Nginx+Tomcat在Windows下做负载均衡

一、 为什么需要对 Tomcat 服务器做负载均衡：

Tomcat 服务器作为一个 Web 服务器，其并发数在 300-500 之间，如果有超过 500 的并发数便会出现 Tomcat 不能响应新的请求的情况，严重影响网站的运行。另外，在访问量大的情况下， Tomcat 的线程数会不断增加。由于 Tomcat 自身对内存的占用有控制，当对内存的占用达到最大值时便会出现内存溢出，对网站的访问严重超时等现象，这时便需要重新启动 Tomcat 以释放占用的内存，这样做便会阻断网站运行。

所以对 Tomcat 做负载均衡便很有必要。目前可以和 Tomcat 做负载均衡的主流服务器是 Apache ，但是 Nginx 由于功能多、配置简单等优点逐渐成为很多负载均衡服务器的首选。 Nginx 的并发数可达到 50000 ，所以理论上可以和 Tomcat 以 1:100 的比例来配置，这样便可以很好的解决网站并发瓶颈问题。

二、 Nginx+Tomcat 在 Windows 下负载均衡配置方法：

Nginx+Tomcat 在 Windows 下做负载均衡相对在 Linux 下简单不少，因为不论是 Nginx 还是 Tomcat 只需要下载 Windows 下的安装包解压到某个目录下，然后就可以做配置了。

               我选择的 Nginx 是 nginx-0.8.49 这个版本， Tomcat 选择的是 apache-tomcat-6.0.26 。

         下面就是配置过程 :

         1. 将 nginx-0.8.49.rar 压缩包直接解压到某个目录下 ( 如 D:/ 负载均衡 /nginx) 。

       2. 将 apache-tomcat-6.0.26.rar 压缩包解压，因为是做负载均衡，所以至少要解压两个。 ( 如分别解压到 D:/ 负载均衡 /tomcat_1 和 D:/ 负载均衡 /tomcat_2 下面 ) 。

         3. 将要发布的项目发布到两个 Tomcat 根目录下的 webapps 下，保证两个 Tomcat 下面的项目名称相同。

         4. 修改其中一个 Tomcat 的配置文件，该配置文件位于 Tomcat 目录下的 /conf/ 下，文件名为 server.xml ，修改其中的 <Server port="8005" shutdown="SHUTDOWN"> 为 <Server port="8006" shutdown="SHUTDOWN"> ，修改其中的

<Connector port="8080" protocol="HTTP/1.1"

               connectionTimeout="20000"

               redirectPort="8443" />

为

<Connector port="8088" protocol="HTTP/1.1"

               connectionTimeout="20000"

               redirectPort="8443" />

修改后的文件如下：

<?xml version='1.0' encoding='utf-8'?>

<!--

  Licensed to the Apache Software Foundation (ASF) under one or more

  contributor license agreements.  See the NOTICE file distributed with

  this work for additional information regarding copyright ownership.

  The ASF licenses this file to You under the Apache License, Version 2.0

  (the "License"); you may not use this file except in compliance with

  the License.  You may obtain a copy of the License at

 

      http://www.apache.org/licenses/LICENSE-2.0

 

  Unless required by applicable law or agreed to in writing, software

  distributed under the License is distributed on an "AS IS" BASIS,

  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  See the License for the specific language governing permissions and

  limitations under the License.

-->

<!-- Note:  A "Server" is not itself a "Container", so you may not

     define subcomponents such as "Valves" at this level.

     Documentation at /docs/config/server.html

 -->

<Server port="8006" shutdown="SHUTDOWN">

 

  <!--APR library loader. Documentation at /docs/apr.html -->

  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />

  <!--Initialize Jasper prior to webapps are loaded. Documentation at /docs/jasper-howto.html -->

  <Listener className="org.apache.catalina.core.JasperListener" />

  <!-- Prevent memory leaks due to use of particular java/javax APIs-->

  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />

  <!-- JMX Support for the Tomcat server. Documentation at /docs/non-existent.html -->

  <Listener className="org.apache.catalina.mbeans.ServerLifecycleListener" />

  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />

 

  <!-- Global JNDI resources

       Documentation at /docs/jndi-resources-howto.html

  -->

  <GlobalNamingResources>

    <!-- Editable user database that can also be used by

         UserDatabaseRealm to authenticate users

    -->

    <Resource name="UserDatabase" auth="Container"

              type="org.apache.catalina.UserDatabase"

              description="User database that can be updated and saved"

              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"

              pathname="conf/tomcat-users.xml" />

  </GlobalNamingResources>

 

  <!-- A "Service" is a collection of one or more "Connectors" that share

       a single "Container" Note:  A "Service" is not itself a "Container",

       so you may not define subcomponents such as "Valves" at this level.

