http://blog.csdn.net/dangerous_fire/article/details/6278435

gdufo 2012-06-02 08:55 发表评论

               开学以后，连续几天休息不好，总是犯困，也许这就是“春困秋乏”的症状吧。最近老师提出了负载均衡功能的需求，以减轻

网站的高峰期的服务器负担，现在学校的硬件设施还是蛮好的，有三，四台服务器可以提供使用，也很大程度的上方便了我做一些测试。

因为这个子项目，假期三个同学已经基本完工，所以我也只能出点微薄之力，把这个负载均衡搞定，具体用不用我不管，起码是我的一个

小功能。

 

               其实无论是分布式，数据缓存，还是负载均衡，无非就是改善网站的性能瓶颈，在网站源码不做优化的情况下，负载均衡可以说

是最直接的手段了。其实抛开这个名词，放开了说，就是希望用户能够分流，也就是说把所有用户的访问压力分散到多台服务器上，也可以

分散到多个tomcat里，如果一台服务器装多个tomcat，那么即使是负载均衡，性能也提高不了太多，不过可以提高稳定性，即容错性。

当其中一个主tomcat当掉，其他的tomcat也可以补上，因为tomcat之间实现了Session共享。待tomcat服务器修复后再次启动，就会

自动拷贝所有session数据，然后加入集群。这样就可以不间断的提供服务。如果要真正从本质上提升性能，必须要分布到多台服务器。

同样tomcat也可以做到。网上相关资料比较多，可以很方便的查到，但是质量不算高。我希望可以通过这篇随笔，系统的总结。本文的

例子是同一台服务器上运行两个tomcat，做两个tomcat之间的负载均衡。其实多台服务器各配置一个tomcat也可以，而且那样的话，可以使用

安装版的tomcat，而不用是下文中的免安装的tomcat，而且tomcat端口配置也就不用修改了。下文也会提到。

 

               tomcat的负载均衡需要apache服务器的加入来实现。在进行配置之前请先卸载调已安装的tomcat，然后检查apache的版本。

我这次配置使用的是apache-tomcat-6.0.18免安装版本，我亲自测试后推断安装版的tomcat在同一台机子上会不能启动两个以上，可能是

因为安装版的tomcat侵入了系统，导致即使在server.xml里修改了配置，还是会引起冲突。所以我使用tomcat免安装版。

apache使用的是apache_2.2.11-win32-x86-no_ssl.msi。如果版本低于2.2负载均衡的配置要有所不同，因为这个2.2.11和2.2.8版本

集成了jk2等负载均衡工具，所以配置要简单许多。别的版本我没有具体测试，有待考究。这两个软件可以到官方网站下载。

 

                 把Apache安装为运行在80端口的Windows服务，安装成功后在系统服务列表中可以看到Apache2.2服务。服务启动后在浏览器中

输入http://localhost进行测试，如果能看到一个"It works!"的页面就代表Apache已经正常工作了。把tomcat解压到任意目录，赋值一个另命名。

起名和路径对配置没有影响。但要保证端口不要冲突，如果装有Oracle或IIS的用户需要修改或关闭相关接口的服务。当然jdk的配置也是

必须的，这个不再过多叙述。

     

                 首先，在Apache安装目录下找到conf/httpd.conf文件,去掉以下文本前的注释符（#）以便让Apache在启动时自动加载代理（proxy）

模块。

 

    LoadModule proxy_module modules/mod_proxy.so
     LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
     LoadModule proxy_balancer_module modules/mod_proxy_balancer.so
     LoadModule proxy_connect_module modules/mod_proxy_connect.so
     LoadModule proxy_ftp_module modules/mod_proxy_ftp.so
     LoadModule proxy_http_module modules/mod_proxy_http.so

 

向下拉动文档找到<IfModule dir_module>节点，在DirectoryIndex index.html后加上index.jsp，这一步只是为了待会配置完tomcat后能看到小

猫首页，可以不做。继续下拉文档找到Include conf/extra/httpd-vhosts.conf，去掉前面的注释符。

 

然后打开conf/extra/httpd-vhosts.conf，配置虚拟站点，在最下面加上

 

 

然后回到httpd.conf，在文档最下面加上

 

 

