Apache Tomcat Native library (zz)

启动Tomcat时出现The Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path:

在从Tomcat 5.0.28转向5.5.X时，在启动时发现出现如下信息
[org.apache.catalina.core.AprLifecycleListener]-[INFO] The Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: （...你的系统环境PATH路径...）

在停止时发现出现如下信息
[org.apache.catalina.core.AprLifecycleListener]-[INFO] Failed shutdown of Apache Portable Runtime

于是，想消除这个问题，通过查阅 http://tomcat.apache.org/tomcat-5.5-doc/apr.html

Tomcat can use the Apache Portable Runtime to provide superior scalability, performance, and better integration with native server technologies. The Apache Portable Runtime is a highly portable library that is at the heart of Apache HTTP Server 2.x. APR has many uses, including access to advanced IO functionality (such as sendfile, epoll and OpenSSL), OS level functionality (random number generation, system status, etc), and native process handling (shared memory, NT pipes and Unix sockets).

These features allows making Tomcat a general purpose webserver, will enable much better integration with other native web technologies, and overall make Java much more viable as a full fledged webserver platform rather than simply a backend focused technology.

发现 Tomcat 可以用 Apache Portable Runtime 来提供更强性能，提升Web静态页面的处理能力，不再需要专门的Web Server来处理静态页面了。

但是APR的支持需要安装三个本地组件
APR support requires three main native components to be installed:
1、APR library
2、JNI wrappers for APR used by Tomcat (libtcnative)
3、OpenSSL libraries

解决：Windows下的安装配置与使用
1、先去 http://tomcat.heanet.ie/native/ 下载编译好的 tcnative-1.dll 文件，也可以下载tomcat-native.zip自己进行编译
2、修改一下 catalina.bat，加上
　　set CATALINA_OPTS="-Djava.library.path=../../APR/lib"
因为我把这个DLL放在与Tomcat目录同级的APR/lib目录下，所以采用了相对路径。或者把dll加到你的系统变量PATH里之类的，最简单的方法应当就是把tcnative-1.dll文件放在Tomcat的bin目录下：），或者直接这里C:\WINDOWS\system32

这样设置后，启动可以看到信息如下：
[org.apache.coyote.http11.Http11AprProtocol]-[INFO] Initializing Coyote HTTP/1.1 on http-9091
在停止时发现出现如下信息
[org.apache.coyote.http11.Http11AprProtocol]-[INFO] Pausing Coyote HTTP/1.1 on http-9091
......
[org.apache.coyote.http11.Http11AprProtocol]-[INFO] Stopping Coyote HTTP/1.1 on http-9091

这样就配置成功了。性能方面目前没有做详细的测试。
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相关的文档参见
http://tomcat.apache.org/tomcat-5.5-doc/apr.html

相关的性能测试结果参见
http://www.javaworld.com.tw/jute/post/view?bid=9&id=139958&sty=3&age=0