Comments on: Using Tsung for Load Testing Rails or Web Apps http://austinmills.name/?p=40 Austin Mills: Code, Methodologies, Games, etc. Tue, 07 Sep 2010 12:20:50 +0000 http://wordpress.org/?v=2.6.2 By: Austin Mills http://austinmills.name/?p=40#comment-53695 Austin Mills Thu, 20 Aug 2009 19:15:11 +0000 http://austinmills.name/?p=40#comment-53695 Ben: Great, thanks for the update! Ben:

Great, thanks for the update!

]]> By: Ben http://austinmills.name/?p=40#comment-53693 Ben Thu, 20 Aug 2009 18:18:49 +0000 http://austinmills.name/?p=40#comment-53693 Great writeup, thank you. Tsung now has Ubuntu packages, so you don't need to compile. You can grab the latest deb at http://tsung.erlang-projects.org/dist/ubuntu/ Then just sudo dpkg -i on it. Great writeup, thank you.
Tsung now has Ubuntu packages, so you don’t need to compile. You can grab the latest deb at http://tsung.erlang-projects.org/dist/ubuntu/

Then just sudo dpkg -i on it.

]]> By: Austin Mills http://austinmills.name/?p=40#comment-38329 Austin Mills Mon, 12 Jan 2009 21:42:05 +0000 http://austinmills.name/?p=40#comment-38329 Chris, It depends on what your setup is with EC2. If you only have a single EC2 server, you just point Tsung to the external IP of that instance. If you have a loadbalancer and want to test the whole cluster, then you could point at the loadbalancer. EC2 by itself doesn't provide load-balancing (until later this year, but there are open-source projects for this), so you'll be using something external anyway, or running something like Pound/etc. on one of your instances. In our case, instead of going through the loadbalancer like the one that we have set up for our production cluster, I went directly to a single EC2 instance. For us it's reasonable to say that the performance of our system scales linearly (within certain bounds), so I can take the results from load-testing a single instance and feel pretty good that our N-instance cluster will provide N times that performance (up to a certain point, at least). YMMV, based on the details of your setup, but you should definitely start with testing a single instance before looking at the performance of your whole system, so you have a context for the results. Then if the cluster results aren't linearly improving over the single-node results, you have some things to look at. :) Chris,

It depends on what your setup is with EC2. If you only have a single EC2 server, you just point Tsung to the external IP of that instance. If you have a loadbalancer and want to test the whole cluster, then you could point at the loadbalancer. EC2 by itself doesn’t provide load-balancing (until later this year, but there are open-source projects for this), so you’ll be using something external anyway, or running something like Pound/etc. on one of your instances.

In our case, instead of going through the loadbalancer like the one that we have set up for our production cluster, I went directly to a single EC2 instance. For us it’s reasonable to say that the performance of our system scales linearly (within certain bounds), so I can take the results from load-testing a single instance and feel pretty good that our N-instance cluster will provide N times that performance (up to a certain point, at least).

YMMV, based on the details of your setup, but you should definitely start with testing a single instance before looking at the performance of your whole system, so you have a context for the results. Then if the cluster results aren’t linearly improving over the single-node results, you have some things to look at. :)

]]> By: Chris http://austinmills.name/?p=40#comment-38325 Chris Mon, 12 Jan 2009 20:25:02 +0000 http://austinmills.name/?p=40#comment-38325 Silly question maybe, but how does Tsung work with the cloud of servers EC2 gives you? How exactly does the load get spread across all of them and your results collated? Silly question maybe, but how does Tsung work with the cloud of servers EC2 gives you? How exactly does the load get spread across all of them and your results collated?

]]> By: Dmitry http://austinmills.name/?p=40#comment-33773 Dmitry Thu, 23 Oct 2008 21:46:16 +0000 http://austinmills.name/?p=40#comment-33773 Yeah I figured the request logging would be on the server side, I'll give it a shot to try everything at command line. Thanks agian. Dmitry Yeah I figured the request logging would be on the server side, I’ll give it a shot to try everything at command line.

