Performance testing MongoDB

So, this morning I was hacking around in the mongo shell. I had come up with three different ways to aggregate the data I wanted, but wasn't sure about which one I should subsequently port to code to use within my application.

So how would I decide on which method to implement? Well, lets just choose the one that performs the best. Ok, how do I do that? Hmmm. I could download and install some of the tools out there, or I could just wrap the shell code in a function and add some timings. OR, I could use the same tool that I use to performance test everything else; JMeter. To me it was a no brainer.

So how do we do it?

There is a full tutorial here.

Simply put, you need to do the following:

1. Create a Sampler class. 
2. Create a BeanInfo class. 
3. Create a properties file. 
4. Bundle up into a jar and drop into the apache-jmeter-X.X\lib\ext folder 
5. Update search_paths=../lib/ext/mongodb.jar in jmeter.properties if you place the jar anywhere else. 

How I did it

I tend to have a scratch pad project set up in my IDE, so I decided just to go with that. Just to be on the safe side, I imported all the dependencies from:

• apache-jmeter-X.X\lib 
• apache-jmeter-X.X\lib\ext 
• apache-jmeter-X.X\lib\junit

I then created the two classes and the properties file.

	import java.util.ArrayList;
	import org.apache.jmeter.samplers.AbstractSampler;
	import org.apache.jmeter.samplers.Entry;
	import org.apache.jmeter.samplers.SampleResult;
	import org.apache.jmeter.testbeans.TestBean;
	import org.apache.jorphan.logging.LoggingManager;
	import org.apache.log.Logger;
	import com.mongodb.DB;
	import com.mongodb.Mongo;
	import com.mongodb.ServerAddress;
	public class Sampler
	extends AbstractSampler
	implements TestBean {
	private static final long serialVersionUID = -678108159079724396L;
	private static final Logger log = LoggingManager.getLoggerForClass();
	public final static String SCRIPT = "Sampler.script"; //$NON-NLS-1$
	private static int classCount = 0; // keep track of classes created
	public Sampler() {
	classCount++;
	trace("Sampler()");
	}
	public SampleResult sample(Entry e) {
	trace("sample()");
	SampleResult res = new SampleResult();
	String data = getScript(); // Sampler script
	String response = null;
	Mongo m = null;
	res.setSampleLabel(getTitle());
	res.sampleStart();
	try {
	ArrayList<ServerAddress> addrs = new ArrayList<ServerAddress>();
	addrs.add(new ServerAddress(YOUR_REPLICASET_BOX_1, YOUR_REPLICASET_PORT_1));
	addrs.add(new ServerAddress(YOUR_REPLICASET_BOX_2, YOUR_REPLICASET_PORT_1));
	m = new Mongo(addrs);
	DB db = m.getDB(YOUR_DB_NAME);
	boolean authenticated = db.authenticate(YOUR_DB_USERNAME, YOUR_DB_PASSWORD.toCharArray());
	db.eval(getScript());
	response = Thread.currentThread().getName();
	res.setSamplerData(data);
	res.setResponseData(response.getBytes());
	res.setDataType(SampleResult.TEXT);
	res.setResponseCodeOK();
	res.setResponseCode("200");
	res.setSuccessful(true);
	res.setResponseMessage("OK");// $NON-NLS-1$
	}
	catch (Exception ex) {
	log.debug("", ex);
	res.setResponseCode("500");// $NON-NLS-1$
	res.setSuccessful(false);
	res.setResponseMessage(ex.toString());
	}
	finally {
	res.sampleEnd();
	m.close();
	}
	return res;
	}
	private String getTitle() {
	return this.getName();
	}
	public String getScript() {
	return getPropertyAsString(SCRIPT);
	}
	public void setScript(String script) {
	setProperty(SCRIPT, script);
	}
	/*
	* Helper method
	*/
	private void trace(String s) {
	String tl = getTitle();
	String tn = Thread.currentThread().getName();
	String th = this.toString();
	log.debug(tn + " (" + classCount + ") " + tl + " " + s + " " + th);
	}
	}

view raw Sampler.java hosted with ❤ by GitHub

	import java.beans.PropertyDescriptor;
	import org.apache.jmeter.testbeans.BeanInfoSupport;
	import org.apache.jmeter.testbeans.gui.TextAreaEditor;
	public class SamplerBeanInfo extends BeanInfoSupport {
	public SamplerBeanInfo() {
	super(Sampler.class);
	createPropertyGroup("sampler", new String[]{"script"});
	PropertyDescriptor pd = property("script");
	pd.setValue(NOT_UNDEFINED, Boolean.FALSE);
	pd.setValue(DEFAULT, "");
	pd.setValue(NOT_EXPRESSION, Boolean.TRUE);
	pd.setPropertyEditorClass(TextAreaEditor.class);
	}
	}

view raw SamplerBeanInfo.java hosted with ❤ by GitHub

	displayName=MongoDB Script Sampler
	sampler.displayName=Script
	script.displayName=The script to run
	script.shortDescription=Add your mongo shell script as you would via the mongo shell.

view raw SamplerResources.properties hosted with ❤ by GitHub

I then exported the jar to apache-jmeter-X.X\lib\ext, and fired up jmeter.

Go through the normal steps to set the test plan up:

1. Right click Test Plan and add a Thread Group. 
2. Right click the Thread Group and add a Sampler, in this case a MongoDB Script Sampler. 
3. Add your script to the textarea; db.YOUR_COLLECTION_NAME.insert({"jan" : "thinks he is great"}) 
4. Run the test

Happy days.  You can then use JMeter as you would for any other sampler.


Future enhancements

This is just a hack that took me 37 minutes to get running, plus 24 minutes if you include this post. This can certainly be extended to allow you to enter the replicaset config details for instance and to pull the creation of the connection out so we're not initiating this each time run a test.