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Simple Performancetesting with Grinder

Posted by ice09 on November 4, 2009

In the last post, I created a prototype with some technologies which were new to me, especially Gaelyk.

As it turned out, the prototype behaved quite differently in my local system and when deployed in the Google App Engine. What seems really strange to me is that even after all five number series had been cached, every 3-4th request took quite long, at least locally. In the deployed version, this seemed to be different and not too slow (even though I suppose a pure Java version would be significantly faster).

Now, how can I test without too much trouble if the deployed site is “just fast enough”?
Having looked around quite some time, Grinder looked most promising to me, with respect to easy of usage and features.


Download Grinder and Jython 2.2.1 – it must be this version, not the current 2.5.x – this just does not work.

Install Jython.

Create and – they can go in any directory, the most simple usage will be in the grinder/lib directory: (change directory accordingly):


# A simple example using the HTTP plugin that shows the retrieval of a
# single page via HTTP. The resulting page is written to a file.
# More complex HTTP scripts are best created with the TCPProxy.
import string
from net.grinder.script.Grinder import grinder
from net.grinder.script import Test
from net.grinder.plugin.http import HTTPRequest

test1 = Test(1, "Request resource")
request1 = test1.wrap(HTTPRequest())
log = grinder.logger.output

class TestRunner:
    def __call__(self):
        result = request1.GET("http://localhost:8080/data.groovy")
	if string.find(result.getText(), "counter") < 1:
        # result is a HTTPClient.HTTPResult. We get the message body
        # using the getText() method.


Now you can start the Grinder console with:
java -cp grinder.jar net.grinder.Console

Afterwards, start the Grinder agent with:
java -cp grinder.jar net.grinder.Console

Now, you must sync the data first, as shown in the screenshot. Afterwards, just start the tests.


According to the config, the agent runs indefinitely in 10 Threads. The site in the Jython script is called and in the resulting page, the expression counter is searched. If it is not present, the test fails. You can verify this by stopping the server, it will start increasing the failure counter immediately.

All in all, we have a very easy load test with very few lines of code.

As a result, the remote Google App Engine runs much more stable, so I just presume that the memcache implementation of the local Google App Engine server is not as good/stable as the remote one. But this is just a guess.

However, be careful with Gaelyk besides from using it for prototypes, because if the site is not called continuously, it kind of fells asleep really fast (some minutes) and needs its time for wakeup, which is quite annoying. I just don’t know what causes this, Gaelyk or the GAE.
You can verify this by just loading the Gaelyk home page. The first call often really feels kind of slow.


One Response to “Simple Performancetesting with Grinder”

  1. You can try the GrinderStone Eclipse plugin. It allows to debug and create Grinder scripts in a fast way. You can check it out from

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