       Documentation at /docs/config/service.html

   -->

  <Service name="Catalina">

 

    <!--The connectors can use a shared executor, you can define one or more named thread pools-->

    <!--

    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-"

        maxThreads="150" minSpareThreads="4"/>

    -->

   

   

    <!-- A "Connector" represents an endpoint by which requests are received

         and responses are returned. Documentation at :

         Java HTTP Connector: /docs/config/http.html (blocking & non-blocking)

         Java AJP  Connector: /docs/config/ajp.html

         APR (HTTP/AJP) Connector: /docs/apr.html

         Define a non-SSL HTTP/1.1 Connector on port 8080

    -->

    <Connector port="8088" protocol="HTTP/1.1"

               connectionTimeout="20000"

               redirectPort="8443" />

    <!-- A "Connector" using the shared thread pool-->

    <!--

    <Connector executor="tomcatThreadPool"

               port="8080" protocol="HTTP/1.1"

               connectionTimeout="20000"

               redirectPort="8443" />

    -->          

    <!-- Define a SSL HTTP/1.1 Connector on port 8443

         This connector uses the JSSE configuration, when using APR, the

         connector should be using the OpenSSL style configuration

         described in the APR documentation -->

    <!--

    <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"

               maxThreads="150" scheme="https" secure="true"

               clientAuth="false" sslProtocol="TLS" />

    -->

 

    <!-- Define an AJP 1.3 Connector on port 8009 -->

    <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />

 

 

    <!-- An Engine represents the entry point (within Catalina) that processes

         every request.  The Engine implementation for Tomcat stand alone

         analyzes the HTTP headers included with the request, and passes them

         on to the appropriate Host (virtual host).

         Documentation at /docs/config/engine.html -->

 

    <!-- You should set jvmRoute to support load-balancing via AJP ie :

    <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">        

    -->

    <Engine name="Catalina" defaultHost="localhost">

 

      <!--For clustering, please take a look at documentation at:

          /docs/cluster-howto.html  (simple how to)

          /docs/config/cluster.html (reference documentation) -->

      <!--

      <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>

      -->       

 

      <!-- The request dumper valve dumps useful debugging information about

           the request and response data received and sent by Tomcat.

           Documentation at: /docs/config/valve.html -->

      <!--

      <Valve className="org.apache.catalina.valves.RequestDumperValve"/>

      -->

 

      <!-- This Realm uses the UserDatabase configured in the global JNDI

           resources under the key "UserDatabase".  Any edits

           that are performed against this UserDatabase are immediately

           available for use by the Realm.  -->

      <Realm className="org.apache.catalina.realm.UserDatabaseRealm"

             resourceName="UserDatabase"/>

 

      <!-- Define the default virtual host

           Note: XML Schema validation will not work with Xerces 2.2.

       -->

      <Host name="localhost"  appBase="webapps"

            unpackWARs="true" autoDeploy="true"

            xmlValidation="false" xmlNamespaceAware="false">

 

        <!-- SingleSignOn valve, share authentication between web applications

             Documentation at: /docs/config/valve.html -->

        <!--

        <Valve className="org.apache.catalina.authenticator.SingleSignOn" />

        -->

 

        <!-- Access log processes all example.

             Documentation at: /docs/config/valve.html -->

        <!--

        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" 

               prefix="localhost_access_log." suffix=".txt" pattern="common" resolveHosts="false"/>

        -->

      </Host>

    </Engine>

  </Service>

</Server>
 

5. 修改 Nginx 配置文件 nginx.conf ，该文件位于 Nginx 根目录下的 /conf 下面。

① 在 #gzip  on; 后面加入下面配置 :

upstream backend {

                   server localhost:8080;

                   server localhost:8088;

                   ip_hash;

         }

         其中 server localhost:8080 为第一个 Tomcat 的启动地址， server localhost:8088 为第二个 Tomcat 的启动地址， ip_hash 用于做 session 同步。

② 修改第一个 server{} 配置中的 listen  80; 改为新的端口号，因为我的本机 80 端口被 IIS 占用，因此将此处改为 listen 800; 。并将

location / {

            root   html;

            index  index.html index.htm;

        }

改为：

location / {

            root   html;

            index  index.html index.htm;

                            proxy_pass                  http://backend; 

           proxy_redirect              off;

           proxy_set_header            Host $host;

           proxy_set_header            X-Real-IP $remote_addr;

           proxy_set_header            X-Forwarded-For $proxy_add_x_forwarded_for;

           client_max_body_size        10m;

           client_body_buffer_size     128k;

           proxy_connect_timeout       90;

           proxy_send_timeout          90;

           proxy_read_timeout          90;

           proxy_buffer_size           4k;

           proxy_buffers               4 32k;

           proxy_busy_buffers_size     64k;

           proxy_temp_file_write_size  64k;

        }

其中 proxy_pass 参数和 upstream backend{} 对应。

         经过上面这些步骤，负载均衡配置就完成，下面前分别启动两台 tomcat ，然后双击 nginx 根目录下的 nginx.exe 文件或者用 start nginx 启动 nginx ，打开浏览器，输入地址 :http://localhost:800 便可看到下面画面 :

 

这说明已经成功跳转到 Tomcat 上面。下面以来电秀具体项目为例，输入地址： http://localhost:800/ldxwebpersonal/personal/index/index.action 便可看到下面来电秀首页画面 :

 

我们再看看两个 Tomcat 下面的日志显示 :

端口号为 8080 的显示 :

 

端口号为 8088 的显示 :

 

这说明两个 tomcat 已经实现负载均衡。

 

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