Tomcat+session共享问题

2018-02-02 17:16:00
aolens
原创
663

前言

在Tomcat集群中,当一个节点出现故障,其他节点该如何接管故障节点的Session信息呢?本文带来的解决方案是基于MSM+Memcached实现Session共享。

相关介绍

MSM

MSM–Memcached Session Manager是一个高可用的Tomcat Session共享解决方案,除了可以从本机内存快速读取Session信息(仅针对黏性Session)外,同时可使用Memcached存取Session,以实现高可用。

工作原理

Sticky Session(黏性) 模式下的工作原理

#Tomcat本地Session为主Session,Memcached 中的Session为备Session

安装在Tomcat上的MSM使用本机内存保存Session,当一个请求执行完毕之后,如果对应的Session在本地不存在(即某用户的第一次请求),则将该Session复制一份至Memcached;当该Session的下一个请求到达时,会使用Tomcat的本地Session,请求处理结束之后,Session的变化会同步更新到 Memcached,保证数据一致。

当集群中的一个Tomcat挂掉,下一次请求会被路由到其他Tomcat上。负责处理此此请求的Tomcat并不清楚Session信息,于是从Memcached查找该Session,更新该Session并将其保存至本机。此次请求结束,Session被修改,送回Memcached备份。

Non-sticky Session (非黏性)模式下的工作原理

#Tomcat本地Session为中转Session,Memcached为主备Session

收到请求,加载备Session至本地容器,若备Session加载失败则从主Session加载

请求处理结束之后,Session的变化会同步更新到Memcached,并清除Tomcat本地Session

实现过程

实验拓扑

#系统环境:CentOS6.6
nginx 安装配置
#解决依赖关系


[root@scholar ~]# yum groupinstall "Development Tools" "Server Platform Deveopment"  -y
[root@scholar ~]# yum install openssl-devel pcre-devel -y
[root@scholar ~]# groupadd -r nginx
[root@scholar ~]# useradd -r -g nginx nginx
[root@scholar ~]# tar xf nginx-1.6.3.tar.gz
[root@scholar ~]# cd nginx-1.6.3
[root@scholar nginx-1.6.3]# ./configure \
> --prefix=/usr/local/nginx \
> --sbin-path=/usr/sbin/nginx \
> --conf-path=/etc/nginx/nginx.conf \
> --error-log-path=/var/log/nginx/error.log \
> --=/var/log/nginx/access.log \
> --pid-path=/var/run/nginx/nginx.pid \
> --lock-path=/var/lock/nginx.lock \
> --user=nginx \
> --group=nginx \
> --with- \
> --with- \
> --with- \
> --with- \
> --=/usr/local/nginx/client/ \
> --=/usr/local/nginx/proxy/ \
> --=/usr/local/nginx/fcgi/ \
> --=/usr/local/nginx/uwsgi \
> --=/usr/local/nginx/scgi \
> --with-pcre
[root@scholar nginx-1.6.3]# make && make install[/php]


为nginx提供SysVinit脚本


[root@scholar ~]# vim /etc/rc.d/init.d/nginx


#新建文件/etc/rc.d/init.d/nginx,内容如下:


#!/bin/sh
#
# nginx - this script starts and stops the nginx daemon
#
# chkconfig: - 85 15
# description: Nginx is an HTTP(S) server, HTTP(S) reverse \
# proxy and IMAP/POP3 proxy server
# processname: nginx
# config: /etc/nginx/nginx.conf
# config: /etc/sysconfig/nginx
# pidfile: /var/run/nginx.pid
# Source function library.
. /etc/rc.d/init.d/functions
# Source networking configuration.
. /etc/sysconfig/network
# Check that networking is up.
[ "$NETWORKING" = "no" ] && exit 0
nginx="/usr/sbin/nginx"
prog=$(basename $nginx)
NGINX_CONF_FILE="/etc/nginx/nginx.conf"
[ -f /etc/sysconfig/nginx ] && . /etc/sysconfig/nginx
lockfile=/var/lock/subsys/nginx
make_dirs() {
# make required directories
user=`nginx -V 2>&1 | grep "configure arguments:" | sed 's/[^*]*--user=\([^ ]*\).*/\1/g' -`
options=`$nginx -V 2>&1 | grep 'configure arguments:'`
for opt in $options; do
if [ `echo $opt | grep '.*-temp-path'` ]; then
value=`echo $opt | cut -d "=" -f 2`
if [ ! -d "$value" ]; then
# echo "creating" $value
mkdir -p $value && chown -R $user $value
fi
fi
done
}
start() {
[ -x $nginx ] || exit 5
[ -f $NGINX_CONF_FILE ] || exit 6
make_dirs
echo -n $"Starting $prog: "
daemon $nginx -c $NGINX_CONF_FILE
retval=$?
echo
[ $retval -eq 0 ] && touch $lockfile
return $retval
}
stop() {
echo -n $"Stopping $prog: "
killproc $prog -QUIT
retval=$?
echo
[ $retval -eq 0 ] && rm -f $lockfile
return $retval
}
restart() {
configtest || return $?
stop
sleep 1
start
}
reload() {
configtest || return $?
echo -n $"Reloading $prog: "
killproc $nginx -HUP
RETVAL=$?
echo
}
force_reload() {
restart
}
configtest() {
$nginx -t -c $NGINX_CONF_FILE
}
rh_status() {
status $prog
}
rh_status_q() {
rh_status >/dev/null 2>&1
}
case "$1" in
start)
rh_status_q && exit 0
$1
;;
stop)
rh_status_q || exit 0
$1
;;
restart|configtest)
$1
;;
reload)
rh_status_q || exit 7
$1
;;
force-reload)
force_reload
;;
status)
rh_status
;;
condrestart|try-restart)
rh_status_q || exit 0
;;
*)
echo $"Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-
reload|configtest}"
exit 2
esac


为脚本赋予执行权限


[root@scholar ~]# chmod +x /etc/rc.d/init.d/nginx


添加至服务管理列表,并让其开机自动启动


[root@scholar ~]# chkconfig --add nginx
[root@scholar ~]# chkconfig nginx on


配置nginx


[root@scholar ~]# vim /etc/nginx/nginx.conf
upstream {
server 172.16.10.123:8080;
server 172.16.10.124:8080;
}
server {
listen 80;
server_name ;
location / {
proxy_pass ;
index index.jsp index.html index.htm;
}
}
[root@scholar ~]# service nginx start
Starting nginx: [ OK ]


tomcat安装配置
安装jdk


[root@node1 ~]# rpm -ivh jdk-7u79-linux-x64.rpm
[root@node1 ~]# vim /etc/profile.d/java.sh
export JAVA_HOME=/usr/java/latest
export PATH=$JAVA_HOME/bin:$PATH
[root@node1 ~]# . /etc/profile.d/java.sh


安装tomcat


[root@node1 ~]# tar xf apache-tomcat-7.0.62.tar.gz -C /usr/local/
[root@node1 ~]# cd /usr/local/
[root@node1 local]# ln -sv apache-tomcat-7.0.62/ tomcat
[root@node1 local]# vim /etc/profile.d/tomcat.sh
export CATALINA_HOME=/usr/local/tomcat
export PATH=$CATALINA_HOME/bin:$PATH
[root@node1 local]# . /etc/profile.d/tomcat.sh


提供脚本


[root@node1 local]# vim /etc/rc.d/init.d/tomcat
#!/bin/sh
# Tomcat init script for Linux.
#
# chkconfig: 2345 96 14
# description: The Apache Tomcat servlet/JSP container.
# JAVA_OPTS='-Xms64m -Xmx128m'
JAVA_HOME=/usr/java/latest
CATALINA_HOME=/usr/local/tomcat
export JAVA_HOME CATALINA_HOME
case $1 in
start)
exec $CATALINA_HOME/bin/catalina.sh start ;;
stop)
exec $CATALINA_HOME/bin/catalina.sh stop;;
restart)
$CATALINA_HOME/bin/catalina.sh stop
sleep 2
exec $CATALINA_HOME/bin/catalina.sh start ;;
*)
echo "Usage: `basename $0` {start|stop|restart}"
exit 1
;;
esac
[root@node1 local]# chmod +x /etc/rc.d/init.d/tomcat
[root@node1 local]# chkconfig --add tomcat
[root@node1 local]# chkconfig tomcat on