ProxyRequests Off 是告诉Apache需要使用反向代理，ip地址和端口唯一确定了tomcat节点和配置的ajp接受端口。loadfactor是负载因子，

Apache会按负载因子的比例向后端tomcat节点转发请求，负载因子越大，对应的tomcat服务器就会处理越多的请求，如两个tomcat都

是1，Apache就按1：1的比例转发，如果是2和1就按2：1的比例转发。这样就可以使配置更灵活，例如可以给性能好的服务器增加处理

工作的比例，如果采取多台服务器，只需要修改ip地址和端口就可以了。route参数对应后续tomcat配置中的引擎路径（jvmRoute）。

                 如果仅仅为了配置一个可用的集群，Tomcat的配置将会非常简单。分别打开两个tomcat的server.xml配置文件，其中一台可以采用默认

的设置，只需要修改两个地方，而另一个要有较大改动以避免与前一台冲突。如果两台不在同一台服务器上运行，对于端口就不需做改动。首先是

配置关闭端口，找到<Server port="8005" shutdown="SHUTDOWN">，第一台不变，把第二台改为9005。

                下面配置Connector的端口，找到non-SSL HTTP/1.1 Connector，即tomcat单独工作时的默认Connector，保留第一台默认配置，在8080端

口侦听，而把第二台设置为在9080端口侦听。往下找到AJP 1.3 Connector，<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />，这是

tomcat接收从Apache过来的ajp连接请求时使用的端口，保留第一台默认设置，把第二台端口改为9009。第一台tomcat的server.xml中找到

<Engine name="Catalina" defaultHost="localhost">，去掉这段或改为注释，把上方紧挨的<Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">

注释符去掉，对于第二台，去掉注释符并把jvm1改为jvm2。

               向下找到<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>，去掉注释，这里的配置是为了可以在集群中的所有tomcat节点

间共享会话（Session）。如果仅仅为了获得一个可用的tomcat集群，Cluster只需要这么配置就可以了。

               只需要简单的几步就配置完成，然后可以测试一下是否配置成功。引用网上的一个测试方法，就是在webapps目录下新建test目录，在test目

录下新建test.jsp文件，代码我稍作改动如下：

 

 

在test目录下继续新建WEB-INF目录和web.xml，在<web-app>节点下加入<distributable />，这一步非常重要，是为了通知tomcat服务器，

当前应用需要在集群中的所有节点间实现Session共享。如果tomcat中的所有应用都需要Session共享，也可以把conf/context.xml中的

<Context>改为<Context distributable="true">，这样就不需对所有应用的web.xml再进行单独配置。测试代码完成！

 

先启动Apache服务，在先后启动两台tomcat，分别点startup.bat批处理。如果一切顺利的话，就会启动成功。再次访问http://localhost，

可以看到小猫页面。访问http://localhost/test/test.jsp。可以看到包括服务器地址，端口，session等信息在内的页面。

                然后你可以测试一下容错功能，关闭一个tomcat，看看服务是否正常，然后重启tomcat，关掉另一台tomcat，看看

是否也可以继续提供服务。当然你也可以配置多台tomcat，但是原理都一样。

 OK，讲到这里。

gdufo 2012-06-02 08:54 发表评论

• 1 Preface
• 2 Test plan
  • 2.1 Setup
  • 2.2 Test Scenario
• 3 Before we start
• 4 Configuring ZK
• 5 Preparing Testing Scripts
  • 5.1 Load CSV file as the variable of the user name and password
  • 5.2 Set account & password as variables
  • 5.3 Generate new desktop ID for redirecting to a new page
  • 5.4 Specify parameter
  • 5.5 Add the listeners for creating reports
• 6 Running the test
• 7 Trouble-shooting & Tips
• 8 Downloads
• 9 Comments

Preface

Dennis Chen has shared a small talk illustrating how you can execute a loading test with ZK applications using JMeter. Now, in this small talk we will take a real application as an example to demonstrate in detail how you can actually apply the ideas illustrated in Dennis’ article to perform a stress test.

Test plan

We will be using the "shopping cart" example from ZK Essentials as the template application to perform the stress test.

