Getting started with Gatling for stress test

I was looking for a stress tool to test a java product via its HTTP API.
Gatling was in my “to try list” for a couple of reasons:

I gave it a try and my first impressions were very good.
The wiki has a very good “getting started” and “first steps” sections with useful examples.
I propose here to show an alternate set of “first steps” by stress-testing Jenkins.

Here are my steps (on a Mac Book Pro with os x 10.8.3)

1) installation and configuration of jenkins

I discovered there is a one click install of Jenkins for MacOsX.
http://jenkins-ci.org/content/thank-you-downloading-os-x-installer
Jenkins is automatically launched and ready to be used.
Server can be accessed over HTTP on: http://localhost:8080/
I created a fake job that does nothing and launched it a couple of time to have some history:

01_job_jenkins

2) installation of Gatling

I chose to download the 1.5.1 instead of the 2.0 as this last one is still under development and because 1.5.1 seems to have the feature I need.
I followed the “getting started” wiki page
Basically the installation and configuration was, here again, very quick:

  • unzip
  • launch 3 shell command :

    sudo sysctl -w kern.maxfilesperproc=200000
    sudo sysctl -w kern.maxfiles=200000
    sudo sysctl -w net.inet.ip.portrange.first=1024

and that’s it!

3) preparation of the simulation

For our test of jenkins, we will use the recorder to write the simulation script.
The recorder will allow us to create a script that mimick what users could do on Jenkins.
For this simple example, we will just click on the job, click on a build and click on “console output” for this build.

First, we set-up Gatling’s recorder:

02_recorder

Now that Gatling recorder is ready :

This creates a scala script in /path/to/gatling/user-files/simulations/Jenkins
You can take a look a the generated code (I added some comments in the file)

4) stress testing jenkins

If we launch the script as it, we will simulate the connection of a single user.
The reports gives a global view of the result of the test with the stats for the 22 requests performed.

03_result_1_user

To see what happens when 500 users connect simultaneously on my server, I just have to change the last part of the script to:

setUp(scn.users(500).protocolConfig(httpConf))

The result shows that half of the request1 performed failed (260 out of 240).

04_result_500_users

Failures are caused because Gatling will consider a request times out after 60 seconds.
Note that this timeout is defined in path/to/gatling/conf/gatling/conf

To be a little more realistic, we can simulate the fact that all the users are connecting gradually during 1 minutes (the whole 100 people of the R&D are checking the console output of the main job from 8h00 to 8h01 in the morning for example !). This can be scripted like that:

setUp(scn.users(500).ramp(60).protocolConfig(httpConf))

In that case, only 20 requests failed and other parts of the reports are interesting to look at.

  • Number of active active sessions:

05_number_of_sessions

=> we can see the growth during 1 minute and gradual shutdown

  • Number of requests per seconds

06_number_requests_per_sec

=> we can see that the 20 requests that fails are in the middle of the simulation when we reach the maximum number of active sessions

5) conclusion

This test is not very realistic for many reasons like:

  • there is no network involved as I do everything on my laptop
  • Jenkins user will retrieve bigger content on jenkins and have different behaviors

Yet, it is a good start and quite easy to perform.
Next steps would use more advanced features of Gatling.

Would you have any questions or experience to share, don’t hesitate to contact me.
If I have more to share on the topic, expect a follow-up.

8 thoughts on “Getting started with Gatling for stress test

  1. Hello,

    I am technically not that strong. Can you please help me with the installation process on MAC OSX 10.9.1? I have downloaded gatling 2.0.

    Thanks

    Ankit

  2. Hi
    I tried with feeders and it worked well. As a loadrunner script , how to replay the script by handling dynamic values just like Web Reg save param function does ??
    More that , do We need to learn scala to work with gatling ?

    • I don’t need to learn Scala to work with Gatling. The scenario configuration file is in Scala but it is using its own DSL and I don’t find it more complicated to update it than updating an XML or a JSON file.

      About Web Reg Save and loadrunner, I am not familiar with LoadRunner so I can not answer on this one.

  3. Hello,

    Thank you for the tutorial. Have you tried to use this through HTTPS traffic? I am attempting to do so but am getting this error
    “15:02:01.810 [WARN ] i.g.h.a.AsyncHandlerActor – Request ‘request_0’ failed: javax.net.ssl.SSLProtocolException: handshake alert: unrecognized_name”.

    I know it’s a certificat problem just not sure how to solve it.

    Do you have any ideas?

    Thank you!

Leave a Reply

Your email address will not be published. Required fields are marked *