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<?xml version="1.0"?> | |
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<!DOCTYPE document | |
[ | |
<!ENTITY sect-num '16'> | |
]> | |
<document prev="remote-test.html" next="boss.html" id="$Id: best-practices.xml 1175606 2011-09-25 22:28:22Z sebb $"> | |
<properties> | |
<title>User's Manual: Best Practices</title> | |
</properties> | |
<body> | |
<section name="§-num;. Best Practices" anchor="best_practices"> | |
</section> | |
<section name="§-num;.1 Limit the Number of Threads" anchor="limit_threads"> | |
<p>Your hardware's capabilities will limit the number of threads you can effectively | |
run with JMeter. It will also depend on how fast your server is (a faster server | |
gives makes JMeter work harder since it returns request quicker). The more | |
JMeter works, the less accurate its timing information will be. The more work | |
JMeter does, the more each thread has to wait to get access to the CPU, the more | |
inflated the timing information gets. If you need large-scale load testing, consider | |
running multiple non-GUI JMeter instances on multiple machines.</p> | |
</section> | |
<section name="§-num;.2 Where to Put the Cookie Manager" anchor="put_cookie_manager"> | |
<p>See <a href="build-web-test-plan.html#adding_cookie_support">Building a Web Test</a> | |
for information.</p> | |
</section> | |
<section name="§-num;.3 Where to Put the Authorization Manager" anchor="put_auth_manager"> | |
<p>See <a href="build-adv-web-test-plan.html#header_manager">Building an Advanced | |
Web Test</a> for information.</p> | |
</section> | |
<section name="§-num;.4 Using the Proxy Server" anchor="proxy_server"> | |
<p>Refer to <complink name="HTTP Proxy Server"/> for details on setting up the proxy | |
server. The most important thing to do is filter out all requests you aren't | |
interested in. For instance, there's no point in recording image requests (JMeter can | |
be instructed to download all images on a page - see <complink name="HTTP Request"/>). | |
These will just clutter your test plan. Most likely, there is an extension all your files | |
share, such as .jsp, .asp, .php, .html or the like. These you should "include" by | |
entering ".*\.jsp" as an "Include Pattern". </p> | |
<p>Alternatively, you can exclude images by entering ".*\.gif" as an "Exclude Pattern". | |
Depending on your application, this may or may not be a better way to go. You may | |
also have to exclude stylesheets, javascript files, and other included files. Test | |
out your settings to verify you are recording what you want, and then erase and start | |
fresh.</p> | |
<!--TODO: most uses for include/exclude are now | |
covered by the Grouping features. include/exclude may still be useful to filter hosts out, so | |
that regular browsing with the proxy enabled and the browser configured won't fill your test | |
plan with crap. Think about other uses. --> | |
<p>The Proxy Server expects to find a ThreadGroup element with a Recording Controller | |
under it where it will record HTTP Requests to. This conveniently packages all your samples under one | |
controller, which can be given a name that describes the test case.</p><!--TODO: is this best practice? I don't think so!--> | |
<p>Now, go through the steps of a Test Case. If you have no pre-defined test cases, use | |
JMeter to record your actions to define your test cases. Once you have finished a | |
definite series of steps, save the entire test case in an appropriately named file. Then, wipe | |
clean and start a new test case. By doing this, you can quickly record a large number of | |
test case "rough drafts".</p><!--TODO: no need to wipe out now - you can create a new controller and | |
resume recording into it--> | |
<p>One of the most useful features of the Proxy Server is that you can abstract out | |
certain common elements from the recorded samples. By defining some | |
<a href="functions.html">user-defined variables</a> at the Test Plan level or in | |
<complink name="User Defined Variables"/> elements, you can have JMeter automatically | |
replace values in you recorded samples. For instance, if you are testing an app on | |
server "xxx.example.com", then you can define a variable called "server" with the value of | |
"xxx.example.com", and anyplace that value is found in your recorded samples will be replaced | |
with "${server}". | |
<note>Please note that matching is case-sensitive.</note> | |
</p> | |
<p> | |
If JMeter does not record any samples, check that the brower really is using the proxy. | |
If the browser works OK even if JMeter is not running, then the browser cannot be using the proxy. | |
Some browsers ignore proxy settings for localhost or 127.0.0.1; try using the local hostname or IP instead. | |
</p> | |
<p> | |
The error "unknown_ca" probably means that you are trying to record HTTPS, and the browser has not accepted the | |
