Tomcat 配置优化

（一）连接器优化

默认配置

    <Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />

增加URIEncoding

    <Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" URIEncoding="UTF-8"/>

增加Executor

    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="3000" minSpareThreads="800"/>

    <Connector executor="tomcatThreadPool" port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" URIEncoding="UTF-8"/>

使用Http11NioProtocol协议(利用java的异步IO技术)

    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="3000" minSpareThreads="800"/>

    <Connector executor="tomcatThreadPool" port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol"
               connectionTimeout="20000"
               redirectPort="8443" URIEncoding="UTF-8"/>

使用Http11AprProtocol协议(安装起来最困难,但是从操作系统级别来解决异步的IO问题,大幅度的提高性能.)

    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="3000" minSpareThreads="800"/>

    <Connector executor="tomcatThreadPool" port="8080" protocol="org.apache.coyote.http11.Http11AprProtocol"
               connectionTimeout="20000"
               redirectPort="8443" URIEncoding="UTF-8"/>

要支持Apr协议，需要按照apr的几个包以及tomcat-native

[root@centos02 ~]# wget -P ~ http://mirrors.tuna.tsinghua.edu.cn/apache//apr/apr-1.6.2.tar.gz
[root@centos02 ~]# wget -P ~ http://mirrors.tuna.tsinghua.edu.cn/apache//apr/apr-util-1.6.0.tar.gz
[root@centos02 ~]# wget -P ~ http://mirrors.tuna.tsinghua.edu.cn/apache//apr/apr-iconv-1.2.1.tar.gz
[root@centos02 ~]# yum -y install gcc gcc-c++ autoconf automake expat-devel
[root@centos02 ~]# tar -zxf apr-1.6.2.tar.gz -C /usr/local
[root@centos02 ~]# tar -zxf apr-util-1.6.0.tar.gz -C /usr/local
[root@centos02 ~]# tar -zxf apr-iconv-1.2.1.tar.gz -C /usr/local
[root@centos02 ~]# cd /usr/local/apr-1.6.2/
[root@centos02 apr-1.6.2]# ./configure --prefix=/usr/local/apr
[root@centos02 apr-1.6.2]# make && make install
[root@centos02 apr-1.6.2]# cd ../apr-iconv-1.2.1
[root@centos02 apr-iconv-1.2.1]#
[root@centos02 apr-iconv-1.2.1]# ./configure --prefix=/usr/local/apr-iconv --with-apr=/usr/local/apr
[root@centos02 apr-iconv-1.2.1]# make && make install
[root@centos02 apr-1.6.2]# cd ../apr-util-1.6.0
[root@centos02 apr-util-1.6.0]# ./configure --prefix=/usr/local/apr-util --with-apr=/usr/local/apr --with-apr-iconv=/usr/local/apr-iconv/bin/apriconv
[root@centos02 apr-util-1.6.0]# make && make install
[root@centos02 ~]# tar -zxf /usr/local/apache-tomcat-7.0.55/bin/tomcat-native.tar.gz -C /usr/local
[root@centos02 ~]# cd /usr/local/tomcat-native-1.1.31-src/jni/native/
[root@centos02 native]# ./configure --with-apr=/usr/local/apr
[root@centos02 native]# make && make install
[root@centos02 native]# vi /etc/profile
export LD_LIBRARY_PATH=/usr/local/apr/lib
[root@centos02 native]# source /etc/profile
#启动服务
[root@centos02 native]# catalina.sh start

其他参数acceptCount(当tomcat的线程数达到maxThreads后，新的请求就会排队等待，超过排队数的请求会被拒绝)、连接超时、maxKeepAliveRequests(每个TCP连接接受最大的Http请求数目)

    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="3000" minSpareThreads="800"/>

    <Connector executor="tomcatThreadPool"  port="8080" protocol="org.apache.coyote.http11.Http11AprProtocol"
               acceptCount="1000"
               connectionTimeout="20000"
               keepAliveTimeout="30000"
               maxKeepAliveRequests="8000"
               URIEncoding="UTF-8"
               redirectPort="8443"
     />

（二） 修改JVM参数

vi catalina.sh

JAVA_OPTS="-server -Xms2048m -Xmx2048m -Xmn512m -XX:PermSize=256M -XX:MaxPermSize=256m -Xss256k -XX:SurvivorRatio=4 -XX:MaxTenuringThreshold=15 -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=73 -XX:+UseCMSCompactAtFullCollection -XX:+CMSParallelRemarkEnabled -XX:CMSFullGCsBeforeCompaction=2 -Djava.awt.headless=true"

注：jdk8.0不支持PermSize及MaxPerSize了

年轻代：
UseParNewGC：对年轻代采用多线程并行回收。
MaxTenuringThreshold：设置垃圾最大年龄。
ParallelGCThreads：收集器并行线程数
老年代：
UseConcMarkSweepGC：年老代并发回收，GC次数多时，减少每次GC耗时。
CMSParallelRemarkEnabled：尽量减少 mark 的时间。
CMSInitiatingOccupancyFraction：年老代到90%满的时候开始执行对年老代的并发垃圾回收（CMS），需满足(Xmx-Xmn)*(100- CMSInitiatingOccupancyFraction)/100>=Xmn。
CMSFullGCsBeforeCompaction：指定进行多少次fullGC之后，进行tenured的内存空间压缩，对 0 的理解认为是每次都会
其他：
java.awt.headless：避免linux上图形输出异常

参考：
http://tomcat.apache.org/tomcat-7.0-doc/config/http.html
http://tomcat.apache.org/tomcat-7.0-doc/config/executor.html