在慢速網絡上Tomcat線程數開到300以上的水平，不配APR，基本上300個線程狠快就會用滿，以后的請求就只好等待。但是配上APR之后，Tomcat將以JNI的形式調用Apache HTTP服務器的核心動態鏈接庫來處理文件讀取或網絡傳輸操作，這時並發的線程數量明顯下降，從原來的300可能會馬上下降到只有幾十，新的請求會毫無阻塞的進來。
Tomcat 可以使用 apr 來提供更好的伸縮性、性能和集成到本地服務器技術，用來提高 tomcat 的性能。而tomcat native在具體的運行平台上提供了一種優化技術，它本身是基於 ARP（Apache Portable（輕便） Runtime）技術。在我們應用了tomcat native后，tomcat在跟操作系統級別的交互方面可以做得更好，並且它更像apache一樣，可以更好地作為一台 web server。tomcat 可以利用apache的apr接口，使用操作系統的部分本地操作，從而提升性能APR 提升的是靜態頁面處理能力。
(1).Tomcat的三種運行模式介紹
Tomcat 有三種 運行模式，bio、nio、apr。
bio(blocking I/O)，阻塞式I/O操作，表示Tomcat使用的是傳統的Java I/O操作(即java.io包及其子包)，對於每一個請求都要創建一個線程來進行處理，所以開銷較大不適合處理高並發的場景。Tomcat在默認情況下，就是以bio模式運行的。遺憾的是，就一般而言，bio模式是三種運行模式中性能最低的一種。我們可以通過Tomcat Manager來查看服務器的當前狀態。
nio是Java SE 1.4及后續版本提供的一種新的I/O操作方式(即java.nio包及其子包)，基於緩沖區、並能提供非阻塞I/O操作的Java API實現，比傳統的I/O處理方式（bio）有更高的並發運行性能。是Tomcat8的默認運行模式。
apr(Apache Portable Runtime/Apache可移植運行庫)是Apache HTTP服務器的支持庫。從操作系統級別解決異步I/O問題，大幅度提高服務器的並發處理性能，也是Tomcat生產環境運行的首選方式。要tomcat支持apr，必須安裝apr和native，這樣tomcat才可以利用apache的apr接口，使用操作系統的部分本地操作，從而提升性能。
(2).安裝Tomcat Native
注意：Tomcat Native已經集成到Tomcat8安裝目錄下的bin目錄。
1）安裝依賴包
注意：這里有個apr-devel，作為依賴apr也會被安裝。
[root@youxi1 ~]# yum -y install apr-devel gcc gcc-c++ openssl-devel openssl
2）解壓Tomcat Native包，編譯安裝
[root@youxi1 ~]# tar zxf /usr/local/tomcat8.5/bin/tomcat-native.tar.gz -C /usr/local/src/ [root@youxi1 ~]# cd /usr/local/src/tomcat-native-1.2.18-src/native/ [root@youxi1 native]# ./configure --with-apr=/usr/ --with-java-home=/usr/local/jdk1.8.0_191 --with-ssl [root@youxi1 native]# make && make install //編譯安裝 ---------------------------------------------------------------------- Libraries have been installed in: //庫安裝在如下地址 /usr/local/apr/lib If you ever happen to want to link against installed libraries in a given directory, LIBDIR, you must either use libtool, and specify the full pathname of the library, or use the `-LLIBDIR' flag during linking and do at least one of the following: - add LIBDIR to the `LD_LIBRARY_PATH' environment variable during execution - add LIBDIR to the `LD_RUN_PATH' environment variable during linking - use the `-Wl,-rpath -Wl,LIBDIR' linker flag - have your system administrator add LIBDIR to `/etc/ld.so.conf' See any operating system documentation about shared libraries for more information, such as the ld(1) and ld.so(8) manual pages. ---------------------------------------------------------------------- [root@youxi1 native]# echo $? 0
說明：./configure有兩個參數需要注意下，--with-apr=/usr/提供的是查找apr的路徑可以更詳細的一點，--with-java-home后面跟隨的地址要和"echo $JAVA_HOME"輸出地址一致。
3）根據安裝完成后的提示操作
把庫添加到/etc/ld.so.conf
[root@youxi1 native]# vim /etc/ld.so.conf /usr/local/apr/lib //添加該行 [root@youxi1 native]# ldconfig //重新加載 [root@youxi1 native]# echo "ldconfig" >> /etc/rc.local //這是開機自啟文件的軟鏈接，需要源文件有執行權限 [root@youxi1 native]# ll /etc/rc.local lrwxrwxrwx. 1 root root 13 5月 14 09:12 /etc/rc.local -> rc.d/rc.local
配置環境變量
[root@youxi1 native]# vim /etc/profile.d/jdk8.sh //這是之前的JDK環境變量文件 export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/apr/lib //新增一行 [root@youxi1 native]# . /etc/profile.d/jdk8.sh //刷新
(3).配置APR
1）修改conf/server.xml里的協議
這個協議是<service>標簽里的<Connector>標簽的參數protocol，默認協議是HTTP/1.1。我們將協議修改為org.apache.coyote.http11.Http11AprProtocol
[root@youxi1 native]# vim /usr/local/tomcat8.5/conf/server.xml <Connector port="8080" protocol="org.apache.coyote.http11.Http11AprProtocol" //將HTTP/1.1修改為當前值 connectionTimeout="20000" redirectPort="8443" />
2）在bin/catalina.sh中引用apr
