Measuring Web Application Performance (Stress-Testing) and Bandwidth Requirements [closed]

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I am in the process of measuring the bandwidth requirements and how a Web application behaves in terms of response time and memory requirements when the number of users is increased.

Is there a particular good tool that can help us here? I believe JMeter is the standard tool. But are there other tools considering that the site is IE only.

Your answer is extremely appreciated.

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Well, the question is how do you want to profile? Do you want to simulate real-world activity? Or do you just want to bombard the heck out of the site?

Load Testing Individual Pages

I don't think you can go wrong with using Apache Bench (ab). It's dirt simple to use, and can really stress your application. My typical usage is:

ab -c 10 -n 1000 http://www.example.com/path/to/page

The -c parameter is the number of simultaneous requests to issue. I would suggest starting low (like 5 to 10) and working your way up. Watch the output for failed requests and falling response rate. You're limited to about 1000 connections on most linux machines, so don't go too crazy.

The -n parameter is how many requests to issue. I would suggest doing at least 100 times the number of concurent requests to get a good average...

Another great use for apache bench is to benchmark individual database queries. Just create a simple script that runs the query, and load away. This can be a really good way to detect fast but expensive queries that will take your server down in production yet seem fine in testing.

Load Testing The Whole Application

I've had good luck with WebLoad. There's an Open Source version if you don't have a good budget that will get you started. But I'd suggest springing for the pro version. With it, you can setup a distributed test environment (as simple as installing the client on every machine in the office, as complex as spinning up a bunch of VMs for it).

The cool thing, is that you can program it in javascript. So you can tell it to take random click paths through the site with random delays. This should simulate a user far better than you could do manually. Then, once you have it setup, push the tests to the distributed engine and hit go.

It supports many different load profiles (stair-step where it adds load little by little for the duration of the test, etc). So you can simulate a slashdot-effect profile, normal day-to-day usage, etc.

The reports it generates are immensely useful. It shows you the slow urls, where the bottlenecks are, etc.

There are plenty of other test platforms and systems out there. This was just one that I found that I felt worked pretty well at the time (I did a comparison about 2 to 3 years ago). I am not affiliated with the company in any way.

Load Testing parts of the application

This is a really useful technique called profiling. The how to and tools are fairly language specific, so I won't go into too much detail here (since you don't have a language tag on your question). But the point is that once you find a slow page, you'll need to profile it to figure out what's slowing it down. Then fix the low hanging fruit (the parts that are the slowest). Then re-test to see if you made a difference or not...

Conclusion

Since it's almost impossible to simulate real-world load, this is really more of an art than a science. Have at it, and have fun. Don't take the results to seriously though, even with the best testing, you're likely to miss something... So I wouldn't take them as gospel and go telling the CEO that you tested that it's capable of 100k concurent users. Since when the day it crashes happens (and if you are lucky it will crash), he will blame you since you told him it would work...

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Just a thought, you say IE only so is it hosted on IIS? if so then you might want to look at Microsft's WCAT (Web Capacity Analysis Tool), more information is available here:

http://support.microsoft.com/kb/231282

Although it isn't open source but it is free - do you need the source.