JMeter Proxy server certificate. | |
</p> | |
<!--TODO: Describe how to use this to record against one server[name] | |
and run against another. Actually, this particular example may be beter for the HTTP Request Defaults... | |
a good similar example for the variables is http vs. https.--> | |
<!--SUMMARY of all TODO's above: we need some actual usage to identify best practices | |
with this new features.--> | |
</section> | |
<section name="§-num;.5 User variables" anchor="user_variables"> | |
<p> | |
Some test plans need to use different values for different users/threads. | |
For example, you might want to test a sequence that requires a unique login for each user. | |
This is easy to achieve with the facilities provided by JMeter. | |
</p> | |
<p>For example:</p> | |
<ul> | |
<li>Create a text file containing the user names and passwords, separated by commas. | |
Put this in the same directory as your test plan. | |
</li> | |
<li> | |
Add a CSV DataSet configuration element to the test plan. | |
Name the variables USER and PASS. | |
</li> | |
<li> | |
Replace the login name with ${USER} and the password with ${PASS} on the appropriate | |
samplers | |
</li> | |
</ul> | |
<p>The CSV Data Set element will read a new line for each thread. | |
</p> | |
</section> | |
<section name="§-num;.6 Reducing resource requirements" anchor="lean_mean"> | |
<p> | |
Some suggestions on reducing resource usage. | |
</p> | |
<ul> | |
<li>Use non-GUI mode: jmeter -n -t test.jmx -l test.jtl</li> | |
<li>Use as few Listeners as possible; if using the -l flag as above they can all be deleted or disabled.</li> | |
<li>Rather than using lots of similar samplers, | |
use the same sampler in a loop, and use variables (CSV Data Set) to vary the sample. | |
Or perhaps use the Access Log Sampler. | |
[The Include Controller does not help here, as it adds all the test elements in the file to the test plan.] | |
</li> | |
<li>Don't use functional mode</li> | |
<li>Use CSV output rather than XML</li> | |
<li>Only save the data that you need</li> | |
<li>Use as few Assertions as possible</li> | |
</ul> | |
<p> | |
If your test needs large amounts of data - particularly if it needs to be randomised - create the test data in a file | |
that can be read with CSV Dataset. This avoids wasting resources at run-time. | |
</p> | |
</section> | |
<section name="§-num;.7 BeanShell server" anchor="beanshell_server"> | |
<p> | |
The BeanShell interpreter has a very useful feature - it can act as a server, | |
which is accessible by telnet or http. | |
</p> | |
<note> | |
There is no security. Anyone who can connect to the port can issue any BeanShell commands. | |
These can provide unrestricted access to the JMeter application and the host. | |
<b>Do not enable the server unless the ports are protected against access, e.g. by a firewall.</b> | |
</note> | |
<p> | |
If you do wish to use the server, define the following in jmeter.properties: | |
</p> | |
<pre> | |
beanshell.server.port=9000 | |
beanshell.server.file=../extras/startup.bsh | |
</pre> | |
<p> | |
In the above example, the server will be started, and will listen on ports 9000 and 9001. | |
Port 9000 will be used for http access. Port 9001 will be used for telnet access. | |
The startup.bsh file will be processed by the server, and can be used to define various functions and set up variables. | |
The startup file defines methods for setting and printing JMeter and system properties. | |
This is what you should see in the JMeter console: | |
</p> | |
<pre> | |
Startup script running | |
Startup script completed | |
Httpd started on port: 9000 | |
Sessiond started on port: 9001 | |
</pre> | |
<p> | |
As a practical example, assume you have a long-running JMeter test running in non-GUI mode, | |
and you want to vary the throughput at various times during the test. | |
The test-plan includes a Constant Throughput Timer which is defined in terms of a property, | |
e.g. ${__P(throughput)}. | |
The following BeanShell commands could be used to change the test: | |
</p> | |
<pre> | |
printprop("throughput"); | |
curr=Integer.decode(args[0]); // Start value | |
inc=Integer.decode(args[1]); // Increment | |
end=Integer.decode(args[2]); // Final value | |
secs=Integer.decode(args[3]); // Wait between changes | |
while(curr <= end){ | |
setprop("throughput",curr.toString()); // Needs to be a string here | |
Thread.sleep(secs*1000); | |
curr += inc; | |
} | |
printprop("throughput"); | |
</pre> | |
<p>The script can be stored in a file (throughput.bsh, say), and sent to the server using bshclient.jar. | |
For example: | |
</p> | |
<pre> | |
java -jar ../lib/bshclient.jar localhost 9000 throughput.bsh 70 5 100 60 | |
</pre> | |
</section> | |
<section name="§-num;.8 BeanShell scripting" anchor="bsh_scripting"> | |