Setup

• ZK 5.0.11
• zk testing demo ( a demo based on the shopping cart sample)
• Jmeter 2.5.1

Test Scenario

1. User enters his user name and password for authentication
2. Login successfully to the shopping site, redirect to index.zul
3. User selects an item and drag to the shopping cart
4. User checks out

Since this is a stress test, we can apply 50, 100, 150,... concurrent users to perform the test scenario simultaneously. In our example we have created a max of 300 accounts, which allows you to perform the test with as many as 300 concurrent users.

Before we start

As mentioned above we will be using the "shopping cart" example from ZK Essentials as the template application. However there is only one set of login/password in the current shopping cart implementation which is not sufficient for multiple users. To support multiple users, we have modified the shopping cart example to generate multiple accounts, so that each user will be logged in using a different account. This is done as follows, and it will be triggered as you click "createUserBtn" in login.zul:

1. prepare a CSV file that includes a list of user names and passwords:

2. Add the following code to LoginViewCtrl.java

Configuring ZK

• Set IdGenerator for your ZK app

As illustrated in Dennis’ small talk, you need to define IdGenerator to fix the desktop IDs and component IDs so that we can record and play the testing script. The IdGenerator is implemented as follows:

• Define your IdGenerator in zk.xml

Then, define your IdGenerator in zk.xml, for example,

Preparing Testing Scripts

Now we are ready to record the scripts. We will be recording 6 HTTP requests as illustrated in the image below. What we need to do is to configure the parameters of these 6 requests based on the application that we wish to test.

Load CSV file as the variable of the user name and password

• Add a CSV Data Set Config

First we need to add a CSV Data Set Config here. The element will iterate the csv data set to simulate muti-users login into the application. Please specify a fully qualified name to the Filename field (ex: C:\mycsv\users.csv ), and specify the variable name to the Variable Names field for later use.

• Add BSF PostProcessor

Then we need to ask jmeter to generate the accounts and passwords automatically based on our CSV file. What we need to do is to add a BSF PostProcessor element, set the language to beanshell, and define:

var username = vars.get("username");

var password = vars.get("password");

vars.put("user","{\"value\":\""+username+"\",\"start\":2}");

vars.put("pwd","{\"value\":\""+password+"\",\"start\":2}");

This script will get the username and password variables generated by CSV Data Set Config element, and combine the result and some text as a parameter which will be used as user names and passwords later.

Set account & password as variables

With these settings ready, we can now set the parameter dtid as ${dtid} and use EL to replace a fixed account and password in the first ajax request (i.e. the login request). For example if we send zk/zk as user name and password, then we will be seeing

data_3: {"value":"zk","start":2} //for username

data_4: {"value":"zk","start":2} //for password

in the recorded jmeter’s request. Then, we use ${user} and ${pwd} to replace {"value":"zk","start":2} for handling the accounts and passwords dynamically.

Generate new desktop ID for redirecting to a new page

After an user logged into the system, he will be redirected to index.zul. Since the URL is changed, the desktop and it’s id will also be changed, we need to retrieve the desktop id again using ${__intSum(${dtid},1,dtid)}.

Specify parameter

The last 3 http requests are for adding products to the shopping cart, check out, and close the browser tab. What we need to do is just to modify their tdtid to ${__intSum(${dtid},1,dtid).

Add the listeners for creating reports

There are many different elements that allows you to generate different kinds of reports, such as Aggregate Report and Graph Results. You can add these listeners to Thread Group or HTTP request depending on the report you wish to generate.

Now we have completed all the settings and have saved these configurations as test.jmx.

Running the test

Now we are ready to start the application and to run the test.

1. Generate accounts

Start your web server, and access login.zul. Click createUserBtn for creating multiple accounts.



2. Run the testing script
1. Open jmeter’s menu, File > Open , and load test.jmx.
2. Specify your IP and port, for example we use localhost/8080 as ip and port number



3. In Thread Group ( the root element), set the number of concurrent users to test.



4. Perform Run > Start to run the test.

You can then observe the average response time, 90% line response time, median response time and other results by accessing the Aggregate Report .