#两个tomcat节点都执行以上操作
访问测试
准备测试页


[root@node1 local]# cd tomcat/webapps/
[root@node1 webapps]# mkdir -pv test/WEB-INF/{classes,lib}
[root@node1 webapps]# cd test/
[root@node1 test]# vim index.jsp
<%@ <a href="https://www.ropainteriorbarata.com/">calzoncillos boxer baratos</a> page language="java" %>
<html>
<head><title>TomcatA</title></head>
<body>
<h1><font color="red">TomcatA.scholar.com</font></h1>
<table align="centre" border="1">
<tr>
<td>Session ID</td>
<% session.setAttribute("scholar.com","scholar.com"); %>
<td><%= session.getId() %></td>
</tr>
<tr>
<td>Created on</td>
<td><%= session.getCreationTime() %></td>
</tr>
</table>
</body>
</html>


#另一个节点将TomcatA替换为TomcatB,颜色设为蓝色
[root@node1 test]# service tomcat start

此时Session信息并不一致,接下来我们通过配置MSM实现Session共享

memcached安装

#解决依赖关系


[root@scholar ~]# yum groupinstall "Development Tools" "Server Platform Deveopment" -y
#安装libevent
#memcached依赖于libevent API,因此要事先安装之
[root@scholar ~]# tar xf libevent-2.0.22-stable.tar.gz
[root@scholar ~]# cd libevent-2.0.22-stable
[root@scholar libevent-2.0.22-stable]# ./configure --prefix=/usr/local/libevent
[root@scholar libevent-2.0.22-stable]# make && make install
[root@scholar ~]# echo "/usr/local/libevent/lib" > /etc/ld.so.conf.d/libevent.conf
[root@scholar ~]# ldconfig


#安装配置memcached


[root@scholar ~]# tar xf memcached-1.4.24.tar.tar
[root@scholar ~]# cd memcached-1.4.24
[root@scholar memcached-1.4.24]# ./configure --prefix=/usr/local/memcached --with-libevent=/usr/local/libevent
[root@scholar memcached-1.4.24]# make && make install


提供脚本
[root@scholar ~]# vim /etc/init.d/memcached
#!/bin/bash
#
# Init file for memcached
#
# chkconfig: - 86 14
# description: Distributed memory caching daemon
#
# processname: memcached
# config: /etc/sysconfig/memcached
. /etc/rc.d/init.d/functions
## Default variables
PORT="11211"
USER="nobody"
MAXCONN="1024"
CACHESIZE="64"
RETVAL=0
prog="/usr/local/memcached/bin/memcached"
desc="Distributed memory caching"
lockfile="/var/lock/subsys/memcached"
start() {
echo -n $"Starting $desc (memcached): "
daemon $prog -d -p $PORT -u $USER -c $MAXCONN -m $CACHESIZE
RETVAL=$?
[ $RETVAL -eq 0 ] && success && touch $lockfile || failure
echo
return $RETVAL
}
stop() {
echo -n $"Shutting down $desc (memcached): "
killproc $prog
RETVAL=$?
[ $RETVAL -eq 0 ] && success && rm -f $lockfile || failure
echo
return $RETVAL
}
restart() {
stop
start
}
reload() {
echo -n $"Reloading $desc ($prog): "
killproc $prog -HUP
RETVAL=$?
[ $RETVAL -eq 0 ] && success || failure
echo
return $RETVAL
}
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
restart
;;
condrestart)
[ -e $lockfile ] && restart
RETVAL=$?
;;
reload)
reload
;;
status)
status $prog
RETVAL=$?
;;
*)
echo $"Usage: $0 {start|stop|restart|condrestart|status}"
RETVAL=1
esac
exit $RETVAL