[root@youxi1 native]# vim /usr/local/tomcat8.5/bin/catalina.sh # Register custom URL handlers # Do this here so custom URL handles (specifically 'war:...') can be used in the security policy JAVA_OPTS="$JAVA_OPTS -Djava.protocol.handler.pkgs=org.apache.catalina.webresour ces" //這是第253行，在這下面添加一行參數 JAVA_OPTS="$JAVA_OPTS -Djava.library.path=/usr/local/apr/lib" //只要添加這一行
注意：只要添加一行。
3）重啟Tomcat
[root@youxi1 native]# ps aux | grep /usr/local/tomcat8.5/ root 1113 0.6 11.9 2327404 119308 ? Sl 17:15 0:31 /usr/local/jdk1.8.0_191/bin/java -Djava.util.logging.config.file=/usr/local/tomcat8.5/conf/logging.properties
-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources
-Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /usr/local/tomcat8.5/bin/bootstrap.jar:/usr/local/tomcat8.5/bin/tomcat-juli.jar
-Dcatalina.base=/usr/local/tomcat8.5 -Dcatalina.home=/usr/local/tomcat8.5 -Djava.io.tmpdir=/usr/local/tomcat8.5/temp org.apache.catalina.startup.Bootstrap start root 3078 0.0 0.1 112728 1004 pts/0 R+ 18:30 0:00 grep --color=auto /usr/local/tomcat8.5/ [root@youxi1 native]# kill -9 1113 [root@youxi1 native]# !ps ps aux | grep /usr/local/tomcat8.5/ root 3081 0.0 0.1 112728 1000 pts/0 R+ 18:30 0:00 grep --color=auto /usr/local/tomcat8.5/ [root@youxi1 native]# /usr/local/tomcat8.5/bin/startup.sh Using CATALINA_BASE: /usr/local/tomcat8.5 Using CATALINA_HOME: /usr/local/tomcat8.5 Using CATALINA_TMPDIR: /usr/local/tomcat8.5/temp Using JRE_HOME: /usr/local/jdk1.8.0_191 Using CLASSPATH: /usr/local/tomcat8.5/bin/bootstrap.jar:/usr/local/tomcat8.5/bin/tomcat-juli.jar Tomcat started. [root@youxi1 native]# !ps ps aux | grep /usr/local/tomcat8.5/ root 3091 94.6 7.2 2302932 72308 pts/0 Sl 18:31 0:04 /usr/local/jdk1.8.0_191/bin/java -Djava.util.logging.config.file=/usr/local/tomcat8.5/conf/logging.properties
-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources
-Djava.library.path=/usr/local/apr/lib -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /usr/local/tomcat8.5/bin/bootstrap.jar:/usr/local/tomcat8.5/bin/tomcat-juli.jar
-Dcatalina.base=/usr/local/tomcat8.5 -Dcatalina.home=/usr/local/tomcat8.5 -Djava.io.tmpdir=/usr/local/tomcat8.5/temp org.apache.catalina.startup.Bootstrap start root 3108 0.0 0.1 112728 1004 pts/0 R+ 18:31 0:00 grep --color=auto /usr/local/tomcat8.5/
4）查看日志是否支持native
[root@youxi1 ~]# cat /usr/local/tomcat8.5/logs/catalina.out | grep Native 29-Jun-2019 17:47:25.635 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 29-Jun-2019 18:17:01.395 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 29-Jun-2019 18:24:08.267 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 09:40:11.168 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 11:45:02.398 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 11:45:24.769 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 11:54:19.711 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 11:59:23.422 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 12:11:33.778 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 12:32:55.610 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 14:33:56.449 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 17:15:19.203 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib] 30-Jun-2019 18:31:10.739 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent Loaded APR based Apache Tomcat Native library [1.2.18] using APR version [1.4.8].
看最后一行，只有出現這一行才代表成功了。
參考：https://www.cnblogs.com/zishengY/p/7101616.html?utm_source=itdadao&utm_medium=referral