Trouble-shooting & Tips

1. Tips: Performing repeating tests

If you have finished a round of test (for example 0~50) you should restart your server before performing another round of test. This is because after you finish a round of test, there will be an extra item listed in each user’s page because they all ordered an item. This extra item is displayed at the bottom of the page (see the image on the right). As there is a DOM change due to this extra item, components’ IDs and orders are also changed thus different from the script you recorded earlier. To solve this problem, just restart your server before performing another round of test.



2. Trouble-shooting: Erred response



If you encounter the Response data error shown as the image above, it is most likely that you did not implement IdGenerator correctly. Please refer to Configuring ZK section to implement UUID.

3. Trouble-shooting: Timeout error



Timeout errors occur when the desktop id in the Ajax request is no longer available at the server side. This normally happens when the URL is changed. If this happens, you need to retrieve desktop ID again. Please refer to Testing Scripts section to implement Desktop ID.

Timeout may also relate to the max allowed desktops. In ZK there is a setting called “max-desktops-per-session” which defines the max concurrent desktops for each session. The more browser tabs an user opens the more desktops will be saved on the session. If the number exceeds the max allowed desktops then some desktops will be dropped with the timeout error.

By default the number is 15 which means an user can open as many as 15 tabs in a same browser at the same time. If you have configured it to a smaller number for saving the memory, and in your use case the users will be opening up multiple tabs then you should double check whether this is the reason causing the timeout error. To change this setting, use:

1 2 3

<session-config>     <max-desktops-per-session>1</max-desktops-per-session> </session-config>

4. Tips: close browser tab for saving memory

ZK stores desktops in sessions, when user closes the browser tab ZK will send the rmDesktop command to remove the desktop. We can simulate this behavior to save memory when performing a stress test. This is done in the last http request defined in test.jmx. You can refer to the image below:

Downloads

users.csv - users.csv (Please place the csv file under C:/mycsv/)

zk testing demo – the modified shopping cart application used in this small talk

jmeter 2.5.1 – http://jmeter.apache.org/download_jmeter.cgi

test.jmx – test.jmx

gdufo 2012-05-31 23:35 发表评论

gdufo 2009-01-06 08:30 发表评论

gdufo 2008-07-02 20:17 发表评论

目录: E:\Tomcat5.5\conf\web.xml
<!-- listings Should directory listings be produced if there -->
<!-- is no welcome file in this directory? [false] -->
<!-- WARNING: Listings for directories with many -->
<!-- entries can be slow and may consume -->
<!-- significant proportions of server resources. -->
<!-- -->
.....
<servlet>
<servlet-name>default</servlet-name>
<servlet-class>
org.apache.catalina.servlets.DefaultServlet
</servlet-class>
<init-param>
<param-name>debug</param-name>
<param-value>0</param-value>
</init-param>
<init-param>
<param-name>listings</param-name>
<param-value>true</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
......
false --> true
这样就可以浏览了，不过整个Tomcat都是可以浏览，有点危险。
其他就按你自己的配:
目录:E:\Tomcat5.5\conf\Catalina\localhost\jspweb.xml
<?xml version='1.0' encoding='utf-8'?>
<Context docBase="/c:/jspweb/" path="/jspweb">
</Context>
因该和5.0一样了,不过你绝对是浪费5.5的安全特性.....

目录: E:\Tomcat5.5\conf\web.xml
<!-- listings Should directory listings be produced if there -->
<!-- is no welcome file in this directory? [false] -->
<!-- WARNING: Listings for directories with many -->
<!-- entries can be slow and may consume -->
<!-- significant proportions of server resources. -->
<!-- -->
.....
<servlet>
<servlet-name>default</servlet-name>
<servlet-class>
org.apache.catalina.servlets.DefaultServlet
</servlet-class>
<init-param>
<param-name>debug</param-name>
<param-value>0</param-value>
</init-param>
<init-param>
<param-name>listings</param-name>
<param-value>true</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
......
false --> true
这样就可以浏览了，不过整个Tomcat都是可以浏览，有点危险。
其他就按你自己的配:
目录:E:\Tomcat5.5\conf\Catalina\localhost\jspweb.xml
<?xml version='1.0' encoding='utf-8'?>
<Context docBase="/c:/jspweb/" path="/jspweb">
</Context>
因该和5.0一样了,不过你绝对是浪费5.5的安全特性.....

gdufo 2008-07-02 20:00 发表评论