授权并启动服务

[root@scholar ~]# chmod +x /etc/init.d/memcached
[root@scholar ~]# chkconfig --add memcached
[root@scholar ~]# chkconfig memcached on
[root@scholar ~]# service memcached start
#两个memcached节点都执行以上操作

tomcat配置

将所需jar包放入各tomcat节点的tomcat安装目录下的lib目录中


[root@node1 ~]# cd msm/
[root@node1 msm]# ls
javolution-5.4.3.1.jar msm-javolution-serializer-1.8.1.jar
memcached-session-manager-1.8.1.jar spymemcached-2.10.2.jar
memcached-session-manager-tc7-1.8.1.jar
[root@node1 msm]# cp * /usr/local/tomcat/lib/


#各tomcat节点都需执行以上操作


[root@node1 msm]# vim /usr/local/tomcat/conf/server.xml
<?xml version='1.0' encoding='utf-8'?>
<Server port="8005" shutdown="SHUTDOWN">
<Listener className="org.apache.catalina.startup.VersionLoggerListener" />
<Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
<Listener className="org.apache.catalina.core.JasperListener" />
<Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
<Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
<Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />
<GlobalNamingResources>
<Resource name="UserDatabase" auth="Container"
type="org.apache.catalina.UserDatabase"
description="User database that can be updated and saved"
</GlobalNamingResources>
<Service name="Catalina">
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" />
<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />
<Engine name="Catalina" defaultHost="localhost">
<Realm className="org.apache.catalina.realm.LockOutRealm">
<Realm className="org.apache.catalina.realm.UserDatabaseRealm"
resourceName="UserDatabase"/>
</Realm>
<Host name="" appBase="webapps"
unpackWARs="true" autoDeploy="true">
<Context path="/test" docBase="/usr/local/tomcat/webapps/test/" reloadable="true">
<Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"
memcachedNodes="n1:172.16.10.126:11211,n2:172.16.10.212:11211"
failoverNodes="n1"
requestUriIgnorePattern=".*\.(ico|png|gif|jpg|css|js)$"
transcoderFactoryClass="de.javakaffee.web.msm.serializer.javolution.Javolu
tionTranscoderFactory"
/>
</Context>
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
prefix="scholar_access_log." suffix=".txt"
pattern="%h %l %u %t &quot;%r&quot; %s %b" />
</Host>
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
prefix="scholar_access_log." suffix=".txt"
pattern="%h %l %u %t &quot;%r&quot; %s %b" />
</Host>
<Host name="localhost" appBase="webapps"
unpackWARs="true" autoDeploy="true">
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
prefix="localhost_access_log." suffix=".txt"
pattern="%h %l %u %t &quot;%r&quot; %s %b" />
</Host>
</Engine>
</Service>
</Server>


将配置文件同步至另一节点


[root@node1 msm]# scp /usr/local/tomcat/conf/server.xml node2:/usr/local/tomcat/conf/
[root@node1 msm]# service tomcat restart ssh node2 'service tomcat restart'


访问测试

由此可见,Session共享已实现,下面我们模拟TomcatB节点故障,看一下Session是否会发生改变

[root@node2 msm]# service tomcat stop


虽然因为TomcatB故障,导致用户请求被调度到了TomcatA节点上,但Session ID并未发生改变,即Session集群内的所有节点都保存有全局的Session信息,很好的实现了用户访问的不中断

当n2(memcached)节点发生故障,Session信息会不会转移到其他memcached节点呢,我们来试一下

[root@scholar ~]# service memcached stop


Session已转移到n1上,而且Session ID并未发生改变,至此,Tomcat基于MSM+Memcached实现Session共享目的已实现

The end

发表评论
评论通过审核后显示。
文章分类
联系我们
联系人: aolens
Email: aolens@126.com