<subsection name="§-num;.8.1 Overview" anchor="bsh_overview"> | |
<p> | |
Each BeanShell test element has its own copy of the interpreter (for each thread). | |
If the test element is repeatedly called, e.g. within a loop, then the interpreter is retained | |
between invocations unless the "Reset bsh.Interpreter before each call" option is selected. | |
</p> | |
<p> | |
Some long-running tests may cause the interpreter to use lots of memory; if this is the case try using the reset option. | |
</p> | |
<p> | |
You can test BeanShell scripts outside JMeter by using the command-line interpreter: | |
<pre> | |
$ java -cp bsh-xxx.jar[;other jars as needed] bsh.Interperter file.bsh [parameters] | |
or | |
$ java -cp bsh-xxx.jar bsh.Interperter | |
bsh% source("file.bsh"); | |
bsh% exit(); // or use EOF key (e.g. ^Z or ^D) | |
</pre> | |
</p> | |
</subsection> | |
<subsection name="§-num;.8.2 Sharing Variables" anchor="bsh_variables"> | |
<p> | |
Variables can be defined in startup (initialisation) scripts. | |
These will be retained across invocations of the test element, unless the reset option is used.\ | |
</p> | |
<p> | |
Scripts can also access JMeter variables using the get() and put() methods of the "vars" variable, | |
for example: <code>vars.get("HOST"); vars.put("MSG","Successful");</code>. | |
The get() and put() methods only support variables with String values, | |
but there are also getObject() and putObject() methods which can be used for arbitrary objects. | |
JMeter variables are local to a thread, but can be used by all test elements (not just Beanshell). | |
</p> | |
<p> | |
If you need to share variables between threads, then JMeter properties can be used: | |
<pre> | |
import org.apache.jmeter.util.JMeterUtils; | |
String value=JMeterUtils.getPropDefault("name",""); | |
JMeterUtils.setProperty("name", "value"); | |
</pre> | |
The sample .bshrc files contain sample definitions of getprop() and setprop() methods. | |
</p> | |
<p> | |
Another possible method of sharing variables is to use the "bsh.shared" shared namespace. | |
For example: | |
<pre> | |
if (bsh.shared.myObj == void){ | |
// not yet defined, so create it: | |
myObj=new AnyObject(); | |
} | |
bsh.shared.myObj.process(); | |
</pre> | |
Rather than creating the object in the test element, it can be created in the startup file | |
defined by the JMeter property "beanshell.init.file". This is only processed once. | |
</p> | |
</subsection> | |
</section> | |
<section name="§-num;.9 Developing script functions in BeanShell, Javascript or Jexl etc." anchor="developing_scripts"> | |
<p> | |
It's quite hard to write and test scripts as functions. | |
However, JMeter has the BSF (and BeanShell) samplers which can be used instead. | |
</p> | |
<p> | |
Create a simple Test Plan containing the BSF Sampler and Tree View Listener. | |
Code the script in the sampler script pane, and test it by running the test. | |
If there are any errors, these will show up in the Tree View. | |
Also the result of running the script will show up as the response. | |
</p> | |
<p> | |
Once the script is working properly, it can be stored as a variable on the Test Plan. | |
The script variable can then be used to create the function call. | |
For example, suppose a BeanShell script is stored in the variable RANDOM_NAME. | |
The function call can then be coded as <code>${__BeanShell(${RANDOM_NAME})}</code>. | |
There is no need to escape any commas in the script, | |
because the function call is parsed before the variable's value is interpolated. | |
</p> | |
</section> | |
<section name="§-num;.10 Parameterising tests" anchor="parameterising_tests"> | |
<p> | |
Often it is useful to be able to re-run the same test with different settings. | |
For example, changing the number of threads or loops, or changing a hostname. | |
</p> | |
<p> | |
One way to do this is to define a set of variables on the Test Plan, and then use those variables in the test elements. | |
For example, one could define the variable LOOPS=10, and refer to that in the Thread Group as ${LOOPS}. | |
To run the test with 20 loops, just change the value of the LOOPS variable on the Test Plan. | |
</p> | |
<p> | |
This quickly becomes tedious if you want to run lots of tests in non-GUI mode. | |
One solution to this is to define the Test Plan variable in terms of a property, | |
for example <code>LOOPS=${__P(loops,10))}</code>. | |
This uses the value of the property "loops", defaulting to 10 if the property is not found. | |
The "loops" property can then be defined on the JMeter command-line: | |
<code>jmeter ... -Jloops=12 ...</code>. | |
If there are a lot of properties that need to be changed together, | |
then one way to achieve this is to use a set of property files. | |
The appropriate property file can be passed in to JMeter using the -q command-line option. | |
</p> | |
</section> | |
</body> | |
</document> |