Thanks agian.
Dmitry

]]> By: Austin Mills http://austinmills.name/?p=40#comment-33772 Austin Mills Thu, 23 Oct 2008 21:35:24 +0000 http://austinmills.name/?p=40#comment-33772 I'm not familiar with Sing-Tsung -- looks interesting, but it might be introducing a layer of abstraction that's making it difficult to troubleshoot. It might be worth trying it from the command line and seeing if there's a difference. As for a community, there's a mailing list here which gets a decent amount of traffic, that's probably the best place to look or ask: https://lists.process-one.net/mailman/listinfo/tsung-users And sorry for not being more clear, but when I referred to request logging, I meant logging on the app server side (that is, not in Tsung), which almost all servers support, but the method of turning it on would be very server-dependent. I’m not familiar with Sing-Tsung — looks interesting, but it might be introducing a layer of abstraction that’s making it difficult to troubleshoot. It might be worth trying it from the command line and seeing if there’s a difference.

As for a community, there’s a mailing list here which gets a decent amount of traffic, that’s probably the best place to look or ask: https://lists.process-one.net/mailman/listinfo/tsung-users

And sorry for not being more clear, but when I referred to request logging, I meant logging on the app server side (that is, not in Tsung), which almost all servers support, but the method of turning it on would be very server-dependent.

]]> By: Dmitry http://austinmills.name/?p=40#comment-33771 Dmitry Thu, 23 Oct 2008 21:14:27 +0000 http://austinmills.name/?p=40#comment-33771 BTW sorry, but where do I turn on request logging? ~Dmitry BTW sorry, but where do I turn on request logging?

~Dmitry

]]> By: Dmitry http://austinmills.name/?p=40#comment-33770 Dmitry Thu, 23 Oct 2008 21:11:06 +0000 http://austinmills.name/?p=40#comment-33770 Also I'm using a GUI plug-in for tsung on called Sing-Tsung and it's making things quite difficult on me :) My Record session xml reflects the correct steps but they're not show correctly on my sing-tsung GUI it's weird and I can't figure out what's making it do that. Wheh, is there like a tsung community where people help? I've went onto the process-one forum but not much help on there. :) Gald I found you. Thanks a million ~Dmitry Also I’m using a GUI plug-in for tsung on called Sing-Tsung and it’s making things quite difficult on me :) My Record session xml reflects the correct steps but they’re not show correctly on my sing-tsung GUI it’s weird and I can’t figure out what’s making it do that. Wheh, is there like a tsung community where people help? I’ve went onto the process-one forum but not much help on there. :) Gald I found you.

Thanks a million
~Dmitry

]]> By: Dmitry http://austinmills.name/?p=40#comment-33769 Dmitry Thu, 23 Oct 2008 21:00:11 +0000 http://austinmills.name/?p=40#comment-33769 Awesome, thanks Austin. ~Dmitry Awesome, thanks Austin.

~Dmitry

]]> By: Austin Mills http://austinmills.name/?p=40#comment-33768 Austin Mills Thu, 23 Oct 2008 20:53:19 +0000 http://austinmills.name/?p=40#comment-33768 Dmitry: Ideally, the web requests from Tsung should be very similar to the web requests made by a user using your web app. I would recommend a couple of things: 1. Read through your session file (if you used the recorder, it's the output from the recorder). That will give you a step-by-step view of what Tsung is doing on a per-session basis and let you see if perhaps a step is being missed. 2. Set up Tsung so that it only runs a single session, using 1 client (which can be done easily by setting the interarrival higher than the duration in the 'load' section of the XML) and look at the logs on your webserver. This will let you trace through on the server side a single session (I usually turn on request logging so I can see each request as it happens) and can help verify that Tsung is doing what you expect it to. Hope that helps, --Austin Dmitry: Ideally, the web requests from Tsung should be very similar to the web requests made by a user using your web app. I would recommend a couple of things:
1. Read through your session file (if you used the recorder, it’s the output from the recorder). That will give you a step-by-step view of what Tsung is doing on a per-session basis and let you see if perhaps a step is being missed.
2. Set up Tsung so that it only runs a single session, using 1 client (which can be done easily by setting the interarrival higher than the duration in the ‘load’ section of the XML) and look at the logs on your webserver. This will let you trace through on the server side a single session (I usually turn on request logging so I can see each request as it happens) and can help verify that Tsung is doing what you expect it to.

Hope that helps,
–Austin

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