How can I replay Apache access logs back at my servers to do real world load testing?

Question

I looked at http://serverfault.com/questions/2107/tools-for-load-testing-http-servers but I couldn't see how to replay my own existing logs in any of those tools. I have a bug that only occurs under certain load operations which my existing JMeter and AB testing stuff can't reproduce.

I want to simply give the tool access_logs and have it play them back, either faster or at the same speed.

Answer 1

You can use Jmeter's Access Log Sampler component.

There's a short tutorial on it's use in this PDF.

Answer 2

Assuming all you've got in your access log are GET requests, and you don't mind the requests bunching up at the limit of resolution of the timestamps in the logs, about 10 lines of $SCRIPTING_LANGUAGE should do the trick. POSTs, cookies, HTTP auth, and more subtle timing are a far more interesting exercise.

Answer 3

I would do something a little differently. I do understand your question, but if your looking at loading up your server you might want to look into the 'ab' tool. It comes with most installations of apache. Running:

ab -c 15 -n 1000 http://site.name/

Will perform 1000 requests doing 15 requests at a time. I know this isn't exactly what your looking for, and this will only query the one address you give it. If you need load this is a quick way and simple way to do it, and it will give you some potentially very useful statistics for debugging.