Random selection from CSV file in Jmeter

Question

I have a very large CSV file (8000+ items) of URLs that I'm reading with a CSV Data Set Config element. It is populating the path of an HTTP Request sampler and iterating through with a while controller.

This is fine except what I want is have each user (thread) to pick a random URL from the CSV URL list. What I don't want is each thread using CSV items sequentially.

I was able to achieve this with a Random Order Controller with multiple HTTP Request samplers , however 8000+ HTTP Samplers really bogged down jmeter to an unusable state. So this is why I put the HTTP Sampler URLs in the CSV file. It doesn't appear that I can use the Random Order Controller with the CSV file data however. So how can I achieve random CSV data item selection per thread?

Answer 1

There is another way to achieve this:

• create a separate thread group
• depending on what you want to achieve:
  • add a (random) loop count -> this will set a start offset for the thread group that does the work
  • add a loop count or forever and a timer and let it loop while the other thread group is running. This thread group will read a 'pseudo' random line

It's not really random, the file is still read sequentially, but your work thread makes jumps in the file. It worked for me ;-)

Answer 2

There's no random selection function when reading csv data. The reason is you would need to read the whole file into memory first to do this and that's a bad idea with a load test tool (any load test tool).

Other commercial tools solve this problem by automatically re-processing the data. In JMeter you can achieve the same manually by simply sorting the data using an arbitrary field. If you sort by, say Surname, then the result is effectively random distribution.

Note. If you ensure the default All Threads is set for the CSV Data Set Config then the data will be unique in the scope of the JMeter process.