How to do load testing using jmeter and visualVM?
I want to do load testing for 10 million users for my site. The site is a Java based web-app. My approach is to create a Jmeter test plan for all the links and then take a report for the 10 million users. Then use jvisualVM to do profiling and check if there are any bottlenecks.
Is there any better way to do this? Is there any existing demo for doing this? I am doing this for the first time, so any assistance will be very helpful.
Answer
You are on the correct path, but your load limit is of with a high factor.
Why I'm saying this is cause your site probably will need more machine to handle 10Milj Concurrent users. A process alone would probably struggle to handle concurrent 32K TCP-streams. Also do some math of the bandwidth it would take to actually handle 10Milj users.
Now I do not know what kind of service you thinking of providing on your site, but when thinking of that JVisualVM slows down processing by a factor 10 (or more for method tracing), you would not actually measure the "real world" if you got JMeter and JVisualVM to work at the same time.
JVisualVM is more useful when you run on lower loads.
To create a good measurement first make sure your have a good baseline. Make a test with 10 concurrent users, connect up JVisuamVM and let it run for a while, not down all interesting values.
After you have your baseline, then you can start adding more load. Add 10times the load (ea: 100 users), look at the changes in JVisualVM. Continue this until it becomes obvious that JVisualVM slows you down, for every time to add extra load, make sure you have written down the numbers your are interested in. Plot down the numbers in a graph.
Now... Interpolate the graph (by hand) for the number of users you want. This works for memory usage, disc access etc, but not for used CPU time, cause JVisualVM will eat CPU and give you invalid numbers on that (especially if you have method tracing turned on).
If you really want to go as high as 10Milj users, I would not trust JMeter either, I would write a little test program of my own that performs the test you want. This would be okey, since the the setting up the site to handle 10Milj will also take time, so spending a little extra time of the test tools are not a waste.