

02:58:14.816420 IP localhost.44195 > localhost.6666: Flags [.], ack 2, wbpmf拼音26个字母顺序in 342, option企业信息化服务平台s [nop,nop,TS val 10251637 ecr 10251636], length 0

服务端那边发送了FIN包,说明服务端cl客户端是什么意思啊ose掉了连接。服务端的输出如下:

~/codeDir/phpCodbpm心率多少正常e/hyperf-skeletphp中文网on # php server.php

st客户端英文ring(17)bpm心率多少正常 "Client: Connect 1"

string(5) "ping

"

string(5) "ping

"

string(5) "ping

"

str服务端异常是怎么回事ing(5) "ping

"

string客户端微信(5)企业信息化建设现状及前景 "ping

"

string(5) "ping

"

string(5) "ping

"

string(5) "ping

"

string(5) "ping服务端和后端

"

string(10) "close fd 1"

然后我们在客户端那边ctrl + c来关闭连接客户端无法与登录队列进行通讯

~/codeDir/phpCode/客户端打开hyperf-skeleton # nc 127.0.0.1 6666

ping

pingphp是前端还是后端

ping

ping

pinphp是什么g

ping

ping

ping

ping

^Cpunt!

~/code客户端下载安装Dir/phpCode/hype服务端渲染rf-skelebpmfton #

此时,tcpdump的输出如下:

03:03:02.25766php文件用什么软件打开7 IP localhost.44195 > localhost.6666: Flags [F.], seq 4bpm心率多少正常6, ack 2, win 342, optbpmf正确写法与格式io客户端打开nphp文件用什么软件打开s [nop,nop,TS val 10280414 ecr 10251636], length 0

03:03:02.257734 IP localhost.6666 > localhobpm系统st.44195: Flags [R], seq 2678621620, win 0, length 0

应用层心跳

1、制定pinbpm系统g/pong协议(mysql等自带ping协议)

2、客户端灵活的发送ping心跳包

3、服务端OnRecive检查可用性回复pong

例如:

$server->on('receive', function (\Swoole\Server $server, $fd, $reactor_id, $data)
{
if ($data == 'ping')
{
checkDB();
checkServiceA();
checkRedis();
$server->send('pong');
}
});

结论

1、tcp的keepalive最简单,但是有兼容性问题,不够灵活

2、swoole提供的keepalive最实用,但是需要bpmf客户端配合,复杂度适中

3、应用层的keepalive最灵活但是最麻烦